Conventional tillage systems

Soil tillage comprises all the physical, mechanical, chemical or biological actions conducted to prepare the seedbed for seed germination, emergence and establishment, root development and crop growth.
Conservation tillage embraces one principle of conservation agriculture “Minimum soil disturbance” and includes practices that keep the disturbance of the soil and loss of organic matter to a minimum, reducing soil and water losses. Mostly, the soil is not turned using ploughs.
No or minimal mechanical soil disturbance
Direct seeding involves growing crops without mechanical seedbed preparation or soil disturbance after the harvest of the previous crop. The term direct seeding is used synonymously with no-till farming, zero tillage, no-tillage, direct drilling, etc.
No-tillage involves slashing the weeds and previous crop residues or spraying herbicides for weed control, and seeding directly through the mulch using direct seeding implements. All crop residues are retained, and fertiliser and amendments are either broadcast on the soil surface or applied during seeding.
Soil cover with mulch or stubble plays an important role in conservation tillage. Mulch reduces evaporation losses, increases infiltration, and helps the building-up of biological micro flora and fauna/soil organic matter (SOM), thus improving long term soil structure and fertility. A mulch cover can reduce weed development, but also increase pest and disease infestation. For more information please refer to section ‘mulching’.
Effects:
  • Minimal destruction of soil structure through pulverisation, compaction and/or plough pan development
  • Slower mineralisation of soil organic matter through less exposure to climatic elements and soil micro and macro fauna
  • No disturbance of worms and other soil inhabitants, maintained soil biodiversity and balanced activity and food web in the soil including natural predation.
  • Better infiltration and circulation of air and water into and through the soil profile through maintained bio-pores and vegetative cover and optimal rooting
  • Reduced evaporation from bare soil surfaces
  • Soil regeneration rate through mineralisation and decomposition and re-structuring higher than soil degradation through loss of porosity and soil particles (erosion) and loss of plant nutrients (fertility)
  • Improved nutrient retention and availability for plant growth and reduced leaching of nitrogen and other nutrients
  • Improve timely field operations

How is it achieved? (Means and practices)

  • No ploughing, discing, harrowing etc.
  • Use of direct seeding through crop residues
  • No crop residue burning
  • No incorporation of crop residues into the soil
  • Permanent bed planting/planting station ridgeline/rip line
  • Use of crop rotations, balanced biodiversity and pesticides for weed/pest control instead of ploughing or using high rates of chemicals that endanger soil life and disturb the soil and ecological processes including the hydrological cycle and water quality

The use of the different systems for conservation tillage depends on the primary objectives, farm equipment and power available, physical condition of the land and the crops grown. Some tillage systems are designed for using animal- or tractor-drawn equipment, other are suited for hand labour. Conservation tillage systems common in East Africa include:

  • No-till or zero-tillage
  • Reduced or minimum tillage
  • Pitting systems
  • Stubble- and residue-mulch tillage
  • Ridge and furrow

Conservation tillage is part of the concept of conservation agriculture, whose basic principles are little or no soil disturbance, diverse crop rotations and permanent soil cover.

No-Till or Zero-Tillage Systems – Conservation Tillage

For more information see: Conservation tillage
No-tillage is generally defined as planting crops into soil that has remained untilled after the harvest of the previous crop.
Conservation tillage includes the WHEN and HOW this tillage is done. The “when” basically refers to the moisture-state of the soil. Conservation tillage takes into account both environmental and tillage factors .This system involves opening a narrow slot only wide and deep enough to obtain proper seed coverage and with at least 30% mulch cover. Permanent, continuous no-tillage should follow, while the soil should remain covered by crop residues or green manure cover crops. Crop residues should remain undisturbed on the soil surface after seeding.
No-tillage and reduced tillage have been used since ancient times by indigenous cultures. This was because tillage to any depth required more energy and power than was generally possible with hand labour. The ancient Egyptians and the Incas in the Andes of South America used a stick to make a hole in the ground and place seeds by hand into the unprepared soil (Derpsch, 1998). Even today in some parts of the world that use shifting cultivation, seed is dropped into a hole after clearing the forest by burning. Tillage, indeed, greatly aided the enhancement of food production by creating a seedbed for easier planting and by controlling competition by weeds. However, tillage also accelerated soil loss and soil structural degradation hence leading to the current food shortage and persistent crop failure in most parts of Sub Saharan Africa.
There are a number of reasons for adopting no-tillage in addition to the effects listed above the following are the most attractive to farmers;
  • Reduction in the cost of production: For instance, production costs per acre (0.405 ha) of soybeans under no-tillage are reduced by US$ 27.00 in Argentina, by US$ 14.18 in the USA and by US$ 11.50 in Brazil (Derpsch, 1998). According to FAO recent studies have shown that practicing conservation tillage leads to:
    • Less labour and farm power
    • Up to 60% fuel savings
    • Up to 50% savings in tractors
    • Up to 40% savings in tractor size
    • Up to 3 times longer tractor-life
    • Reduction in machinery capital
  • Timely farm operation is easily achieved through no till. Farmers are able to plant well in good time since the focus on land preparation is mostly neither intensive nor subjective. Studies have shown that timely planting contributes up to 40% of the yield hence the ability of Conservation Agriculture to increase yield is largely drawn from this principle.

 

Benefits and constraints of No-Tillage
Some of the benefits of no-tillage include:

  • Prevention of soil erosion
  • Prevention of soil compaction
  • Preservation of soil structure, soil aggregates and macro-pores
  • Improvement of soil moisture and water use efficiency through mulching
  • Promotion of beneficial organisms such as earthworms
  • No-till mulching enhances soil microbial activity, transfers organic matter to the soil improving its nutrient status
  • Less inputs of fuel, energy and labour
Despite the wealth of research information in Africa showing the benefits of no-tillage, this farming system is not yet extensively practised (Lal, 1973, 1983)

The ecological constraining factors for spreading no-tillage in Africa are:

  • Effects of climate change resulting in low precipitation with low biomass production
  • Short growing seasons
  • Sandy soils with tendency for compaction
  • Soils at risk of waterlogging

Where no-tillage is not possible, the second best choice is minimum tillage.

Steps to No-Tillage Adoption

Before adoption of the no-tillage system following factors must be consider:

  • Farmers must improve their knowledge about the system (especially weed control) before trying the technology on their farms
  • The change to no-tillage should be planned at least one year before implementation
  • Plan to acquire no till implements (direct seeders) and obtain proper orientation on their utilisation. The implements so acquired should match the available farm power.
  • It is advisable to start with a small portion/section and advance with time (e.g. 10% of the farm)
  • Soil tests should be done, and nutrient deficiencies corrected, aiming at a balanced nutrient and pH status. If soils are acidic, farmers should apply small quantities of lime each year (instead of large amounts only once)
  • Avoid soils with bad drainage. It is known that no-tillage does not work on badly drained soils or if soils suffer from water-logging
  • Level the soil surface, as uneven surfaces make exact seeding impossible
  • Eliminate soil compaction
  • Use crop rotations and green manure crops, these are basic in no-tillage system
  • Produce the highest amount of mulch cover possible. Choose crops varieties/species with higher biomass than others ( e.g. maize instead of beans) and include green manure cover crops in the rotation. Crop residues and green manures must be left on the soil surface, being incorporated biologically into the soil as they decompose
  • Buy a no-till seeding (planter) only after having met all requirements mentioned above
  • Learn constantly and stay up to date with new developments

Reduced or Minimum Tillage Systems

This refers to those tillage practices where by minimum or no disturbance is effected on the soil for purposes of crop production. It involves the making of furrows or holes where seed is planted. The rest of the field remains undisturbed and crop residue is left on the surface. This practice reduces soil erosion; causes build up of organic matter in the soil, hence better chemical and physical soil fertility. Minimum tillage also implies reduced labour, energy, and reduced time demand in land preparation. Hence, cropping can be done in time at less cost. In most commercial farming, the weeding in minimum tillage systems would be done using herbicides.

It differs from traditional tillage by having one or more of the following components:

  • Less operations
  • Less soil disturbance
  • Requires less power
  • Seedbed is prepared only where the seeds are planted
  • Residues remain on topsoil (are not buried)
  • Reduced use of several types of equipment
Only the necessary operations to optimise soil conditions for seed germination and crop establishment and growth are performed: minimise human and machine traffic and thus avoid soil compaction and destruction of soil structure; to avoid soil erosion; to conserve soil moisture; and to use less labour and mechanical energy.

Minimum tillage practices include:

1) Dibble stick planting
Dibble stick planting
© ACT, Kenya

Planting stick or machete can be used to create holes to plant the seed in an un-ploughed field with stubble/crop residue. The cut hardwood stick from the bush is sharpened at one end and used to make planting holes. The holes are made in lines at evenly spaced intervals that make it easier to weed and apply fertiliser or manure.

2) Disc-plant (stubble-harrowing)
This tool is used to loosen the soil, chop up crop residues and cut weeds. Afterwards planting is done without further soil disturbance and the crop residues are left on the surface
3) Strip and spot tillage
This involves scraping out shallow planting holes in un-ploughed soil, sowing the seed in the holes, then covering. This approach is common throughout the Sahel (Mali, Niger, Chad, and other countries). The only equipment needed is the hand hoe (Jjembe) and a planting stick. You can plant in the dry or just after the rains. The following are the steps involved:
  • Dig small shallow holes at the correct distance from each other. Make the holes just deep enough to plant the seeds.
  • Put the correct number of seeds in the hole, and cover them with soil.
  • About 2 weeks after the crop emerges, use a stick to make a hole about 10 cm away from each plant. Put fertiliser into the hole.

Advantages

  • Less labour requirement compared to conventional cultivation.
  • More attractive to vulnerable households due to labour factor and not a huge chunk of land is required.
  • Planting done on time
  • Do not require expensive equipment – just a hoe and a stick.

Disadvantages

  • Weed control may be difficult
  • Do not break a hardpan caused by hoeing at the same depth year after year.
  • Crop roots may not grow well as with planting basins, and less water will infiltrate into the soil.
4) Ripping
Ripping
© ACT, Kenya
A ripper is a chisel-shaped implement pulled by animals or a tractor. It breaks up surface crusts and opens a narrow slot or furrow in the soil, about 5 – 10 cm deep.
Many conservation tillage systems use a ripper with a single chisel fixed to a plough or ridger frame. In ripping, only shallow parallel furrows are cut using a ripper without disturbing the soil between the planting rows. The ripper should cut regular lines to facilitate subsequent weeding with ox-drawn weeders. Planting is usually done at the same time. The distance between the furrows depends on the recommended spacing for the crop. Ripping can reduce or eliminate the need for ploughing.
The ripper is faster than ploughing, as tillage is limited to only a thin opening for planting. Because of this narrow working width, pulling a ripper requires about half the draught force of that needed for pulling a conventional single-furrow plough.
The ripper is smaller and lighter than a plough, and is easier to operate. The farmer can also use smaller animals, or animals that may be weaker at the end of the dry season. The ripper is also cheaper to buy and cheaper to maintain. As a result of these advantages, the farmer can work larger acreages each season, and achieve timeliness in operations, thus taking advantage of the early rains. This is important, especially in seasons of lower-than-normal rains or, generally, for marginal-rainfall zones. The weed problem can be serious in a rip tillage system. Therefore, action should be taken to lessen the
problem over the longer term. The ripper (e.g. the Magoye ripper) is a useful weeding tool.

Advantages

  • Ripper attachments fit on a normal plough beam hence cheaper than complete implements.
  • Can be used to make planting slots in dry soil allowing early planting.
  • Disturbs the soil less than ploughing hence reduces soil erosion and encourages water infiltration into the soil.

Disadvantages

  • Difficult if there is a lot of residue on the surface because the residue wraps around the ripper shaft.
  • Disturbs up to 30% of the soil surface.
  • Quite difficult to use on fields with tree stamps.

Case study 1: Study on effects of ripping in Wanging’ombe Village Southern Tanzania 

Nineteen farmers of Wanging’ombe Village were introduced to ripping and improved soil cover with Mucuna in 2001. Five of these have doubled maize grain yield and increased sunflower production by 360% compared to conventional mould board tillage (Table 5). However, there is confounding of the treatments, since the variable was not only tillage technique and cover crop, but also use of industrial fertilisers. The other 14 farmers could not attain similar yields because they could not afford to buy industrial fertilisers.
Farmers in Mayale Village reported that the performance of crops and crop yields were more stable since the adoption of Conservation Agriculture (CA) technologies. They were able to harvest a maize crop from ripped plots in 2001 when rainfall was merely 560 mm albeit a substantial (67.2%) labour saving (Table 7). Ripping enabled capture of rainwater along with in situ storage and cover crops (especially Mucuna) provided soil surface mulch for moisture retention, thus increasing crop stability against drought stress.
Table 1: Mean* maize and sunflower yields under CA (ripping and mucuna) practices in Wanging’ombe and Mshewe Wards
Ward Crop Conventionalcultivation** CA practices*** Increase (%)
Wanging’ombe Maize yield (kg/ha) 1125 2250 100
Wanging’ombe Sunflower yield (kg/ha) 750 2700 360
Mshewe Maize yield (kg/ha) 1500 2900 93
Mshewe Sunflower yield (kg/ha) 625 1500 140

* Means of 5 CA FFS members in Wanging’ombe and 8 in Mshewe.
** Planting behind the plough at the start of the rains followed by two hand hoe weedings.
*** Opening of planting furrows with ox-drawn ripper on un-ploughed fields prior or at onset of rains, hand planting of seeds, two weedings with ox-cultivator.

Table 2: Maize grain yield on farmer trial plots at Mayale in 2001. Means of 7 farmers.

No. Treatment Field Capacity (hahr-1)*1 Labour input (Manday/ha-1) **2 Maize grain yield (kgha-1)
1 Ox ripper 0.0719 a 31.6 b 1344 a
2 Ox ripper planter 0.0721 a 29.6 b 1059 b
3 Ox tied ridges 0.0194 b 102.6 a 1021 b
4 Ox plough 0.0211 b 96.2 a 1066 b
Grand mean 0.0461 65.0 1122
Coefficient of Variation (%) 29% 11% 22%

*1 Ability in terms of how many hectares can be worked in 1 hour by the ox-team (2 operators and a pair of oxen) using the respective implement.
**2 Labour input for the planting operation (i.e. opening of planting furrow, placement of seed, fertilizer and seed covering).
Source: Mkomwa et. al. 2002.

More labour saving benefits would be reaped if the full ripper and planter attachment were used, since it is possible for one person to open up the land and plant seeds. The ripper planter was not the choice of farmers, as it was more expensive than the ripper (Tsh 190,000 compared 120,000) and seed metering, using farmer (un-graded) seeds, was uneven.

Case study 2: Makundi’s success story

Pastor Humphrey Makundi from northern Tanzania has one acre in his nearby farm. Normally he would harvest 6 bags of maize. He ripped with improved maize seeds intercropped with lablab. He also established contours that reduced runoff on his cattle pasture. He managed to harvest 10 bags that season [2004]. In the following season he rented 4 more acres and harvested 10 bags of maize from each acre, totalling 50 bags in one season.

Pitting systems

Matengo pits

Structures called “matengo” pits are used in the Southern Highlands of Tanzania. The pits can be up to 1m x 1m and 30 cm deep, but the actual size is determined by depth of the soil and ease of digging. The pits are laid out on sloping land forming a grid to cover the entire surface. Soil taken from the pits is used to form ridges around the pits.
Crops are grown on the ridges and the weeds and crop residues are thrown into the pits. A rotational system is usually practiced using crops such as maize, beans and sweet potato, and the pits are regularly moved and new ridges built where the organic matter has accumulated. The pits also serve as structures to conserve water.

 

Zai basins
Zai basins
© ACT, Kenya

“Zai” basins are used in semi-arid areas to concentrate manure and runoff into basins or pits where the crops, e.g. sorghum, are planted. Zai pits have traditionally been used in the dry regions of Burkina Faso and Mali in West Africa. The pits are about 15-20 cm deep and 30 cm in diameter, with 1 m between the rows.

Topsoil from the excavation is mixed with manure and put back in the pit where a few cereal seeds are then planted. The pits also concentrate rainfall runoff around the plants, thus improving moisture supply to the roots.

Planting holes
Planting holes
© ACT, Kenya

There are at least two systems being used in certain areas of Kenya and Tanzania. One of these is a system of planting 5 or 9 maize plants in large holes of about 1.5 m diameter (4 or 8 plants along the edge and 1 in the middle, respectively). The soil is first dug out to sufficient depth to break through any hardpan, if present, and allow free drainage. The topsoil is returned, together with manure, and the remaining soil placed around the hole to catch rainfall and concentrate it where the plants are growing.

The second system, developed in Dodoma, is known as “chololo” pits. The holes are similar to the above but only about 25 cm deep and 30 cm in diameter, being spaced at 60 cm within the rows and 90 cm between rows. The rows are arranged roughly on the contour. The soil from the pits is put on the lower side of the pit, forming a half-moon shape that traps runoff into the pit. Planting is done in the pits.

Further systems: Stubble- and Residue-Mulch tillage, Ridge and furrow

Stubble- and Residue-Mulch tillage

This involves cutting the roots of weeds and other plants and leaving the crop residues on the surface or mixed into the top few centimetres of the soil.
The cutting is usually done with a tined implement with blades or sweeps attached to the tines to uproot or undercut the weeds. The result is to reduce erosion and to conserve water by reducing runoff, and also to regulate soil temperature and increase soil fertility and organic matter content. Equipment used for planting must have special furrow openers to avoid clogging with trash.

Ridge and furrow systems
Simple or tied ridging cultivation results in better soil and water management than conventional ploughing.
The ridges and furrows help to regulate runoff flow, to increase water infiltration and storage and reduce soil and nutrient losses. The system is most suitable for gentle slopes, especially in marginalrainfall areas. Row crops are planted either on the ridge top, in the furrow or along both sides of the ridge.
A ridger can be used for ridge and furrow cultivation. Sometimes a discontinuous furrow is made by making cross-ties that interrupt water flow in the furrow, thus creating a series of basins or pools to retain water for a while and to promote slow seepage. This is called tie-ridging. The ridges may be maintained for several seasons to reduce construction work. Usually seedbed preparation and planting are done in one combined operation.
A system of broad ridges (beds) and furrows has been found to be useful on vertisols (black-cotton soils) because it allows drainage and facilitates cultivation. Modifications of the animal-drawn mouldboard plough have been used for making broad ridges for growing wheat and other crops on such soils in Ethiopia and Kenya.
Tied ridges for water conservation
© C. Gachene and G. Kimaru, RELMA, 2003
Contour ridges
© ACT, Kenya

Equipment

Hand tools

The following hand tools will be mostly utilized in conservation tillage:

Hand tools
© ACT, Kenya
  • A hoe or jembe is a common household farm tool in East Africa. It should be as narrow as possible (10 cm wide is good size).
  • A long string: Used to measure off the correct distance. Tie knots in the string at the plant spacing are preferred but bottle tops could also be used to demarcate the spacing interval.
  • Two sticks to mark the rows and to make sure the rows are parallel.
  • Two strong pegs to hold the string at both ends.
  • Fertiliser cups to apply fertiliser or lime.
  • An empty drink can to apply manure.
Tined cultivators
  • Rippers 

The most commonly used ripper in East Africa is Mogoye ripper which originated from Zambia. This is a single tine implement used for opening furrow for insitu water harvesting. The opened furrow is also used for planting. The implement uses the same mould board plough frame with only the mould board attachment being replaced by ripper attachment. The implement can therefore be drawn by oxen, donkey or horse. The implement is designed to fit in all plough frames hence a farmer with ox plough will not incur any extra cost apart from acquiring the ripper attachment.

Rippers
© ACT, Kenya
Ripper drawn by oxen
© ACT, Kenya
Ripping with donkey
© ACT, Kenya
Sub-soiler
© ACT, Kenya
  • Sub-soilers
    Sub-soiler is an implement used for breaking the hard pan/plough pan. There exist various types of sub-soilers depending on the farm power available. Tractor powered sub soiler commonly used in large scale farms can either be single or double chiselled tine. The animal powered sub soiler consists mainly of a single chisel tine which penetrates the soil surface breaking the hard pan/plough pan. The implement uses the same mould board plough frame with only the mould board attachment being replaced with sub soiler attachment. The implement just like the ripper can be drawn by oxen, donkey or horse. The implement is designed to fit in all plough frames hence a farmer with ox plough will not incur any extra cost apart from acquiring the sub soiler attachment. Sub-soiling is a remedial measure which is not undertaken every season hence farmers should only use sub soiler in fields with hard pan/plough pan.
Sub-soiler breaking the plough pan
© ACT, Kenya

Planting implements 
Jab planter
© ACT, Kenya

 

Jab planter

This is a hand/manually operated direct planting implement with ability to sow both seeds and fertiliser simultaneously. The implement exists in many models depending on the manufacturing company but the operational principle is normally the same. There exists a single hopper and a double hopper jab planter. The implement is able to plant variety of crop seeds depending on the selected seed plate and the jab plant type.

 

 

Animal drawn direct planter
© ACT, Kenya
  • Animal drawn direct planter 

This is an animal powered implement with the ability to directly sow seeds and fertiliser simulteneouly. It requires an operator to direct the planting operation while the pulling is done by trained oxen, donkey or horse. The implement also exists in many models depending on the manufucturer however the operational principle for seed and fertiliser distribution largely remain the same. The implement unlike the jab planter has provision to plant a wide range of seed crops due to the presence of several sets of seed plates which only require replacement during calibration process.

Tractor drawn direct seeder
© ACT, Kenya
  • Motorized/tractor drawn direct seeder 

This is a tractor powered direct planter with the ability to sow both crop seeds and fertiliser simultaneously in several rows. The implement exists in several models and sizes depending on the manufacturing company and the tractor power available respectively. It is able to plant variety of crop seeds due to availability of several sets of seed plates. Once calibrated and set accordingly, the implement is able to maintain uniform spacing throughout the farm.

 

 

 

 


 

Case study 3: Case of a large scale CA farmer in Laikipia Kenya “Lengetia farm”

The farm is located in Lamuria division where it boarders large scale ranches inhabited with wild game and livestock ranching. They own 680 acres of land and rent a total of 4200acres from his neighbouring ranch known by the name Ol Pajeta. This is an ASAL region where rainfall is not reliable and ranges between 750 – 800mm. The farm falls within zone 5 (Lower Highland Ranching Zone). The farmer grows wheat and barley as main crops while canola and a little sun flower as rotational crops.
From 1997-2002, Mr. Sessions was practicing conventional tillage for production of wheat and barley on 1000 acres. He faced a myriad of problems ranging from reduced soil fertility, high fertiliser requirement, and high cost of farm machine operations due to increase in oil market, increased soil erosion, emergence of plough pans and finally the decline in wheat market due to trade liberalisation within COMESA countries. This situation therefore made his production cost high to the extent that his produce could no longer become competitive. In 2000, he saw an Australian no till planter in one of his family friend’s farm. After getting explanation about its use and importance combined with knowledge he had acquired from reading several agricultural magazines and journals on tillage, he decided that he needed to acquire such a machine at whatever cost. In 2002, he had an Australian pneumatic direct seeder assembled in his farm by the manufacturer’s mechanics that travelled purposely to ensure that the machine was operating in good order and the user was well versed with its operation manual. He immediately embarked on growing wheat and barley using conservation agriculture and increased crop acreage from 1000 – 1500 acres by the year 2003. In 2004 he increased the acreage under CA again from 1500-4700 acres which excluded 420 acres which he rented in Timau area of central division. Until now, he is perhaps one of the CA adopters in the district who is able to exploit the advantages which come with its adoption.
The benefit of adopting CA did not come immediately after acquisition of the machines. Because he understood the process of practicing the new farming technique, he immediately embarked on restoring the soil biomass by accumulating and spreading the crop residue evenly on the crop fields after every harvest. Despite the fact that he had few herds of livestock, he never allowed them to graze freely on the crop fields like they did before, instead he isolated some portion of his land for grazing and also bailed fodder for the livestock. With a GPS Australian sprayer, he usually sprays herbicide as soon as the weeds emerge in the harvested fields. His reason for doing this is to reduce the weed seed bank and from the time he started adopting CA. To date, he believes he has reduced the weed seed bank by about 30%.
Even though he did not retrench some of his employees after adopting the new farming practice, his cost of production has gone down by about 55%. This was due to considerable reduction in tractor power requirement, reduced farm operations hence reduction in manpower and reduced fuel consumption. To sum it all at this point, he says, “because of CA, my blood pressure has gone down and one cannot cost that”
The yield has been on the increase and because of enormous mulch developed in the crop fields due to accumulation of crop residues, moisture retention is greatly improved and he does not worry much about rainfall pattern since he is sure to continue with his season calendar as usual thanks to in situ water harvesting property of CA. At first his neighbouring wheat farmers thought that he was irrigating his land since his crops were ever green and healthy while theirs was a total crop failure due to lack of rainfall. He says that the region, being semi arid, requires a sustainable agricultural practice to enable a farmer to acquire a harvest which would be profitable.
(Source – http://www.infonet-biovision.org/PlantHealth/Conservation-tillage-systems)
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When It’s Cold, Think About managing Weeds In Warm-season Pastures

Bermudagrass’s dormant period is the time to take care of weed control in those warm-season pastures, said Dirk Philipp, assistant professor for the University of Arkansas System Division of Agriculture.
Weeds are more than just an aesthetic problem. “Technically, weeds compete with forage species for available resources such water, sunlight, nutrients; they reduce overall forage quality, palatability, some maybe toxic,” he said. “As a result, nutrient-use efficiency is reduced, animal gains are not at an optimum, and farm economics suffer.”
Philipp said that “late February and early March is the time to treat bermudagrass pastures for buttercup and henbit — both of which are very prolific.”
While both weeds can be treated earlier, as spring approaches, they both grow at a faster rate and the herbicides will be effective. Philipp said that for henbit, products containing metsulfuron are recommended, while for buttercup, glyphosate or paraquat is recommended.
“As with all pesticides, read labels carefully as restrictions may apply,” Philipp said.
At the UA animal science research farm in Fayetteville, Philipp said researchers had very good experiences with glyphosate applied late February/early March. Because bermudagrass cannot be grazed or hayed for 60 days after dormant application, “the earlier the application, the better,” he said. “If you go out and think you need to spray, then it’s probably too late.”
Herbicides still work at relatively low temperatures, as long it is not freezing and an early application in early February can be followed up with a second one in early March.
Philipp had additional notes on weed control:

  • It is probably impossible to keep fields entirely free of undesirable plants, so don’t get discouraged
  • Observe and monitor the different annual, perennial, broadleaf and grassy weeds year-round to learn when they appear so you can be prepared.

To help minimize weed encroachment and make herbicide control more effective, even indirectly, he advises producers to stay on top of their fertilizer programs.
“Inadequate fertilizer applications may weaken the forage stand,” Philipp said, adding that producers should  “keep pH/liming requirements in check.”
He also said that growers should let the stand develop a dense canopy, but remove forage on a regular basis to open up the canopy for light penetration to the lower leaves, and to use grazing methods in accordance with your needs to increase efficiency of forage utilization.

(Source – http://www.farms.com/news/when-it-s-cold-think-about-managing-weeds-in-warm-season-pastures-88471.aspx)

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Break it up: Subsoiling study eyes winter tillage

When deep tillage is used on cropfields could be as important as how and where the operation is practiced.

The most common time of year to deep till — also known as subsoiling — is in the fall immediately following harvest. But sometimes growers are forced to delay subsoiling until mid-winter.

Research at the Ohio Agricultural Research and Development Center’s Northwest Agricultural Research Station near Hoytville, Ohio, will determine whether winter subsoiling is as beneficial as fall subsoiling.

“The best time to subsoil is in the fall, but sometimes because of late harvest, unsuitable weather or other circumstances, growers delay subsoiling until January,” said Randall Reeder, the Ohio State University agricultural engineer conducting the study. “No research data exists on subsoiling in mid-winter in Ohio. We hope the weather cooperates and gives us an opportunity to conduct the research.”

Subsoiling with a low disturbance tillage tool is a conservation practice that breaks up soil 12-18 inches deep, allowing increased water movement, better aeration of the roots and access to additional minerals and nutrients for plant growth. The benefits associated with subsoiling are the alleviation of soil compaction and improved corn and soybean yields. By comparison, conventional tillage breaks up the soil 6-8 inches below the surface, and in areas compacted by heavy combines and grain carts such a practice is not adequate.

Ten years of Ohio State research has shown that subsoiling works well on the silty clay loam soil commonly found in northwest Ohio. The soil type tends to “compact naturally,” creating drainage problems that are compounded with additional compaction from heavy machinery, Reeder said.

“The culmination of Ohio State research has proven the benefits of subsoiling in November. Now we want to find out if January subsoiling can be just as effective,” Reeder said.

Subsoiling is best practiced in the fall because the freezing and thawing cycles associated with the onset of Ohio’s winters help to settle the soil prior to planting in the spring. One of the concerns of delayed subsoiling is running the risk of a loose soil structure that is not conducive to seed germination and root growth.

“The longer a grower waits to subsoil — say, as late as March — the higher the risk of decreased yields,” Reeder said.

Like other production practices, subsoiling has its advantages and disadvantages. Low-disturbance subsoiling equipment is capable of breaking up deep soil while leaving surface residue virtually untouched, affording the farmer the benefits of both deep tillage and no-till. Residue from the previous crop remains on the surface and the following season’s crop is planted directly into it, minimizing soil erosion.

“A grower has three options with subsoiling: not to subsoil at all, subsoil every year, or subsoil occasionally,” Reeder said. “Our research has shown that subsoiling every two or three years produces the same benefits as subsoiling every year, which is good news for farmers because of the expense. Note that our research plots are farmed with relatively light equipment, so we are not recompacting the soil the way many farmers do.”

A disadvantage of subsoiling is the increased horsepower needed compared to no-till or chisel plowing, which raises production costs for the farmer. But the benefits of subsoiling can outweigh the extra expense.

Based on Ohio State research on Hoytville soil, subsoiling can increase yields 5 percent to 10 percent. For 1,000 acres of corn, that can translate into a $15,000 to $30,000 savings for the grower, Reeder said.

(Source – https://www.agriculture.purdue.edu/aganswers/story.asp?storyID=4095)

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Maize: Growth and development

Different growth stages are numbered 0 to 10. Growth stage 0 lasts from planting of the seed up to when the seedling is just visible above the soil
surface. Growth stage 10 is reached when the plant is biologically mature.
Growth stage 0: from planting to seed emergence
During germination, the growth point and the entire stem are about 25 to 40 mm below the soil surface. Under warm, moist conditions seedlings
emerge after about six to 10 days, but under cool or dry conditions this may take two weeks or longer. The optimum temperature range for germination is between 20 and 30 ºC, while optimum moisture content of the soil should be approximately 60 % of soil capacity.
Growth stage 1: four leaves completely unfolded
The maximum number of leaves and lateral shoots is predetermined and a new leaf unfolds more or less every third day. The growth point at this
stage is still below the soil surface and aerial parts are limited to the leaf sheath and blades. Initiation of tasselling also occurs at this stage.
Growth stage 2: eight leaves completely unfolded
During this period, leaf area increases five to 10 times, while stem mass increases 50 to 100 times. Ear initiation has already commenced. Tillers begin to develop from nodes below the soil surface. The growth point at this stage is approximately 5,0 to 7,5 cm above the soil surface.

Growth stage 3: twelve leaves completely unfolded

The tassel in the growth point begins to develop rapidly. Lateral shoots bearing cobs develop rapidly from the sixth to eighth nodes above the soil surface and the potential number of seedbuds of the ear has already been determined.

Growth stage 4: sixteen leaves completely unfolded
The stem lengthens rapidly and the tassel is almost fully developed. Silks begin to develop and lengthen from the base of the upper ear.
Growth stage 5: silk appearance and pollen shedding
All leaves are completely unfolded and the tassel has been visible for two to three days. The lateral shoot bearing the main ear as well as bracts has
almost reached maturity. At this point demand for nutrients and water is high.

Growth stage 6: green mealie stage
The ear, lateral shoot and bracts are fully developed and starch begins to accumulate in the endosperm.

Growth stage 7: soft dough stage
Grain mass continues to increase and sugars are converted into starch.
Growth stage 8: hard dough stage
Sugars in the kernel disappear rapidly. Starch accumulates in the crown of the kernel and extends downwards.
Growth stage 9: physiological maturity
When the kernel has reached its maximum dry mass, a layer of black cells develops at the kernel base. Grains are physiologically mature and only
the moisture content must be reduced.
Growth stage 10: drying of kernels (biological maturity)
Although grains have reached physiological maturity, they must dry out before reaching biological maturity. Under favourable conditions, drying takes place at approximately 5 % per week up to the 20 % level, after which there is a slowdown.

(Source – http://www.arc.agric.za/arc-gci/Fact%20Sheets%20Library/Maize-infopak.pdf)

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The challenge of tillage development in African agriculture

Tillage has been an important aspect of technological development in the evolution of agriculture, in particular in food production. The objectives of tilling the soil include seedbed preparation, water and soil conservation and weed control. Tillage has various physical, chemical and biological effects on the soil both beneficial and degrading, depending on the appropriateness or otherwise of the methods used. The physical effects such as aggregate-stability, infiltration rate, soil and water conservation, in particular, have direct influence on soil productivity and sustainability.

Tillage technology began with the use of stick or metal jab for seeding and with gradual agricultural development the technology passed through a phase of ploughing – animal-drawn ploughs, subsequently followed by tractor-drawn implements and recently with more powerful machinery. At the centre of all this development, is the availability and employment of energy sources. In developed countries and in some developing countries today, fossil fuel is the main energy source, whilst in most developing tropical countries human labour is still predominant. However, animal draught power has been the tradition in many developing countries, particularly in the semi-arid tropics. A major constraint on the use of animals is and has been the availability of adequate fodder.

Recently, many developing countries have introduced tractors and various implements in attempts to increase food production. The general lesson learnt in most such countries is that often the machinery chosen has not been matched to the various agro-ecological zones and soil types. Furthermore technicians engaged in the tillage operations have not been properly trained. This has resulted in widespread soil degradation and loss in soil productivity.

Today there are major problems facing the modernization of African agriculture. Food production must necessarily keep pace with population growth. Many countries will soon have limited new land for agricultural development leaving no alternative other than intensifying yield per unit area. Soil management and conservation must play a major role in increasing crop yields and soil productivity on a sustainable basis.

Tillage and residue management which have direct influence on soil and water conservation are two important components of soil management in Africa, especially in the semi-arid tropics. This agro-ecological zone has a great potential for increased agricultural roductivity but at the same time poses a major challenge due to the various soil and climatic constraints, and the ease with which serious soil degradation occurs if farm operations are not carefully managed.

Tillage aspects of soil management, in particular, research, development and technology transfer to users to increase agricultural production in Africa are discussed and highlighted in this paper.

TILLAGE EFFECTS ON SOIL AND CROP PRODUCTION

One of the basic and important components of agricultural production technology is soil tillage. Various forms of tillage are practised throughout the world, ranging from the use of simple stick or jab to the sophisticated para-plough. The practices developed, with whatever equipment used, can be broadly classified into no tillage, minimum tillage, conservation tillage and conventional tillage. Energy plays a key role in the various tillage systems.

An important question underlying all these practices is: why till? Much has been written on this topic and it can be summarized as follows:

  • seedbed preparation
  • soil and water conservation
  • erosion prevention
  • loosening compacted soil
  • weed control

The best management practices usually entail the least amount of tillage necessary to grow the desired crop. This not only involves a substantial saving in energy costs, but also ensures that a resource base, namely the soil, is maintained to produce on a sustainable…<more>

( Source – http://www.fao.org/docrep/t1696e/t1696e08.htm)

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