사과(沙果)園 土壤의 硝化作用에 미치는 添加窒素肥料의 影響 = The Effect of Applied Ammonium Salts on the Rate of Nitrification in Apple Orchard Soils

다국어 초록 (Multilingual Abstract)

Each of the five apple orchard soils (Table 1), which was treated with different kinds of ammonium salts, was incubated at 30℃ under a humid condition for a definite period. Then the amounts of nitrate produced and water-extractable ammonium nitrogen (NH_4-N) from the soil were determined.
In proportion to increasing the addition of ammonium salts to the soil, the rate of nitrification in the (NH_4)_2HPO_4-applied soil was increased, but reversely that in the (NH_4)_2SO_4-applied soil was decreased except in the case of Soil-E. This repression in the latter could not be avoided by the addition of Potassium Phosphate to the soil (Fig. 1, 2, 3).
In the case of the (NH_4)_2HPO_4-application the level of water extractable NH_4-N from the soil were lowered, which in the case of the (NH_4)_2SO_4-, CH_3COONH_4-and the (NH_4)_2SO_4+Potassium Phosphateapplication, became extremely high (Fig.3,4,5). It seems that the difference of the amounts of water-extractable NH_4-N among these salts is due to the amounts of NH_4-N adsorbed to the soil. As a result of extrapolating the concentration of water extractable NH_4-N VERSUS amounts of added water curve, the concentration of NH_4-N in the liquid phase of the incubated soil was estimated at more than 400ppm in the case of (NH_4)_2SO_4 and CH_3COONH_4 (Fig. 5). Also it is known that the growth of nitrifying bacteria is prevented when the concentration of ammonium ion (NH_4^+) in the soil solution is higher than 400ppm.
When CH_3COONH_4 was applied to the soil, the amounts of nitrate produced were decreased with increasing the amounts of this salt at the initial stage of incubation, but after 14-day incubation there was a tendency for the nitrate amount to increase. This change was in accordance with the amounts of water-extractable NH_4-N from the soil (Fig.3).
The addition of Calcium to the soil increased the rate of nitrification to a great extent (Table 2, 3). And it was shown that this increase was closely associated with the rise in soil pH (Table 3).
Of these results, it was suggested that one of the reasons for the difference of the rate of nitrification among the applied ammonium salts may depend upon the difference of the ability of NH_4^4 adsorption to the soil, although the rate of nitrification in the soil which has a hich Calcbium saturation may not be so much influenced by NH_4^+ adsorption ability.

목차 (Table of Contents)

• Ⅰ. 緖 言
• Ⅱ. 實驗材料 및 方法
• Ⅲ. 結 果
• Ⅳ. 考 察
• Ⅴ. 摘 要