POTENTIAL OF SOME GREEN MANURE COVER CROP S FOR CONSERVATION AND RECUPERATION OF TROPICAL SOILS

The crops of cowpea (Vigna unguiculata), crotalaria (Crotalaria juncea and Crotalaria paulina), pigeon pea (Cajanus cajan), feijlo-bravo-do- ceara (Canavalia brasiliensis), jackbean (Canavalia ensiformis), lab-l ab (Dolichos lab lab), and mucuna-preta (Stizolobium aterrimum) were e valuated as green manure and cover crops in an Ultisol soil in Vicosa, MG, Brazil. The rate of crop establishment and percent of soil covera ge were evaluated. Fresh and dry biomass, root density and nutrient co ntent were determined at flowering stage for each species. Jackbean wa s the best species for both rate of crop establishment and percent of ground coverage. Pigeonpea was the best in terms of root penetration i n the soil, biomass production and nutrient immobilization. The crotal arias and cowpea were the most sensitive to soil compaction, having th eir root mass concentrated at the soil surface.