Optimizing site-specific nutrient management to enhance rice productivity in tidal wetlands

Indonesia’s 8.92 million hectares of tidal wetlands have significant potential for rice production; however, varying soil nutrient status remains a major constraint to productivity. Fertilization practices that are inconsistent with soil nutrient status result in suboptimal yields. This study aimed to (1) identify key nutrients limiting rice yield and (2) develop an optimal site-specific fertilization package for tidal wetland rice systems. Field experiments were conducted in Murung Karamat and Danda Jaya villages, Barito Kuala Regency, South Kalimantan. The results indicated that nitrogen (N) and potassium (K) were the primary yield-limiting nutrients. Nitrogen omission reduced rice yields by 30.4% (1.17 t ha -1 ) in Murung Karamat and 19.8% (0.95 t ha -1 ) in Danda Jaya, while potassium omission reduced yields by 18.7% (0.88 t ha -1 ) and 7.5% (0.40 t ha -1 ). The implementation of site-specific nutrient management has significantly increased rice productivity. In Murung Karamat, yield increases of 0.94 t ha -1 (21.4%) and 0.88 t ha -1 (20.0%) were achieved through the Rice Crop Manager (RCM) and the Swamp Soil Test Kit (SSTK). In Danda Jaya, RCM increased yields by 16.3% compared with farmer practices. These results demonstrate that precision fertilization, supported by decision-support tools such as the RCM and SSTK, can significantly increase rice yields in tidal wetland environments. RCM and SSTK show strong potential as decision-support tools for site-specific fertilization in tidal wetland rice cultivation.