Evaluation of nutrient management support system (NuMaSS) as a tool for site specific nutrient management for corn

The dynamic and complex nature of soil makes each farm distinct from one another. Individual farm has specific nutrient needs, thus requires specific nutrient management. NuMaSS is a software designed to diagnose and predict site-specific acidity and nitrogen(N) and phosphorus(P) constraints in soils. This software has been extensively tested on-farm worldwide. In the Philippines, selected farms of the acidic uplands of Matalom, Leyte and Bontoc, Southern Leyte were among the validation sites. Almendras et al. (LSU) evaluated NuMaSS as nutrient decision aid for the acid upland soils in Leyte. Six farms were established in Matalom, Leyte from June 2003 to Nov 2005 and in two farms in Bontoc, Southern Leyte from July to Nov 2006. The farms were planted to VisCA var 2 during the 2003 wet season and Pioneer Yellow Corn Hybrid during the succeeding cropping periods. Findings revealed that: NuMaSS diagnosed all test farms as acidic and N and P deficient. The software recommended lime to farms with aluminum(Al) saturation values that exceeded the critical level of 30%. Initially, NuMaSS recommended higher rates of N and P relative to regional recommendation due to very low organic carbon and extractable P in the soil, which further decreased in the succeeding cropping. Trends through the three cropping seasons showed that NuMaSS recommendation resulted in highest corn yield, which was comparable to the regional recommendation. Omission of N from the NuMaSS recommendation did not result in significant yield difference. However, delition of P drastically reduced yield. Results imply that NuMaSS can diagnose and predict acidity and P constraints. However, where P is limiting, its sensitivity to N is undermined. The intervening effect of climate and management were other factors that influenced the enhancement and reduction of fertilizer efficiency and profitability. Generally, employment of site-specific nutrient management and farm management strategy improved corn productivity and profitability. NuMaSS was a useful decision aid tool in coming up with these strategies. The software is easy to use even for inexperience extension officers. The software, however, needs improvement in its N algorithm. The project showed that NuMaSS, a product of technological advances from developed countries, is workable locally, but can be improved by linking it with other local diagnostic tools such as soil test kit.