EL BATAN, Mexico (CIMMYT) – Zero tillage, the agricultural practice of sowing seed directly into unplowed soil and residues of previously grown crops, has been proven for the first time to dramatically boost wheat yields and deliver significant economic benefits to smallholder farmers in seasons of excess rainfall.
A new study involving more than 200 small-scale wheat farmers across 15 villages in Haryana state, northern India, showed that zero tillage of wheat into recently-harvested rice fields can lead to harvests of nearly 16 percent more grain than farmers who followed conventional practices, when heavy rains fall late in the wheat season.
Conventional tillage for wheat in the study area of Karnal district is drawn-out, laborious and costly. Farmers remove residues of the previous rice crop, repeatedly run the tractor over the field to plow and prepare the soil, toss wheat seed by hand onto plots and finally plow it in using a rotary tiller.
“In conventionally tilled wheat plots, heavy downpours during grain development or near harvest can flood the field and sicken plants,” said Jeetendra Prakash Aryal, lead author of the study, published in Agriculture, Ecosystems and Environment, and an economist at the International Maize and Wheat Improvement Center (CIMMYT).
In zero tillage, the wheat seed is inserted directly into the soil, through crop residues and standing stubble, at a precise depth and in a single tractor pass using a specialized seeding implement. According to Aryal, not plowing and thus leaving the rice stubble and roots enhances the absorption and drainage of excess water and fosters a healthy crop.
Zero tillage for wheat is gaining in popularity in Haryana but is far from widespread. “Farmers in the state grow more than 2.5 million hectares of wheat, mainly in rice-wheat rotations, but zero tillage is used on only 0.3 million hectares — just over one-eighth of the wheat area,” said M.L. Jat, CIMMYT senior cropping systems agronomist and co-author of the study.
Haryana farmers’ slow adoption of zero tillage appears to be losing money for all concerned, according to Jat. “Based on our results, if this climate-smart practice had been used for wheat on 1 million hectares in Haryana in 2014-2015, farmers would have harvested 660,000 tons more grain, worth about $150 million,” Jat explained. “Moreover, the state government would have saved much of the $175 million it has paid to wheat farmers in compensation for yield lost to untimely and excess rainfall.”
Vital grain of civilization and food security under threat
Grown on 29 million hectares in India, mostly with irrigation during the country’s relatively drier winter months, wheat accounts for nearly a quarter of the dietary calories and protein in South Asia and furnishes income for hundreds of millions of farmers region-wide.
The crop suffers increasingly from climate change effects, including South Asia’s rising temperatures and progressively unpredictable rainfall. Studies have shown for instance that each 1 degree Celsius increase in average night-time temperature — a decisive factor for wheat development — reduces yields 6 percent.
“Regarding precipitation, 1982-2015 weather data from Karnal show that untimely, excess rainfall during critical stages in the wheat season occurs once every four years,” said Aryal. “The 2014-15 downpours reduced the district’s wheat output more than 17 percent from what was harvested the preceding year.”
More evidence and support for climate-resilient cropping
The economic and environmental advantages of zero-tillage for wheat in South Asia’s rice-wheat rotations have been amply documented. Eliminating plowing lightens tractor use, saving farmers diesel and reducing carbon emissions. Crop residues on the soil surface also help to capture and retain water in dry years.
“This is the first study to show that zero tillage provides higher yields for irrigated wheat where unexpected or poorly-distributed rainfall causes water logging under conventional tillage,” said Aryal. “It means that zero tillage might be the best option for South Asian wheat crops under diverse conditions and particularly as climate change makes precipitation increasingly erratic.”
According to Jat, the slow adoption of zero tillage for wheat in Haryana is due partly to the need for a special tractor-drawn implement for sowing, as well as to farmers’ lack of awareness of the practice and its benefits.
State officials have actively promoted zero tillage and the government recently reiterated its support for purchasing the seeder, which was developed and tested by Indian institutions and CIMMYT.
“The government of Haryana has taken a policy decision to aggressively promote the seeder for zero tillage and residue management and to provide 1,900 seeders on subsidy this year,” said Suresh Gehlawat, assistant director of agriculture, Haryana.
Given the seeder’s cost (about $2,000) and its capacity (able to sow as much as 3 hectares of wheat a day), CIMMYT and partners are promoting markets of local service providers who own the implement and can sow on hire, rather than having all smallholder farmers try to purchase a seeder.
Headquartered in Mexico, the International Maize and Wheat Improvement Center (CIMMYT) is the global leader in publicly funded research for development for wheat and maize and for wheat- and maize-based farming systems. CIMMYT works throughout the developing world with hundreds of partners, belongs to CGIAR and leads the CGIAR Research Programs on Wheat and Maize. CIMMYT receives support from CGIAR Fund Donors, national governments, foundations, development banks and other public and private agencies. www.cimmyt.org