淮北滨海地区生土农田养分产投分析

在江苏淮地区的新垦土生荒土上，对水稻－小麦－水稻、水稻－油菜－水稻、水稻－绿肥－水稻３种种植模式不同施肥下的氮、磷、钾产投入与土壤肥力关系进行了分析，结果表明：在生荒土上，随着各植年限的增加，氮、磷的产股比有 大的提高。三季种植后，土壤有机质净增量与有机质投入量，总投氮与土壤全氮、碱解氮，总投磷量与土训速 效磷，总投钾量与速效钾呈显著正相，肥料投入对土土壤肥力演变起决定性作用，表６，参１２。

Output-input analysis of Nutrients in the Farmland Ecosystem with Immature Soil as Plough Layer

An experiment was conducted in the seashore region of northern Jiangsu to probe the causality of fertility enhancement of the immature soil formed after land leveling with application of some organic manures such as pig manure,cake manure and straws.The result showed that the nutrient output-input ratios increased with the number of cropping seasons in the immature soil.There was a significant positive correlations between the contents of soil organic matter and the amount applied organic material to the soil.The contents of soil total N,available N,available P and available K were also positively correlative with respective nutrient inputs into the soil and with respective nurtient differences between the input and output.It was concluded that inputs of organic material and nutrients were the key factors that control the fertility evolution of the immature soil.