Climate variability and trends affect global crop yields and are characterized as highly dependent on location, crop type, and irrigation. U.S. Great Plains, due to its significance in national food production, evident climate variability, and extensive irrigation is an ideal region of investigation for climate impacts on food production. This paper evaluates climate impacts on maize, sorghum, and soybean yields and effect of irrigation for individual counties in this region by employing extensive crop yield and climate datasets from 1968–2013. Variability in crop yields was a quarter of the regional average yields, with a quarter of this variability explained by climate variability, and temperature and precipitation explained these in singularity or combination at different locations. Observed temperature trend was beneficial for maize yields, but detrimental for sorghum and soybean yields, whereas observed precipitation trend was beneficial for all three crops. Irrigated yields demonstrated increased robustness and an effective mitigation strategy against climate impacts than their non-irrigated counterparts by a considerable fraction. The information, data, and maps provided can serve as an assessment guide for planners, managers, and policy- and decision makers to prioritize agricultural resilience efforts and resource allocation or re-allocation in the regions that exhibit risk from climate variability.

The sensitivity of the standardized ASCE grass-reference Penman-Monteith evapotranspiration (ASCE-PM E To ) equation to climate variables in different regions has not yet been studied. Sensitivity analyses for the standardized daily form of the ASCE-PM equation were conducted on wind speed at 2 m height ( U2 ) , maximum and minimum air temperatures ( Tmax and Tmin ), vapor pressure deficit (VPD), and solar radiation ( Rs ) in the following regions of the United States: semiarid (Scottsbluff, Nebraska, and Bushland, Texas), a Mediterranean-type climate (Santa Barbara, California), coastal humid (Fort Pierce, Florida), inland humid and semihumid (Rockport, Missouri, and Clay Center, Nebraska), and an island (Twitchell Island, California). The sensitivity coefficients were derived for each variable on a daily basis. In general, E To was most sensitive to VPD at all locations, while sensitivity of E To to the same variable showed significant variation from one location to another and at the same location with...

Significant air temperature changes have occurred globally during the 20^th century, which are spatially variable to a considerable degree and these changes can have substantial implications in agroecosystem productivity. The agroclimate indicators that are responsible in these contexts are first fall frost (FFF), last spring frost (LSF), climatological growing season (CGS) length, and heat accumulation (growing degree days, GDD). We explore spatial and temporal trends associated with these indices across the continental U.S. (CONUS) during 1900–2014 using datasets collected at 1218 sites. On average, FFF has been occurring later (by 5.4 days century⁻¹), and LSF has been occurring earlier (by 6.9 days century⁻¹), resulting in the average lengthening of the CGS (by 12.7 days century⁻¹). Annual GDD has been increasing by 50 °C century⁻¹. We also report trends for agricultural belts and climate regions. We developed relationships between county-level crop yields vs. agroclimate changes and found that all crops (maize, soybean, sorghum, spring wheat, winter wheat, and cotton) responded positively to a lengthened CGS, while responding negatively to increase in GDD, except cotton. Overall, we find that the observed changes in agroclimate, were beneficial for crop yields in the CONUS, albeit some crop and region specific exceptions.

Limited water resources coupled with the increase of the human population calls for more efficient use of water in irrigated agriculture. Potato (Solanum tuberosum L.) is one of the most widely grown crops worldwide and is very sensitive to water stress due to its shallow rooting system. With the dilemma of potato sensitivity to drought and limited available water resources restricting crop production, researchers and crop growers have been investigating different approaches for optimizing potato yield and improving crop water use efficiency under different irrigation methods. While potato response to water is affected by other management practices such as fertilizer management, the present review is focused on the potato response to water under different environments and different irrigation methods and the impact on potato quality and potato diseases. Variable results obtained from research studies indicate the non-transferability of the results from one location to another as potato cultivars are not the same and potato breeders are still making effort to develop new high-yielding varieties to increase crop production and or develop new varieties for a specific trait to satisfy consumers exigence. This review is a valuable source of information for potato growers and scientists as it is not only focused on the impact of irrigation regimes on potato yield and water productivity as most reviews on water management, but it also presents the impact of irrigation regime on diseases in potatoes, tuber specific gravity, metabolite content of the tubers and the quality of the processed potato products.

The evapotranspiration crop coefficients (Kc) that are used to estimate actual evapotranspiration (ETa) using a two-step approach (i.e., Kc×reference ET) for limited irrigated and rainfed maize are extremely rare. The effects of full and limited irrigation and rainfed practices on maize ETa and soil water dynamics were quantified. Grass- and alfalfa-based crop coefficients (Kco and Kcr) were developed for full- and limited-irrigation settings as well as for rainfed conditions. Four irrigation regimes [fully irrigated treatment (FIT), 75% FIT, 60% FIT, 50% FIT] and rainfed treatments were implemented. In general, depletion in available soil water increased with the decrease in irrigation regime from FIT to rainfed treatment. Maize ETa increased with irrigation amounts and ranged from 481 mm for the rainfed treatment to 620 mm for the FIT in 2009 and from 579 to 634 mm for the same treatments, respectively, in 2010. Reduction in seasonal ETa relative to FIT were 22, 9, 7, and 2% for the rainfed, 50%...