Intensive production gains in India

Rice is the staple food of about 65% of the total population in India, the second most populous country in the world. But, like many rice-growing countries, farmers in India have problems with water scarcity, weeds, and nutrient management.

The promise of aerobic rice
Signs of water scarcity are already evident in India’s agricultural areas. Because of overpumping of groundwater for agriculture and household use, the water table (top layer of groundwater) is dropping and thus greatly affecting the long-term sustainability of water resources for food production. With the alarming threat of water scarcity, scientists from the International Rice Research Institute (IRRI) and national partners have begun research activities on aerobic rice with farmers to solve this problem. The Irrigated Rice Research Consortium (IRRC) and the Challenge Program on Water and Food (CPWF) are two programs that support research activities in India through the Water Technology Centre (WTC) of the Indian Agricultural Research Institute (IARI).

The WTC has been working with farmers in Bulandshar, Uttar Pradesh, where they use a rice-wheat cropping system. During the wet season, they test the performance of potential aerobic rice varieties. They choose varieties based on yield, water savings, and farmers’ preference (which includes eating quality and marketability of the variety).

Pusa Sugandh 3 and Pusa Rice Hybrid 10 were varieties that performed well under aerobic conditions in the experiment field. Water savings of about 60% were observed and yields rivaled that of puddled transplanted paddy. However, farmers who tried growing aerobic rice usually encountered weed problems.

Benefits of direct seeding
Systems of transplanting rice into puddled fields give rice a size advantage over any germinating weeds, and the subsequent flooding of the soil suppresses most weed growth. Transplanting, however, requires substantial labor, and, as labor increases, direct seeding of rice offers an alternative. Weeds are a major constraint to direct seeding, as rice and weeds emerge together. High yield losses may occur if control measures are not effective. In direct-seeded rice, dry rice seeds can be sown directly into dry or moist nonpuddled soil (dry direct seeding as used in aerobic rice) or pregerminated rice seeds can be sown into puddled soil (wet direct seeding).

In India, concern about the sustainability of rice production systems has been raised due to the impact of puddling on the soil structure and groundwater depletion caused by pumping for irrigation. Dry direct seeding can address some of these concerns. Options with either conventional dry tillage or zero tillage (no cultivation) have been developed with farmers and researchers and are being promoted by the IRRC Labor Productivity Work Group (LPWG) and its partners in rice-wheat areas.

Studies by the LPWG showed that crop performance and weed populations are affected by different cropestablishment and weed management practices. Rice yield with direct seeding can be achieved that is as good as or better than that of transplanted rice, but greater attention needs to be given to weed management.

Many farmers are now testing direct seeding and gaining confidence with the options. In Uttarakhand, where the work started in 2002, only a few fields were directly seeded. Now, in 2007, more than 100 farmers are growing direct-seeded rice. Farmers see quick, visible economic benefits. Direct seeding can also save 20% of the overall labor needed for transplanting and reduce irrigation costs by 30%. Further, direct-seeded rice can mature 10–15 days earlier than a transplanted crop, which allows earlier sowing of wheat and higher yields.

Wet direct seeding also helped farmers in West Bengal who were severely affected by flooding this year. Farmers were able to establish rice by wet direct seeding after their transplanted rice and nurseries were lost to the flood waters. Many of these areas were resown with some of the drum seeders that had been recently distributed through projects and nongovernment organizations.

Researchers are now working with farmers who are direct seeding to gain a greater understanding of their information needs and decision-making, which will guide the development of information sources and enable constraints to be overcome. Researchers are also monitoring the changes in weed species that occur in farmers’ fields and in experiments to identify potential threats and anticipate difficulties in future work.

Gains in nutrient and crop management
Low soil fertility is widespread in irrigated rice areas of India as a result of long-term intensive cultivation with imbalanced use of nutrient inputs, resulting in the mining of some essential nutrients from the soil and the depletion of soil fertility. Research on the development and evaluation of site-specific nutrient management (SSNM) started in the Cauvery Delta of Tamil Nadu in collaboration with Tamil Nadu Agricultural University (TNAU) in the mid-1990s. In the late 1990s, the research expanded to the rice-wheat system in northern India through collaboration with GB Pant University of Agriculture & Technology.

On-farm trials conducted in the Cauvery Delta from 2001 to 2004 confirmed consistent increases in grain yield and profit with the use of locally adapted SSNM practices compared with the existing fertilizer practices of farmers. SSNM included reduced use of nitrogen (N) fertilizer within 2 weeks after transplanting when crop growth was slow and the need for N was small; better matching of N fertilizer use within the growing season to the needs of the crop for supplemental N as determined with a leaf color chart (LCC); and application of phosphorus (P) and potassium (K) fertilizer tailored to the location-specific needs of the crop. In trials across 25 farmers’ fields for four seasons, the improved management of N alone increased net profit by US$48–68/hectare/crop in the Old Cauvery Delta and by $32–33 in the New Cauvery Delta. The research clearly showed that the existing K fertilizer recommendation and use by farmers were insufficient in the New Cauvery Delta. Further increasing K fertilizer use increased profit by $36/hectare/crop in the New Cauvery Delta.

Focused group discussions with SSNM and non-SSNM farmers in the Cauvery Delta revealed significantly less pesticide use by SSNM farmers. SSNM did not reduce the costs for fertilizer or labor, but it markedly altered the timing of N fertilizer and increased the use of K fertilizer. The annual net financial benefit for the two rice seasons per year averaged $168/hectare higher for SSNM farmers, largely because of increased rice yields.

Locally adapted SSNM practices continued to be promoted by TNAU from 2005. During 2005-06, 295 demonstration trials were conducted in farmers’ fields across the Cauvery Delta. The grain yield increase because of SSNM ranged from 0.34 to 1.07 tons/hectare, with an average of 0.75 ton/hectare. Farmers realized additional profits of $50–140/hectare per season.

Meanwhile, the needs for N, K, and sulfur (S) continued to be assessed in farmers’ fields across northern India. Collaboration was established with Punjab Agricultural University in 2007 to formulate options that give farmers greater flexibility in implementing improved N management.

The PSWG aims to increase awareness of the SSNM approach and the opportunities it provides for tailoring fertilizer use to field-specific needs of rice; ensuring use of N, P, K, and S in optional amounts and ratios; and reducing the occurrence and development of rice diseases and insect pests. A second edition of Rice: a practical guide to nutrient management was published in 2007. It will be translated for distribution in India.

Trina Mendoza (t.mendoza@cgiar.org), David
Johnson (d.johnson@cgiar.org), and Roland Buresh (r.buresh@cgiar.org)

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