Почвозащитное и ресурсосберегающее земледелие

Indo-Gangetic Plains

Conservation Agriculture the key to food security
Resource-conserving technologies produce high wheat yields while reducing farmers’ costs by 20 percent. A shift to conservation agriculture in rice would create positive synergies in the production of both crops

In South Asia’s breadbasket, farmers practice zero-tillage to reduce costs and grow more wheat. Alternate wetting and drying of rice fields helps cut water consumption by up to 50 percent. Yields of both cereals improve after laser-assisted land-levelling. Farmers save on fertilizer with ‘needs-based’ nitrogen management and use legumes to suppress weeds.

For rice, the Rice-Wheat Consortium, an eco-regional initiative of national agricultural research systems and the CGIAR, promoted the substitution of long-season cultivars with short-seasons ones, and direct dry-seeding which, by eliminating the need for transplanting, reduces water use, energy costs and labour requirements. In dry-seeding, fields are prepared in June and a short-season rice crop is sown after irrigation to establish it before the onset of the monsoon in July.

During crop growth, various approaches are being promoted to help farmers increase rice output with the same amount of water, or use less water without reducing yields. One approach is alternate wetting and drying, in which the paddy is flooded and the water is allowed to dry out before re-flooding. Another is aerobic rice, where seeds are sown directly into the dry soil, then irrigated. Both approaches result in water savings of 30 to 50 percent. Raised-bed planting also produces significantly higher rice yields.

Another resource-conserving technology introduced to the IndoGangetic Plains is laser-assisted land-levelling. Many fields have uneven surfaces, which lead to wasted water, sub-optimal germination and lower yields. Traditionally, farmers have levelled their fields using scrapers and wooden boards. Now, laser-guided tractors, operated by private contractors, offer more precise levelling of fields at prices smallholders can afford. Recent studies in northwest India found that the technology is far more efficient than traditional levelling, reducing water applications by as much as 40 percent, improving the efficiency of fertilizer, and boosting rice and wheat yields by from 5 to 10 percent. It is equally profitable on all farm sizes. 

Farmers have also introduced new crop rotations that disrupt the life cycles of insect pests and weeds, and promote soil health. In Pakistan’s Punjab province, smallholder farmers rotate rice with berseem clover, a fodder that improves soil fertility and suppresses weeds that might otherwise infest subsequent cereal crops. On the eastern plains, where fields generally remain fallow for 80 days after the wheat harvest, a summer mungbean crop planted on zero-tilled soil produces 1.45 tonnes per ha, worth Us$745. Mungbeans also add nitrogen to the soil through biological nitrogen fixation. 

To reduce the wasteful use of fertilizer, the Rice-Wheat Consortium promoted ‘needs-based’ nitrogen management by introducing a leaf colour chart indicating the best times for fertilization. The charts were originally designed for rice, but were spontaneously adapted to wheat by farmers. Using the charts, farmers have reduced fertilizer applications by up to 25 percent with no reduction in yield.

Village surveys conducted across the plains in 2009 found that one in three farm households had adopted at least one resource-conserving technology, with the highest rates – of almost 50 percent – in the northwest. Farmers learned about the technologies from a variety of sources, including other farmers and equipment manufacturers, and most had integrated them into their traditional crop management practices. In northwest India, zero-tillage seed drills were the most common item of agricultural machinery after tractors. Their high adoption rate was made possible by the ready availability of seed drills developed by the private sector, with strong support from state and local governments. 

The impact of Save and Grow practices and technologies is reflected in recent increases in wheat production in India. Following poor yields from 2003 to 2007 in Punjab state, for example, wheat productivity has increased steadily, and average output exceeded 5 tonnes per ha in 201219. In 2014, India’s overall wheat production reached a record 96 million tonnes.

Source: FAO. 2016. Save and Grow: Maize, rice, wheat. Rome.