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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Soil erosion and conservation

Several mechanical methods are used to control and prevent erosion.

Flumes

Flumes are artificial channels that control the flow of water down a slope and release it into an area where its impact is reduced. They are often placed at the head of gullies to prevent the backward erosion of the headwall by water flowing over the top.

Dams

Debris dams are sited in the floor of gullies. Built of wood planks or tyres, they trap material moving down the gully floor. Often this technique is used in conjunction with pair planting.

Detention dams are small dams on farms or sites such as ephemeral waterways which, under heavy rainfall, can create erosion within the waterway. The dams are designed with a wide spillway that allows some storage of water, and in flood conditions allows a steady and slow release of water over the spillway.

Bulldozing

Where an earthflow has occurred, land smoothing is used to stabilise the soil. Bulldozers smooth the surface of the earthflow, so water will run off rather than pond and saturate the unstable soil. This technique is expensive.

Infilling can be used where tunnel gully erosion has occurred. The gully edges are pushed into the centre, which is compacted. The contour of the land is then shaped to spread run-off. This method was used successfully in the early 1960s at Wither Hills near Blenheim.

Furrows

Pasture furrows were introduced in the 1950s, notably in Canterbury’s cultivated downlands, to control run-off and prevent sheet and rill erosion.

In the pasture phase of crop rotation, small channels are ploughed about 10 metres apart across the slope. These divert run-off to grassed waterways, which then feed into natural streams and rivers.

A variant of pasture furrows are graded banks, which are much wider and further apart. These were used in Northland.

Cultivation techniques

Conservation tillage is where crop-growing soils are left, after harvest, covered in crop residues. This acts as a mulch, protecting the soil from wind erosion and raindrop impact.

With contour cultivation, all cultivation is done across the slope. This creates a series of mini-barriers to the downward flow of water.

Direct drilling is a method where pasture seeds or crops are drilled straight into the soil, under pasture. The advantage is that being unploughed, the soil is not vulnerable to erosion.

(Source – http://www.teara.govt.nz/en/soil-erosion-and-conservation/page-8)

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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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No-Till Technology: Impacts on Farm Income, Energy Use and Groundwater Depletion in the Plains

The adoption of a no-till feedgrain production system in a crop rotation with irrigated wheat production increases farm income, reduces underground water depletion, conserves energy, and reduces labor needs. Simultaneous attainment of these items might be considered compatible multiple goals of Great Plains farmers facing rising production costs, a declining water table and narrowing profit margins.

Benefits from the no-till system are due to improved wheat residue management techniques and the increasing availability of no-till equipment. Chemical weed control in wheat stubble provides increased soil moisture retention, reduced soil exposure to wind and water erosion and, in some cases, a savings in total production costs when compared with conventional tillage practices. Variable production costs are reduced somewhat by the no-till system in irrigated feed grain production but are higher than conventional tillage for dryland sorghum production. Machinery depreciation costs are reduced significantly for both no-till irrigated and dryland feedgrain production.

Increased profitability of the no-till feedgrain production system over conventional tillage is due largely to three items: (1) increased yields, (2) reduced fuel and labor requirements of irrigating and tillage, and (3) savings in machinery depreciation costs. No-till practices, however, require larger expenditures for chemicals.

In addition, harvesting expenses are increased due to higher grain yields from the no-till system.

In summary, the discounted stream of profits (5 percent) are 50 percent higher with no-till using the average pumping lift of 353 feet and a constant natural gas price for the next 10 years. If gas prices rise in relation to all other inputs, profits increase by 67 percent with no-till practices. Profits can be doubled with no-till in the high lift, rising gas price situation at 5 or 10 percent discount rates. With gas prices held constant, 67 to 69 percent higher profits are realized with the respective discount rates. If the low pumping lift situation is considered, profits are increased at the five percent rate about 50 percent with rising gas prices. If gas prices remain constant, profits are 45 percent higher in the low pumping lift situation. Somewhat  smaller increases in profitability are realized at a 10 percent discount rate.

Both water use efficiency and energy use efficiency increase with no-till feedgrain production. Increased yields per acre from no-till coupled with lower irrigation requirements and diesel use for tillage increase resource use efficiency.

The implications of this analysis regarding increased profits, reduced energy and labor use, and conservation of scarce groundwater raise the question as to why producers are not rapidly adopting-no-till practices. Recent changes in the relationship of fuel costs versus herbicide costs are only now being realized by many producers. Availability of new herbicides is increasing each year supported by substantial research to indicate regional and crop specifications. Improved machinery, particularly planters and drills, is being developed to compensate for seeding in heavier residue. Producer acceptance of “trash” farming has been slow, however.

Clean-till attitudes and psychology are being gradually eroded by the current economic advantages of limited tillage practices in more arid regions (Stewart and Harman).

Reporting of on-farm results in recent years supporting research findings indicates the importance of continued public policy support of research and education programs. Economic analyses of this type provide the basis for evaluating ongoing research results. Evaluations of resource use, impacts on production efficiency and assessments of profitability can provide impetus for continued public support. In addition, if higher profits accrue to agriculture as a result of new and improved means of efficient resource use, the financial condition of commercial agriculture may also be improved.

(Source  – http://ageconsearch.umn.edu/bitstream/32516/1/10010134.pdf)

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Weed control in no-tillage corn

Weed Control

Weed control in no-tillage corn is often more difficult  than in conventionally tilled corn. As a general rule, herbicide effectiveness decreases with the amount of crop and weed debris on the soil surface. This debris ties up herbicides and also presents a physical barrier to the uniform distribution of the herbicide on the soil for residual activity. Consequently, selection of herbicide rates and application methods is critical. Read and follow instructions on the herbicide label. On the other hand, residue cover provides some suppression of many weed species. In addition, there is generally less incidence of large-seeded weeds in continuous notillage systems.

Control of Existing Vegetation at  Planting

The types of weeds present and the type of cover determine the herbicide program required to control vegetation present at planting. It is necessary to consider the burndown materials and the postemergence characteristics of the other herbicides to be used in relationship  to the weed infestation.

Annual grasses and broadleaf weeds can be controlled with nonselective herbicides, such as glyphosate or paraquat. In general, no alteration in the residual herbicide program is needed to supplement the nonselective herbicide in these instances, although some herbicide labels require slightly higher rates to compensate for herbicide adsorption on the cover crop or other plant material.

When planting in perennial grass sods, a single paraquat application may not be sufficient to give satisfactory control. Control of orchardgrass and fescue requires use of the highest labeled rates of atrazine in addition to paraquat. The use of atrazine plus simazine combinations in perennial sods is not recommended because, unlike atrazine, simazine does not have postemergence activity and will not aid in burndown of these grass sods. In very vigorous orchardgrass or fescue sods, two applications of paraquat are sometimes required to achieve complete control.

The use of glyphosate should be considered for control of existing perennial broadleaf and grass weeds at planting. Care must be taken to allow these weeds to reach the minimum growth stages listed on the label before application is made. Often, this delays corn planting to the point that alternative crops or tillage methods should be considered as a means of control.

The use of glyphosate should also be considered when heavy infestations of annual weeds are present and have advanced to the stage at which paraquat will give only partial control.

Control of Annual Grasses

Fall panicum and other annual grasses can be major problems in no-tillage corn production. Simazine has good activity on annual grasses, and a combination of atrazine and simazine will give good control, especially of late-season flushes of these annual grasses. Chloroacetamide herbicides, including metolachlor, alachlor, and acetochlor, also provide good residual control of annual grasses and suppression of yellow nutsedge. These herbicides can be used in combination with atrazine, or in combination with atrazine and simazine.

Control of Triazine-Resistant Pigweed

Triazine-resistant pigweed is a major problem in a large part of our no-tillage corn acreage. The weed has no susceptibility to the triazine herbicides.Residual chloroacetamide herbicides afford fair-to-good control of this weed with optimum activation rainfall. If there is not  sufficient rainfall for activation or if very heavy rainfall occurs early in the season, pigweed control with these compounds will be inadequate, and a postemergence herbicide application will be required. Excellent preemergence residual control of pigweed can be obtained when flumetsulam, mesotrione, or pendimethalin are included in the pre-emergence herbicide application. These compounds are available in prepackaged mixes.

One product used extensively in Virginia no-till corn, Lumax, contains atrazine and metolachlor for general residual weed control, plus mesotrione for residual control of pigweed.

Control of Perennial Broadleaf Weeds

In the absence of tillage, herbaceous perennial broadleaf weeds can become very troublesome in no-till corn plantings. These species must be controlled with systemic herbicides at growth stages when translocation towards underground perennial plant structures is maximized. Generally, these perennials have not emerged at the time of planting, and making applications before planting are ineffective.

In most cases, the use of glyphosate-resistant corn hybrids represents the most effective overall method for perennial broadleaf weed control in no-till corn. Growers should also consider control of these perennials in rotational crops. Where soybeans are part of the rotation, perennial broadleaf weed control should be considered in glyphosate-resistant soybeans, because the soybean canopy is extremely effective in aiding the control of these species.

Control of Perennial Grasses

There are several excellent postemergence methods for perennial grass control in no-till corn. Johnsongrass can be controlled with nicosulfuron or with glyphosate in a glyphosate-resistant corn hybrid.Because of potential maize dwarf mosaic virus transmission to corn from dying johnsongrass following these applications, maize dwarf mosaic virus-tolerant corn hybrids must be used where postemergence johnsongrass herbicide programs will be employed.Bermudagrass control in no-till corn requires the use of glyphosate in glyphosate-resistant corn hybrids.Several postemergence herbicides, including halosulfuron, mesotrione, and glyphosate, can be used for the control of yellow nutsedge.

(Source – http://pubs.ext.vt.edu/424/424-030/424-030_pdf.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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