Zero-Tillage: Averting Dry Wells and Depleted Soils in South Asia

According to information from the International Water Management Institute (IWMI), by 2025 Pakistan and large parts of India will suffer "absolute water scarcity." This means they will lack the fresh water needed to maintain current levels of irrigated agriculture and will even have to shift water out of agriculture to meet domestic, industrial, and environmental demands. Raj Gupta, CIMMYT scientist and regional facilitator of the Rice-Wheat Consortium for the Indo-Gangetic Plains (RWC), *a researcher with considerable experience in water issues, talks of the region’s "double jeopardy" concerning water supplies and quality: “Excessive pumping is depleting subsoil water in many regions, while in others poor drainage is raising water tables nearly to the surface, creating sodic or saline conditions.”

The latter point touches on another, more immediate concern for rice-wheat farmers: declining soil quality. The rising demand for food and the subdivision of agricultural land over successive generations have intensified land use to the point where fallowing is practically unthinkable. The average per capita holding in Asia is now only 0.3 hectares, compared with 2.8 hectares for sub-Saharan Africa. Khushi Muhammed and his sons, for example, support a 15-member household in Sheikupura District, Pakistan, by growing rice and wheat on about 20 hectares—but he shares this land with three brothers. In Bayana Village, Uttar Pradesh, India, farmer Pramod Tyagi and his family work 12 hectares, producing potatoes, green vegetables, rice, wheat, lentils, and peas to support a household of 21 persons.

What are the practical effects of these problems? Start with organic matter. Many farmers remove as much as 10 tons of straw per hectare over an entire year's cropping. Some is used for fodder, but much is burned, filling the region’s air with unhealthy soot for a month or more and robbing the soil of organic material. Declining soil fertility—among other things from the unbalanced or insufficient use of fertilizer—is also affecting crop yields. Finally, yearly puddling of soils for rice, followed by intensive tillage for wheat—an average 6–7 tractor passes—obliterates soil structure and, in many areas, creates a nearly impenetrable “plow pan” immediately beneath the topsoil.

Time for Less Tillage

Arguably, the same agricultural policies that brought food self-sufficiency to South Asia have helped bring on these dilemmas (see: "In India and Pakistan, Grain Farmers Mean Business"), and central governments are lowly reforming policies to encourage innovation, productivity, and resource conservation.

However, certain researchers, among them CIMMYT agronomist Peter Hobbs, began proposing more sustainable farming options for South Asia more than a decade ago. Their ideas began with the soil—the indispensable resource base for all agriculture. “We’ve been hammering on tillage as a platform for a suite of options to lower costs, increase productivity, and improve soils,” says Hobbs. “In recent years we’ve realized that reduced tillage also saves water and cuts greenhouse gas emissions from agriculture.”

Working through the RWC, Hobbs and associates in national research programs have helped farmers test and share a wheat seeding practice that reduces costly and time-consuming cultivation to a single tractor pass. This simple amendment of sowing wheat directly into rice stubble, known as zero-tillage, has an astonishing range of benefits.

First, farmers’ costs (fuel, tractor rental or maintenance, water pumping) are slashed. The early-established wheat crop also shades weeds more effectively, reducing their growth and the need for herbicides. In many cases, yields improve because the grain matures before the pre-monsoon heat can wilt it. Moreover, since it enables wheat to take advantage of residual moisture from rice, zero-tillage saves farmers around 1 million liters of water per hectare, compared with conventional practices. This water ay represent an actual savings (important if farmers are eventually charged more for water and related expenses), or it may be used elsewhere for productive agriculture. Finally, by burning an average 60–70 liters less diesel fuel per hectare sown, tractors emit much less carbon dioxide under zero-tillage—nearly 800,000 tons less, if the practice were adopted even on 5 million of the rice-wheat region’s 12 million hectares.

In the 2000–01 crop season, use of zero-tillage in the western Indo-Gangetic Plains (India and Pakistan’s breadbaskets) increased to around 100,000 hectares, expanding from 12,000 the previous year and only 1,200 the year before that (see figure). “The pace of adoption now depends mainly on the speed at which private manufacturers can make zero-tillage planters,” says Larry Harrington, director of CIMMYT’s Natural Resources Group. The four- wheel tractor version of the planter costs about US$400—well within reach of tractor operators’ budgets, since a single planter can sow an average of 80 hectares per season. More farmers without tractors can hire sowing services, because zero-tillage reduces the cost of sowing. This saves the farmers money and frees up their time for other profitable activities. A variant of the zero-tillage planter is available for the two-wheel tractors used in the eastern rice-wheat regions, and another reduced tillage option that requires no machinery at all is being tested and promoted by the RWC for the farmers with fewest resources. Finally, building on trust gained through successful promotion of zero-tillage, the RWC is testing another innovation—growing crops on raised soil beds. Water savings under bed planting are even more dramatic than those for zero-tillage alone, and average between 30% and 50%.“Farmers are testing beds mainly with wheat right now, but we look forward to a time when rice and any other crops will be grown on permanent beds, with no tillage necessary throughout the year,” says CIMMYT wheat agronomist Ken Sayre, who with many colleagues in South Asia and the RWC is promoting beds and other resource-conserving land management practices.

Farmer-Driven Research

By and large, farmers testing zero-tillage say they intend to continue using the practice, and they are vociferously apprising researchers of the improvements needed. “Rather than spend long years ‘cooking’ technologies on experiment stations, the RWC and its partners have given farmers promising technologies to test under their conditions,” says Gupta. “Now farmers are coming back and asking for focused assistance. ”According to Mushtaq Ahmad Gill, who leads the On-farm Water Management Directorate (OFWM) of Punjab Province, Pakistan, this approach has been crucial: "If the last five years of our efforts to promote resource-conserving technologies like zero-tillage have taught us anything, it’s that we must work with the farmers.”

Water at Issue?

Gill is convinced that resource-conserving practices are essential if South Asia’s farmers are to deal with water shortages, energy constraints, the demands of exploding populations, and global economic and marketing challenges. "Water is the lifeblood of Pakistan’s crops and economy. Persistent drought has reduced canal water supplies and caused the mining of aquifers, the deterioration of water quality, higher production costs, and lower wheat yields," he says. "We must learn to grow more rice and wheat with less water, less energy, and less land. The simple answer is conservation tillage. In about 200 villages of Punjab, more than 4,000 farmers who used locally developed equipment to grow wheat on 30,000 hectares with zero-tillage last year got 17% more yield than conventional tillage, besides saving about 3,000 rupees per hectare on tillage, diesel, herbicides, and water. These farmers are the salesmen of this innovative technology for the region."

Joint Efforts by CGIAR Centers and Funding Partners on Rice-Wheat Systems

With newly approved funding from the Asian Development Bank (ADB), several CGIAR centers and partners are launching a series of collaborative projects through the Rice Wheat Consortium (RWC) on issues central to rice-wheat cropping systems and agriculture in South Asia. Topics include the following: salt and water balances; the cultivation of rice on raised beds; nutrient, weed, and soil management in rice-wheat systems; crop diversification, including potatoes; and the introduction of legume crops in rice-wheat systems. “The focus will be on farmer participatory research, although some of the work involves more basic research as well,” says J.K. Ladha, IRRI rice-wheat coordinator and a soil scientist who has worked for years in the region. “All the key issues will be covered—crops, soil, water, and diversification.”

The collaboration features participation at each research site by most international centers that work through the RWC. The ADB project is just one of many conducted by the Consortium, and it relies on complementary support from other approved projects, national programs, and international centers. Over the years a number of generous partners including ADB have supported the RWC. Among them are the following:

The Directorate General, International Cooperation of the Government of the Netherlands (DGIS)
The CGIAR Finance Committee
The Australian Centre for International Agricultural Research (ACIAR)
The Department for International Development, UK (DFID)
The International Fund for Agricultural Development (IFAD)
The United States Agency for International Development (USAID)

According to RWC facilitator, Raj Gupta, ADB supported the Consortium in its early efforts to set up an ecoregional program focused on natural resource management. “Their new funding is allowing us to improve cooperation between international centers and national programs,” he says. “Contributions from the CGIAR Finance Committee, obtained with help from the World Bank, were crucial when other support had waned. In recent years, DGIS has provided generous, unfettered contributions for testing and promoting technologies such as zero-tillage. ACIAR, USAID, DFID, and IFAD have also assisted with money for key research, and we are just beginning another project with funding from New Zealand.”

Finally, national research systems of the participating countries have also provided funding and significant in-kind support for RWC activities, and international centers like CIMMYT have drawn on their own unrestricted funds to ensure that work goes forward.

* Led by South Asian agricultural research systems, the RWC is an alliance of those systems, international research centers, and advanced research institutes. CIMMYT contributes technical and management support. The RWC fosters sustainable improvements in agroecosystem productivity, together with the preservation of natural resources, in areas of the Indo-Gangetic Plains dominated by rice-wheat cropping patterns.