不整地玉米膝高期淹施15N－尿素後氮素之追蹤

Abstract

本試驗前後於學甲兩處及霧峰一處不整地秋作玉米田進行。基肥於播種時施用N、P2O5、K2O各70，105及70kg/ha。試驗方法係於玉米膝高期設置內框和外框，以三種水量（5mm，50mm及100mm）淹施尿素（以N計70kg/ha)；內框內施用5atom%的15N標識尿素，而內框與外框所圍部分則施用一般尿素，並於尿素淹施後的特定時日追蹤內框所施標識氮素在土壤中之動態及玉米之吸收。Five atom % 15N-urea was used to study both the uptake by crop and the residual N in soil of the urea-N flood-fertigated with different depths of water (i.e,5mm,25mm50mm and 100mm) at the knee-high stage in no-till maize field. The rate of N applied was 70 kg/ha. A double flame was used to flood-fertigate the corn plant. In the subplot surrounded by the inner flame, the 15N-urea together with the afore-mentioned depths of water was flood-fertigated, while in the plot between the outer and inner flames, the ordinary urea together with the same depth of water as in the inner flame was flood-fertigated. The plant uptake of labelled nitrogen as well as the distribution of residual 15N in the soil profile were studied.