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  • SSNM approach
  • SSNM in three steps
  • Initial concept of SSNM
  • Current version of the SSNM approach
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  • Principles of N management
  • Background on making an N Recommendation
  • Using the SSNM approach to formulate locally adapted N recommendation
  • Using the Leaf Color Chart (LCC) for fertilizer N management
  • FAQs on N Management
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  • Principles of P and K management
  • Background on making P and K recommendations
  • Using SSNM approach to formulate P recommendations
  • Using SSNM approach to formulate K recommendations
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  • Bangladesh
  • China
  • India
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  • Myanmar
  • Philippines
  • Vietnam
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  • Introduction to SSNM version 1.1
  • N management
  • P&K management
  • Implementing SSNM recommendations
  • Making an SSNM recommendation for rice
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  • SSNM: an approach for optimizing nutrient use in intensive rice production
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  • Nutrient omission plot
  • Potassium addition plot
  • Zinc addition plot

Cauvery Delta Zone, Tamil Nadu, India

		Previous Team Leader   Dr. S. Ramanathan Director of Research (to 31 May 2006) Tamil Nadu Agricultural University Coimbatore, Tamil Nadu
Team Leaders Dr. B. Chandrasekaran Director of Research Tamil Nadu Rice Research Institute Aduthurai, Tamil Nadu   Dr. V. Ravi Professor and Head Soil and Water Management Research Institute Kattuthottan, Thanjavur Tamil Nadu Email: tnj_swmri@sancharnet.in   Dr. Ramasamy Rajendran Professor of Agronomy Tamil Nadu Rice Research Institute Aduthurai, Tamil Nadu Email: rajendrankmu@yahoo.co.in     Site Characteristics   Tamil Nadu is one of the most important states for rice production in India because of its favorable soil and climatic conditions. The state ranks fifth in rice production in India, with yields among the highest in the country. Within Tamil Nadu, the Cauvery Delta Zone is a major area for production of irrigated rice.
		Fig. 1. The sites for the development and evaluation of SSNM in the Cauvery Delta Zone, Tamil Nadu, India.

The Cauvery Delta Zone has a humid tropical monsoon climate with an average annual rainfall of about 1000 mm. Most of the rain falls during the monsoon season from September to December, which is also associated with lower solar radiation and temperature of 20–30°C.

Farmers grow one or two rice crops per year, commonly established by transplanting. The double rice cropping system has the following two seasons:

• Kuruvai or dry season from June to September. This is the season with higher attainable yields due to relatively high solar radiation. Rice cultivars are typically short duration: about 110–115 days from seed to harvest.
• Thaladi or wet season from October to February. This is the season with lower attainable yields due to relatively low solar radiation. Rice cultivars are typically medium duration: about 130–135 days from seed to harvest.

The single rice cropping system is typically from August to January. This is a wet season referred to as samba. Rice cultivars are typically long duration: about 155 to 165 days from seed to harvest. Farmers also grow non-rice crops such as pulses, cotton, and sesame after wet-season rice (thaladi or samba).

Rice soils in the Cauvery Delta Zone are dominated by alluvial soils low in soil organic C and total N, with a neutral to slightly alkaline pH. Soils in the Old Delta are heavier in texture (clay loam to clay), whereas soils in the New Delta are lighter in texture (sandy loam to clay loam) with good drainage.

Development and Evaluation of SSNM

Research on SSNM started in 1997 in farmers’ fields at a site near Aduthurai in the Old Delta, and a site near Thanjavur in the New Delta (Fig. 1). From 2001 to 2005, the research expanded to include on-farm trials across more villages in both the Old and New Delta.

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