AN APPROACH FOR USE OF CLEANING CROPS AS READILY

为了评价猪屎豆属植物作为清洁作物的生长和氮（N）吸收潜力，在日本大坂通过田间和盆栽试验研究了几种猪屎豆属植物的干物质生产、根瘤形成和氮吸收的种间差异。结果表明，短花锦鸡儿、苍白锦鸡儿和印加锦鸡儿的营养生长旺盛，叶面积和分枝量不断扩大。所有的物种都有很高的干重和大量的N含量。每种植物的引入为以后的小麦作物提供了大量的必需氮。研究了植物快速分解的几个指标，如总C，N和木质素含量，并讨论了掺入小麦作物可能增加N供应和生长抑制。并对短花田菁、长喙田菁和长喙田菁的氮沉积能力进行了评价。绿色肥根系沉积物中的氮素占后茬作物全氮的比例较高，表明活性根瘤的氮素排泄是绿色肥配施土壤氮素缺乏的调节剂。

To evaluate the potentials of growth and nitrogen (N) uptake of genus Crotalaria used as a cleaning crop, interspecific differences in dry matter production, root nodule formation, and N uptake among several species were investigated in field and pot experiments at Osaka, Japan. C.spectabilis, C.breviflora, C.pallida, and C.incana exhibited vigorous vegetative growth, expanding leaf area and branching. All the species had high dry weights and a great N content. Incorporation of each species provided a large amount of N necessary for the succeeding wheat crops. Several indicators for rapid decomposition of the plants, such as total C, N and lignin contents, were investigated, and the possible increases in N supply and growth inhibition by incorporation to wheat crops were discussed. N-depositing capacity of C.breviflora, C.spectabilis and Sesbania rostrata was also evaluated. The proportion of N derived from rhizodeposited materials of green manures to total N in succeeding crop was relatively high, suggesting that excretion of N from active root nodules should be considered as regulator in N starvation in soil incorporated green manures.