Dynamics of soil NH4-N as affected by rice straw and nitrogen rates
2000
Espiritu, A.J. | Corpuz, A.A. | De Dios, J.L. (Philippine Rice Research Inst., Maligaya, Munoz, Nueva Ecija (Philippines))
Field experiment was set up during the 1996 wet season (WS) and 1997 dry season (DS) at PhilRice [Philippines] CES to determine the effect of rice straw on soil ammonium nitrogen (NH4-N) dynamics at different nitrogen (N) rates. Four levels of N, i.e., 0, 90, 120, and 150 kg/ha, and 0, 90, 120, and 180 kg/ha were used during the 1996 WS and 1997 DS, respectively. Incorporation of rice straw (4 t/ha) was done one month before transplanting. Freshly collected soils were extracted and analyzed for NH4-N using the Indophenol (Colorimetric) method. The soil NH4-N of plots with straw incorporation was higher than in the no straw treatment. The dynamics of soil NH4-N peaked at 7 DAT [days after transplanting] and decrease to a minimum of 63 DAT and the pattern were similar for both 1996 WS and 1997 DS. Decreasing trend of soil NH4-N was common on all treatments, but the magnitude was lesser in plots applied with straw
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