Site-specific nutrient management and rice yields in Agusan del Norte [Philippines]
2004
Mabayag, C.A. | Palo, Z.M. | Javier, L.C.,Philippine Rice Research Inst. Agusan, Basilisa, RTR, Agusan del Norte (Philippines)
Due to variations in agro-climatic conditions, generalized fertilizer recommendations are not effective when exploiting the yield potential of modern high-yielding rice varieties. In Caraga region, the soil is considered highly fertile due to high organic matter content (e.g. 6.3 percent in RTR, Agusan del Norte). Despite the high soil fertility level, the region had the lowest average grain yield (2.8 t/ha)when compared to yields in other regions in the country (BAS 2002). High pest incidence, frequent rainfall and low solar radiation, poor drainage, and inappropriate nutrient management are considered the major constraints to increasing rice yields in the region. Hence, proper diagnosis of the limiting nutrients in the soil with Minus-one Element Technique (MOET) and use of Leaf Color Chart (LCC) to assess the 'real time' crop need for nitrogen (N). Fertilizers are essential in developing the appropriate site-specific nutrient management (SSNM). Results of MOET tests showed that soil nutritional status varied in three farm sites in Agusan del Norte. In Barangay [village] 2, RTR, K was most limiting, followed by N and S. In Avancena, Sanghan soil was deficient in S, K, and N. In Central Sanghan soil was deficient in N and K. Fertilizer K at 144 kg K2O/ha each was applied in Brgy. 2, RTR, Avancena, and Central Sanghan. Ammonium sulfate was applied to supply N and S and each application was based on LCC. In SSNM plots in wet season (WS), grain yield were 4.5 t/ha in Barangay 2, RTR, 4.1 t/ha in Avancena, and 2.0 t/ha Central Sanghan. With SSNM, average yield increase across farm sites ranged from 0.5 to 1.5 percent in WS. In DS, yield increase with SSNM ranged from 6 to 37 percent. Yield increase differences could be attributed to variation in indigenous nutrient supply, climatic condition, and pest incidence (case in Central Sanghan in WS).
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