Current fertilizer recommendations normally consist of one recommendation with fixed amounts and timings for large rice-growing areas. They do not assist farmers in dynamic decision-making and do not consider needs of rice grown in different places and seasons.
To eliminate wastage of fertilizer and increase farmers' income, new technologies that would consider adjustments in fertilizer amounts and timing of application to the location- and season-specific needs of rice are needed. An approach that feeds rice with nutrients as and when needed (called site-specific nutrient management or
SSNM) ensures the correct nutrients are applied at the right time and in the amount needed by the rice crop. See:
The need for SSNM
Much of the nutrients required by the rice plant come from soil. But this supply of
nutrients is typically insufficient to meet the nutrient requirements for high rice
yields. The use of fertilizers is consequently essential to fill the deficit between
crop needs for nutrients and the supply of nutrients from soil and available organic
inputs.
Current fertilizer recommendations in Asia are typically
of the blanket type recommendations --- having fixed rate and timing over large rice-growing
areas. Such recommendations assume the crop need for nutrients is constant among years and
over large areas. But crop growth and crop demand for nutrients are strongly influenced by
climate and crop-growing conditions, which can vary greatly among locations, seasons, and
years.
Principles of SSNM
Site-specific nutrient management (SSNM) is an approach of feeding rice with nutrients as
and when needed. The application and management of nutrients are dynamically adjusted to
crop needs of the location and season. The SSNM approach aims to increase farmers' profit
through: i) increased yield of rice per unit of applied fertilizer; ii) higher rice yields;
and iii) reduced disease and insect damage. The features of SSNM are:
1) This approach firstly advocates the wise and optimal use of existing indigenous nutrient
sources such as crop residues and manures.
2) Application of nitrogen, phosphorus, and potassium fertilizer is adjusted to the location-
and season-specific needs of the crop.
a. Use of the leaf color chart ensures that nitrogen is applied at the right time and in
the amount needed by the rice crop. This prevents wastage of fertilizer.
b. The yield in nutrient omission plots is used to determine the P and K fertilizer required
to meet the crop needs. This ensures that phosphorus
and potassium are applied in the ratio required by the rice crop.
3) Local recommendation for application of zinc, sulfur, and micronutrients are followed.
4) SSNM further provides guidelines for selection of the most economic combinations of available
fertilizer sources.
5) SSNM is a component of integrated crop management (ICM), which includes the use of quality
seeds, optimum plant density, integrated pest management, and good water management.
Use of leaf color chart (LCC)
 Recognizing the
limitations of the costly chlorophyll (SPAD) meter as an on-farm tool to assess
plant N status, a leaf color chart (LCC) modified from prototypes developed in Japan and China,
was recently developed through IRRI-NARES (National Agricultural Research and Extension System)
collaboration.
The approach makes use of leaf color as a visual and subjective indicator of plant
N deficiency. LCC is used as a reference tool to monitor the leaf color and compare
it with its six color panels of different shades of green to determine the need for N application.
Download guide
on how to use the LCC in pdf format
(134KB).
Download guide on how
to use the LCC - RTOP 2005 version (PDF File:339 KB)
Promotion of SSNM
The SSNM approach evolved gradually to include location-specific
adjustments with variety,
crop establishment, application of organic fertilizers, and water management. Guidelines have
been developed to take into consideration specific conditions and needs at
RTOP sites.
Interdisciplinary NARES teams are already involved in on-farm evaluation
of innovative nutrient
management strategies in Bangladesh, China, India, Indonesia, Nepal, Pakistan, the Philippines,
Thailand, and Vietnam. The involvement of public and private sector partners is being strengthened
in order to facilitate the dissemination of information and the delivery of SSNM to rice farmers.
Training manuals for SSNM have been designed for:
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