PHONNIE DU TOIT, ARC-GRAIN CROPS INSTITUTE
Conservation agriculture is a new concept for the vast majority of developing grain farmers in South Africa. In large parts of the summer rainfall area these farmers apply conventional production methods such as mouldboard ploughing and maize mono-cropping.
Conservation agriculture requires a high level of management and switching over to this production system will take the farmer through various learning phases. It is an integrated system built on the following
Minimum soil disturbance – Conventional tillage methods are replaced by reduced or no-tillage and crops being planted byadapted planting equipment.
Establishment and maintenance of an organic soil cover in the form of a mulch.
Implementation of crop diversification and rotations, as opposed to mono-cropping.
A lesson from abroad
Although farming conditions in the South Americas might be more favourable compared to that in South Africa, there is one important lesson to be learned from the recent advances that occurred on the grain production front of that continent.
During the nineties the practice of no-till, a key component of conservation agriculture, took countries such as Brazil and Argentina by storm. The lesson to learn from this is that the main actors in all this, often called “zero-till revolution”, were farmers. It was the farmers themselves who pioneered and demanded the development of a more sustainable system.
Implementing conservation agriculture in the developing sector
Reducing the risk of dry seasons
The impact of conservation agriculture appears to be less striking in dry areas than in areas known for more favourable climatic conditions. The challenge to farmers in dry regions is to minimise all soil water losses as far as possible, as this will determine the level of water available to plants, which in turn will have a large impack on yield.
The implementation of conservation agriculture creates such an opportunity. Establishing a mulch of crop residue on the soil surface over time can make a significant contribution to reduce runoff, improve water infiltration and the water holding capacity of the soil.
Maintaining a soil cover
A conflict of interest often occurs as developing grain farmers in general rely on crop residues to be utilised by livestock. Some commercial conservation agriculture practising farmers with livestock in their farming system, apply controlled grazing.
Their practice is to withdraw the livestock once there is no evidence of maize kernels in their dung. The minimum mulching requirement for conservation agriculture systems is a 30% cover of crop residue at
planting time. Developing farmers are sceptical about the attainability of a proper soil cover especially in dry seasons when crop yields are low. Under such circumstances the establishment of fodder type sweet sorghums should be considered, as the high biomass of the crop can help to supply the fodder as well as crop residue reserves.
Effective weed control
Proper weed control is one of the difficulties associated with reduced tillage systems. Experience has shown that when developing farmers are exposed to the advantages of chemical weed control, usually seen as an advanced form of technology, they will start their own experimentation on certain herbicide combinations.
Developing farmers exposed to Roundup Ready maize cultivars and
the implication of these cultivars for effective weed control, responded
almost surprisingly positive. Even when the relative high cost of the
seed was emphasised, farmers remained optimistic about the potential
benefits of this group of cultivars.
Grain legumes as rotation crops in conservation agriculture
Although developing grain farmers in South Africa acknowledge the value and potential of grain legumes such as soybeans and cowpeas in a cropping system, they in many cases still fail to expand in growing these crops.
This is mainly due to the lack of a reliable market for the grain especially in the case of cowpeas. The only way to fully exploit the value of grain legumes in crop rotation is to improve the seed supply system and to create better market opportunities for the producer.
Conservation agriculture equipment and the gap
A number of suppliers of mechanised agricultural equipment in South Africa have recently started to exploit the demand for no-till planters. The current price of a two row no-till planter varies between R40 000 and R80 000 per unit.
Much more should be done to close the existing gap between developing farmers and these agri-businesses, since obtaining a suitable planter supported by an effective after sale service is a crucial step in starting with the practice of conservation agriculture.
Preparing to make the shift to conservation agriculture
Farmers need to be convinced that conservation agriculture can be successfully implemented under their unique production conditions. On-farm experiments provide an ideal “classroom” to expose farmers to conservation agriculture practices and to compare it with the conventional system over time.
Farmers considering conservation agriculture as an alternative production system are encouraged to become engaged in such activities through their local organisational structures. In this way many valuable lessons can be learned and much money can be saved.
Conservation agriculture is no cure for poor farming practice and the basic principles of good crop management should always apply. Prior to any attempt to change to conservation agriculture, farmers should make sure to remove all possible conditions that will limit the production potential:
Brake any plough pan that might exist in the soil
Rectify all problems of soil acidity the year before entering conservation agriculture
Correct any soil nutrient imbalances
Get rid of high infestations of problem weeds such as coach grass
Stopping the degradation of our vulnerable soils and opting for a more sustainable grain production system should also now rank much higher on the agenda of farmers in the developing sector of our country.
This been said, we should remember that such a significant change in a system as in Brazil for example, could not have happened without the purposeful devotion and team effort from all relevant role-players.
The implementation of conservation agriculture includes more than no-till or “spray and plant”, as it is called by some farmers who have been very superficially introduced to the concept.
In 2004 it was reported that 45% of the total land cultivated in Brazil, is now estimated to be managed with no-till. In the case of land cropped by smallholder farmers (<50 ha), this figure is even reported to exceed 80%.