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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
  • Indonesia
  • 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

Nueva Ecija, Central Luzon, Philippines 

 

		Research Results

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 three villages in 2003. Rice grain yield in plots fully fertilized with N, P, and K provided an estimate of the attainable yield target, which was higher in the dry than wet season. 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 averaged <1 t ha⁻¹ for P and K in both seasons.

Table 1. Rice yields obtained with the nutrient omission plot technique in farmers’ fields in three villages in Nueva Ecija Province, the Philippines, 2003.

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⁻¹ fertilizer N) of 25 for the dry season and 18 for wet season. See N management for more details.

Total fertilizer P₂O₅ and K₂O were estimated from attainable yield target, P-limited yield, and K-limited yield (Table1) using the nutrient decision support system (NuDSS). Straw input was estimated as 2.5 t ha⁻¹ for both seasons.

Table 2. Fertilizer N, P₂O₅, and K₂O requirements estimated from results with the nutrient omission plot technique in three villages in Nueva Ecija Province, the Philippines, 2003.

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

On-farm evaluation of SSNM

In SSNM, fertilizer N is applied several times during the season based on crop needs as determined by the leaf color chart (LCC). Fertilizer P is all applied within 14 days after transplanting (DAT) or 21 days after sowing (DAS); and fertilizer K is applied twice — about 50% before 14 DAT or 21 DAS and 50% at early panicle initiation. Rice yields averaged for 17 farmers’ fields in 2001 and 2002 and 27 farmers’ fields in 2003 were higher with SSNM compared with the farmers’ fertilizer practice (FFP) (Fig. 1).

Fig. 1. Performance of SSNM compared with the farmers’ fertilizer practice in Nueva Ecija Province, the Philippines. * indicates a significant difference between the two treatments at P<0.05 in a given year.

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