01912naa a2200217 a 450000100080000000500110000800800410001910000160006024501210007626000090019752012550020665000130146165000190147465000290149365000120152265000330153470000150156770000150158270000160159777300810161315559012025-03-17       1992    bl uuuu     u00u1 u    #d1 aVERA, R. R.  aDevelopment of sutainable ley-farming systems for the acid-soil savannas of tropical America.h[electronic resource]  c1992  aABSTRACT: The paper reviews the evolution of the agricultural and livestock sectors in the neotropical savannas of Latin America, and their contribution to economic development and human nutrition. It is shown that the savannas are responsible for an increasing share of total agricultural production in Brazil, Colombia and Venezuela. The natural resources of these savanna lands are discussed, with emphasis on the physico-chemical characteristics of the soils, and the constraints that they impose on crop and pasture production. The development of acid-soil tolerant crops and forages is briefly summarized. Mechanisms of adaptation are described, and the contribution of adapted germplasm to soil enhancement is discussed. Lastly, the paper reviews studies conducted in Colombia to research crop-pasture integration in tropical ley-farming systems, using selected adapted rice lines and grass and legume forages as experimental models. Evidence collected over four consecutive years clearly shows the technical feasibility of developing alternative systems that combine annual crops and grazed pastures using low external inputs and enhancing soil characteristics. Ex-ante economic analysis reveals that these systems are also highly profitable.  asavannas  aAcidez do Solo  aAgricultura Sustentável  aCerrado  aDesenvolvimento Sustentável1 aTHOMAS, R.1 aSANINT, L.1 aSANZ, J. I.  tAnais da Academia Brasileira de Ciênciasgv. 64, supl. 1, p. 105-125, 1992.