Improving rice production in rainfed lowlands using the nutrient manager tool

Rainfed rice farmers have low grain yields because of regular drought occurrence. To a considerable extent of low yield is caused b y the limited availability of nutrients as insufficient water empedes nutrient absorption by the plants causing limited growth and access to available water resources in turn. Site Specific Nutrient Management (SSNM) was developed to improve rice crop nutrition and help farmers optimize their nutrient management. aBut the Nutrient Manager, the tool enabling SSNM, has not been validated in rainfed environments. This study aimed to validate the use of Nutrient Manager for rainfed lowland rice in the Philippines and to determine its effect on grain yield and productivity. Participatory experiments in farmers' fields were set up in 2011 wet season in Pangasinan and Tarlac, where rainfed rice is still common. Tested were three treatments: farmer's practice (FP), Nutrient Manager's Recommendation (NM), and Nutrient Manager Recommendation with additional 10 kg P205/ha and 20 kg K20/ha (NM and PK). Covering 50 sq m, each treatment was replicated in 10 farmers' fields in each region. The results showed a relative increase compared with FP of 8% and 14% grain yield in the NM and NM and PK treatments, respectively. Furthermore, the NM and PK treatment produced the highest (4.9 t/ha) in both regions. This can be attributed to the low availability of P and K under water-limited conditions. Obviously, the NM and PK treatmens was better in providing sufficient macronutrients needed for good plant growth under these conditions. Apart from the increased yields, the NM and NM and PK treatments had lower fertilizer costs, reflecting the efficiency of the site-specific, recommendations. In conclusion, recommendations by the Nutrient Manager increased yield and productivity, and reduced costs. As technology is user-friendly and accessible in many parts of the country, the findings can be used to further adapt the Nutrient Manager to rainfed lowland environments.