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Conservation Agriculture/ Direct Drilling/ No-Tillage

Conservation Agriculture is an internationally recognized term to describe crop production systems that include the following aspects:

· Minimal Soil Disturbance

· Soil cover with plants and/or residues from previous crops

· Use of diverse rotations and cover crops

Direct drilling, zero-tillage and no-tillage are all aspects of conservation agriculture systems in that with each there is no excessive soil disturbance or cultivation except for the accurate placement of seed at sowing time.

 

Today it is estimated that there are over 106 million hectares(262 million acres) of cropland devoted to conservation agriculture practices(Derpsch & Friedrich, 2009). Up to half this area is located in South America, with the remainder in North America(36%), Australia(11%) and other countries contributing up to three per cent of the overall total.

In the UK it is estimated that approximately 45 per cent of the total arable area is under minimum tillage with some farmers now beginning to experiment with no-tillage and direct drilling techniques. Ireland has one of the lowest rates of uptake of minimum tillage throughout Europe with approximately 4 per cent of the arable area converted from plough based systems. There is no no-tillage system being practiced in Ireland today(Geraghty, 2009).

 

Conservation systems such as minimum-tillage and no-tillage are primarily concerned with sustainable soil management. If soils are managed in a sustainable way they lead to sustainable crop production and sustainable profits on farms.

Organic matter levels have reduced by fifty per cent over the last four decades in intensively cultivated land. Soil organic matter dramatically improves soil structure, soil water relations and soil fertility. Intensive tillage has an adverse effect on soil organic matter levels by causing accelerated biological oxidation of the organic portion of the soil. But soil organic matter levels can be increased by reducing tillage and soil disturbance, retention of residues, straw and stubble and by growing beneficial cover crops during fallow periods in the crop production cycle. Levels may be further enhanced by the application of organic manures and composts thereby enhancing soil fertility.

 

A combination of minimal soil disturbance and residue presence will encourage soil biological activity resulting in the growth of diverse bacterial and fungal populations in the soil. These species further process this organic matter and release nutrients contributing to overall soil fertility levels. The activity of other species such as beneficial nematodes, micro fauna and earthworms will also enhance the physical, biological and chemical attributes of the soil.

 

The use of varied rotations is vital for the overall success of a direct drilling system. The inclusion of break crops such as oilseed rape and beans will reduce build up of excessive crop residue on the soil surface and will present an opportunity to use effective integrated weed and pest management techniques aimed at controlling grass and other weed species and preventing the build up of pathogens and pest species in the soil.

 

Cover crops when used judiciously can suppress weed development, reduce pathogen levels in the soil, harness available soil nutrients and in the case of legumes fix atmospheric nitrogen for the succeeding crop. It is equally as important to pay the same degree of care and attention to the growth of a cover crop as you would with the main cash crop being grown.

 

All profitable crop production systems are based on the sustainable management of the soil. Organic matter is the lifeblood of any soil regardless of the texture, location or climate. Take good care of the most important resource you have.

Soil Texture:

• Soils are made up of sand, silt and clay in variable proportions
• Know your texture and improve management, cultivations, fertility and input usage
• Sands – larger particles, feel gritty, poor moisture/nutrient retention, low fertility
• Silts – medium particles, feel silky, slow moisture/nutrient movements, low fertility
• Clays – small particles, feel sticky, good moisture/nutrient retention, high fertility
• Sands and silt soils can suffer from capping and/or erosion; compaction risk in clays

Organic Matter:

• Organic Matter levels in intensive tillage land have halved in last 50 years
• Sustainable agriculture needs sustainable levels of soil organic matter
• Soil organic matter is composed of plant roots and residues and living/dead microbes
• Soil organic matter improves soil structure, soil fertility and water relationships
• For sustainable agriculture we need to put in more than we take out
• Raise levels by reducing tillage, incorporating straw or using cover crops
• Raise levels by using organic manures and sludges, liming or using autumn N

Soil Structure:

• Don’t confuse soil texture with soil structure
• Soil Structure is the arrangement of the different soil particles
• It determines air and water movements and provides a home for seeds/roots/microbes
• Soil structure influences farm operations and the impact of land use on environment
• Get into habit of using a spade for examining soil structure– shapes/holes/spaces/roots
• What you see will tell you an awful lot about what you can do

Earthworms:

• Healthy soils have high earthworm populations
• They affect soils biologically, physically and chemically
• Encourage their presence by reducing tillage and tillage depth
• Return residues to the soil – straw incorporation or green manures
• Avoid certain chemicals(eg methiocarb) and high levels of liquid manure

Soil Cultivations:

• Only practical time to deal with soil structure issues or problems is between crops
• So cultivate or deal with compaction when soils are ready – not when you are ready
• Better to cultivate/condition soils that are getting wet rather than soil that is drying out
• When ploughing – try to plough at shallower depths year on year
• Never ever ever over-cultivate a soil – it costs you money and damages soil structure
• Powered cultivators are often set at high speeds and turn soil into powder as a result
• Try to have some soil cover at all times, be it residue, a cover crop or cash crop
• Try and move towards reduced cultivations and minimum tillage
• Where possible try and introduce direct drilling – means rotations will be necessary

 

The above notes come courtesy of John Geraghty one of the leading arable and soil tillage specialists in Ireland, he may be contacted at aggeraghty@hotmail.com

 

Click on the image to gain access to a very informative South American site from Rolf Derpsch which will gain you access to the best in direct drilling/no till from around the world.

 

 

 

 

 

Drilling Considerations

Careful assessment of fields before combining will show which fields are in "good heart" and most suited to direct drilling. Dig trenches to check for compaction and see what kind of root development has taken place. Is there any earthworm population working for you or any worthwhile level of humus present? Feed the dreaded slugs with pellets before, during and after drilling as required.

If attention is paid to reducing full trailers to perhaps 2/3 of full and running them on the tramlines, with tyres at the minimum pressure, then these selected fields will be left in reasonably good condition. When combining these fields, effective chopping and spreading of straw and trash is critical, particularly when wide headers are used in high yielding crops, where the sheer volume of trash is immense and some combines are just not capable of handling the residue effectively.

To improve the residue management, stubble length can be much longer to reduce the volume of straw going through the combine. Long stubble is easier to drill into than poorly spread straw. In the early learning stages it could be worth considering removing the straw as this will make the drilling task simpler and easier - eg. when straw is baled or following rape/beans where there is little residue or spring drilling into autumn stubbles. Experience will prove invaluable for effective direct drilling results. Build up your experience through a variety of small on farm trials.

Due to the high drilling speeds that the Moore Unidrill is capable of - whilst maintaining an even depth (7-10 mph or 10-15 kmh.) and the resultant productivity, farmers can afford to be more selective on when to drill, particularly with direct drilling. While the establishment costs are at their absolute lowest with direct drilling, the level of management required to achieve good results is at its highest.

Despite the tight windows that UK and Irish weather imposes, the productivity and adaptability of the Moore Unidrill coupled with a firm weather proof surface, found in the direct drilling situation, enables farmers to choose their drilling days more discerningly to achieve optimum results.