红壤的供氮能力及化肥氮的去向

采用盆栽试验 ,研究了由第四纪红色黏土和红砂岩发育的不同侵蚀程度红壤以及施用有机或无机肥 1 0年以上培肥的红壤在不加外源氮肥条件下的自然供氮能力 ,以及施用1 5N肥源后肥料氮在土壤 -作物系统中的去向。结果表明 :红砂岩发育红壤 (红砂土 )的矿化量和供氮量显著高于第四纪红黏土 (红黏土 ) ,同一母质中轻度侵蚀红壤的矿化量和供氮量又显著高于重度侵蚀红壤。培肥后红壤的矿化量和供氮量显著提高 ,其中有机培肥红壤高于无机培肥红壤。侵蚀红壤的氮肥利用率低 ,土壤残留氮率较高 ,氮肥损失率不大 ,其中红砂土的氮肥残留率明显低于红黏土 ,而氮肥损失率却显著高于红黏土。培肥后红壤的氮肥利用率明显增加 ,其中有机培肥红壤的氮肥利用率和残留率显著高于无机培肥的红壤 ,而氮肥损失率却明显低于无机培肥红壤。

SOIL NITROGEN SUPPLY CAPACITY AND FATE OF APPLIED FERTILIZER NITROGEN IN RED SOILS

A pot experiment was conducted to study soil nitrogen(N)supply capacity in eroded and improved red soils. The eroded red soils were derived from Quaternary red clay and red sandstone.The improved red soils derived from Quaternary red clay had been applied with organic manure or inorganic fertilizers for more than 10 years.Results showed that the amount of soil N mineralized and supplied to plant in the soil derived from red sandstone was higher than in that derived from Quaternary red clay.Soil N supply capacity of the improved red soils increased significantly with the soil applied with organic manure taking the lead.When N fertilizer was applied to eroded soils the N taken up by plant was low,with high N residue left in the Quaternary red clay in particular,and unaccounted for N was low with a lower value in Quaternary red clay.When N fertilizer was applied to improved soils efficiency of N fertilizer was high.Both plant and soil recoveries in the improved soil applied with organic manure were higher than in that applied with inorganic fertilizers.