POTASSIUM-CONSTRAINED HIGH YIELDS IN IRRIGATED RICE

Nutritional constraints often restrict yields of field crops in farmers’ fields. Determination of cut-off yield would increase the understanding of yield-limiting nutrients. The present study aimed to determine minimum rice yield target of high-yielding subpopulation in farmers’ fields and to identify the most limiting nutrient in farmers’ fields. Popular high yielding rice was grown in 42 farmers’ fields with two treatments – farmers’ nutrient management plan (FP) and improved nutrient management plan (INM). Nutrient composition was determined from Y-leaf after 45– 50 days of transplanting. Yield cutoff value was determined from compositional nutrient diagnosis (CND) generic model. The CND generic model gave 6.90 Mg ha⁻¹ as minimum cutoff yield of the high-yield subpopulation. Potassium (K) was identified as the main yield limiting nutrient for rice in piedmont soils. Rice in farmers’ fields may require higher K fertilizer dose for better yield.

Keywords:

• cutoff yield
• nutrient ratio
• compositional nutrient diagnosis
• variance ratio function

ACKNOWLEDGMENT

We appreciate financial support from DFID funded project on Poverty Elimination through Rice Research Assistance (PETRRA) to conduct the experimentation.