Twin-row planting in soybean (Glycine max L.) has been proposed for optimizing resource use and seed yield. Experiments were conducted in 2018 and 2019 on a Dundee silt loam to assess soybean seed yield and irrigation water use efficiency (IWUE) in response to single-row (SR) and twin-row (TR) planting geometries under rainfed (RF), all row or full irrigation (FI), and alternate row or half irrigations (HI). Averaged across two crop years and three irrigation regimes, TR enhanced seed yield by 13% over SR (4.5 vs. 4.0 Mg ha −1). The final plant stands established in the FI, HI, and RF under TR were 32, 33, and 31 plants m −2 , whereas 30, 31, and 27 plants m −2 were established under SR. Under both SR and TR, irrigations produced a higher number of pods per plant than of RF. Averaged across crop years, yields in the irrigation-planting geometry combinations were 4.8 Mg ha

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.

We develop a dynamic model of groundwater extraction for irrigation where climate change and technical change are included as exogenous state variables in addition to the usual state variable of the stock of groundwater. Our key contributions are (i) an intuitive description of the conditions under which groundwater extraction can be non-monotonic, (ii) a numerical demonstration that extraction is non-monotonic in an important region overlying the Ogallala Aquifer, and (iii) the predicted gains from management are substantially larger after accounting for climate and technical change. Intuitively, optimal extraction is increasing in early periods when the marginal benefits of extraction are increasing sufficiently fast due to climate and technical change compared to the increase in the marginal cost of extraction. In contrast, most previous studies include the stock of groundwater as the only state variable and recommend a monotonically decreasing

We assessed the potential profitability of twin‐row (TR) planting geometry as a water productivity‐enhancing practice and of skip‐row irrigation (SRI) as a water‐conserving practice in furrow‐irrigated cotton (Gossypium hirsutum L.) and soybean (Glycine max L.). Data from agronomic experiments carried on Dundee silt loam soils indicate that, on average, TR planting increases profitability by US$344 ha−1 for all‐row irrigated (ARI), $401 ha−1 for SRI, and $334  ha−1 for rainfed (RF) cotton. For soybean, the gains were $178 ha−1 for ARI irrigated, $178 ha−1 for SRI, and $121 ha−1 for RF. Converting from ARI to SRI irrigation can conserve 88 mm of irrigation water on average for cotton and 91 mm of irrigation water on average for soybean, while improving cotton profits by $55–113 ha−1. Soybean growers can expect a reduction in profits from SRI of ∼$11 ha−1. Incentive payment for soybean growers of ∼$0.132 mm−1 of saved water would compensate farmers for the expected losses of adopting SRI in the Delta of Mississippi.