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There is limited adoption of irrigation scheduling tools that could improve application timing and water use efficiency in row-crop production systems common to the mid-southern United States. The objectives of this manuscript are to describe a sensor-based irrigation scheduling method and review its effects on water applied and crop productivity. The effects of scheduling irrigation based on the recommended construction, deployment, and utilization of the WATERMARK 200SS granular matrix (WATERMARK) sensor on water applied, crop productivity, and crop water use efficiency were reviewed for corn (Zea mays L.), soybean [Glycine max L. (Merr.)], peanut (Arachis hypogaea L.), and cotton (Gossypium hirsutum L.) produced in the Prairie region of Arkansas and the Delta regions of Arkansas and Mississippi. For corn and soybean, on-farm research indicates the recommended irrigation threshold of −85 to −100 cbar reduces total water applied up to 40% while maintaining or improving yield up to 3%, net returns up to $39 acre−1, and irrigation water use efficiency up to 51% for soil textures ranging from very fine sandy loam to clay. Similarly, for peanut and cotton, results indicate the irrigation threshold that minimizes water use while maximizing yield and net returns is −50 cbar and −100 cbar, respectively. The recommended method for scheduling irrigations with a WATERMARK 200SS soil moisture sensor promotes the efficient use of water in row-crop production systems common to the mid-southern USA. [ABSTRACT FROM AUTHOR]

This article identifies irrigated row-crop farmer factors associated with the adoption of water-conserving practices. The analysis is performed on data from a survey of irrigators in Mississippi. Regression results show that the amount of irrigated area, years of education, perception of a groundwater problem, and participation in conservation programs are positively associated with practice adoption; while number of years farming, growing rice, and pumping cost are negatively associated with adoption. However, not all factors are statistically significant for all practices. Survey results indicate that only a third of growers are aware of groundwater problems at the farm or state level; and this lack of awareness is related to whether farmers noticed a change in the depth to water distance in their irrigation wells. This evidence is consistent with a report to Congress from the Government Accountability Office (GAO) that recommends policies promoting the use of: (1) more efficient irrigation technology and practices and (2) precision agriculture technologies, such as soil moisture sensors and irrigation automation. [ABSTRACT FROM AUTHOR]

Optimizing overhead irrigation practices will ensure that water loss is minimized, and each unit of water is used most effectively by the crop. In order to optimize overhead irrigation setup, a study was conducted over two years in Mississippi to quantify the optimal overhead irrigation duration and intensity for six soil types commonly found in row-crop production regions in the state. Each soil type was transferred to containers and measured for total water infiltration and water infiltration over time using a two-nozzle rainfall simulator in a track sprayer. The rainfall simulator was calibrated to apply 2.1 mm of water per minute. The rainfall simulator ran on a 2.4 m track for 90 s, with 3.2 mm total water applied during that time. After the 90 s overhead irrigation event, each container was undisturbed for 150 s and assessed for irrigation penetration through the soil profile. Commercially available irrigation nozzles were measured for droplet size spectrum. Results showed that across soil type, organic matter was the primary factor affecting water infiltration through the profile, followed by soil texture. Irrigation nozzle volumetric median droplet sizes ranged from 327 µm to 904 µm. The results will improve overhead irrigation setup in Mississippi, improving irrigation water use efficiency and reducing losses from soil erosion over the application of water and reduced crop yield. [ABSTRACT FROM AUTHOR]

Field level data from a voluntary water use reporting program in the Delta region of Mississippi (MS), USA, provides empirical evidence that crop growers increase the amount of groundwater pumped for irrigation during periods of high temperature (degree days above 32 C). Regression analysis reveals that growers apply excess irrigation to cope with high temperature conditions while growing season evapotranspiration and precipitation are not significant factors in their decision of how much irrigation to apply. The existing literature indicates that excess water does not alleviate the harmful effect of extreme heat, making the excess irrigation wasteful and costly. Additional degree days above 32 C are associated with a 4.6 mm increase in irrigation depth (46 m3ha−1). This result may be partially explained by the fact that most farmers use visual cues (such as leaf folding which correlate with air temperature) to initiate irrigation events regardless of soil moisture contents. To quantify the impact of this mismatch, we estimate that shifting the underlying sensitivity in the farmers' minds by 1 C would reduce groundwater pumpage by 800862 mega liters across the Delta region of Mississippi, USA. The monetary cost of mismanaging heat stress with excessive irrigation is estimated at a minimum of over US$33 million per year. We further identify two additional possible distortions affecting the demand for irrigation groundwater: (i) overestimated benefits from irrigation; and (ii) underestimated groundwater pumping cost. The policy implication is that more efforts and incentives should be placed for programs that affect the producers' water management mindset, such as "Master Irrigator" programs that will reduce or eliminate the identified groundwater distortions and optimize benefits from irrigation. • Irrigators in Mississippi Delta over-apply irrigation because of high temperatures. • Precipitation and evapotranspiration do not determine amount of irrigation. • Perceived benefits from irrigation are higher than realizable and groundwater pumping costs are lower than in reality. • Increased irrigation water use efficiency may result in higher total water use. • Educational programs may be the best way to reduce or eliminate the distortions. [ABSTRACT FROM AUTHOR]

Naturally forming or mechanically induced hardpans limit water infiltration and crop productivity in many agricultural regions including the Mid-South U.S. This research was conducted to determine whether low-till parabolic subsoiling and furrow irrigation interact to influence soil water dynamics and maize production in the Mid-South. The factorial effects of subsoiling frequency (no subsoiling, NS; subsoiling only before cotton, CS; subsoiling only before maize, MS; and subsoiling every year, ES) × irrigation frequency (no irrigation, NI; low-frequency irrigation, LI; and high-frequency irrigation, HI) on infiltration, grain yield, and profit over specified costs were investigated for the maize portion of a maize-cotton rotation experiment in a silty clay loam soil near Tribbett, Mississippi. Subsoiling before maize improved the infiltration of irrigation (p < 0.05) but not the infiltration of in-season rainfall for irrigated treatments. By subsoiling before maize, high-frequency irrigation maximized grain yield in just one—rather than three—out of five years. Subsoiling before maize also increased non-irrigated yield in all five years. Overall, the combination of subsoiling only before maize and low-frequency irrigation achieved the largest average profit and a relatively small risk. These findings support the practice of low-till parabolic subsoiling before maize as a hydrologically effective and economically viable strategy to conserve freshwater resources in the Mid-South. • In-row subsoiling before maize with low-frequency furrow irrigation was optimal. • In-row subsoiling improved infiltration of irrigation but not of heavy rainfall. • Subsoiling timing affects profitability and water conservation in the Mid-South. [ABSTRACT FROM AUTHOR]