Conservation Agriculture


Farmers stop ploughing on Kazakhstani steppe

Zero-tillage, soil cover and crop rotation would help many countries to reverse land degradation and produce more food. Kazakhstan’s wheat growers are already well advanced in the transition to full conservation agriculture.

Kazakhstan is one of the world’s leading adopters of conservation agriculture. Direct-seeded, untilled land produces higher wheat yields than ploughed land, and carries lower production costs. Rotating wheat with other crops generates extra income and leaves residues that conserve soil moisture and suppress weeds.

The area of land that is no longer ploughed at all rose from nil in 2000 to 1.4 million ha by 2008. That increase is attributed to very high adoption rates on large farming enterprises of more than 50 000 ha, where managers are striving to increase production while reducing costs. However, the approach has also been taken up on small to medium-sized farms, a category which, in sparsely populated Kazakhstan, ranges from 500 to 2 500 ha. The adoption rate has been particularly high on farms with rich black soils, where high returns provide the capital needed for investment in CA machinery.

In zero-tilled areas, weeds are often controlled with herbicides. However, many farmers have found that combining zero-tillage with permanent soil cover also helps to suppress weeds. Without tillage, the natural store of weed seeds in the soil diminishes over time, and decomposing residues release humic acids, which block the seeds’ germination. While zero-tillage usually requires increased use of herbicides in the first few years of adoption, after four or five years the incidence of weeds – and herbicide use – decreases considerably.

Another advantage of retaining crop residues in northern Kazakhstan is that it increases the availability of water to the wheat crop. Annual precipitation ranges from 250 to 350 mm, and winter snow accounts for around 40 percent of it; when the snow is blown away by wind, the soil surface is left bare and dry. Retaining the stubble of the previous wheat crop traps the snow which, when the weather warms, melts into the soil. That has two benefits: more moisture is available along the soil profile and erosion is reduced or even eliminated. On-farm research has found that the use of residues to capture snow, along with zero-tillage, can increase yields by 58 percent.

Progress in the adoption of the third pillar of CA, diverse crop rotations, which would increase land productivity and help farmers to better manage wheat pests and diseases, has been slower. The vegetation period on the northern steppes in summer is short, with a high frequency of dry years. However, areas of traditional summer fallows are declining, as farmers take advantage of available – and sometimes abundant – rainfall to grow oats, sunflower and canola. Studies have shown the high potential of other rotational crops, including field peas, lentils, buckwheat and flax. A three-year study found that forage sorghum sown late in May and harvested in August provided not only fodder for sale or silage, but also left a durable post-harvest stubble that was very effective in trapping that precious snow.