FAO Agricultural Engineer, Theodor Friedrich talks about minimum tillage
All over the world farmers are tilling their land using tractors and animals. What's wrong with that?
Basically we don't need to plough the soil to receive a good crop. It is that simple. A natural healthy soil is the best environment for crop production. With tillage we often damage the soil.
That means agriculture contributes worldwide to land degradation and erosion?
Yes, definitely. Arable farming, especially where a plough is used, is a major contributor to the destruction of soil which leads to erosion and the loss of soil.
Does this apply to the developed and the developing countries in the same way?
This applies to all countries. Just look back to the 1930s, when the dust-bowls occurred in the United States. Because of mechanized tillage, huge areas were affected by soil loss.
The difference is that many developed countries are located in temperate zones, whereas the developing countries are in tropical zones, where there is often a very thin soil layer or very fragile soils. This means that the effects of degradation and soil erosion in tropical zones are much worse than in temperate zones. Also higher temperatures and heavier rainfall in tropical areas contribute to faster soil degradation and erosion.
Are you suggesting that farmers should stop tilling their fields?
Basically, yes. You certainly have to differentiate according to the types of soil, but generally I would say that we do not need to till our soil as we are doing today.
What is the alternative?
Well, we don't simply stop tilling and still produce. We replace tillage by managing the fields.
A soil, left alone, develops a good structure through biological processes. That structure cannot be improved by tillage. Of course, if we have an already degraded and compacted soil, we have to go step by step and assist the process of soil structuring before we can farm completely without any tillage. The first step is usually not to use the plough any more and only to loosen the soil with a chisel. For most crops like grains we don't need to move the soil, we just plant the seeds. It's different with crops such as potatoes, sugar beets or peanuts, here we still have to till in order to get the harvest out.
But what happens after the harvest?
After the harvest the soil must be covered with residues, straw, stems, or, even better, other crops should be planted which could be used as a fodder or cover crop. Crop rotation that favours the development of a soil structure is essential.
What about weed control?
Many people say, when we till less, we have to use more herbicides. In the beginning this may be right, when we start to move from conventional tillage to reduced tillage. But after some years the use of herbicides will decline. It all depends on the crop rotation. With good crop rotation, the use of herbicides will decrease. Also farmers could shift to very simple herbicides, if required, with very little damage to the environment.
Do you have strong financial arguments to convince farmers to shift to conservation tillage?
The financial arguments are the strongest for our new approach. The immediate result for the farmers is, that with conservation tillage, labour and energy costs are reduced dramatically. They don't need heavy tractors any more for soil tillage. Soil tillage is the operation in farming that is most energy intensive. In many developing countries, where farmers use animal traction, tillage is the bottleneck to get the seedbed prepared. Reducing tillage means that farmers have more time for timely planting. This is very important in Africa, for example, where every day, every week you lose in planting time can lead to reductions in yield.
Is animal tillage as controversial as tractor tillage?
Definitely not. The extreme cases of soil destruction are the result of mechanized tillage operations, simply because the farmers till deeper and faster, and the weight of the machines causes soil compaction.
Animal traction is less harmful, but it can still contribute to a certain extent of soil erosion. This is less related to the tillage as such, but to the fact that if the soil is left open and exposed to wind and rain, erosion occurs.
What type of machines are required for minimum tillage?
This is actually one of the major constraints for the transfer from conventional tillage to minimum tillage. Despite the clear advantages for the farmer, there is still a need for different machines. Farmers need a planter that can operate on soil which has residues still on the surface. These planters already exist for animal traction and manual mechanization as well, but they are more expensive than conventional planters.
Because of the residues on the surface, farmers probably cannot weed mechanically any more, so they might use herbicides. The equipment for this could be expensive. Cuts may be cut where farmers get together and share equipment.
Does this concept mean FAO has changed its position on mechanization?
Not regarding mechanization, but regarding soil tillage. In the past we rather uncritically favoured all techniques of mechanization and tillage. When we promote animal traction, for example, the first thing we recommend is a plough. This we have to change. We should combine animal traction and reduced tillage, and should introduce a zero-tillage planter.
Is there any country which already applies conservation tillage?
Yes, there are several countries, particularly in South and North America. A special example is Brazil with a long history of zero-tillage that dates back more than 20 years. It started with mechanized large farming and then spread down to the small farmers. In Brazil the area under zero-tillage is actually growing, which means the farmers believe in it now.
22 June 1998