Site-Specific Nutrient Management for Maize Production in Favorable Environments of the Philippines

Increasing the productivity and profitability of maize requires the effective use of nutrients from naturally-occurring indigenous and fertilizer sources to achieve high and sustainable yield. On-farm trials were conducted at key production sites in Isabela, Bukidnon, and Nueva Ecija with one or two hybrid maize crops per year within 2005 to 2007 to develop and evaluate a site-specific nutrient management (SSNM) approach for irrigated and favorable rainfed maize in the Philippines. Attainable yields of 7-10 t ha(-1) were obtained in the dry season and 7-8 t ha(-1) in the wet season from treatments supplied with ample fertilizer. Grain yields from omission plots followed the same trends as the attainable yield. Yield response to fertilizer application followed the order N>>P=K. Fertilizer recommendations in the SSNM treatment were calculated based on the site-specific attainable yield and yield response to fertilizer application: The SSNM approach increased yield on average by 1.0 t ha(-1) (+21%) compared to the farmer's fertilizer practice (FFP) measured in the same cropping seasons. Yield increase in the SSNM were associated with higher application of fertilizer N (+18%), P (+143%) and K (+135%). Fertilizer P and K application rates in the SSNM plots accounted for the partial removal of P and K in grain and stover to avoid nutrient depletion in the soil. Fertilizer cost was 55% higher in the SSNM, while profit (gross benefit over fertilizer cost) increased by PhP 5,789 ha(-1) (+8%) over the FFP.