Effects of Fertilization Regimes on Grain Yields and Economic Returns of Pathum Thani 1 Rice Grown on Sapphaya Soil Series

Fertilizer has been considered as one of the most important inputs, driving productivity and economic returns of rice farming systems. This study aimed to determine an optimized fertilizer rate to maximize grain yields, economic returns over fertilizer cost, and agronomic fertilizer nutrient use efficiency (ANUE) of Pathum Thani 1 rice grown on Sapphaya soil series. A completely randomized design with 5 replications was used. The treatments involved 4 fertilizer regimes: 1) no fertilizer application (control, C), 2) fertilizer application based on soil analysis (SSF) at a rate of 4–4.4–4 kg N–P2O5–K2O/rai (1 rai = 0.16 hectare), 3) fertilizer application based on precision fertilizer management (PF) at a rate of 7.86–2.52–13.39 kg/rai and 4) fertilizer application based on traditional farmer practice (F) at a rate of 15.5–5–0 kg/rai. The results uncovered that grain yields (1,055 kg/rai) and economic return (7,724 Baht/rai) of rice received the PF treatment were significantly highest (P < 0.05), which were approximately 78, 37, and 27 % greater than those in the C, SSF, and F treatments, respectively. Similarly, the economic return of the PF was approximately 73, 46, and 35 % superior to those in the C, SSF, and F treatments, respectively. Moreover, ANUE (nitrogen and phosphorus) of rice received PF were greater (P < 0.05) than other treatments. These results suggest that productivity and economic returns of Pathum Thani 1 rice grown on Sapphaya soil series can be optimized by applying fertilizer at a rate of 7.86–2.52–13.39 kg N–P2O5–K2O/rai.