Evaluation of different fertilizer combination and timing in dry direct seeded rice under rainfed lowland

Field experiments were established at International Rice Research Institute (IRRI) [Philippines] in 2017 wet season to evaluate the effect of fertilizers applied in dry direct seeding of rice in rainfed lowland conditions. Ten fertilizer treatments with rates of 100 kg N ha-1 – 40 kg P2O5/ha – 40 kg K2O/ha were imposed having different kinds of fertilizer combinations using complete fertilizer (14-14-14), urea (46-0-0), ammonium sulphate (21-0-0), solophos (0-18-0), and muriate of potash (0-0-60) during basal application, active tillering (AT) and panicle initiation (PI). In 2018WS, top five performing treatments were validated in the farmers field. Results shows that 29 days after sowing, DAS of 2017 WS, plots with basal application after seeding had the most number of tillers linear/m (135-15 vs. 90-92), biomass (78-85 g/m vs. 31-34 g/m), canopy covers (NDVI values 62-67 vs 40-44)) and leaf area index (1.05-1.35 vs 0.44-0.50) as compared to those with delay application of fertilizer. Grain yield shows that basal application of urea (46-0-0, NPK) in combination with solophos (0-18-0) and Muriate of potash (0-0-60) prior to sowing (0 DAS) gave higher yield (4.6 t/ha) compared to other treatment and control (2.65 t/ha). In 2018 WS validation in the farmers field, soil types such as clay loam, loam, and silty loam gave different response to urea, ammonium sulphate, and complete. In Bukay Pait with clay loam soil, complete fertilizer in combination of urea (3.74 t/ha) was significantly higher with other treatments while ammonium sulfate had the lowest yield (2.67 t/ha). In Nipaco and Tayug with silty loam soil type, application of complete as basal was significant different to other treatments having 4.2 t/ha and 3.8 t/ha, respectively. In conclusion, fertilizer application during sowing or basal application helps improve the yield of dry direct seeded rice.