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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

Potassium (K) addition plot technique 

3.  Surround the plot with a small soil bund with a height sufficient to prevent movement of surface water inside and outside the plot. For transplanted rice, do this about 14 days after transplanting; for direct-seeded rice, do this 10–14 days after sowing rice.

4.  Uniformly broadcast KCl (60% K₂O) within the plot about 14 days after transplanting or 10-14 days after sowing wet-seeded rice. The added KCl should be enough to supply at least 30 kg K₂O ha⁻¹. (A higher rate of K₂O can be used at locations where severe K deficiency is suspected.)

5.  After 4 days, place channels in the soil bund (i.e., break the soil bund) to allow water to freely flow in and out of the K addition plot. The plot would then receive irrigation water as part of the normal practice of irrigating the farmer’s field.

6.  Within 20 days after transplanting and sowing rice, identify a representative 5 x 5 m area in the farmer’s field at least 10 m away from the K addition plot. This area must have the same cropping and fertilizer history as the area where the K addition plot is placed. Mark this area with bamboo or wooden stakes. It will be used for measuring rice yield produced from the farmer’s K management practice.

7.  At early panicle initiation, repair the soil bund around the K addition plot with a height sufficient to prevent movement of surface water inside and outside the plot.

8.  Uniformly broadcast KCl at 30 kg K₂O ha⁻¹ within the K addition plot.

9.  After 4 days, place channels in the soil bund (i.e., break the soil bund) to allow water to freely flow in and out of the K addition plot. The plot would then receive irrigation water as part of the normal practice of irrigating the farmer’s field.

10.  Other than for K application, manage the rice within the K addition plot exactly as in the adjacent farmer’s field throughout the growing season.

Management of potassium addition plots 

Farmers use their own field management and irrigation operation practices. All the farmer’s field operations and fertilizer applications in the K addition plot must be identical to the adjacent farmer’s field and to the area designated for the measurement of yield in the farmer’s field. The K addition plot will receive an extra application of at least 60 kg K₂O ha⁻¹ in addition to the farmer’s K application rate.

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