Temporal Stability of Soil Water Storage along a Transect in a Farmer's Corn Field.

Soil water storage during crop development is a major factor determining cereal biomass production under rainfed farming. The present study was aimed to understand the inherent spatial and temporal variability in soil water storage and its relation to biomass production in Corn (Zea mays L.) in a farmer’s field. A representative transect was selected in the corn field. Based on the results of the spatial analysis of soil water content, soil water content sensor access tubes were installed at 45 locations at a depth of 0 to 80 cm and measurements taken at 10 m intervals along the transect. Soil water contents were measured, approximately on a biweekly basis, using a capacitance probe. Temporal stability of spatial patterns of soil water storage observed along the transect at different crop growth stages was analyzed by (1) checking the reliability of a location to maintain its rank in a cumulative probability function (2) ranking the average relative differences in soil water storage for each location from the mean spatial water storage for different sampling times (3) calculating the Spearman rank correlation coefficient of soil water storage between different sampling times considering all the locations. Temporal stability of the spatial pattern of soil water storage was mainly explained by the distribution of soil texture and elevation along the transect. Even though the spatial average standard deviation of soil water storage along the transect was low (~ 2.5cm) during the crop growth, the high variability existing with biomass production (~ 5 t ha^-1) was mainly due to the spatial variability in soil texture. Temporal stability of the spatial pattern of soil water storage helped to characterize the spatial variability in Corn biomass production along the transect.