15N Studies of the Behavior of Fertilizer Nitrogen in Three Different Soils (Lysimeter Trials)

摘要: A lysimeter trial is described in which the fate of 15N was monitored a sand, loam and clay soil by using it over period 6 years. The following results were obtained. 1. uptake fertilizer nitrogen plants, determined 15N, lower than conventional method (“difference method”). Nitrate better utilized plants ammonium 15N. total only gives hints these differences. 2. extent to utilize between 38 58%; case differences this figure 48 68%. 3. Plants remove more from when N applied without fertilization. influence two nutrient forms subordinate significance. 4. After six years 26 54 % remains soil. resulting sequences are > sand nitrate. 5. immobilization most pronounced first four but then decreased considerably; sandy even slightly regressive. 6. biggest part deposited uppermost layer amount deeper layers diminished appreciably. type has greater form nitrogen. 7. If left compared with losses soil's reservoir (plants' uptake, leaching) there negative balance for mainly