Abstract
Sustainable food production, clean development mechanisms, and the rational and environmentally responsible use of natural resources are increasingly important themes in discussions of Brazilian agriculture and livestock production. In this context, land uses involving extreme landscape modification, monocultures, and pasture degradation remain the primary threats to sustainability. Pasture degradation is the most important current threat to sustainable animal production, while continuous monoculture systems increase the frequency of pests and diseases in croplands, causing massive damages. These problems have been mitigated to some extent by important new technologies such as no-till management (NTM), integrated crop-livestock systems, and integrated crop-livestock-forestry systems. Integrated systems are key alternatives for restoring degraded pastures and for producing slash that can be used in annual no-till agriculture to improve chemical, physical, and biological soil attributes. Understanding how different integrated systems affect physical soil attributes can help improve soil management and conservation via quantitative indicators of quality and sustainability, and can also increase the efficiency of pastures and integrated systems. However, studies that assess the long-term impacts of agricultural and livestock soil management practices on pastures and subsequent crops are rare in Brazil. The goal of the proposed study is to assess the soil quality under rotating crops in continuous integrated livestock-pasture systems (both fertilized and unfertilized), by examining physical soil attributes, soil quality indicators (the limiting water range), soil resistance to penetration, and soil water content at various depths in a long-term experiment installed in 1993-1994 by Embrapa's cattle division (Gado de Corte) in Campo Grande, Mato Grosso do Sul state, Brazil. The project will focus on experimental plots that have been managed as continuous pastureland and different integrated systems and crop rotations. Physical soil attributes will be quantified in five systems: S1 - continuous pastureland; S2 - integrated crop-livestock (1 year of agriculture and 3 years of grazing); S3 - integrated crop-livestock(4 years of grazing and4 years of agriculture); S4 - integrated crop-livestock(4 years of agriculture and 4 years of grazing); and S5 - integrated crop-livestock-forestry. An area of natural Cerrado vegetation will be used as a control. In addition to physical attributes (soil resistance to root penetration, density of soil, total, macro, and micro porosity, mean aggregate diameter, field capacity, and wilting point), soil fertility will also be assessed in annually collected samples. Integrated systems are expected to increase crop and pasture productivity and quality, in addition to improving soil quality and sustainability, and should thereby offer greater economic returns to farmers. (AU)
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