Evaluating integrated fertilizer strategies for sustainable paddy yield improvement in Mahaweli System B, Sri Lanka

Abstract

In Sri Lanka's dry-zone region, the Mahaweli System B area is central to national paddy production, benefiting from supplementary irrigation from the Maduru Oya reservoir. However, the high dependency on chemical fertilizers, subsidized by the government, has led to escalating environmental concerns and diminishing returns in paddy yields. Consequently, farmers have increasingly adopted integrated fertilizer management practices that blend organic and inorganic inputs to balance cost, yield, and environmental impact. This research investigates the effectiveness of these farmer-adapted integrated fertilizer strategies compared to conventional chemical-only fertilizer applications, focusing on yield performance, soil health, and economic feasibility. Data were collected through surveys of 100 farmers in the Dimbulagala block, assessing a range of factors including soil nutrient levels, crop residue management, fertilizer application rates, and land preparation practices. The findings reveal that while integrated practices support soil health and nutrient availability, yield outcomes vary significantly based on the type, timing, and quantity of fertilizers used. Notably, farmers who adopted a comprehensive management approach—incorporating organic inputs with optimized land preparation and crop residue practices—achieved better yields and improved soil quality. This study underscores the need for context-specific fertilizer recommendations that prioritize sustainability and long-term soil fertility. Further research on fine-tuning integrated nutrient management practices may enhance both productivity and ecological health, thereby supporting the livelihoods of paddy farmers in Mahaweli System B.