Under the System of Rice Intensification (SRI), fertilizer type can change both rice performance and soil condition even when similar amounts of nitrogen, phosphorus and potassium are supplied. The 2005 study reported that combining chemical and organic fertilizer promoted plant development, increased grain yield, improved soil physical and chemical properties, and raised fertilizer-use efficiency compared with other fertilizer-source treatments under SRI.
This explainer places that finding within the wider evidence on nutrient management in SRI and paddy rice. It examines why organic and mineral nutrient sources can behave differently, how different fertilizer strategies affect yield and soil properties, where purely organic nutrition may perform less effectively, and why local soil fertility, water management, amendment type and application rate influence the effectiveness of an integrated nutrient-management program.
What fertilizer type changes under SRI
SRI is a crop-management system rather than a fertilizer recipe. Its core practices usually change seedling age, plant spacing, soil aeration, irrigation and weed management, so the root zone in an SRI field can differ substantially from a continuously flooded, densely planted rice field. Nutrient supply therefore interacts with a management environment in which roots may explore a larger volume of soil and alternate wetting can change oxygen availability, nutrient transformations and microbial activity. Fertilizer performance can consequently vary according to field conditions, nutrient sources and the wider management system.
The 2005 study compared fertilizer sources while maintaining equivalent nominal quantities of nitrogen, phosphorus as P2O5 and potassium as K2O. This design addressed whether the form in which nutrients are supplied can alter crop and soil responses. Coordinated chemical and organic fertilization promoted plant development and grain yield, improved physical and chemical soil status, and increased fertilizer-use efficiency. The results support the role of fertilizer source as an important component of nutrient management under SRI.
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