Ammonium release of some paddy soils in the lower north, central plain and northeast of Thailand
2006
Wassana Khaokaeo(Kasetsart University. Bangkhen Campus, Bangkok (Thailand). Faculty of Agriculture. Department of Soil Science) | Tasnee Attanandana(Kasetsart University. Bangkhen Campus, Bangkok (Thailand). Faculty of Agriculture. Department of Soil Science) | Jongruk Chanchareonsook(Kasetsart University. Bangkhen Campus, Bangkok (Thailand). Faculty of Agriculture. Department of Soil Science) | Prapa Sripichitt(Kasetsart University. Bangkhen Campus, Bangkok (Thailand). Faculty of Agriculture. Department of Agronomy)
Fertilizer management is one of the key factors for high yielding of rice besides good variety and suitable soil management. Nitrogen fertilizer application on rice is one of the crucial factors for maximum porfit. Ammonium release or accumulation after submergence was known to be the index of nitrogen supplying capacity of the soils. The data is useful for effective fertilizer application. The study on ammonium release of 18 soil series which are the representative paddy soils in the lower North, Central Plain and Northeast of Thailand was performed. The works comprise 3 experiments: (1) Amount and pattern of ammonium release. The results showed that ammonium contents of all soils studied increased with time of submergence. The ammonium content reached the peak at 28 days of submergence. The amount released was higher with higher total nitrogen and pH of the soils. The amount released of the soils followed the equation. Y = A-Be sup (-ct) except four soils series, this might be due to the discontinuous release of ammonium at the first 28 days of submergence. The amount of ammonium release depends on soil total nitrogen. (2) Comparison of the temperature of soil incubation on ammonium release. The higher ammonium content incubated at 40 deg C was observed as compared to the ammonium content at 30 deg C incubated temperature. A highly significant correlation was observed between the amounts of ammonium released at the two temperatures. (3) Comparison of extractable ammonium using four different extracting solutions was investigated, there were 2 NKCl, Mehlich I, 0.25 MH2SO4 and 1 percent ascorbic acid. A significant correlation was observed between Mehlich I and 0.25 MH2SO4 extractable ammonium and the ammonium released at 28 days of incubation.
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