Organic matter and maize straw influence on soil moisture in an Oxisol under different tillages

Cultivation system is one of the main parameters inherent to soil water dynamics. Studies indicate that in soil conservation systems, such as no-tillage and crop-livestock integration, soil quality is maintained and even improved due to higher input of organic matter and straw kept on the soil surface. Thereby, the aim of this study was to analyze the influence of the spatial variation of maize straw and organic matter content on soil moisture of an Oxisol at the municipality of Jatai, southwest of Goias. Nine soil-sampling points were used in 1 ha, allocated to three different types of soil management (No-Tillage, Crop-Livestock Integration and Conventional Tillage). For the study of organic matter, soil samples were collected in nine points and three depths (0 to 0.12 m, 0.12 to 0.24 m and 0.24 to 0.36 m) for each point. The dry mass of straw was determined by a stove at 65°C, after sampling in the area using a circle with internal area of 1.0 m², released randomly near the sampling point. Soil moisture was determined immediately after straw sampling at the same site, using a time domain reflectometry sensor. The results indicated good distribution of straw on both systems, but there was no correlation between straw and soil moisture. The organic matter content was highly correlated with soil moisture, especially in No-Tillage and Crop-Livestock Integration systems. The authors recommend the increase of organic matter of the soils for better maintenance of soil moisture. Key words: Soil physical properties, soil water content, soil management systems, no-tillage, crop-livestock integration.