Legumes&Nitrogen Fixation

One of the most significant contributions that legume cover crops make to the soil is the nitrogen (N) they contain. Legume cover crops fix atmospheric N in their plant tissues in a symbiotic or mutually beneficial relationship with rhizobium bacteria. In association with legume roots, the bacteria convert atmospheric N into a form that plants can use. As cover crop biomass decomposes, these nutrients are released for use by cash crops. Farmers should make an effort to understand this complex process because it will help them to select the proper legumes for their cropping plan, calculate when to incorporate cover crops and plant cash crops that follow, and plan fertilizer rates and schedules for those cash crops. Above all, they need to inoculate legume seed before planting with the appropriate Rhizobium species.

The N associated with cover crop biomass undergoes many processes before it is ready to be taken up for use by cash crops. The process begins with biomass N, which is the nitrogen contained in mature cover crops. From 75 to 90 percent of the nitrogen content in legume cover crops is contained in the above ground portions of the plant, with the remaining N in its roots and nodules (Shipley et al., 1992).

When legume or grass cover crops are killed and incorporated into the soil, living microorganisms in the soil go to work to decompose plant residues. The biomass nitrogen is mineralized and converted first to ammonium (NH4) and then to nitrate compounds (NO3) that plant roots can take up and use. The rate of this mineralization process depends largely on the chemical composition of the plant residues that are involved (Clement et al., 1995), and on climatic conditions.

Determining the ratio of carbon to nitrogen (C:N) in the cover crop biomass is the most common way to estimate how quickly biomass N will be mineralized and released for use by cash crops. As a general rule, cover crop residues with C:N ratios lower than 25:1 will release N quickly. In the southeastern U. S., legume cover crops, such as hairy vetch and crimson clover, killed immediately before corn planting generally have C:N ratios of 10:1 to 20:1 (Ranells and Wagger, 1997). Residues with C:N ratios greater than 25:1, such as cereal rye and wheat, decompose more slowly and their N is more slowly released.

A study conducted in 1989 reported that 75 to 80 percent of the biomass N produced by hairy vetch and crimson clover residues was released eight weeks after the cover crops were incorporated into the soil (Wagger, 1989a). This amounted to 71 to 85 pounds of N per acre. However, not all of the released N was taken up by the subsequent corn crop. The corn utilized approximately 50 percent of the N released by both residues. (This value may be con-sidered the N uptake efficiency of corn from legume residues. This value is similar to the N uptake efficiency of corn from inorganic fertilizer sources, such as ammonium nitrate.) The N not taken up by the following crops may still contribute to soil health. Living microbes in the soil may use the nitrogen to support population growth and microbial activity in the soil.

(Source – http://www.cefs.ncsu.edu/resources/organicproductionguide/covercropsfinaljan2009.pdf)

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Spectrum of the Pests on Cereal Crops and Influence of Soil Fertilisation

Different biotic factors such as predators, parasitoids and different pathogens affect the pests of cereals. Also affecting them are the abiotic factors temperature, rainfall, humidity, wind and sunshine (Sehgal 2006).

Climatically, the slowly rising temperatures are very important for the spectrum of pests. Winters are shorter, temperatures below freezing occur on average on fewer days than before and the soil is frozen to shallower depths. This results in pest species occurring at northern localities, whereas  before they had appeared only at lower latitudes (Gallo 2002).

Past research has shown that fertilisation of the soil affects a pest’s presence. Fertilisation had a positive effect on the crops, especially on their height and density, leading to a higher presence of pests. Stimulation of plant growth and development is the main goal of fertilisation. Regeneration of the plants is important if the pests damage the plants.

Organic fertilisation is very important because it suppresses the plant pathogens and also affects the frequency of pests (Sokolov 1991). Healthy vital plants are preferred by many pests on cereal species (Price 1991; Breton & Addicott 1992; Preszler & Price 1995).

The variety of a crop can also affect the occurrence of a pest. Ovipositonal behaviour, variability of eggs, growth and survival of the young larvae of the cereal leaf beetle were adversely affected by the trichome density on wheat leaves(Schillinger& Gallun 1968). Eggs per plant and larval survival decreased asthe length and density of trichomes increased (Hoxie et al. 1975).

Differences in the yields between the varieties and the year’s volume in the same level of the damage were detected. Later varieties were better able to compensate for the damage than earlier varieties in years with similar weather (Šedivý 1995).

Influence of a new farming system on pests and their natural enemies has began a few years ago (Khamraev 1990; Pfiffner 1990; Xie et al. 1995).

Material And Methods

Our research was conducted at Nitra-Dolná Malanta. The whole area (530 m2 ) used in the tree-year experiment (2004–2006) was split into 8 identical plots (each of 60 m2 ) separated by a 1 m belt where soil was superficially cultivated.

Pests were monitored on spring barley cvs. Jubilant (2004) and Annabell (2005, 2006), and on winter wheat cvs. Samanta (2004) and Solara (2005, 2006). At every sampling date 5 m2 of winter wheat and spring barley was swept using a standard sweeping net. Collecting began at the shooting phase, ended at wax ripeness of cereal crops and was done every 7–10 days, depending on the weather.

The insects collected from each crop were determined. Spiders were removed from samples, and aphids were excluded from the analysis at they were used in another study. We determined the influence of fertilisation and nutrition on the pests in the control variants(0) without fertilisation, and variants fertilised (F) with manure (40 t/ha) + fertilisers(winter wheat for 7 t yield: 70 kg N/ha, 30 kg P/ha, 0 kg K/ha; spring barley for 6 t yield: 30 kg N/ha, 30 kg P/ha, 0 kgK/ha).Climatic data were provided by the meteorological station nearthe Slovak University of Agriculture at Nitra, Slovak Republic. All results were evaluated with mathematical-statistic analysis Statgraphics.

Results and disscusion

Spring barley

In 2004, insects were first collected in the last decade of April; during next 2 years collecting began in the first decade of May. The beginning of collecting was affected by the weather during the years. The last insects occurred in the first decade of July. The date of the maximum occurrence of the pests changed during the research. Maximum of the insects was recorded between the May and (307pieces/5m2 ) a June (357pieces/5 m2) in 2004.The abundance of the insects decreased at about 45% after this time. The lowest abundance of insects was in May during the low average day temperatures. Maximum occurrence of total insects was in the last decade of May and in the first decade of June. Our results are similar to results of Gallo (2002), who maximum of the insects recorded in the first decade of May and June. Only one maximum of occurrence was recorded in 2004.Only one maximum was recorded in 2006 too. Two maximum of occurrence were recorded in 2005.

The maximum occurrence of the pests(89 pieces/5 m2 ) was recorded on spring barley at the beginning of the June in 2006. Phyllotreta (18 pieces/5m2 ), Thysanoptera (21 pieces per 5 m2 ) and Oulema gallaeciana (12 pieces/5 m2 )were dominant pests. Other authors presented the same spectrum of dominant pests (Gallo & Pekár 1999). There were no insects recorded on spring barley in July. The spring barley was in the wax ripeness. Abundance of the natural enemies increased at about 28% in the second decade of June but it decreased compared to the first decade about 80% by the end of month.

Different occurrence of the insectswasin20.The maximum of the collected insects (102 pieces per 5 m2 ) was at the end of June. The total number of insects 114 pieces/5 m2 was recorded in the first decade of June and from which there were 84pieces/5m2 pests. There was recorded maximum amount of natural enemies(14 pieces/5 m ). The second maximum of total insects(262 pieces/5m2) and also pests (177 pieces/5 m2 ) was recorded in the last decade of May. The collecting was realised in the first decade of July in 2005. The amount of the pests decreased at about 34% and natural enemies at about 63% in 2005. During the three years study the effect of fertilisation was monitored in the spring barley (Figure 2).According the results, more pests were recorded on fertilised variants.The more pests were recorded on the non-fertilised variants only in 2004. Our results are different from results of Samsonova (1991), according which the fertilisation had no effect on the occurrence of the pests. Levine (1993) results are similar to ours.

The occurrence of the insects had the similar character on fertilised and non-fertilised variants. The relation between fertilised and non-fertilised variants had not statistically significant difference

Total amount of collected insects on spring barley had increasing tendency during the all years. Total amount of the pests was 1630 pieces per 5 m2 collected during the entire period in2004.

This number decreased at about 55%in 2006.The amount of natural enemies had also decreasing tendency. While 66 pieces/5 m2 of natural enemies were collected in 2004, this amount decreased at about 67% in 2006 (Table 1). This drop could be caused by higher temperature during the year 2006.

According to Honěk (2003), McAvoy and Kok (2004), the temperature influenced occurrence and development of the pests in crops. Difference between the year 2004 and the other years 2005 and 2006 was statistically evident.

Winter wheat

The beginning of collecting was realised in the second decade of April and the last collections were realised in the first decade of July during the years 2004–2006.The last collection was realised atthe end of June in 2006.The beginning was affected by the weather during the years.

The first maximum of the pests was recorded in the last decade of April(247 pieces/5 m2 )in 2004. The second maximum was recorded at the end of May (350 pieces/5 m2 ) and at the beginning of June(285 pieces/5 m2 ).Thrips (44 pieces/5 m2 ) had the highest occurrence. The cereal leaf beetle was recorded at most in April. It was found occasionally in the crops in the next time. Aphids(58 pieces/5 m2) were recorded in the crops in June. Maximum occurrence of the pests was recorded in the last decade of May (284 pieces/5 m2 ), the second one in the second decade of June (314 pieces/5 m2 ) in 2005. There were trips (26 pieces/5 m2 ) and flea beetle (38 pieces/5 m2 ) and also cereal leaf beetle(15 pieces/5 m2).The aphids were not recorded in this year. During the terms with the highest level of the pests, there were also recorded the highest occurrence of the natural enemies (53pieces/5 m2).

Our results were similar to the results of Gallo and Pekár (1999, 2001),which presented the same spectrum of the pests. The high occurrence of the pests was recorded also in the first(266 pieces/5 m2) and in the second (197 pieces/5 m2 ) decade of June. The highest occurrence had again thrips (18 pieces per 5 m2 ), flea beetle (24 pieces/5 m2) and cereal leaf beetle (10 pieces/5 m2). Frittfly Oscinella fritt was recorded (6 pieces/5 m2) during the entire year.

The higher occurrence ofthe pests could be caused by higher temperature during the year. According to Petr et al. (1987), and McAvoy and Kok (2004), the temperature influenced occurrence and development of the pests in the crops. The influence of the fertilisation was study during three years research on winter wheat.

According to our results, the higher occurrence of the pests was recorded on fertilised variants. The higher occurrence of the pests was recorded on the non-fertilised variants only in the year 2004. Our results are different from the results of the other author according which the fertilisation had no influence at the pests (Samsonova 1991).The similar results reached Levine (1993) and Gallo and Pekár (1999).The occurrence of the insects had the similar character on fertilised and non-fertilised variants. Maximum amount of the pests was recorded one decade sooner on the fertilised variants than on the non-fertilised variants. Relation between fertilised and non-fertilised variants had not statistically significant difference.

The total number of insects had a decreasing tendency during the three years and in both variants of fertilisation. While 3259/5 m2 of insects were collected in 2004, this number decreased by about 51% in 2006. This decrease was expressive on the non-fertilised variantsin 2006, it began on the fertilised variants after the first year. The same decreasing tendency had also pests and their natural enemies. Their occurrence decreased at about 59%during the study. Difference between the year 2006 and the other years 2005 and 2004 was statistically evident.

(Source –  http://www.agriculturejournals.cz/publicFiles/01158.pdf)

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THE PROTECTIVE EFFECT OF HUMATES

 The increase in ionized radiation and pollution of our environment with herbicides, pesticides, heavy metal compounds, and other toxic mutagenic and carcinogenic substances presents a real danger to living organisms today and their progeny in the future.  Considering the soil pollution by water soluble heavy metal salts in the industrial regions and the long-term excessive use of mineral fertilizer, pesticides, and herbicides in agricultural regions, the crops, particularly vegetables and root-crops, accumulate excess amounts of harmful admixtures.  That is why the creation of pure agricultural technologies is one of the most important tasks of our time.

The protective effect of humates develop in the following directions:

  1. Protection from radioactive irradiation and its consequences.

  2. Protection from harmful admixtures in the atmosphere, soil, and subsoil waters in technogenic districts.

  3. Protection from the consequences of the pesticides and other chemicals used in agriculture.

  4. Protection from unfavorable environmental factors in zones of risky agriculture.

  5. Decrease in content of the nitrates that form when nitrogen fertilizer is used.

     Long-term research showed that humic substances bond many organic and non-organic substances into poorly soluble or insoluble compounds, which prevents their penetration from soil into subsoil waters and growing plants.  It reduces the toxic effect of residual amounts of herbicides, soil polluting radio nuclides, heavy metals, and other harmful substances, as well as radiation and chemical contamination.  Tests showed that even after 50% affection of the plant, its vital functions are completely restored due to the humic preparation effect.  This unique quality of humates is particularly important for the regions in Russia, Byelorussia, and Ukraine that are contiguous to the Chernobyl region.   In the future it could be used to gradually restore contaminated land.

     Modern floriculture is not possible without the use of different chemicals necessary to fight weed, pest, and plant disease.  It is widely known, however, that the use of those chemicals causes a number of negative effects due to their accumulation in the soil.  The infamous fact of DDT accumulation led to its complete banning.  However, DDT appearance still occasionally occurs in crops.  Science proved that sodium humate reduces the damaging effect of the pesticide atrazine by increasing its decomposition, which leads to an increase in the crop capacity of barley.

     The use of humates in zones of risky agriculture is particularly important.  Unfortunately, most territories of Russia can be considered risky.  In the south, the humates help to fight the effect of droughts, since it has been established that the humate treatment of plants ensures their drought resistance.  In Siberia and in the north of Russia, humate treatment can save the plants from late frosts.  In the 1960s, a corn crop was saved by colleagues of Irkutsk university, after an unexpected frost.  In 1996, in the Angarsk region, a strong frost happened on the 19th of June.  The parts of the potato fields that had been treated with the humates were the only undamaged parts.

     Watering soil with a 0.01% humate solution substantially increases the biological activity of the soil and boosts plants resistance against the harmful waste in technogenic zones of chemical and coking industries.  In 1998, in Buryatia, wide scale tests were carried out in treating of saline soils with humates.  The results showed a 214% increase in crops of green herbage, in comparison with the control group.

     The ability of humates to create complexes and their high sorption activity are used to bond the ions of heavy metals in contaminated soil.  That is why increased amount of humates (up to 20-30 kg per hectare) should be used on contaminated soil to ensure the contact and create favorable conditions for forming of complexes.

Humates accelerate water-exchange processes and physiological processes in the cell and participate in oxidation processes at the cell level.  They are conducive to complete assimilation of mineral nutrients in the plant, particularly in abnormal cases, such as saline soils, drought, and other unfavorable environmental factors. 

     An important quality of humates is their ability to decrease the level of nitrate nitrogen in produce.  It was proven by tests on a variety of crops (oats, corn, potatoes, root-crops, lettuce, cucumbers) that humate use decreases the nitrate content by 50% on average.  At the Dnepropetrovsk agricultural institute, field tests were carried out on chernozem soils.  Two crop cultures were tested – corn and barley (as second in the crop rotation).  The herbicide atrazine (4 kg per hectare) was used on the corn.  The results showed that atrazine reduced the growth of weeds by 80% and increased the crop capacity of the corn by 19%-20%.  However, the residual amounts of  the herbicide reduced the crop capacity in barley, which was sown after the corn in crop rotation, by 16%.  The use of sodium humate considerably changed the situation.  It stimulated corn growth and increased the crop capacity by an additional 10%, while the nitrates content (NO3) in the corn of honey and pearl ripeness decreased from 280.1 mg/kg to 199.7 mg/kg in laboratory tests and to 707 mg/kg in field tests.  Barley grown after the corn was noted to improve its germination, growth, and mass gaining, while containing less atrazine and more chlorophyll in the leaves.  The crop capacity of the barley increased by 5.2 centner per hectare, with a total crop capacity reaching 30.9 centner per hectare.  It was also noted that the atrazine content in the final produce decreased by 52%-71%, which made it an ecologically pure produce.

Thus, humic preparations are the reliable protection for plants and crops against harmful admixtures from our environment (soil, subsoil waters, rain-water, and the atmosphere), which is more polluted each day.  They also protect crops from unfavorable environmental factors (drought, ionizing radiation, etc.).

(Source – http://www.teravita.com/Humates/Chapter5.htm)

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DOES NO-TILL FARMING REQUIRE MORE HERBICIDES?

“More” compared with…?

There is obviously a wide variety of no-till farming systems and so there is an equally wide variety of conventional tillage based agricultural systems. The use of herbicides is a common feature and widespread practice in many intensive farming systems. This applies equally to tillage based conventional farming as to no-till farming. Herbicides are a useful tool for weed management, particularly in the first years after shifting from conventional farming to no-till farming. It is much easier, to do no-till farming with herbicides than without.  If now no-till farming is introduced in an environment of traditional peasant farming, where no herbicides are used at all, these no-till farming systems will obviously use “more” herbicides than the traditional conventional systems.

However, in many conventional systems herbicides are already frequently used and mechanical weed control has nearly disappeared in intensive farming. In such a system, the shift to no-till farming might not necessarily increase the use of herbicides dramatically. Even where it does increase the amount of active ingredient applied per area and year, the environmental impact is not necessarily worse, as often there is a shift from herbicides with relatively high environmental impact to other herbicides with less impact.

Therefore, it is difficult to generalize and no-till farming systems might not always require more herbicides than conventional farming systems.

What are the conditions for increased herbicide use under no-till?

Nevertheless, most of the scientific literature shows that notill farming does in fact require more herbicides than conventional systems comparing similar cropping systems.

There is no doubt that there are significant areas under notillage systems, where herbicide overuse is creating environmental problems. These systems are characterized by monocultures and, in absence of soil tillage, by herbicide use being the only weed management strategy applied. These areas are the ultimate proof for the statement, that no-till farming uses more herbicides. Many of these areas are also cropped with genetically modified crops, which are resistant to a specific herbicide. Therefore, the herbicide use in these cases is restricted to a single product. However, under such a condition, even soil tillage would not really improve the herbicide use. Such cropping systems, with or without tillage, can be considered as not conforming to good agricultural practice.

What is the weed control effect  of tillage?

Soil tillage has been developed for a number of reasons, such as to facilitate the preparation of a seedbed for a more efficient seeding. However, weed control has always been attributed to soil tillage and, particularly, the development of the mouldboard plough was very effective for weed management. But, in the long term, the weed control effect of tillage has proven to be insufficient and herbicides have become the tool of choice in intensive farming. The problem of tillage is that by creating a good seedbed for the seeds, it creates the same conditions for the weeds. While weed seeds are buried deeply with the mouldboard plough, the same plough brings to the surface the weed seeds that had been buried the season before. The seed bank in most agricultural soils is probably large enough that the plough does not have a long lasting control effect on weeds which multiply by seeds. On the other side, weeds propagating through sprouts or roots can even be multiplied by tillage implements, which only cut and mix them with the soil, so that the number of potential weed plants is increased. Through soil carried with tillage implements from one field to another, the weed population is also spread throughout the entire farmland.

Therefore, the use of tillage for weed control is not the ultimate answer, nor is the move to no-till the ultimate doom in terms of weed control.

How can herbicide use be  reduced?

This brings us back to herbicides. In all farming situations, not only in no-till farming, the use of herbicides can be reduced by applying the products correctly, using the right equipment with the appropriate settings under optimal conditions. Often the application of herbicide is done with even less care than the application of other pesticides, as herbicides are usually considered less toxic than, for example, insecticides. It leads then to increased application rates as the product is not reaching the target, but is wasted in the environment. This can become a problem, where herbicides have not been used traditionally and where, therefore, there is no appropriate equipment available for the application of herbicides once more intensive farming systems are introduced. For example, in the case of Uzbekistan, farmers start using the existing air blast sprayers, which are traditionally used for application of defoliants in cotton, for herbicide application. Similar cases can be found in other

Central Asian countries, such as Mongolia or Kazakhstan, where frequent cultivation of black fallow has been the only weed management strategy for the past few years and where the spray rigs are sometimes in very bad conditions. In FAO projects carried out in these countries, the simple upgrade of existing sprayers with upgrade kits, comprising pumps, controls, hoses and nozzles, reduced the herbicide use compared to farmers practice before the upgrade by 10 to 15 % while the weed control efficiency was at the same time improved by 20 % to values above 90 % control.

What are alternatives for weed management under no-till?

However, the main question remains, whether there are any alternative strategies for weed control that are applicable in no-till farming systems and which would allow reducing the dependency on herbicides. There is actually a wide range of options and principles within a weed management strategy that allow managing weeds without tillage and herbicides.

This starts with a forward looking strategy of weed control, to avoid the maturation and seeding of weeds in the first place by not allowing weed growth even in the off season. Applying this strategy, the farmers in an FAO project in Kazakhstan noticed after only two years of no-till cropping without even using a diversified crop rotation that the weed pressure and, hence, the need for herbicide use was being reduced compared to the conventional tillage based systems.

Another general point is to determine, at which point weeds are actually damaging the crop. It is often not necessary to eradicate the weeds completely, but only to avoid the setting of seeds and competition with the crop. Leaving weeds in a crop at a stage where the crop can suppress them and where there is no damage or problem for the harvest can actually help with managing other pests, such as termites or ants, which in absence of weeds would damage the crop.

A second aspect comes from the soil tillage itself. Farmers who do no-till for several years will notice that weed germination is reduced where the soil is not touched. Once the superficial weed-seed bank is depleted and no new seeds are added, the other seeds still remaining in the soil will not germinate as they will not receive the light stimulus for germination. For this reason, the no-till planters from Brazil,

for example, where no-till farming is reaching nearly 50 % of the total agricultural area, are designed to avoid any soil movement and to cover the seed slot immediately with mulch to create an “invisible” no-till seeding. This is done to reduce the emergence of weed seeds

The most powerful no-tillage and non-chemical weed control in no-till systems, however, is soil cover and crop rotation. Maintaining the soil covered with an organic mulch or a live crop can allow, under certain conditions, notill farming without using any herbicide. For this purpose, it is important to know the allelopathic effects of cover crops. These effects result from substances in the plants which can suppress other plant growth. Cover crops are crops which can be grown between commercial crops to maintain permanent soil cover. Crop rotations have to be designed in such a way, that the soil is always covered and that the variety of crops in the rotation facilitates the management of weeds. For managing the cover crops, a knife roller is used, which breaks the plants and rolls them down.

Applied at the right time, this tool can actually kill some of the cover crops without need of herbicide and achieve complete weed control throughout the next cropping season, provided the planting is done with minimum soil movement. Applying a knife roller, for example, in a well developed cover crop of black oat (Avena strigosa) at milk stage, will completely kill the cover crop, which on the other side will provide good weed control. In Brazil after a cover crop of black oat, there is usually no additional herbicide applied for the following crop There is a lot of scientific and practical evidence that weed infestation under no-till farming using certain cover crops and diversified crop rotations is declining in the long term, allowing a similar decline in herbicide use. Farmers using these principles of good agricultural practice in no-tillage systems report declining pesticide use in general, which also includes declining herbicide use at a level lower than comparable conventional systems.

Starting no-till farming with the establishment of good cover crops and a forward looking weed management allows the introduction of no-till farming in small holder farms in Africa without any herbicide use at all and with a reduction of manual weeding requirements. Spectacular effects were achieved in an FAO project in Swaziland using no chemical inputs and increasing both yields and reducing the drudgery of farm work by introducing a no-till farming system combined with permanent soil cover and crop rotation better known as Conservation Agriculture.

Conclusions

There is no question that herbicide use in agriculture and particularly in no-till farming systems can be a problem. There is plenty of scientific and practical evidence of excessive herbicide use in no-till farming. However, this is not an inherent characteristic of no-tillage farming, as there are alternative ways for weed management even without returning to soil tillage and cultivation. If correctly applied, these practices allow a sustainable use of herbicides in an integrated weed management programme  and even completely non-chemical weed control is possible. These practices are already successfully applied in commercial farming, but globally they are not yet sufficiently known or appreciated. Therefore, the general perception remains that no-tillage farming requires increased herbicide rates, which in reality not true as a general statement.

(Source – http://www.fao.org/ag/ca/CA-Publications/Pesticide%20Outlook%202005.pdf)

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Cover and Green Manure Crop Benefits to Soil Quality

Soil Quality and Resource Management

Soil is one of the five resources—soil, water, air, plants, and animals—that NRCS deals with in resource planning. Soil is intimately related to the other four resources, and its condition can either negatively or positively impact the other resources. For example, if the soil surface is functioning adequately, the soil will allow water to infiltrate, thus reducing the potential for erosion and increasing the amount of water stored for plant use. This function of soil affects water quality, plant growth, and the health of animals. In addition, protection of the surface layer resists wind erosion, thus protecting the air resource. Soil Quality is a critical factor in the management of natural resources, and the protection or enhancement of soil quality is the key component of all resource management assistance activities in the NRCS.

What is Soil Quality?

Soil quality is the capacity of a specific kind of soil to function within natural or managed ecosystem boundaries to:

* sustain plant and animal productivity

* maintain or enhance water and  air quality

* support human health and habitation.

As defined, the terms soil quality, soil health, and soil condition are interchangeable.

Effects of Conservation Practices

One of the goals of conservation planning is to consider the effects of conservation practices and systems on soil quality. This is the first technical note in a series on how conservation practices affect soil quality. This technical note is designed to compliment local or regional information on the specific nature of cover crops. Cover and Green Manure Crop Benefits to Soil Quality

1. EROSION – Cover crops increase vegetative and residue cover during periods when erosion energy is high, especially when main crops do not furnish adequate cover. Innovative planting methods such as aerial seeding, interseeding with cyclone seeder, or other equipment may be needed, when main crop harvest, delays conventional planting of cover crops during recommended planting dates.

2. DEPOSITION OF SEDIMENT – Increase of cover reduces upland erosion, which in turn reduces sediment from floodwaters and wind.

3. COMPACTION – Increased biomass, when decomposed, increases organic matter promoting increased microbial activity and aggregation of soil particles. This increases soil porosity and reduces bulk density. Caution: plant cover crops when soils are not wet, or use other methods such as aerial seeding.

4. SOIL AGGREGATION AT THE SURFACE – Aggregate stability will increase with the addition of and the decomposition of organic material by microorganisms.

5. INFILTRATION – Surface cover reduces erosion and run-off. Cover crop root channels and animal activities, such as earthworms, form macropores that increase aggregate stability and improve infiltration. Caution: Macropores can result in an increase in leaching of highly soluble pesticides if a heavy rain occurs immediately after application. However, if only sufficient rainfall occurs to move the pesticide into the surface soil after application, the risks for preferential flow are minimal. Cover crops, especially small grains, utilize excess nitrogen.

6. SOIL CRUSTING – Cover crops will provide cover prior to planting the main crop. If conservation tillage is used, benefits will continue after planting of main crop. Increases of organic matter, improved infiltration, and increased aggregate stability reduce soil crusting.

7. NUTRIENT LOSS OR IMBALANCE – Decomposition of increased biomass provides a slow release of nutrients to the root zone. Legume cover crops fix atmospheric nitrogen and provide nitrogen for the main crop. Legumes utilize a higher amount of phosphorus than grass or small grains. This is useful in animal waste utilization and management. Small grains are useful as catch crops to utilize excess nitrogen, which reduces the potential for nitrogen leaching. Caution: To prevent nutrient tie ups, cover crops should be killed 2-3 weeks prior to planting main crop. Tillage tools are used to kill and bury cover crops in conventional tillage systems. However, with conservation tillage systems, cover crops are killed with chemicals and left on or partially incorporated in the soil.

Caution: Research has shown that incorporation of legume cover crops results in more rapid mineralization. However, due to delay in availability of nitrogen from legume cover crop in conservation tillage, a starter fertilizer should be applied at planting. (Reeves, 1994). An ARS study done in Morris, Minnesota reported dramatically higher carbon losses through C02 remissions under moldboard plow plots as compared to no-till. It was reported that carbon was lost as C02 in 19 days following moldboard plowing of wheat stubble that was equal to the total amount of carbon synthesized into crop residues and roots during the growing season. Long-term studies indicate that up to 2 percent of the residual organic matter in soils are oxidized per year by moldboard plowing” (Schertz and Kemper, 1994).

8. PESTICIDE CARRYOVER – Cover crops reduce run-off resulting in reduced nutrient and pesticide losses from surface runoff and erosion. Increased organic matter improves the environment for soil biological activity that will increase the breakdown of pesticides.

9. ORGANIC MATTER – Decomposition of increased biomass results in more organic matter. Research shows cover crops killed 2-3 weeks prior to planting main crop, results in adequate biomass and reduces the risk of crop losses from soil moisture depletion and tie up of nutrients.

10. BIOLOGICAL ACTIVITY – Cover and green manure crops increase the available food supply for microorganisms resulting in increased biological activity.

11.WEEDS AND PATHOGENS – Increased cover will reduce weeds. Caution: Research has shown reductions in yield are possible in conservation tillage cotton systems following winter cover crops. Reductions are attributed to interference from residue (poor seed/soil contact), cool soil temperatures at planting, increased soil borne pathogens, and increased insects and other pests. Harmful effects from the release of chemical compounds of one plant to another plant (allelopathic) are possible with crops like cotton, but losses can be reduced by killing the cover crop 2-3 weeks prior to planting main crop, and achieving good seed/soil contact with proper seed placement. Cover crops have shown some allelopathic effects on weeds reducing weed populations in conservation tillage (Reeves, 1994).

12. EXCESSIVE WETNESS – Cover and green manure crops may remove excess moisture from wet soils, resulting in reduction of “waterlogging” in poorly drained soils. Caution: transpiration of water can be a detriment in dry climates. Planners should adjust the kill date of cover crops to manage soil water.

 Summary

Cover and Green Manure Crops as a conservation practice can improve soil health. Soil quality benefits such as increased organic matter, biological activity, aggregate stability, infiltration, and nutrient cycling accrue much faster under no-till than other tillage practices that partially incorporate the residue.

One example comes from the Jim Kinsella farming operation near Lexington, Illinois. He reports that organic matter levels have increased from 1.9 percent 6.2 percent after 19 years of continuous no-till (Schertz and Kemper, 1994). Future technical notes will deal with other conservation practice effects on soil quality. The goal of the Soil Quality Institute is to provide this information to field offices to enable them to assist landusers in making wise decisions when managing their natural resources.

(Sources – http://soils.usda.gov/sqi/management/files/sq_atn_1.pdf)

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Comparison of the effect of liquid humic fertilizers

Maize (Zea mays L.) is one of the most highly consumed  crops, and the most important foodstuff after wheat and  rice around the world. The global production of maize is 604 million tons, with a planting area of up to 140 million hectares. Iran produces 2 million tons of maize on 350000 hectares of land. However, the production from hybrid maize seeds in Iran is highly limited (FAO, 2002).

This plant, photosynthetically, is of C4 type and thrives in tropical and semitropical climates (Emam, 2008) and is native for central and southern America (Khodabandeh, 1998). Based on its role in production of grain and forage and providing food for livestock, as well as its industrial use, maize has become an important crop in Iran, as well as in other parts of the world. Expanding the area under  maize cultivation in Iran in order to become self-sufficient is one the most important goal pursued by the government and as a result of implementing programs designed to increase grain maize production over the last few years, this crop has seen a very fast growth in terms of planting area and yield.

Humic substances (HS) are the result of organic decomposition of the natural organic compounds comprising 50 to 90% of the organic matter of peat, lignites, sapropels, as well as of the non-living organic matter of soil and water ecosystems. Authors believe that humic substances can be useful for living creatures in developing organisms (as substrate material or food source, or by enzyme-like activity); as carrier of nutrition; as catalysts of biochemical reactions; and in antioxidant activity (Kulikova et al., 2005). Yang et al. (2004) argued that humic substances can both directly and indirectly

affect the physiological processes of plant growth. Soil organic matter is one of the important indices of soil fertility, since it interacts with many other components of the soil. Soil organic matter is a key component of land ecosystems and it is associated with the basic ecosystem processes for yield and structure(Pizzeghello et al., 2001).

Classically, humic substances are defined as a general group of heterogeneous organic materials which occur naturally and are characterized by yellow through dark colors with high molecular weight (Kulikova et al., 2005).  Shahryari et al. (2011) experienced the effect of two types of humic fertilizers (peat and leonardite derived) on germination and seedling growth of maize genotypes. They reported that interaction of “genotype × solutions (peat and leonardite based humic fertilizers and control) was significant in terms of the length of primary roots.

Application of leonardite based humic fertilizer had a remarkably more effect on relative root growth of Single Cross 794 and ZP 434 than other genotypes. In their experiment, the relation between germination rate and primary roots was positively significant under the condition of application of both types of humic fertilizers; but there was not the same relation for control treatment.

They argued that all types of various humic substances as a biological fertilizer can have an either similar or different effect in early growth stages of maize, as peat and leonardite based fertilizers that they applied produced more seedling roots than control, however the length of coleoptiles was higher in treatment with application of leonardite based humic fertilizer and control than treatment with application of peat based humic fertilizer. They believe that if used in lower quantity these natural fertilizers can have a lot of effect on plant growth.

Hence, in order to recognize how effective they might be, investigations should be considered based on various amounts of humic fertilizers. Finally, they suggested that both peat and leonardite based humic fertilizers could be used to stimulate growth of primary roots in maize which are critical for an optimal establishment of maize in the field.

Gadimov et al. (2009) claimed that humic substances are natural technological products with a miraculous biological effect on crops and concluded that a scientific and practical program is required to make use of this technology in the world, particularly in developing countries. Also, Shahryari et al. (2009) concluded that potassium humate is a miraculous natural material for increasing both quantity and quality of wheat and can be used to produce organic wheat. Thus, application of biological products such as humic fertilizers to provide nutrition for crops can be one of the useful methods to achieve some of the objects of organic crop production.

In addition, Shahryari et al. (2011) studied the response of various maize genotypes against chlorophyll content of the leaves at the presence of the two types of humic fertilizers. In their experiment, solutions (two types of peat and leonardite based liquid humic fertilizers and control) and interaction of “genotypes × solutions” produced significant difference at 1% probability level in terms of chlorophyll content of the leaves. Genotypes such as Single Cross 704 and 505 had the highest index for chlorophyll content when treated by leonardite based humic fertilizer. Peat based humic fertilizer decreased the index for chlorophyll content in genotypes such as 500, OS499 and 505, while leonardite based humic fertilizer decreased the index for chlorophyll content of the leaves in genotypes such as Golden West and Single Cross 704. However, peat based humic fertilizer did not have such an effect on these two maize genotypes.

Meanwhile, leonardite based humic fertilizer had no effect on index for chlorophyll content of leaves in genotypes such as 500, OS499 and 505. Genotypes such as ZP677 and ZP434 produced no response against the application of the two types of humic fertilizers. This study was aimed to compare the effect of liquid peat and leonardite based humic fertilizers on the yield of maize genotypes in Ardabil Region.

MATERIALS AND METHODS

This experiment was conducted at Agriculture Research Station of Islamic Azad University, Ardabil Branch (5 km west of Ardabil City) in 2009 – 2010 cropping year. The region has a semiarid and cold climate, where the temperature during winter season usually drops below zero. This region is located 1350 m above the sea level with longitude and latitude being 48.2°E and 38.15°N, respectively.

Average annual minimum and maximum temperatures are -1.98and 15.18°C, respectively; whereas maximum absolute temperature is 21.8°C; and mean annual precipitation has been reported to be 310.9 mm. The soil of the field was alluvial clay with a pH ranging from 7.8 to 8.2.

Vegetative materials included six maize genotypes prepared from the Agriculture and Natural Resources Research Center of Ardabil Province. The Experiment was conducted as split plot in the basisof randomized complete block design with three replications. The main factor included three conditions (peat based humic fertilizer; leonardite based humic fertilizer; without the application of humic fertilizer) and the sub factor included six maize genotypes (ZP677, Golden west, OS499, ZP434, Ns540 and Single Cross 704). Each of experimental blocks included 3 plots, 320 cm length in rows, with80 cm from each other containing plants at 20 cm distances.

Pretreatment of seeds were done on the basis of 220 ml per 10 L of water to be applied for 1 ton of seeds. Moreover, irrigation was done in flooding manner. Weed-fighting was done both mechanically and manually during all growth stages. Liquid humic fertilizer was prepared and applied based on 400 ml per 50 L of water for 1 ha of maize plantation. The prepared solution was sprayed upon the aerial part of the plants during 5th leaf stage, appearance of reproductive organs, flowering and grain filling stages. All the samples were taken randomly from competitive plants at middle rows. Study traits included grain number per ear row, number of grain row per ear, ear number, weight of 1000 grains, biological yield, vegetative yield and grain yield.

Statistical analysis

Analysis of variance of data and mean comparison of them was done using MSTATC and SPSS programs. Mean comparison was done using Duncan’s multiple range test, at 5% probability level. Due to abnormality of data for ear number and its high coefficient of variation, square root conversion was used to normalize it.

RESULTS AND DISCUSSION

Results from analysis of variance for study traits suggest that there was a significant difference  between experimental conditions in terms of grain yield and biological yield at 1 and 5% probability levels, respectively. In addition, there was a nonsignificant difference between study genotypes in terms of all evaluated traits except for number of grain row per ear and wet biomass at 1% probability level. Furthermore, there was no difference observed between the interaction of genotype and experimental conditions for any trait being studied, and this was in agreement with the report of Shahryari et al. (2009). This means that under study genotypes had the same responses to potassium humate.

Moreover, results from mean comparison of data (Table 2) for studied genotypes indicate that genotype OS499 (110.70 g) had the highest 1000 grain weight, whereas genotype Single Cross (81.20 g) had the lowest 1000 grain weight on average. Based on mean comparison of 1000 grain weight, genotypes OS499 and ZP434 were placed in the same group as NS540, whereas genotype ZP677 was placed in the same group as Golden West. Genotype ZP677 (with a mean value of 15.48) and genotype ZP434 (with a mean value of 13.49) had the highest and lowest values of number per ear, respectively; and genotypes such as Golden West and Single Cross were placed in  the same group as NS540 and had no difference in terms of this trait. Genotype ZP677 (with a mean value of 20.89 ton/ha) and genotype OS499 (with a mean value of 16.93 ton/ha) had the highest and lowest biological yield respectively and genotype OS499 was placed in the same group as ZP434, whereas genotypes such as Golden West and Single Cross were placed in the same group as NS540. Genotype ZP677 (with a mean value of 108.68 ton/ha) was the best among other genotypes in terms of wet biomass, whereas ZP434 (with a mean value of 77.52 ton/ha) had the lowest value for wet biomass. ZP677 was placed in the same group as NS540, whereas genotypes Golden West and OS499 were placed in the same group as ZP434 and had no difference in terms of this trait.

Shahryari and Shamsi (2009a) reported that potassium humate increased the rate of biological yield of wheat from 3.26 to 3.72 g/plant; but it had no effect on harvest index. Also, they found that uses of potassium humate increased grain yield. Results from mean comparison of data  for experimental conditions being studied indicate that application of leonardite based liquid humic fertilizer produced the highest biological yield(21.99 ton/ha on average), whereas no application of humic fertilizer produced the lowest biological yield(14.97 ton/ha on average). In this respect, both types of applied humic fertilizers had similar effects. Application of leonardite based liquid humic fertilizer produced the highest grain yield (7.09 ton/ha on average) among the conditions being studied, whereas under the condition of without humic fertilizer obtained the lowest value(4.07 ton/ha).

Ayas and Gulser (2005) reported that humic acid leads to increased growth and height and subsequently increased biological yield through increasing nitrogen content of the plant. It has also been reported that application of humic acid in nutritional solution led to increased content ofnitrogen within aerial parts and growth of shoots and root of maize (Tan, 2003). In another investigation, the application of humic acid led to increased phosphorus and nitrogen content of bent grass plant and increased the accumulation of dry materials (Mackowiak et al.,2001). Humic acid leads to increased plant yield through positive physiological effects such as impact on metabolism of plant cells and increasing the

concentration of leaf chlorophyll (Naderi et al., 2002).

Also, spraying humic acid on wheat crop increased its yield by 24% (Delfine et al., 2002). In general, the results from this study indicate that the application of leonardite based humic fertilizer increased biological yield by 46.89% compared to control, whereas peat based humic fertilizer increased biological yield by 34.47% compared to control. Seyedbagheri (2008)evaluated commercial humic acid products derived from lignite and leonardite in different cropping systems from 1990 to 2008. The results of those evaluations differed as a result of the source, concentration, processing, quality, types of soils and cropping systems. Under their research, crop yield increased from a minimum of 9.4%to a maximum of 35.8%. However, application of humic fertilizer in this study increased the biological yield by 40.68% on average. Application of leonardite based humic fertilizer increased the grain yield of maize by 74%.

Also, peat based humic fertilizer increased the grain yield by 44.7%. Overall, the mean increase for grain yield under the condition of application of humic fertilizers was as high as 59.45%. Similar results were also presented by Shahryari et al. (2009b) on wheat. They reported increase of grain yield (by 45%) from 2.49 ton/ha to 3.61 ton/ha affected potassium humate derived from sapropel in normal irrigation conditions.

Conclusion

Results from this experiment indicate that the application of liquid humic fertilizer can positively affect the maize yield and some agronomic traits related to it. These desirable effects can be a consequence of its effect on the physiology of the maize. In general, application of humic acid can lessen the need for chemical fertilizers and subsequently reduce environmental pollution, and compared with other chemical and biological fertilizers, they are affordable. Finally, it can be said that application of humic fertilizer not only increases the yield of maize, but also can play a significant role in achieving the goals of sustainable agriculture

( Source http://www.academicjournals.org/ajb/PDF/pdf2012/13Mar/Khaneghah%20et%20al.pdf)

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HUMIC SUBSTANCES AND THEIR INFLUENCE ON SOIL FERTILITY

Humic substances are a good source of energy for beneficial soil organisms. Humic substances and non-humic (organic)  compounds provides the energy and many of the mineral requirements for soil microorganisms and soil animals. Beneficial  soil organisms lack the photo synthetic apparatus to capture energy from the sun thus must survive on residual carbon containing substances on or in the soil. Energy stored within the carbon bonds function to provide energy for various  metabolic reactions within these organisms. Beneficial soil organisms (algae, yeast, bacteria, fungi, nematodes, mycorrhizae, and small animals) perform many beneficial functions which influence soil fertility and plant health. For  example the bacteria release organic acids which aid in the solubilization of mineral elements bound in soil. Bacteria also release complex polysacharides (sugar based compounds) that help create soil crumbs (aggregates). Soil crumbs give soil a desirable structure. Other beneficial soil microorganisms such as the Actinomyces release antibiotics into the soil. These antibiotics are taken up by the plant to protect it against pests. Antibiotics also function to create desirable ecological balances of soil organisms on the root surface (rhizoplane) and in soil near the root (rhizosphere). Fungi also perform many beneficial functions in soils. For example, micorrhizae aid plant roots in the uptake of water and trace elements. Other fungi decompose crop residues and vegetative matter releasing bound nutrients for other organisms. Many of the organic compounds released by fungi aid in forming humus and soil crumbs. Beneficial soil animals create tunnel-like channels in the soil. The channels allow the soil to breath, and exchange gases with the atmosphere. Soil animals also aid in the formation of humus, and help balance the concentration of soil microorganisms. A healthy fertile soil must contain sufficient carbon containing compounds to sustain the billions of microscopic life forms required for a fertile and a healthy plant. A living soil is a fertile healthy soil.

Humus functions to improve the soil’s water holding capacity. The most important function of humic substances within the soil is their ability to hold water. From a quantitative standpoint water is the most important substance derived by plants from the soil. Humic substances help create a desirable soil structure that facilitates water infiltration and helps hold water within the root zone. Because of their large surface area and internal electrical charges, humic substances function as water sponges. These sponge like substances have the ability to hold seven times their volume in water, a greater water holding capacity than soil clays. Water stored within the top-soil, when needed, provides a carrier medium for nutrients required by soil organisms and plant roots.

Available water is without doubt the most important component of a fertile soil. Soils which contain high concentrations of humic substances hold water for crop use during periods of drought. This is why growers who apply humate-based fertilizers and integrate production practices which preserve humic substances, can frequently harvest a crop during periods of dry weather.

Humic substances are key components of a friable (loose) soil structure. Various carbon containing humic substances are key components of soil crumbs (aggregates). Complex carbohydrates synthesized by bacteria and humic substances function together with clay and silt to form soil aggregate. As the humic substances become intimately associated with the mineral fraction of the soil, colloidal complexes of humus-clay and humus-silt aggregates are formed. These aggregates are formed by electrical processes which increase the cohesive forces that cause very fine soil particles and clay components to attract each other. Once formed these aggregates help create a desirable crumb structure in the top soil, making it more friable. Soils with good crumb structure have improved tilth, and more porous openings (open spaces). These pores allow for gaseous interchange with the atmosphere, and for greater water infiltration.

The mean residence times of these organo-mineral complex aggregates varies with different humic substances. The mean residence time of humic substances within these aggregates, based on radiocarbon dating, using extracts from nondisturbed soil, is as follows: humin, 1140 years; humic acid, 1235 years; and fulvic acid, 870 years. Man has shortened the residence time of humic substances by excessive fertilizing and by using tilling practices that cause excessive weathering of soils. Soils abused by applications of anhydrous ammonia and by other destructive practices (those which destroy humic substances) can shorten residence times by several hundred years. The turnover time of organic carbon added each year from plant and animal residues averages approximately 30 years, under ideal conditions. In order to retain humic substances within the soil growers need to implement production practices which prevent their decomposition. Growers need to develop practices which retain the residence time of humic substances. It is essential to avoid destructive fertilization practices, rotate crops, minimize pesticides usage, deep plowing, and mix crop residues in the top soil by using minimum tillage practices. Soils which contain adequate humic substances have improved tilth (work ability) and are thus more efficiently maintained for crop production.

Degradation or inactivation of toxic substances is mediated by humic substances. Soil humic substances function to either stabilize or assist in the degradation of toxic substances such as: nicotine, aflatoxin, antibiotics, phenols, and most organic pesticides. In the microbial degradation process not all of the carbon contained within these toxins is released as CO2. A portion of these toxic molecules, primarily the aromatic ring compounds are stabilized and integrated within the complex polymers of humic substances. Humic substances have electrically charged sites on their surfaces which function to attract and inactivate pesticides and other toxic substances. For this reason the Environmental Protection Agency recommends the use of humates for clean up of toxic waste sites. Many bioremediation companies apply humate based compounds to toxic waste sites as a part of their clean up program. Growers interested in cleaning up their soils (destroying various toxic pesticides) can accelerate the degradation of poisons (toxins) by applying humic substances. Growers who farm soils lowin humus need to include the purchase of humic substances in their fertilizer budget. The cost of humic substances can bemore than offset by reduced costs of other fertilizer ingredients.

Humic substances buffer (neutralize) the soil pH and liberate carbon dioxide. Humic substances function to buffer the hydrogen ion (pH) concentration of the soil. Repeated field studies have provided experimental evidence that the additionof humic substances to soils helps to neutralize the pH of those soils. Both acidic and alkaline soils are neutralized. Oncethe soil is neutralized, then many trace elements formerly bound in the soil and unavailable to plant roots, because of alkaline or acidic conditions, become available to the plant roots. Humic substances also liberate carbon dioxide (CO2) from calcium carbonates present within the soil. The released CO2 may be taken up by the plant or it may form carbonic acids. The carbonic acids act on soil minerals to release plant nutrients.

Soil enzymes are stabilized and inactivated by humic substances. Soil enzymes (complex proteins) are stabilized by humicsubstances within the soil by covalent bonding. Stabilization renders these enzymes less subject to microbial degradation. Once stabilized and bound to the humic substances enzyme activity is greatly reduced or ceases to function. However many of these bonds are relatively weak. During periods of pH change within the soil, these enzymes can be released.When some components of humic substance react with soil enzymes they are more tightly bound. For example, phenolicenzyme complexes are frequently attached to clays, further stabilizing the enzymes. These enzyme stabilization processes help to restrict the activity of potential plant pathogens. As the potential plant pathogen release enzymes designed to break down the plant’s defenses, the pathogens enzymes become bound to humic substances. As a result the pathogens are unable to invade potential host plants.

Soil temperatures and water evaporation rate are stabilized by humic substances. Humic substances function to help stabilize soil temperatures and slow the rate of water evaporation. The insulating properties of humic substances help maintain a more uniform soil temperature, especially during periods of rapid climate changes, such as cold spell or heat waves. Because water is bound within the humic substances and humic substances reduce temperature fluctuations, soil moisture is less likely to be released into the atmosphere.

The electrical features of humic substances influence known chemical reactions. Both groups of complex organic acids, humic acids (HAs) and fulvic acids (FAs) have been proven to be involved in three specific chemical reactions. These reactions are commonly termed: (1) electrostatic (columbic) attraction, (2) complex formation or chelation, and (3) water bridging. Electrostatic attraction of trace minerals reduces leaching into subsoil. Electrostatic attraction of metal cations to anionic sites on the humic substance keeps these ions from leaching into the subsoil. The metal cation is loosely attached, thus can be released when attracted to another stronger electrical charge. The cation is readily available in the soil environment for transport into the plant roots or exchanged for another metal cation Electrically charged sites on humic substances function to dissolve and bind trace minerals. When a complex reaction with metal cations occurs on the humic substance surface it is termed chelation. Two negatively charged sites on the humic substance attract metal cations with two negative charges. As a result the cation binds itself to more than one charged anionic site. By forming organo-metal chelates, these organic acids bring about the dissolution of primary and secondary minerals within the soil. These minerals then become available for uptake by plant roots. The greater the affinity of the metal cation for humic acid (HA) or fulvic acid (FA), the easier the dissolution of the cation from various mineral surfaces.

Both the acidic effects and the chelation effects appear to be involved in dissolution of minerals and binding processes. Evidence for the dissolution of minerals can be supported by x-ray diffraction and infrared analysis. Chelation of plant nutrients such as iron (Fe), copper (Cu), zinc (Zn), magnesium (Mg), manganese (Mn), and calcium (Ca) reduces their toxicity as cations, prevents their leaching, and increases their uptake rate by plant roots.

The chelation exchange reaction involves a transition element. The release of these trace minerals into the plant is quite different from the classical cation exchange system. The cation with a plus two charge, present in the chelate, cannot be replaced by a singly charged cation such as H+, K+ or Na+. Cations with one positive charge are unable to replace a metal ion, such as Cu++, with two positive charges. The chelated metal ion can be exchanged by another transitional ion that has two positive charges. The chelates provide the carrier mechanism by which depleted nutrient elements are replenished at the root surface. The chelation process also increases the mass flow of micro nutrient mineral elements of the root. The chelation of heavy toxic metallic elements present within the soil is also influenced by humic substances present. When toxic heavy metals such as mercury (Hg), lead (Pb), and cadmium (Cd) are chelated these organo-metal complexes become less available for plant uptake. Detailed studies of chelation of heavy metals in industrial sludge has illustrated the value of humic substances in preventing uptake of these toxic metals. Keep in mind that free metal cations such as Fe+2, Cu+2, and Zu+2 are incompatible with plant cells. Direct applications of metallic salts, such as iron sulfate, copper sulfate, and zinc sulfate, to correct trace element deficiencies, can cause serious problems when the soils lack sufficient humic substances for buffering. Trace minerals should be applied in an organic chelate, preferably by humic acids (HAs) and fulvic acids (FAs). Many scientific studies have shown that humic substances [humic acids (HAs) fulvic acids (FAs)] present in the root zone reduce the toxicity of metal cations. Water bridging is an important function of humic and fulvic acids. Water bridging by humic substances involves the attraction of a water molecule followed by the attraction of a mineral element cation (Simply illustrated by (-COO – H2O -Fe+) at an anionic site on the humic (HA) or fulvic acid (FA) polymers. The water holding capacity of humic substances and their ability to bind trace mineral elements function together in water bridging. Water bridging is believed to improve the mobility of nutrient ions through the soil solution to the root. These mechanisms also help reduce leaching of plant nutrients into the subsoil. Recent experiments indicate that water bridging may be more common in humic substances than originally believed.

Humic substances aid in the decomposition of soil minerals by forming metal-organic-clay complexes, a process termed soil genesis. Soil formation (soil genesis) involves a complexing of transition mineral elements, such as copper (Cu), zinc (Zn), iron (Fe), and manganese (Mn) from soil minerals with humic acids (HAs), fulvic acids (FAs) and clays. This complexing process inhibits crystallization of these mineral elements. The complexing process is in part controlled by the acidity of these weak acids and the chelating ability of humic substances. In the absence of humic substances trace minerals elements are converted to insoluble precipitates such as metal carbonates, oxides, sulfides, and hydroxides. Thus the presence of humic acids (HAs) and fulvic acids (FAs) within soil inhibit the development of new soil minerals. For example, crystallization of iron to form iron oxides is inhibited by the presence of humic acids (HAs) and fulvic acids (FAs). Soils deficient in humic substances may contain adequate iron, however the iron present is frequently bound in forms which render it unavailable to plant roots. As the concentration of fulvic acids (FAs) increases within a soil.

Transition metal crystallization is first delayed and then inhibited at high fulvic acid (FA) concentrations. Cations of these transition metals (e.g. Cu++, Zn++ and Fe++) are held in large humic polymers by chelation, for future release to soil organisms on plant roots. These physical and chemical processes prevent leaching of plant nutrients into the subsoil.

Stored energy and trace mineral content of humic substances helps sustain soil organisms involved in transmutation. The presence of humic substances within saline soils (those soils which contain high salt concentrations, e.g. sodium chloride) aid in the transmutation of the sodium ions. The transmutation reactions, a biological process that occurs within living organisms, result in the combining of sodium with a second element, such as oxygen, to form a new element. Although the theory of transmutation has met considerable opposition by some traditional physicists and chemists, biologist have recorded convincing data to prove that transmutation occurs in living organisms. Application of humins, humic acids, and fulvic acids to saline soils, in combination with specific soil organisms, results in a reduction in the concentration of sodium salts (e.g. NaCl). The reduction is not correlated with a leaching of the salt, rather with an increase in concentration of further elements. The addition of humic substances to soils containing excessive salts can help reduce the concentration of those salts. By reducing the salt content of a soil its fertility and health can be “brought back” to provide a more desirable environment for plant root growth.

(Source – http://www.calciumproducts.com/articles/Dr._Pettit_Humate.pdf)

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EM in agriculture

 Farming with EM implies the following practices:

•  Always supply organic material to the soil – mulch or compost – to provide a habitat for the micro-organisms of EM and for naturally occurring organisms.

•  Cover the soil with organic matter – mulch and compost – to provide moisture for soil organisms and EM.

•  Supply EM bokashi and work it into the topsoil, in particularly prior to a crop season.

•  Apply the EM solutions – i.e. extended EM, EM5, and EM-FPE – regularly during the growing stage of your crops.

•  Harvest only those parts of the plant that are for use and consumption. Return all crop residues to the fields.

For the preparation of extended EM, EM5, EM-FPE and EM bokashi, please refer to other information leaflets and to the EM application manual by EMRO/APNAN.

Nursery management

(1) EM for seed bath:

To achieve a high germination rate and provide protection against diseases, soak seeds – or pods – in extended EM solution (diluted 1:1,000):

small seeds (e.g. mustard) for 20 to 30 minutes, medium-size seeds (e.g. cucumber) for 30 to 60 minutes, and large seeds (e.g. pumpkin) for 2 to 3 hours.

Exceeding these times for a seed bath may result in complete fermentation and composting of seeds instead of germination. After soaking the seeds or pods may be left to dry under shade for 30 minutes.

(2) In case of vegetative propagation, soak cuttings or tubers etc. for five minutes in the seed bath.

(3) After sowing or planting spray extended EM solution. If seedlings are brought in from outside sources, apply EM prior to planting.

Soil fertility and crop management

(1) Do not cut down on input of manure and compost. Give recommended amounts of compost in dependence of existing soil properties and needs of the crop.

(2) Prepare EM bokashi as a compost bokashi (mixtures if cereal bran, animal manure, oil cake) and apply it at a dosage of 200 gr per sq.m. Work the bokashi into the top two to three inches of soil, two to three weeks prior to crop establishment. If possible apply a thick layer of mulch to retain moisture and thus provide ideal conditions for soil microorganisms and for EM. – If bokashi application is not feasible before crop establishment, apply it with the seeds or around seedlings, but not in direct contact with them.

(3) During the growing period of an annual crop apply extended EM solution at the rate of 20-40 liter per acre diluted at 1:1,000, once a fortnight. For perennial crops spray extended EM solution regularly every two weeks initially. Later decrease application frequency according to effects and results, i.e. once when healthy growth is established. Avoid spraying during the flowering season.

(4) Combine extended EM with EM5 and EM-FPE.

Pest and disease control

As a preventative measure against pest and diseases apply regularly – along with ex-tended EM – sprays of EM5 and EM-FPE on your crop, especially in the early growth stages of annual crops (e.g. once every two weeks). In case of actual pest attack and disease apply both preparations daily or every second day until the disease or the pest recede.

Dilutions for EM5 and EM-FPE are between 1:500 and 1:1,000, volumes are similar to those of extended EM solution.

Weed control

During the preparation of the land provoke germination of all weed seeds in the soil with a thorough application of extended EM. After a week (if moisture is maintained as in a paddy field), when most weed seeds have germinated, plough the seedlings under and follow with the sowing of the crop. After three to four cycles of this practice, the amount of weed seeds reduces and becomes negligible.

Once the crop saplings have grown to 4 to 6 inches, use thick mulch covers to suppress weed growth.

Other EM preparations

In the preparation of EM bokashi and EM-FPE, the farmer should become creative and combine traditional and regional knowledge with EM. The use of EM-fermented mulch and EM-fermented compost is recommended, also the use of EM-soaked charcoal around root systems of trees and other perennials.

Other inputs

The use of agrochemicals such as chemical fertilizers and pesticides reduces the efficacy of EM. All biocides (pesticides, fungicides, weedicides, antibiotics, disinfectants, chlorine etc.) are counteractive to the effect of EM.

Other organic farming inputs such as composts and manures, vermicompost, cow urine or panchkavya, biodynamic preparations, and other microbial preparations may be combined with EM.

EM can be ideally combined with all practices of organic and sustainable farming. To some extent it can also be successfully combined with chemical fertilizers. EM can be made a great tool for a stepwise conversion from chemical farming to full and certifiable organic farming.

(Source – http://www.auroville.com/auroannam/anp/em-agriculture.htm)

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Green Manures – Effects on Soil Nutrient Management and Soil Physical and Biological Properties

Both organic and conventional growers can gain many benefits from increased use of green manures. A wide range of plant species can be grown as green manures as different ones can bring a variety of benefits. Leguminous plants will fix nitrogen from the air whilst non-legumes will conserve nitrogen by preventing nitrate leaching. Green manures add organic matter to the soil, improving its physical and biological properties and they can assist with pest, disease and weed management. Some of the effects on soil physical properties may only become significant after several green manure crops have been grown over a period of perhaps five to ten years. Green manures are often categorised according to the time of year they are grown.

Winter green manures or cover crops are usually sown in the autumn and incorporated in the following spring and may be legumes (e.g. vetch) or non-legumes (e.g. rye). Summer green manures are usually annual legumes (e.g. crimson clover) which are grown to provide a short term boost for fertility. However, they could also be nonlegumes (e.g. mustard).

Longer term green manures are usually pure clover or grass/clover leys grown for two or three years. They are common in organic stockless rotations where they form the main source of nitrogen. However, in conventional farming these rotations would be harder to justify unless there were animals to graze them.

Green manures may also be used in intercropping systems, although in vegetable cropping it is important to avoid too much competition with the cash crop. Protected cropping systems offer particular challenges and opportunities for green manuring whilst fertility building in orchards can be difficult as nitrogen must be provided at the right time to ensure good fruit set and crop quality. Green manures grown as an understory can also attract beneficial insects.

Green manures are often grown to add nitrogen to the soil. In organic systems this represents the main source of nitrogen, whilst for conventional growers, it can be a way of minimising fertiliser inputs. Almost all legumes use Rhizobia bacteria to fix nitrogen from the atmosphere.  Unfortunately finding out how much  nitrogen is actually fixed is not easy  and depends on many factors.  Firstly, the correct strain of bacteria  must be present. Different bacterial  species interact with different groups  of legumes (clovers, lucerne and trefoils, lupins, beans etc.). If the same types of plants are regularly grown then sufficient bacteria will usually be present to establish sufficient nodules. Sometimes it is worth inoculating the seeds with the correct type of bacteria. There are several types available commercially, at a modest cost.

Sometimes the nitrogen fixation still does not occur, even if the roots form a symbiosis with the bacteria. Some strains will infect the plant but not be very effective. They can even drain the plant of resources

<a href=http://www.organicadvice.org.uk/Factsheet%2024.10.pdf>more…</a>

(Source: Horticulture Development Company – http://www.organicadvice.org.uk/Factsheet%2024.10.pdf)

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Peat Profits

Peat is combustible mineral which consists from plants remains and can be mostly found in wetland areas. Peat is a renewable, natural, organic material of botanical origin and commercial significance. Peat forms when plant material, usually in wet areas, is inhibited from decaying fully by acidic and anaerobic conditions. It is composed mainly of wetland vegetation: principally bog plants including mosses, sedges and shrubs. As it accumulates, the peat can hold water, thereby slowly creating wetter conditions, and allowing the area of wetland to expand. Peatland features can include ponds, ridges, and raised bogs. For more information on this process, refer to wetland in general and bog in particular.

Previously peat was often used as a fuel source, but later was mostly rejected due to its low apparent density, high humidity content (up to 80%) and the development of more efficient and promising energy sources as oil and coal. Nevertheless it remains to be one of the most promising natural fertilizers.

In its primary form (after fresh layer excavation) the peat has low liquidity and requires composting and aeration measures. It derives from its primary high acid content and low availability of active nitrogen. The composting procedure stimulates peat decomposition, thus decreasing its acidity and raising its absorption ability.

After composting procedure peat serves as a fertilizer (humates content), improves soil structure (makes it warmer and more loose), raises organic substances content. Due to phenols content it can be a good natural anti-infective agent. As far as peat content prevents from nutrients wash-out, it is really an important stuff for young plants and trees planting.

Important features of peat use – its low mining cost (less than $5 per tonne) and a possibility to use it as a fuel in composting process warming. Instead of composting agrarians can use lime or chalk to reduce primary peat acidity.

Tags: IEASSA, peat, humic, humate, fertilizer, efficiency, acid, anti-infective, phenol

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