Abstract  Identifying the location of irrigated croplands and how they change over time is critical for assessing and managing limited water resources to navigate such challenges as local to global water scarcity, increasing demands for food and energy production, and environmental sustainability. Although efforts have been made to map irrigated area for the U.S., multi-year nationwide maps at field-relevant resolutions are still unavailable; existing products suffer from coarse resolution, uncertain accuracy, and/or limited spatial coverage, especially in the eastern U.S. In this study, we present an approach to map the extent of irrigated croplands across the conterminous U.S. (CONUS) for each year in the period of 1997–2017. To scale nationwide, we developed novel methods to generate training datasets covering both the western and eastern U.S. For the more arid western U.S., we built upon the methods of Xie et al. (2019) and further developed a greenness-based normalization technique to estimate optimal thresholds of crop greenness in any year based on those in USDA NASS census years (i.e., 1997, 2002, 2007, 2012, and 2017). For the relatively humid eastern states, we collected data on the current status of center pivot irrigated and non-irrigated fields and extended these sample points through time using various indices and observational thresholds. We used the generated samples along with remote sensing features and environmental variables to train county-stratified random forest classifiers annually for pixel-level classification of irrigated extent each year and subsequently implemented a logic-based post-classification filtering. The produced Landsat-based Irrigation Dataset (LANID-US) accurately reconstructed NASS irrigation patterns at both the county and state level while also supplying new annual area estimates for intra-epoch years. Nationwide pixel-level locational assessment further demonstrated an overall accuracy above 90% across years. In the 21-year study period, we found several hotspots of irrigation change including significant gains in the U.S. Midwest, the Mississippi River Alluvial Plain, and the East Coast as well as irrigation declines in the central and southern High Plains Aquifer and the southern California Central Valley, Arizona, and Florida. The resulting 30 m resolution LANID-US products represent the finest resolution account of nationwide irrigation use and dynamics across the United States to date. The developed approach, training data, and products are further extendable to other years (either before 1997 or after 2017) for continuous monitoring of irrigated area over CONUS and are spatially applicable to other regions with similar climate and cropping landscapes.

Abstract  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.

Abstract  Hydrologic models such as SWAT are used extensively for predicting water availability and water quality responses to alternative management practices. Modeling results have been used by regulatory agencies for developing remedial measures for impaired water bodies and for water planning purposes. However, comprehensive calibration and testing of these models for predicting daily ET are noticeably absent from most modeling efforts. This is largely due to the limited number of quality, long-term ET and related management datasets. Consequently, more readily available and easily measured components of the water balance, including runoff and stream flow, are often used as calibration targets. ET is often simply ignored or adjusted by manipulating sensitive ET model parameters in order to match other simulated water balance components to measured values. This approach can provide a false sense of confidence that the model is performing properly although significant errors in modeled ET may exist. In essence, the model may provide the right answer for the wrong reasons. This condition may go unnoticed until the calibrated model is used to simulate other components of the water balance such as ET and compared with measured data. Additionally, model errors in ET simulation may vary considerably under irrigated and dryland management practices. The use of default crop database parameters in SWAT‘s embedded production functions appears to be inadequate for accurately simulating ET under dryland conditions, resulting in inaccurate estimations of crop biomass, yield, and irrigation demand. Improper or incomplete calibration and testing of water balance components and the use of uncalibrated crop database parameters can be problematic and lead to improper evaluation of management strategies. In this presentation, we discuss calibration and testing efforts of SWAT simulated ET under both irrigated and dryland cropping systems of the semi-arid Texas Panhandle using lysimetric data from the USDA-ARS Conservation and Production Research Laboratory in Bushland, Texas.

Abstract  In 2003, the U.S. Department of Agriculture surveyed 21 dry-mill ethanol plants to estimate their 2002 production costs, including both variable (feedstock and plant operation) and capital expenses. These plants produced about 550 million gallons of ethanol in 2002. Net feedstock costs for the surveyed plants ranged from 39 to 68 cents per gallon in 2002. For cash operating expenses, the average energy expenditure was 17.29 cents per gallon. Labor costs ranged from 3 to 11 cents per gallon, maintenance costs from 1 to 7 cents, and administrative costs from 1 to 18 cents. For capital expenditures, new plant construction costs from $1.05 to $3.00 per gallon of ethanol. Average investment to expand existing ethanol production capacity was 50 cents per gallon; hence, expansion tends to cost less than new capacity. Comparison with a 1998 survey of ethanol producers showed that total operating costs in 2002 had changed very little from 1998. It also showed that the average cost of building new plants had dropped, possibly due to designs that emphasize economies of scale.

Abstract  Stated in a positive sense, the specific objectives of this study are: (1) To collect and summarize information about the task of defining critical environmental areas in other states; (2) To describe and review some procedures for defining criticality and for delineating critical areas; and (3) To assemble data pertaining to resource inventories in Nebraska. The results of Objective 1 are found throughout this report plus the references cited in the Bibliography. The two sources mentioned most frequently in this report are the one by the Center for Natural Areas, Office of International and Environmental Programs, Smithsonian Institute (which is abbreviated CEA Reference Guide in subsequent references in this report) and Report Eight of the Critical Resources Information Program (CRIP) by the Institute for Environmental Studies, University of Wisconsin-Madison. Objective 2 is achieved in Chapter II where the issue of "criticality" is examined and in Chapter IV when some successful processes for delineating critical areas are described. Chapter III, which discusses several elements of lithe environment" and reports on the inventors status of each in Nebraska, deals particularly with Objective 3. The procedure that is recommended here for delineating critical environmental areas in Nebraska is not an easy one. It commences with a concept about places in the State that should receive special attention because incompatible and harmful uses of the land can cause environmental damage having more than local importance. It ends by recommending a few specific areas where land uses should be carefully managed. Between the initial concept and the final definition of areas are many decisions based on a multitude of data and the diversity of citizen assessments about land-use goals in Nebraska. The decisions about which areas should be selected for critical evaluation must involve both citizens at the local level and experts with technical information. This combination is essential because the nature of the task requires input about land-use goals and about environmental interrelationships. A procedure used in another state (Wisconsin) for this kind of task appears very appropriate for defining CEA in Nebraska. As participants discuss the applicability of specific areas, they will face the issues of criticality discussed in the first portion of Chapter II. Personnel charged with the responsibility of designing a measurement scheme will need to consider the problems summarized in the latter part of Chapter II. Hopefully the background information about data sources and about differentiated areas according to selected phenomena that was described in Chapter III can serve as a working base for subsequent analyses. Nevertheless, in spite of whatever aids are obtained from this report, the task of defining critical environmental areas in Nebraska will be difficult and will expose conflicting and controversial goals in the use of our land. But, given the general importance of the State's rural components, the increasing interaction among all segments of society, and the dependence of humans on their earth environment, the task is essential. Furthermore, the effort is worthwhile because the ultimate objective is the improvement of life in Nebraska.

Abstract  We assessed current water consumption during liquid fuel production, evaluating major steps of fuel lifecycle for five fuel pathways: bioethanol from corn, bioethanol from cellulosic feedstocks, gasoline from U.S. conventional crude obtained from onshore wells, gasoline from Saudi Arabian crude, and gasoline from Canadian oil sands. Our analysis revealed that the amount of irrigation water used to grow biofuel feedstocks varies significantly from one region to another and that water consumption for biofuel production varies with processing technology. In oil exploration and production, water consumption depends on the source and location of crude, the recovery technology, and the amount of produced water re-injected for oil recovery. Our results also indicate that crop irrigation is the most important factor determining water consumption in the production of corn ethanol. Nearly 70% of U.S. corn used for ethanol is produced in regions where 10–17 liters of water are consumed to produce one liter of ethanol. Ethanol production plants are less water intensive and there is a downward trend in water consumption. Water requirements for switchgrass ethanol production vary from 1.9 to 9.8 liters for each liter of ethanol produced. We found that water is consumed at a rate of 2.8–6.6 liters for each liter of gasoline produced for more than 90% of crude oil obtained from conventional onshore sources in the U.S. and more than half of crude oil imported from Saudi Arabia. For more than 55% of crude oil from Canadian oil sands, about 5.2 liters of water are consumed for each liter of gasoline produced. Our analysis highlighted the vital importance of water management during the feedstock production and conversion stage of the fuel lifecycle.

Abstract  The US Energy Independence and Security Act (EISA) of 2007 has contributed to widespread changes in agricultural land uses. The impact of these land use changes on regional water resources could also be significant. Agricultural land use changes were evaluated for the Red River of the North Basin, an international river basin shared by the US and Canada. The influence of the land use change on spring snowmelt flooding and downstream water quality was also assessed using watershed modeling. The planting areas for corn and soybean in the basin increased by 62% and 18%, while those for spring wheat, forest, and pasture decreased by 30%, 18%, and 50%, from 2006 to 2013. Although the magnitude of spring snowmelt peak flows in the Red River did not change from pre-EISA to post-EISA, our uncertainty analysis of the normalized hydrographs revealed that the downstream streamflows had a greater variability under the post-EISA land use scenario, which may lead to greater uncertainty in predicting spring snowmelt floods in the Red River. Hydrological simulation also showed that the sediment and nutrient loads at the basins outlet in the US and Canada border increased under the post-EISA land use scenario, on average sediment increasing by 2.6%, TP by 14.1%, nitrate nitrogen by 5.9%, and TN by 9.1%. (C) 2015 Elsevier B.V. All rights reserved.

Abstract  This paper compares the water footprint profiles of four feedstocks used for biodiesel production: palm, soya, rapeseed and waste cooking oil (WCO). The profiles include: (a) a water scarcity footprint related to freshwater consumption impacts and (b) a water quality degradation footprint related to freshwater degradation impacts. The water scarcity footprint was assessed using two impact assessment methods: one based on water stress indices (WSIs) and the other on the available water remaining (AWARE) indicator. The water degradation footprint was assessed considering the environmental mechanisms covered by the impact categories of eutrophication, aquatic acidification, human toxicity and freshwater ecotoxicity. The water scarcity profiles ranged from 0.002 to 211 world m(3)eq kg(-1) (WSI method) and from 0.008 to 133.57 world m(3)eq kg(-1) oil (AWARE method). Both methods showed that the cultivation stage assumes the primary role in the water scarcity footprint results and identified the same systems with higher water scarcity footprints. However, for the oil systems with closer results, the rank order given by each method is different due to the characterization factors of each method. Nevertheless, the results obtained with the AWARE method give more comprehensive water scarcity footprint results than those obtained when applying WSIs because AWARE considers the aquatic ecosystem water demand. The water degradation footprint of virgin oils is mainly caused by fertilizers and pesticides used in cultivation. WCO systems present lower impacts for all impact categories with the exception of human toxicity-cancer. The choice of locations with lower water scarcity to produce oil crops can be a determinant in the calculation of lower impacts. Moreover, optimizing fertilization schemes or choosing climatic conditions that require less fertilizers, pesticides and water consumption can reduce the impacts of the water footprint profile of vegetable oils.

Abstract  The production of liquid fuels from crude oil requires water. There has been limited focus on the assessment of life cycle water demand footprints for crude oil production and refining. The overall aim of this paper is address this gap. The objective of this research is to develop water demand coefficients over the life cycle of fuels produced from crude oil pathways. Five crude oil fields were selected in the three North American countries to reflect the impact of different spatial locations and technologies on water demand. These include the Alaska North Slope, California's Kern County heavy oil, and Mars in the U.S.; Maya in Mexico; and Bow River heavy oil in Alberta, Canada. A boundary for an assessment of the life cycle water footprint was set to cover the unit operations related to exploration, drilling, extraction, and refining. The recovery technology used to extract crude oil is one of the key determining factors for water demand. The amount of produced water that is re-injected to recover the oil is essential in determining the amount of fresh water that will be required. During the complete life cycle of one barrel of conventional crude oil, 1.71-8.25 barrels of fresh water are consumed and 2.4-9.51 barrels of fresh water are withdrawn. The lowest coefficients are for Bow River heavy oil and the highest coefficients are for Maya crude oil. Of all the unit operations, exploration and drilling require the least fresh water (less than 0.015 barrel of water per barrel of oil produced). A sensitivity analysis was conducted and uncertainty in the estimates was determined.

Abstract  A recent U.S. Department of Energy study estimated that more than one billion tons of biofuel feedstock could be produced by 2030 in the United States from increased corn yield, and changes in agricultural and forest residue management and land uses. To understand the implications of such increased production on water resources and stream quality at regional and local scales, we have applied a watershed model for the Upper Mississippi River Basin, where most of the current and future crop/residue-based biofuel production is expected. The model simulates changes in water quality (soil erosion, nitrogen and phosphorus loadings in streams) and resources (soil-water content, evapotranspiration, and runoff) under projected biofuel production versus the 2006 baseline year and a business-as-usual scenario. The basin average results suggest that the projected feedstock production could change the rate of evapotranspiration in the UMRB by approximately +2%, soil-water content by about -2%, and discharge to streams by -5% from the baseline scenario. However, unlike the impacts on regional water availability, the projected feedstock production has a mixed effect on water quality, resulting in 12% and 45% increases in annual suspended sediment and total phosphorus loadings, respectively, but a 3% decrease in total nitrogen loading. These differences in water quantity and quality are statistically significant (p < 0.05). The basin responses are further analyzed at monthly time steps and finer spatial scales to evaluate underlying physical processes, which would be essential for future optimization of environmentally sustainable biofuel productions.

Abstract  Motivated by the need for sustainable water management and technology for next-generation crop production, the future of irrigation on the U.S. Great Plains was examined through the lenses of past changes in water supply, historical changes in irrigated area, and innovations in irrigation technology, management, and agronomy. We analyzed the history of irrigated agriculture through the 1900s to the present day. We focused particularly on the efficiency and water productivity of irrigation systems (application efficiency, crop water productivity, and irrigation water use productivity) as a connection between water resource management and agricultural production. Technology innovations have greatly increased the efficiency of water application, the productivity of water use, and the agricultural productivity of the Great Plains. We also examined the changes in water stored in the High Plains aquifer, which is the region‘s principle supply for irrigation water. Relative to other states, the aquifer has been less impacted in Nebraska, despite large increases in irrigated area. Greatly increased irrigation efficiency has played a role in this, but so have regulations and the recharge to the aquifer from the Nebraska Sand Hills and from rivers crossing the state. The outlook for irrigation is less positive in western Kansas, eastern Colorado, and the Oklahoma and Texas Panhandles. The aquifer in these regions is recharged at rates much less than current pumping, and the aquifer is declining as a result. Improvements in irrigation technology and management plus changes in crops grown have made irrigation ever more efficient and allowed irrigation to continue. There is good reason to expect that future research and development efforts by federal and state researchers, extension specialists, and industry, often in concert, will continue to improve the efficiency and productivity of irrigated agriculture. Public policy changes will also play a role in regulating consumption and motivating on-farm efficiency improvements. Water supplies, while finite, will be stretched much further than projected by some who look only at past rates of consumption. Thus, irrigation will continue to be important economically for an extended period. Sustaining irrigation is crucial to sustained productivity of the Great Plains “bread basket” because on average irrigation doubles the efficiency with which water is turned into crop yields compared with what can be attained in this region with precipitation alone. Lessons learned from the Great Plains are relevant to irrigation in semi-arid and subhumid areas worldwide.

Abstract  Agroecosystem models and conservation planning tools require spatially and temporally explicit input data about agricultural management operations. The Land-use and Agricultural Management Practices web-Service (LAMPS) was developed to provide crop rotation and management information for user-specified areas within the 48 contiguous states of the USA. LAMPS links three data sources: (1) annual Cropland Data Layers (CDLs) from the CropScape Web service based on high-resolution remote sensing data for recent years provided by the National Agricultural Statistical Service (NASS), (2) maps of irrigated areas compiled by the U.S. Geological Survey, and (3) the Land Management and Operation Database (LMOD) by the USDA Natural Resources Conservation Service containing agricultural management practices. The workflow within LAMPS for generating crop rotation and management information is described in detail, including details of the algorithm for matching annual crop sequences from CropScape to regional rotations in LMOD. Instructions for using the Web service are specified with example input and response listings. A study area of 15 fields in Colorado, USA is presented to demonstrate and evaluate LAMPS outputs using ground observations of crop types. LAMPS automatically detected actual crop rotations with a similarity to the ground observations better than using only CropScape detected dominant crop sequences. LAMPS is available for public use, further nation-wide evaluation, and extension to other spatial data provisioning related to agroecosytem modelling.

Abstract  The Soil Water Assessment Tool (SWAT) is a widely used watershed model for simulating stream flow, overland flow, and sediment, pesticide, and bacterial loading in response to management practices. All SWAT processes are directly dependent on accurate representation of hydrology. Evapotranspiration (ET) is commonly the most significant portion of the hydrologic cycle, especially for irrigated lands in semiarid environments when ET demands are met or exceeded. However, no studies using long-term data to evaluate the SWAT model‘s capacity to estimate daily, monthly, and seasonal ET have been performed. In this study, daily and monthly ET values were simulated using ArcSWAT 2012 for an irrigated lysimeter field at the USDA-ARS Conservation and Production Research Laboratory (CPRL) at Bushland, Texas, and compared to measured ET values from 2001-2010. Crops grown during the study period included cotton, soybean, grain and silage sorghum, sunflower, and corn silage. A one-year warm-up (2000) and equal division of the remaining years were used for the calibration (2001-2005) and validation (2006-2010) periods. SWAT achieved a Nash-Sutcliffe efficiency (NSE) of 0.67 for daily ET during the calibration period, resulting in a “good” performance rating. An NSE of 0.78 resulted in a “very good” rating for the validation period. NSE values for simulated average monthly ET were improved, at 0.77 and 0.85 for the calibration and validation periods, respectively. Analysis of simulated versus measured ET values both during and outside of the growing season revealed better agreement during the former than the latter. The SWAT model generally underestimated ET at both daily and monthly levels but overestimated annual cotton ET due to overestimation of leaf area index during the senescing stage. Overall, SWAT was able to simulate daily and average monthly ET reasonably well for major summer crops grown in the semiarid Texas High Plains. These results should reinforce confidence in the SWAT model‘s capacity to accurately simulate ET in fully irrigated watersheds. However, limitations in accuracy appear to exist for certain crops, such as cotton and sunflower, and particularly under limited irrigation conditions. These deficiencies may be related to issues with the embedded Leaf Area Index (LAI) crop growth model and default plant parameter values in the crop database in SWAT.

Abstract  The High Plains aquifer underlies 111.8 million acres (about 175,000 square miles) in parts of eight States—Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. Water-level declines began in parts of the High Plains aquifer soon after the beginning of substantial irrigation with groundwater in the aquifer area (about 1950). This report presents water-level changes and change in recoverable water in storage in the High Plains aquifer from predevelopment (about 1950) to 2015 and from 2013 to 2015. The methods to calculate area-weighted, average water-level changes; change in recoverable water in storage; and total recoverable water in storage used geospatial data layers organized as rasters with a cell size of 500 meters by 500 meters, which is an area of about 62 acres. Raster datasets of water-level changes are provided for other uses. Water-level changes from predevelopment to 2015, by well, ranged from a rise of 84 feet to a decline of 234 feet. Water-level changes from 2013 to 2015, by well, ranged from a rise of 24 feet to a decline of 33 feet. The area-weighted, average water-level changes in the aquifer were an overall decline of 15.8 feet from predevelopment to 2015 and a decline of 0.6 feet from 2013 to 2015. Total recoverable water in storage in the aquifer in 2015 was about 2.91 billion acre-feet, which was a decline of about 273.2 million acre-feet since predevelopment and a decline of 10.7 million acre-feet from 2013 to 2015.

Abstract  Wastewater discharges from restaurants, kitchens, food processing plants and slaughterhouses contain high proportion of fat, oil, and grease (FOG). Critical overview on the attractive features, current state, and needed advancements are timely essential for FOG-derived biodiesel production. Although FOG conversion into biodiesel does not compete with human food, the high contents of moisture and free fatty acids (FFAs) are the main challenges for FOG efficient utilization. The present review discussed the various methods of high FFAs-lipidic feedstocks pretreatment including acid esterification, steam stripping, nanocatalytic technology, biological conversion, glycerolysis, supercritical esterification, and simultaneous in situ conversion. Comparing to other feedstocks, FOG-derived biodiesel showed better characteristics concerning oxidative stability, flash point, cetane number, and total emissions. In addition, most of the FOG-derived biodiesel fuel met the recommendations of the international standards as well as conventional diesel. Due to its lower price, the economic analysis showed that FOG is a strong competitor to other biodiesel feedstocks. The decrease in feedstocks availability, continuous rise in the crude oil prices, life threatening environmental deterioration, and food-versus-fuel debate support FOG to be a potential biodiesel feedstock in the near future. However, the cost of FOG-biodiesel production is still far away from the acceptable ranges to compete fossil diesel. Lastly, this paper suggested a number of future perspectives in order to enhance the economy and feasibility of FOG-derived biodiesel including developing new methods for efficient conversion of brown grease, integrated approaches for sequential production of biofuels from FOG, and co-esterification of FOG with other lipidic feedstocks.

Abstract  The ability to accurately monitor and anticipate changes in consumptive water use associated with changing land use and land management is critical to developing sustainable water management strategies in water-limited climatic regions. In this paper, we present an application of a remote sensing data fusion technique for developing high spatiotemporal resolution maps of evapotranspiration (ET) at scales that can be associated with changes in land use. The fusion approach combines ET map timeseries developed using an multi-scale energy balance algorithm applied to thermal data from Earth observation platforms with high spatial but low temporal resolution (e.g., Landsat) and with moderate resolution but frequent temporal coverage (e.g., MODIS (Moderate Resolution Imaging Spectroradiometer)). The approach is applied over the Sacramento-San Joaquin Delta region in California—an area critical to both agricultural production and drinking water supply within the state that has recently experienced stresses on water resources due to a multi-year (2012–2017) extreme drought. ET “datacubes” with 30-m resolution and daily timesteps were constructed for the 2015–2016 water years and related to detailed maps of land use developed at the same spatial scale. The ET retrievals are evaluated at flux sites over multiple land covers to establish a metric of accuracy in the annual water use estimates, yielding root-mean-square errors of 1.0, 0.8, and 0.3 mm day−1 at daily, monthly, and yearly timesteps, respectively, for all sites combined. Annual ET averaged over the Delta changed only 3 mm year−1 between water years, from 822 to 819 mm year−1, translating to an area-integrated total change in consumptive water use of seven thousand acre-feet (TAF). Changes were largest in areas with recorded land-use change between water years—most significantly, fallowing of crop land presumably in response to reductions in water availability and allocations due to the drought. Moreover, the time evolution in water use associated with wetland restoration—an effort aimed at reducing subsidence and carbon emissions within the inner Delta—is assessed using a sample wetland chronosequence. Region-specific matrices of consumptive water use associated with land use changes may be an effective tool for policymakers and farmers to understand how land use conversion could impact consumptive use and demand.

Abstract  Global ethanol production has grown rapidly due to national renewable fuel programs. Recently, concern has grown over impacts that land conversion and crop displacement driven by ethanol feedstock production might have on water resources. In this paper, we examine local irrigation decisions of agricultural producers in the Kansas portion of the High Plains Aquifer in response to ethanol market expansion. To identify the effects of ethanol expansion on local irrigation decisions, we examine field-level data on irrigation water use, irrigated acreage, and crop decisions for the years 2003-2017 for over 23,000 fields in Kansas. We measure the response of three irrigation decisions, (i) irrigated acreage, (ii) irrigation per acre, and (iii) total water use to the introduction and capacity expansion of an ethanol plant. We find that ethanol market expansion did lead to increases in irrigation water use for local producers. Specifically, a 1 million gallon/year increase in ethanol capacity within 50KM increases annual total water use by 0.16 acre-ft per field. A 10% increase in ethanol capacity within 50KM leads to a 0.13% increase in irrigated corn acreage.