Growth Response of Three Tropical Leguminous Green Manure Plants to Soils Fertilized with CaCO₃ and Phosphate

抄録

Leguminous green manure plants play an important role in increasing agricultural crop production in infertile soils as they can improve soil quality with less environmental concerns. Many studies have reported suitable green manure plants for temperate regions, but little information is available for tropical regions. Therefore, we clarified the growth response of three common tropical leguminous green manure plants, i.e., cowpea (Vigna unguiculata), sunn hemp (Crotalaria juncea), and green gram (Vigna radiata), on a Haplic Acrisol, which is strongly acidic and low in available phosphate (P) and widespread in Southeast Asia, in comparison with the other P deficient soil, a Eutric Gleysol, which is a slightly acidic and P deficient soil typically found in alluvial area, with controlling soil pH and soil available P. Cowpea was able to yield the highest dry matter production and acquire the largest amount of P among the three green manure plants in the two soils. The amount of P acquired by cowpea from the Gleysol is 6-7 times greater than that from the Acrisol. However, it was also clarified that the P acquiring ability of cowpea would be insufficient even when the Acrisol was ameliorated with CaCO₃ and P fertilizers as the Gleysol. Therefore, it would be necessary to find other green manure species which have higher P acquisition abilities enough to give suitable growth on Acrisols.