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Environmental benefits
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Soil improvements, Productivity and Production System Economics
The complex of the advantages of the crop-livestock integration are still not totally qualified nor even quantified. However, present knowledge indicates that this practice will surely be the basis of the sustainability of crop and livestock production in the Cerrados (Brazil). Most of the tropical forages are known for their adaptation and tolerance/resistance to biotic factors that affect annual crops. In respect to soil treatment maintenance of forage crops is the minimum possible. On the other hand, in the most varied annual crop production systems in the Cerrados biome, the application of soil correction and mineral fertilizer in balanced quantities has been necessary to achieve good harvests. In time, the continual use of these inputs improve/correct the soil chemical fertility. However, the intensively mechanized production of annual crops can result in the physical soil degradation, such as compaction and de-structuring as well as reduction of organic matter, even when using the traditional rotations. Also, a significant increase in the number of biotic crop pest species can occur, with a consequential reduction in productivity and increased costs of pesticide use.
The pastures, on the other hand, exhaust the residual crop nutrients but can recycle nutrients from deeper soil layers thanks to their abundance and depth of the roots’ exploration. Concomitantly, pastures are optimal accumulators of biomass both in and above the soil, practically during the whole period of non-climatic restrictions and for this reason enrich the soil with organic matter. Beyond this, the main tropical forages, particularly the grasses, have not suffered from many pest and disease attacks that are common in cultivated crops and thus break their cycle. Thus, one can say, that in the integration of these activities there exists a natural exchange of benefits in the sense of recuperating lands degraded by monocropping.
Chemical, Physical and Biological Soil Benefits
The soil organic material (SOM) is often considered as “the soil’s font of life” as it furnishes energy and nutrients for soil organisms, which, in turn, stimulate important activities in the natural and agricultural ecosystems such as carbon (C) and nutrient recycling. In the face of the limited use of soil correctives and fertilizers in the Cerrados region, it is easy to perceive the great importance of the nutritional function of the SOM in these ecosystems. In addition, the SOM executes other functions vital to the life cycle, such as, for example: a positive action on the activity of soil flora and fauna that help in soil aggregation - favouring a better water infiltration into the soil profile and reduced erosion and run off; the tying up of toxic types of aluminium and manganese through labile (volatile) C composites; increase in the capacity of effective soil cationic exchange (CCE), especially in soils with a pH greater than 5,5 that determines the better storage and retention of nutrients; better soil water storage capacity; positive action on the stability of soil aggregates, porosity and density; and contribution to decreased soil compaction. (Silva and Resck, 1997; Stevenson and Cole, 1999; Macedo, 2000; Craswell and Lefroy, 2001; Martius et al., 2001 and Palm et al., 2001). However, over years of crop cultivation, the loss of SOM is constant and consequently there is a compromise of the physical, chemical and biological quality of the soil. (Vilela et al., 1999 and Martius et al., 2001). In the contrary, the pastures, especially when well managed, have the capacity to maintain or even improve the level of soil organic matter as opposed to annual crops. This text is translated from the publication Integraçã Lavoura-Pecuária (2003) by João Kluthcouski, Luis Fernando Stone and Homero Aidar (eds.) |
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