Dynamics of soil moisture regime in sugarcane farms as affected by their soil organic matter and physical properties

The dynamics of soil moisture regime as affected by different levels of soil organic matter was studied using water balance model. The study was conducted in the sugarcane field at Land Development Department Region 5 Office, Khon Kaen, Thailand to: a) establish the relationship between soil physical and hydraulic properties and different levels of soil organic matter content, b) monitor soil moisture regime and growth performance of sugarcane under rainfed condition, and c) develop a water balance model for predicting soil moisture regimes. The six levels of soil organic matter were 1.25, 1.27, 2.09, 2.87, 3.89 and 4.90 percent. They were set-up by applying different amounts of compost on Chum Phuang soil series (coarse-loamy, siliceous, isohyperthermic Typic Kandiustults). A bare soil that served as control treatment was added. Soil water balance model was developed to predict soil moisture content under sugarcane cultivation. Increasing the level of soil organic matter resulted in decreased bulk density and improved the porosity of the soil surface layer. Also, it improved the moisture characteristics, increased saturated hydraulic conductivity, increased saturated moisture, and increased field capacity, all of which consequently led to favorable soil moisture regime. The water balance model performance in predicting soil moisture content was satisfactory. There was a highly significant correlation between observed and predicted soil moisture content of each soil layer with R square ranged from 0.77 to 0.94. Soil moisture regime at different soil depths was favorable to plant growth. Moisture contents were within the available moisture range, between field capacity and permanent wilting point, except in the 0-10 cm soil layer that was too dry during crop establishment stage when there was zero rainfall but too wet during period when daily rainfall was more than 50 mm. Increasing the level of soil organic matter improved the yield performance of sugarcane.