紫色水稻土长期定量施肥氮素矿化特性研究

STUDY ON THE CHARACTERISTICS OF NITROGENMINERALIZATION IN PURPLE PADDY SOILS FERTI LIZED FOR NINE YEARS

本文用数学模型对改进的Stamford法(嫌气—间歇淋洗法)研究水稻土氮素矿化的可行性作了检验。结果表明,紫色水稻土9年定量施肥的7个处理中,氮素矿化可分为高、中、低和极低量4种供氮类型。其氮素矿化势(No),以化肥配施高量猪粪的最高;其次为配施高量绿萍、蚕豆青和低量猪粪。矿化势占土壤全氮的8.39％～10.40％。氮素矿化速率常数K值差异不大。两种嫌气培养测定值与矿化势呈显著和极显著正相关。矿化势与土壤全氮、有机质、无定形氧化铁等密切相关。盆栽水稻植株干重、吸氮量也明显反映出供试紫色水稻土供氮能力的差异,而以化肥配施高量猪粪、绿萍为最佳的有机—无机配肥方式。

Four mathematical models were adopted to estamate the theoretical and practical values of modified Stanford's method (i.e anaerobic incubation--interval leaching method) applied to the research of nitrogen mineralization in paddy soils. With the help of three mathematical models, quantitatively fertilized purple paddy soils were divided into four types high, moderate, low and very low in quantity of mineralizable N. The nitrogen minera,lization potential (No) of the soil to which chemical fertilizer together with high level pig manure is applied was the highest, followed by the soil treated with chemical fertilizer combined with high level Azolla imbricata, and with young bean plants and low level pig manre, 'No' constituted 8.39%～10.40% of total soil N. and the nitrogen mineralization rate constant K in different soils appeared varied. Soil mineralizable nltrogen obtained by two anaerobic incubation methods was significantly correlated with No. So were total N, organic matter and amorphous iron oxide. Dry matter yield, N uptake by the rice plants in the pot experiments could refiect the diversities of N-supplying capabilities in the soils tested, showing that the treatments of chemical fertilizer combined with high level pig manure and Azolla imbricata were better than the other treatments in this study.