SPATIAL AND TEMPORAL VARIATION OF SOIL MOISTURE CONTENT AND PENETRATION RESISTANCE AS AFFECTED BY POST HARVEST PERIOD AND STUBBLE BURNING OF WHEAT

摘要

The purposes of this study were to evaluate the spatial and temporal variations of moisture content (MC) and penetration resistance (PR) pre- and post burning period, and develop a mathematical model describing time and depth dependency of PR and soil MC to assess the best timing for soil tillage and planting. Soil moisture content was measured daily in 25 grids at 0-10 cm, 10-20 cm, and 20-30 cm depths while PR was measured with three replicates around the soil sampling locations (75 points in 25 grids) for eleven days following the wheat harvest. The stubble was burned at the fifth day, and the effect of stubble burning on MC and PR was determined during the next six days. Due to rapid capillary rise of water following the stubble burning, MC initially increased slightly in the surface layer for about a day (from 14% to 15%), and started decreasing until the 11th day (6%). The PR of 0-30 cm soil depth (1.29, 1.52, 1.75 MPa for 0-10 cm, 10-20 cm and 20-30 cm) sharply increased after the stubble burning at the same day (1.50, 1.99, 2.39 MPa). The moisture loss was mainly affected by the time elapsed after the harvest. MC and PR measurements in the 11th day at the surface layer in burned (6.91%, 1.41 MPa) and unburned control plots (6.10%, 1.47 MPa) were similar. Piecewise regression modeling precisely described the fluctuation in moisture content and penetration resistance before and after stubble burning.