Nitrogen mineralization in tropical wetland rice soils, 1: Relationship with temperature and soil properties
1996
Manguiat, I.J. (University of the Philippines at Los Banos, Laguna) | Watanabe, I. | Mascarina, G.B. | Tallada, J.G.
To study the effect of temperature on the soil organic N mineralization of tropical flooded rice soils, laboratory incubation experiments using 30 flooded rice soils from the Philippines, Indonesia, Malaysia, and Thailand were conducted under flooded conditions at 25 and 30 degrees C. The rate of N mineralization was determined every week, but the data at 56 and 112d were presented and statistically analyzed in this paper. Eleven soil physico-chemical properties were analyzed for correlating with N mineralization. At 112-d incubation, averages of N mineralization were 33 mg N kg(-1) at 25 degrees C and 47 mg N kg(-1) at 30 degrees C. Average ratios of N mineralization at 30 to 25 degrees C were 1.7 at 56d, and 1.5 at 112d. The ratios, however, varied from less than 1 to more than 2. The percentages of N mineralization at 30 degrees C and at 112d to soil total N content ranged from less than 1 to more than 5, but in two thirds of the cases the values ranked between 2 and 4. Simple correlation coefficients of N mineralization were significant with the properties related to organic matter and soil N (contents of total C, total N, dilute acid soluble carbohydrates, initial NH4(+), and microbial biomass N), and to a lesser extent with CEC. Dilute acid-soluble carbohydrate contents was most positively correlated with N mineralization for both temperatures and incubation periods
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