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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
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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

Zhejiang, China

Attainable yields and nutrient deficits

The nutrient omission plot technique was used to determine attainable yield with full fertilization and nutrient-limited yields. Table 1 shows the results averaged for eight villages in 1997−2004. Rice grain yield in plots fully fertilized with N, P, and K provided an estimate of the attainable yield target. The attainable yield target is 6–7 t ha⁻¹ for early rice, 7–7.5 t ha⁻¹ for late rice, 7.5–8.5 t ha⁻¹ for single hybrid Indica rice, and 8–9 t ha⁻¹ for single Japonica (inbred or hybrid) rice. The yield of rice not fertilized with N but fertilized with other nutrients was used to determine N-limited yield. Similarly, the yield of rice not fertilized with P but receiving other nutrients indicated P-limited yield; and the yield of rice not fertilized with K but receiving other nutrients indicated K-limited yield. The difference between the yield target and a nutrient-limited yield indicated the crop response to the nutrient. This response is usually ≤ 1 t ha⁻¹ for P and K in early rice, and ≤1 t ha⁻¹ for P and ≤ 2 t ha⁻¹ for K in late rice.

Table 1. Rice yields obtained with the nutrient omission plot technique in farmers’ fields in Jinhua in 1997−2004.

SD = standard deviation; n = number of replicated plots.

SSNM-based nutrient requirements

The SSNM approach was used to estimate fertilizer N, P₂O₅, and K₂O requirements based on the results in Table 1. Total fertilizer N required for rice (Table 2) was estimated from the measured response to N (Table 1) and an assumed target agronomic efficiency of N (kg yield increase kg fertilizer N⁻¹) of 15 for both the early and late rice seasons. See N management for more details.

Total fertilizer P₂O₅ and K₂O (Table 2) were estimated from attainable yield target, P-limited yield, and K-limited yield (Table 1) using the nutrient decision support system (NuDSS). Straw input was estimated as 2 t ha⁻¹.

Table 2. Fertilizer N, P₂O₅, and K₂O requirements estimated from results with the nutrient omission plot technique in Zhejiang, China in 1997−2004.

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