Effect of Irrigation, Mulch and Crop Canopy on Soil Temperature in Forage Maize

A field study was conducted with forage maize grown during May and June to characterize the diurnal and seasonal varcation in of soil temperature. In the bare plot maximum soil temperature on clear days was as high as 46°C at 5 cm and 38°C at 30 cm depth, with respective diurnal oscillations of 14.5°C and 3°C. The top 50 cm root zone was exposed to detrimental temperatures (>34°C) for daily periods of 16 to 24 hours. Diurnal soil temperature wave damped at about 50 cm depth. During early growth stages of the crop, straw mulch alone as well as its combination with transparent polyethylene lowered maximum soil temperature by 11 to 4°C and its diurnal fluctuation by 10 to 4°C in the top 20 cm and brought it within the optimal range of 26–31°C. A fully developed maize canopy also substantially reduced the soil temperature. An irrigation decreased the maximum soil temperature of surface 20 cm depth by 11 to 2°C and the effect lasted for 9 to 4 days. Straw mulching and more frequmt irrigation significantly increased the green forage yield.