Abstract
Vertical soil moisture profiles based on the principle of maximum entropy (POME) were validated using field and model data and applied to guide an irrigation cycle over a maize field in north central Alabama (USA). The results demonstrate that a simple two-constraint entropy model under the assumption of a uniform initial soil moisture distribution can simulate most soil moisture profiles that occur in the particular soil and climate regime that prevails in the study area. The results of the irrigation simulation demonstrated that the POME model produced a very efficient irrigation strategy with minimal losses (about 1.9% of total applied water). However, the results for finely-textured (silty clay) soils were problematic in that some plant stress did develop due to insufficient applied water. Soil moisture states in these soils fell to around 31% of available moisture content, but only on the last day of the drying side of the irrigation cycle. Overall, the POME approach showed promise as a general strategy to guide irrigation in humid environments, such as the Southeastern United States.
Highlights
Irrigation efficiency is a primary concern of irrigating farmers around the world
Fereres and Connor [3] pointed out that only 17% of agricultural land is irrigated across the globe; it accounts for approximately 40% of the total agricultural products
Verification of the entropy soil moisture profiles with all known input parameters for all cases shown in Figure 1 using observed data from the USDA Soil Climate Analysis Network (SCAN) site located beside the field
Summary
Irrigation efficiency is a primary concern of irrigating farmers around the world. It is defined as the ratio of the amount of water beneficially used by the crop or its ecosystem to the volume of water applied minus the change in soil moisture storage [1]. To maximize irrigation efficiency, the goal is to only apply the amount of water that the crop can beneficially use. Irrigated agriculture constitutes a significant portion of total agricultural productivity and profit. Fereres and Connor [3] pointed out that only 17% of agricultural land is irrigated across the globe; it accounts for approximately 40% of the total agricultural products. In the United States, only 5%–7% of the total agricultural land is regularly irrigated [4], and yet, it is responsible for over
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