Qualidade do solo em sistemas de integração lavourapecuária no Bioma Pampa.

Abstract

The increasing level of soil degradation has promoted the adoption of agricultural management that combine agricultural production to soil conservation. In this context, Integrated Crop-Livestock Systems (ILP) have been successfully adopted, because they occupy the available resources in agroecosystems, concomitant to the improvement of soil quality. Based on the above, this study was divided into two chapters, where we sought to evaluate the soil quality on family farms in ILP systems, defining physical, chemical and biological indicators able to detect the effects of management practices used in different land use systems. The chapter 1 was developed in the municipality of Arroio do Padre and the chapter 2 in Rio Grande, RS. Were evaluated three land use systems: grazed native field (CN), ryegrass pasture (PA) and maize with succession of ryegrass (MI). In each of the systems, disturbed and undisturbed soil samples were collected in the layers from 0.00-0.05m, 0.05-0.10m and 0.10-0.20m for determining indicators such as: bulk density, soil porosity, mean weight diameter, macronutrients, micronutrients, total organic carbon, total nitrogen, granulometric physical fractionation and densimetric physical fractionation, carbon management index, microbial biomass carbon, basal soil respiration and laser-induced fluorescence. In Chapter 1, we concluded that the factor analysis showed that the "Organic Matter Factor" was the largest contributor to the total variance of the data evaluated in the three layers. The indicators that compose the "Organic Matter Factor " are more associated with the CN, while the indicators of "Aggregation Factor", "Compression Factor" and "Microbial Carbon Factor" are more related to PA, and the indicators soil basal respiration, free light fraction and porosity are more related to the system MI. The bulk density is related to the three land use systems. Only the total porosity was not enough to detect differences between the systems studied. In chapter 2, it was concluded that the factor analysis showed that the factors "Organic Matter", "Light Organic Matter" and "Humified Carbon" were the main contributors to the total variance of the data evaluated in the three layers. The indicators that compose the "Organic Matter Factor" are more associated with the CN and indicators related to "Aggregation Factor", "Granulometric Fractions Factor” and " Total Porosity Factor" are more associated with PA e MI. The bulk density, the heavy fraction of organic matter and microbial carbon are related to the three land use systems. The mean weight diameter and basal soil respiration were not effective to detect differences between land use systems.