Sustainable Resource Management: CONSERVATION FARMING
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Conservation farming is the name given to a sustainable farming system that does not have all the drawbacks of normal farming systems. What do we mean when we say “sustainable”? Our definition is to farm in a manner that is not detrimental to the environment and that can be used over a long period of time.
Conservation farming consists of three components:
- No or minimum till
- Retention of plant stubble on the land
- Crop rotation with various crops
No or minimum till
Toothed implement
The fertiliser and seed are directly put into the furrow in the soil, on the correct depth for the crop in question. The soil is, in other words only worked once, reducing the cost of cultivation.
Retention of plant stubble
If the stubble is retained, it prevents soil erosion by wind and water. It also prevents high soil temperatures, preventing the destruction of bio-organisms in the soil.
The stubble also prevents evaporation of the moisture in teh soil and the moisture will then be used for the degradtion of organisc material in the soil, which has an enriching effect. Earthworms can live in the soil in these conditions, and will help in the degradation of organic material.
Crop rotation Crop rotation refers to the cultivation of different crops on a specific piece of land; the same crop will in other words not be cultivated every year. By rotating crops the soil will not be exhausted and gets the opportunity to recover. Crop rotation also means that crops which places nitrogen back into the soil, like soya or beans, will be part of the crop rotation programme. This will mean a saving on fertiliser.
Conventional farming systems
“Conventional” farming systems in this context refers to the traditional ploughing and sowing systems This includes the burning of stubble. Conventional farming systems have the following disadvantages:
seen on this photograph
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- The turning of the soil, to destroy weeds and to prepare a seedbed, leads to a bare surface where soil erosion is likely.
- During the turning of the soil, carbon dioxide (CO2) is released, which leads to a reduction of carbon in the soil. Remember that carbon forms the basis of chemnical, physical and biological processes in the soil Without carbon, none of these processes can take place.
- The loss of CO2 can be compared with the burning of organic material in the soil, which releases the valuable CO2 into the air. The producer loses this valuable source of carbon.
- The released CO2 moves to the upper atmosphere and contributes to global warming and the greenhouse effect.
- The organic material in the soil is exposed to the sunlight after turning the soil, where is dries out and is rendered useless to enrich the soil.
- The soil’s temperature is heightened by the sun and bio-organisms cannot survive. Walk on bare soil in bare feet and the heightened temperatures can be felt very clearly!
- Input costs are significantly higher than with conservation farming, since ore mechanical processes are required.
- The burning of stubble destorys the valuable protection of the soil surface and wind and water erosion may take place. Eriosion of up to 700 tonnes per hectare has been recorded during just one rainstorm.
- Over and above the loss of soil, which is irreplaceable, recently planted seed can also washed away, resulting in low production.
- Burning of stubble also prevents the enrichment of soil due to plant remnants that could have been degraded and would have increased the organic content of the soil.
- Ploughing may also lead to drying out of the soil and the resultant loss of moisture can mean that the farmer have to wait for the next rains before planting is possible.
Conservation farming
Healthy soil
Conservation farming, on the other hand, has the following advantages, not only for the producer, but also for the future use of the soil for farming:
- The soil, which is our biggest asset, is protected from erosion and the destruction of the structure of the soil.
- Reduced erosion helps to keep water sources clean, since less sediment occurs in the water.
- This in turns helps to prevent the silting up of our dams and also contributes to reduced costs when the water has to be purified for drinking water to cities and towns.
- The moisture content fo the soil is preserved and helps to maintain biological processes in the soil. This leads to increased organic content of the soil which again makes the soil more fertle and productive.
- The carbon content in the soil is increased, and, as already indicated, carbon is the basis of all chemical, physical and biological processes in the soil.
- Crop rotation helps to place nitrogen back into the soil, which leads to reduced fertilisation.
- Minimum till lowers the mechanisation costs dramatically. Smaller tractors can be used since the toothed implements require less power than traditional ploughs, but less tillage is required, with big savings for the producer.
- Conservation farming is a technique which can prevent the degradation of our soils or can help previously degraded soils recover. It can also help prevent the desertification of soils, which is an increasing problem worldwide.
- Conservation farming can also help in poverty alleviation, and can help produce more food while protecting our natural resources.
Please contact the Department for Agriculture: Western Cape for more information at Tel. 021 808 5366
