Management of nitrogen fertilizer at flowering on puddled soils
2016
Girsang, S.S.
The study examined N fertilizer management in flowering in puddled (UY site) soil in two seasons (that is, WS2014 and DS 2014/2015). The experiment was laid out in a completely randomized design (CRD) with twelve locations in the two seasons mentioned. The soil is a silty clay loam and classified as Lithic Haplustept (Soil survey Staff, 2010; Alberto et al., 2014). The results revealed that additional 23 kg N at 68-73 DAT or during flowering can increase rice yield (0.31 Mg/ha in WS and 0.40 Mg/ha in DS). Additional N application at flowering and increase solar radiation at flowering to harvest can still increase rice yield as supported by the yield parameters which measured tiller number, total dry matter, and SPAD reading. Moreover, if factors such as water availability and solar radiation are favourable, compound fertilizer applied at 10 DAT can support rice growth until PI. Low variability of plant performances at flowering in terms of tiller number and total dry matter (TDM) can be used as indicators for an additional 23 kg N/ha at flowering (68-73 DAT). There was high correlation among tiller number, total dry matter (TDM) at 68-73 DAT, and tiller number at harvest (r 0.76). Based on the results, the recommended real-time N management (RTNM) of N using SPAD is at basal, active tillering, panicle initiation, and flowering when the SPAD reading is below 35. Furthermore, adjustments in timing of N application from 73 DAT to 68 DAT and plant spacing from 0.3 m x 0.16-0.18m to 0.3 m x 0.12-0.14m (250,000 plant populations) can increase grain N content and double grain yield gain. This study therefore suggests that nitrogen fertilizer use efficiency and rice yield can be increased by adjusting N fertilization (rate and timing) at flowering, plant population, and solar radiation.
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