Behaviour of ammonium, nitrate and urea fertilizers applied to soils of different pH values for corn as indicated by 15N
1992
Nualchavee Roongtanakiat
One field and one lysimeter experiments, using 15N, were conducted to examine comparative recoveries of nitrogen fertilizer applied as ammonium sulphate (AS), potassium nitrate (PN) and urea (U) for corn in Pak Chong soil limed to different pH values and effects of these fertilizers on the uptake of some nutrient elements, and to obtain the balance sheets of the fertilizers. Results from the field study (with soil pH 5.1) showed similar effects of three fertilizers on plant growth, yields of grain, cob and stubble and the uptake of N, P, K, Ca and Mg. Estimated fertilizer-N recoveries (FR) for AS, PN and U were 25.3, 25.0 and 25.0 percent in corn plants and 69, 7, 68.7 and 51.1 percent in the soil, respectively. In the lysimeter experiment, the three forms of nitrogen fertilizer showed similar effects on growth and yields of corn and on percent FR in corn plants grown in the soils at pH 5.0 and 6.5. However, at the soil pH 8.0, percent FR in corn plants for PN (72.0 percent) was higher than those of AS (53.6 percent) and U (59.6 percent). Percent FR in the plant plus in the soil obtained from the field experiment were slightly higher than those from the lysimeter experiment. The three forms of N-fertilizer gave comparable leaching loss at all soil-pH values though they gave higher leaching losses at higher soil pH values. At soil pH 8.0, the gaseous loss was higher than at soil pH 5.0 and 6.5 and the loss from AS (38.2 percent) and U (31.4 percent ) were higher than that from PN (16.9).
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