caa a22 4500 477111084 CHVBK 20180405111609.0 cr unu---uuuuu 170330e19961001xx s 000 0 eng 10.1007/BF02415525 doi (NATIONALLICENCE)springer-10.1007/BF02415525 Nutrient stocks in managed and natural humid tropical fallows [Elektronische Daten] [L. Szott, C. Palm] Managed fallows which recover nutrients more rapidly than natural secondary vegetation may improve the performance of shifting agriculture systems operating under inadequately long fallow cycles. Our objective was to construct nutrient balances for the soil, vegetation, and litter compartments of six planted leguminous fallows and natural secondary vegetation during 53 months. The fallows were planted on a previously cultivated Ultisol (Acrisol) in the Peruvian Amazon and included:Centrosema macrocarpum (Centrosema),Pueraria phaseoloides (Pueraria),Stylosanthes guianensis (Stylosanthes),Desmodium ovalifolium (Desmodium),Cajanus cajan (Cajanus), andInga edulis (Inga). In addition, in the natural fallow treatment secondary vegetation was allowed to establish and grow naturally. Quantities of extractable P, K, Ca, and Mg, total N, and organic C in soil to a 45 cm depth, and macrouttrients in aboveground biomass, roots, and litter were estimated at fallow planting, at 8, 17, and 29 months afterward, and at fallow clearing (53 months). Total N stocks increased by 10% in the Stylosanthes, Desmodium, Pueraria, and Inga treatments, but changed little in the Cajanus, Centrosema and natural fallows. This difference was largely due to greater net increases in both soil and vegetation compartments in the former group of treatments. In the Inga, Desmodium, and natural fallows, total stocks of P and K at 53 months were about 40% to 80% greater and 12% greater, respectively, than initial values, but Ca and Mg stocks were reduced by 25% to 40%. In the other treatments, there was generally little change in P stocks, but large (30% to 60%) reductions in K, Ca, and Mg during the course of the fallow. Although there were net decreases of stocks of P, K, Ca, and Mg in soil in all treatments during the fallow, storage of P and K in vegetation and litter in the Inga, Desmodium, and natural fallows offset losses of these nutrients from soil. These treatments also tended to accumulate more Ca and Mg in biomass and litter than the other treatments. These results suggest that leguminous fallow vegetation that accumulates large amounts of biomass may increase N, P, and K stocks, but that incomplete recuperation of Ca and Mg may limit the sustainability of short-rotation fallow-based systems on acidic, infertile soils. ei]Section editor: G R Stewart Kluwer Academic Publishers, 1996 Amazon nationallicence humid tropics nationallicence improved fallows nationallicence managed fallows nationallicence nutrient balances nationallicence nutrient stocks nationallicence tropical secondary forest nationallicence Szott L. Tropsoils Program, North Carolina State University, Yurimaguas, Peru aut Palm C. Tropical Soil Biology and Fertility Programme, Nairobi, Kenya aut Plant and Soil Kluwer Academic Publishers 186/2(1996-10-01), 293-309 0032-079X 186:2<293 1996 186 11104 https://doi.org/10.1007/BF02415525 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02415525 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Szott L. Tropsoils Program, North Carolina State University, Yurimaguas, Peru aut NATIONALLICENCE 700 1- Palm C. Tropical Soil Biology and Fertility Programme, Nairobi, Kenya aut NATIONALLICENCE 773 0- Plant and Soil Kluwer Academic Publishers 186/2(1996-10-01), 293-309 0032-079X 186:2<293 1996 186 11104 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer