02712nam a2200433 a 450000100080000000500110000800800410001910000120006024501010007226000560017330000090022949000360023852015350027465000150180965000220182465000090184665000220185565000120187765000100188965000230189965000100192265000180193265000260195065000180197665000120199465000300200665000200203665000090205665300140206565300360207965300150211565300120213065300240214265300200216665300330218665300210221965300190224065300190225915565231996-11-13       1994    bl uuuu      00u1 u    #d1 aLAL, R.  aMethods and guidelines for assessing sustainable use of soil and water resources in the tropics.  aColumbus, OH: Ohio State University/SMSS/USDAc1994  a78p.  a(SMSS Technical Monograph, 21).  aDegradation of soil and water resources, and environmental pollution are perceived to be major problems in the tropics. Vast areas of land are claimed to be accelerated erosion and desertification, compaction and hard setting, acidification, decline in soil organic matter content and biodiversity, and depletion in soil fertility. Theland area degraded by different processes in the tropics is estimed to be 915 x 10 6 ha by water erosion, 474 x 10 6 ha by wind erosion, 50 x 10 6 ha by physical degradation. Soil and environmental degradation, low productivity, and resource-based low-input agriculture go hand-in-hand. Soil and environmental degradation are perpetued by land misuse, and exploitative and fertility-mining systems of subsistence agriculture. Resource-poor farmers of the tropics are trapped in the ever-tightening grip of the soil degradation-low productively-poverty-low input-more degradation cycle. The concept of sustainability, useful and relevant as it is, needs to be made quantitative, objective, and reliable. There is a need to develop criteria and methods for quantitative assessment of sustainable use of soil and water resources. To do this is to: (i) identify soil and water indicators of sustainability, (ii) establish quantitative relationships between soil and water indicators and soil-modifying degradative processes on the one hand and productivity on the other, (iii) define critical limits of soil and water indicators in relation to threshold value beyond which productivity decline is...  aguidelines  anatural resources  asoil  asoil conservation  atropics  awater  awater conservation  aÁgua  aConservação  aConservação do Solo  aMeio Ambiente  aMétodo  aPreservação da Natureza  aRecurso Natural  aSolo  aAvaliacao  aEnvironmental impact assessment  aEvaluation  aMethods  aNature conservation  aRegiao tropical  aSoil sustainability criteria  aSustentabilidade  aSustentability  aTropical zones