SSNM, a success in India's Cauvery Delta Zone

Rice is the lifeline for farmers in the Cauvery Delta Zone, one of the major rice-growing tracts and popularly known as the rice granary of Tamil Nadu State in southern India. The Cauvery Delta has two distinct regions: the Old Delta, which has clay and clay loam soil, and the New Delta, with sandy and sandy loam soil.

Sadly, even though the Cauvery Delta may be the most fertile agricultural zone in drought-prone Tamil Nadu, its irrigated rice area is steadily declining due to the scarcity of water and labor, and diminishing profit. Hundreds of on-farm trials have been conducted to identify and evaluate practices to help boost rice productivity in the area, and results revealed that improved management technologies could increase rice yields—relatively more in the Cauvery New Delta than in the Old Delta.

Rays of hope
We learned that one way of boosting rice productivity is through site-specific nutrient management (SSNM). The findings of the Reaching Toward Optimum Productivity (RTOP) work group of the Irrigated Rice Research Consortium (IRRC) Phase 2 (which followed up on activities begun in the Cauvery Delta from 1994 to 1996) revealed that SSNM increased irrigated rice productivity by 0.45 ton per hectare in the Old Delta and 0.7 ton per hectare in the New Delta as compared with the existing farmers’ fertilizer practice (FFP).
SSNM is a plant-based approach in “feeding” rice with nutrients, as needed. By adopting the SSNM technology, Cauvery Delta farmers could benefit from applying need-based nitrogen (N), phosphorus (P), and potassium (K) fertilizer and achieve higher profit from optimized fertilizer use, reduced pest and disease incidence, and eco-friendly soil and nutrient management.

Improved fertilizer practices were developed through the SSNM approach evaluated with farmers starting in 1997. With SSNM, the use of fertilizer N was optimized and fertilizer K increased, while fertilizer P decreased slightly. The SSNM approach consistently increased grain yield and profit in the Cauvery Delta as confirmed through on-farm evaluation trials conducted during 2001-04.

Spreading the word
During the interactive workshop on SSNM held at Thanjavur, India, in August 2004, SSNM recommendations were developed in consultation with extension workers and fertilizer industry personnel for wider scale adoption of SSNM technology by Cauvery Delta farmers.

Researchers (agronomists and soil scientists) working in the region and extension staff involved in large-scale demonstrations were trained on SSNM. They participated in the monthly zonal workshop meetings of extension staff and discussed the benefits of adopting a fertilizer schedule calibrated through SSNM principles.

In Coimbatore, India, the Tamil Nadu Agricultural University promoted the SSNM approach as a management technology to enhance irrigated rice yields. Booklets and stickers on SSNM recommendations and benefits were distributed to farmers with the help of extension staff.

Since then, the focus has been on making SSNM known throughout the entire Cauvery Delta. On 23 June 2005, another interactive workshop was held at Thanjavur, India, attended by researchers, extension workers, fertilizer industry personnel, and farmers. As proposed during their discussion, large-scale SSNM demonstration plots were laid out in farmers’ fields during 2005-06 (dry and wet seasons) to popularize the SSNM technology, developed by IRRI and its national research and extension partners through a decade of untiring research and extension efforts.