High Plains Research Articles

Major land use and vegetation influences on potential pollinator communities in the High Plains of Texas

In 2016, the annual value of all global crops dependent upon pollination was valued at $ 235–$ 577 billion (US$). Pollination service is threatened by habitat loss, pesticides, and climate change. We collected potential pollinators with blue vane traps in native grasslands, Conservation Reserve Program (CRP) lands, and cropland (land use), and their embedded playa wetlands (land type) in the Southern High Plains of Texas (SHP). We collected vegetation data that included floral cover, floral diversity, native grass cover, introduced grass cover, canopy gap, and duff cover. Our objective was to determine if individual vegetation characteristics influenced potential pollinator abundance and richness in addition to land use or land type as a whole. The top model explaining abundance was land use, land type, and floral cover. Floral cover had a positive influence on all land uses. The top model that explained insect richness was land use x floral cover, land type, canopy gap, and duff cover. Floral cover positively influenced insect richness in native grasslands but negatively influenced cropland and CRP richness. Percent of canopy gap had a slight negative influence on insect richness, and duff cover positively influenced richness. Our recommendations to land managers are to protect playas to preserve undisturbed areas and native floral resources and seed all future CRP contracts with floral rich plantings to provide for pollinators over the entire growing season.Implications for insect conservationOur results show that vegetation characteristics shared by all land uses such as floral cover, canopy gap and duff cover influence pollinator abundance and richness. Therefore, conserving playa wetlands and programs such as the CRP have the potential for enhancing pollinator habitat in working landscapes of the SHP of Texas.

A field experiment characterizing variable detection rates during plant surveys.

Surveys aimed at finding threatened and invasive species can be challenging due to individual rarity and low and variable individual detection rates. Detection rate in plant surveys typically varies due to differences among observers, among the individual plants being surveyed (targets), and across background environments. Interactions among these 3 components may occur but are rarely estimated due to limited replication and control during data collection. We conducted an experiment to investigate sources of variation in detection of 2 Pilosella species that are invasive and sparsely distributed in the Alpine National Park, Australia. These species are superficially similar in appearance to other yellow‐flowered plants occurring in this landscape. We controlled the presence and color of flowers on target Pilosella plants and controlled their placement in plots, which were selected for their variation in cover of non‐target yellow flowers and dominant vegetation type. Observers mimicked Pilosella surveys in the plots and reported 1 categorical and 4 quantitative indicators of their survey experience level. We applied survival analysis to detection data to model the influence of both controlled and uncontrolled variables on detection rate. Orange‐ and yellow‐flowering Pilosella in grass‐ and heath‐dominated vegetation were detected at a higher rate than nonflowering Pilosella. However, this detection gain diminished as the cover of other co‐occurring yellow‐flowering species increased. Recent experience with Pilosella surveys improved detection rate. Detection experiments are a direct and accessible means of understanding detection processes and interpreting survey data for threatened and invasive species. Our detection findings have been used for survey planning and can inform progress toward eradication. Interaction of target and background characteristics determined detection rate, which enhanced predictions in the Pilosella eradication program and demonstrated the difficulty of transferring detection findings into untested environments.

Assessment of heavy metal pollution in urban and peri-urban soil of Setif city (High Plains, eastern Algeria).

Heavy metal pollution is a challenging concern that threatens the soil environment and human health worldwide. The purpose of this work is to assess the heavy metals (Cr, Cu, Zn, and Pb) pollution in the urban and peri-urban soils in and around Setif city, eastern Algeria. The work combines chemical analysis of thirty-six soil samples, statistical valuation and interpretation of chemical data and pollution indices (geoaccumulation index, pollution index, and integrated pollution index) with thematic mapping. The average concentrations (in mg/kg) of Cd, Cr, Cu, Pb, and Zn were found < 0.02, 43.35, 43.75, 331.20, and 78.26mg/kg, respectively. Compared with the French regulatory limits (AFNOR U44-041), Cd, Cr, and Cu still non-hazardous at Setif city scale; however, Zn and Pb concentrations are two to three times higher than the background values referred to the Chinese [Formula: see text] standard (GB15618-1995). The pollution indices indicate that Pb and Zn represent the highest threats among the studied pollutants and polluted wide areas of anthropogenic activities located respectively in the oldest district of the city, near the industrial zone and near uncontrolled landfill of domestic and industrial waste. Cu, Pb, and Zn originate seemly from vehicle emission, particles of brakes and tires, and industrial emissions. However, Cr distribution is uncorrelatable with anthropogenic sources. The Cr with an average concentration less than the background value derives seemly from animal feces and organic fertilizers. The integrated pollution index shows that the accumulation of heavy metals in the soils of Setif city from anthropogenic sources reached alarming levels that can disperse into the environment and threaten the human health. The urbanization and industrial development of Setif city are expected to grow and a subsequent heavy metal pollution will be rising prior issue. Corrective measures should be endeavored by the local authorities to mitigate the current environmental situation and a sustainable development plan for the city should be anticipated to guarantee optimal future environmental conditions.

Secondary Bud Growth and Fruitfulness of Vitis Vinifera L. ‘Grenache’ Grafted to Three Different Rootstocks and Grown within the Texas High Plains AVA

ABSTRACT In recent years, the economic impact of the grape and wine industry within Texas has significantly increased. The majority of grapes grown in Texas are produced within the Texas High Plains American Viticultural Area (AVA). Vineyards within this AVA are subject to late spring frosts that may potentially reduce crop yields, and lower fruit quality. Objectives of this experiment were to compare the growth and fruitfulness of shoots grown from primary and secondary buds of V. vinifera ‘Grenache’ vines grafted onto three rootstocks (110 R, 1103P, and Freedom). Over two growing seasons, field-grown vines were exposed to the following treatments: primary bud growth and forced secondary bud growth (simulated late spring frost). Leaf gas exchange, pruning cane weight, vine yield, and fruit maturity data were collected each year. Bud treatment or rootstock did not influence leaf gas exchange. Cane weight and yield data were greater for shoots grown from primary bud shoots, and rootstock 1103P. In addition, berries grown from primary buds and 1103P rootstocks were more mature compared to fruits from secondary buds or vines grown on other rootstocks. Results offer insight into the potential interaction of ‘Grenache’ scions with grafted rootstocks during a late spring frost within the Texas High Plains AVA.

Running Out: In Search of Water on the High Plains

Running Out: In Search of Water on the High Plains

High plains wheat mosaic emaravirus (high plains disease)

High plains wheat mosaic emaravirus (high plains disease)

Asclepiasdynamics on US rangelands: implications for conservation of monarch butterflies and other insects

AbstractThe genesis of this study is in response to the United States (US) Fish and Wildlife Service (USFWS) listing of the monarch butterfly (Danaus plexippus plexippus) on 17 December 2020 in the US Federal Register as a candidate species under the Endangered Species Act of 1973. Annual censuses have identified that the eastern and western North American monarch migratory populations have been generally declining over the last 20 yr due to a myriad of environmental factors. Monarch reproduction at the larval stage is dependent on the presence of milkweed (Asclepias) plant species. The United States Department of Agriculture‐Natural Resources Conservation Service (USDA‐NRCS) National Resource Inventory rangeland data set (~23,400 on‐site samples; 2032 sites with milkweed presence) was used to evaluate milkweed species densities, geolocations, and environmental gradients. Twenty‐two milkweed species were identified on rangelands across 17 sampled US western states, with seven species comprising 65.5% of milkweed frequency of occurrence. The most dominant milkweed species on non‐federal rangelands wereAsclepias viridis,A. syriaca,A. verticillata, andA. speciosa(constancy &gt;10% where milkweed was present).Asclepias speciosawas the dominant species from the standpoint of total plant density for the data set, whereasA. viridiswas the most frequently occurring species. Total milkweed density estimates based on low, midpoint, and high estimates were 1.3, 4.1, and 6.9Bplants on 13.2 M ha. Seven US states (Kansas, Texas, Nebraska, South Dakota, North Dakota, Oklahoma, and Montana) contained 88.8% of the total estimated ha with milkweed presence. In the Central Great Plains, Northwestern Great Plains, Nebraska Sand Hills, and Flint Hills, Southwestern Tablelands, High Plains, Northwestern Glaciated Plains, and Cross Timbers, Omernik level III ecoregions contained 76.7% of the estimated milkweed plants. Milkweed species density was highest at latitude N35‐40 with decreasing populations toward south (N25‐30) and north (N45‐50) latitudes. Milkweed species densities were greatest at longitude W‐95‐100 and decreased toward the western US with lowest population numbers at W‐120‐125. Analysis of environmental variables showed milkweed species dominance on mollisols, non‐saline sites, neutral pH, well‐drained soils, loam and sandy loam soil textures, and sites with soil organic matter at 1.5–3%. Disturbance gradients and habitat dynamics relating to ecological condition and rangeland health differed among the dominant milkweed species identified in this study.

Annual Rainfall and Dryland Cotton Lint Yield—Southern High Plains of Texas

Agriculture in the Texas High Plains (THP) is in a transition phase of producing crops with a diminishing supply of irrigation-water from the Ogallala aquifer to dryland production systems. This shift is driven by the fact that the depth to the water table of the Ogallala aquifer continues to increase. Dryland cotton production systems are prevalent in the southern counties of the THP and our purpose was to use the long-term dryland cotton lint yields from these counties as precursors of the future cotton production patterns that will emerge in this region. For this purpose, from 1972 to 2018, we calculated the ratio of dryland cotton lint yield per unit of annual rainfall at the county level. This ratio is called crop water productivity (CWP) and has units of mass per unit volume (g/m3). In our analysis, we used cotton lint yield data provided by the National Agricultural Statistics and rainfall data provided by the National Oceanic and Atmospheric Administration. Our results indicated that the three datasets used in our analysis, i.e., cotton lint yield, rainfall and CWP were all normally distributed. In this time period, 1972 to 2018, only one year 2011—a year with a record drought of 179 mm of rain failed to produce a dryland cotton crop in all the counties used in our analysis. The mean cotton lint yield ± standard deviation ranged from a high of 400 ± 175 kg/ha in Lubbock County to a low of 252 ± 144 kg/ha in Andrews County. However, the counties with the largest CWP > 90 g/m3 were Glasscock, Midland and Martin County. The importance of this result is that these counties are in the southern region of the THP and are subject to extreme environmental conditions and yet cotton producers manage to produce a cotton crop in most years. We conclude that management production methods used by these dryland producers represent the future schemes that will need to be adopted in other counties to sustain the emerging dryland cropping systems across the THP.

Two interconnected water transfers for irrigation and drinking water, a structuring project for the high plains of Setif

The “High Plains of Setif” is a mega water transfer project located in Northern Algeria and is divided into two systems: the Western system and the Eastern system. The Western system consists of a new dam and a water transfer of over twenty kilometres and aims at providing irrigation and drinking water for the Setif region. The Eastern system consists of two new dams and a water transfer of more than fifty kilometers, and aims to transfer water between the dams of Tabellout (Oued Djendjen) and Draa Diss for irrigation and l drinking water in the El-Eulma region. The whole project concerns a volume of 310 million m3 water per year transferred for the irrigation of 40,000 hectares, and drinking water for more than 1,300,000 inhabitants by 2040. The aim of this report is to present the mega project of the “High Plains of Setif”, which constitutes a first experience in Algeria ensuring the interconnection of several reservoirs in the territories to be irrigated. Some design adaptations as well as the multiuse of water in the project will also be discussed.

Soil health within transitions from irrigation to limited irrigation and dryland management

AbstractThe decline in groundwater supply in the Texas High Plains is forcing some growers to convert center‐pivot irrigated cropland to dryland production. Transitioning toward reduced water input can lead to declines in soil health. We assessed short‐term changes in soil health indicators in two transition scenarios: (a) from high irrigation method to low irrigation method (center pivot to subsurface drip) and (b) from high irrigation method to dryland (center pivot to dryland), in comparison to continuous center‐pivot management. We monitored changes in chemical and biological indicators in four fields for each transition scenario and in three pivot‐irrigated fields. There were declines in soil water content, potassium (K), sodium (Na), and soil organic carbon with transition from irrigation to reduced irrigation and dryland. Severe drought in the final year revealed reduced amounts of multi‐enzyme activities, total ester‐linked fatty acid methyl ester (EL‐FAME), and total fungi. Transitioning to low water‐input management in this environment complicates efforts to maintain microbial components of soil health. Longer‐term comparisons are needed to detect slow changes in soil health indicators on producers’ fields.

Microbial community structure from southern High Plains beef cattle feedyard manure and relationship with nitrous oxide emissions

AbstractModern molecular techniques enable characterization of the microbial biome in livestock manure, from which there is particular concern over emission of greenhouse gases. This study evaluated how sampling depth, time, temperature, and artificial rainfall affected microbial community structure in feedyard manure, and relationships between the manure biome and known parameters related to nitrous oxide (N2O) emissions. In three large incubation chambers, maintained at different temperatures that received two applications of artificial rainfall, we evaluated manure microbiome composition and abundance of N2O‐producing enzymes (nirK and nirS) using quantitative polymerase chain reaction (qPCR). These data were used with previously published data from the same study on N2O emissions and assessment of manure physicochemical properties, denitrification enzyme activity (DEA), and nitrification activity (NA). Microbiome composition was Firmicutes (50%), followed by 32% Actinobacteria, 11% Proteobacteria, 5% Bacteroidetes, 1% Chloroflexi, and small populations (&lt;0.5%) of Planctomycetes, Deinococcus‐Thermus, Gemmatimonadetes, Verrucomicrobia, Tenericutes, and other organisms. Average bacterial populations varied largely as a function of sampling depth and time. Firmicutes increases tended to coincide with high N2O emissions. Overall, the largest change observed was increased Proteobacteria at 5–10 cm, where relative abundance increased from 10% (17.2 °C) to 24% (46.2 °C) over time and with increased temperature. Firmicutes and Actinobacteria predominated the microbial community of manure, but favorable conditions may lead to increases in Bacteroidetes, Proteobacteria, and Chloroflexi, which could influence N cycling and N2O emissions from feedyards. Copy numbers of nirS at the beginning of the experiment were higher than nirK. Differences in concentrations of nirK and nirS indicated that denitrifying enzymes in feedyard manure, particularly nirS, were sensitive to environmental changes.

Distribution, composition and environmental correlates of high-altitude gravelly pavement herbfields in north-eastern Victoria, Australia

Context Gravelly pavement herbfields are a rare, geographically restricted community found in high mountain areas of south-eastern Australia. Gravelly pavement plant communities occur where there is continuous waterflow, with vegetation comprising sparse, semi-aquatic species on a rock or gravel substratum. Aims This study aimed to further the understanding of the community on the Bogong High Plains, Victoria, by asking questions relating to their location, structure and floristic composition. In particular, we ask what determines the distribution of pavement communities at the landscape-scale; and what abiotic factors govern between- and within-site vegetation patterns? Results Gravelly pavement communities were associated with groundwater outflows and are likely to be formed by an interaction between surface waterflow and slope. This work adds to the current understanding of wetland types in high-mountain Australia because, to our knowledge, this relationship has not been previously described. Floristic patterns vary with slope and elevation, with high-elevation pavements on steep slopes being floristically dissimilar to those at lower elevation on flatter slopes. Species richness was consistent across sites and only a few species were found at high abundance. Within-site patterning is apparent in most pavements, attributable to abiotic factors such as rockiness and water availability, leading to characteristic vegetation patterns. Species such as the sedge Oreobolus pumilio occur on the margins of pavements where water levels are variable, whereas forbs such as Psychrophila introloba are typically found in the middle of pavements where there is constant water supply. Conclusions Gravelly pavement communities are groundwater-dependant ecosystems, restricted at the landscape-scale and contain many rare species and, as such, deserve higher levels of protection than is currently offered.

Scientific Irrigation Scheduling by Utilizing Weather Api and Open Source Modeling in Texas High Plains and Rio Grande Basin

Scientific Irrigation Scheduling by Utilizing Weather Api and Open Source Modeling in Texas High Plains and Rio Grande Basin

Simulating the climate change impacts and evaluating potential adaptation strategies for irrigated corn production in Northern High Plains of Texas

Sustaining irrigated corn (Zea mays L.) production under changing climate and reduced irrigation water availability presents a key challenge for producers in the Northern High Plains (NHP) of Texas. We assessed climate change impacts on corn production at Bushland in the NHP region using the CERES-Maize model under 36 future climate scenarios. These scenarios included nine global climate models (GCMs), two representative concentration pathways (RCPs) 4.5 and 8.5, and two future time periods 2050s (2036–2065) and 2080s (2066–2095). Simulated grain corn yield decreased, under all scenarios in the future, by approximately 31 % on average in the 2050s and by approximately 55 % in the 2080s, under RCP 8.5, mainly due to reduced unit grain weight and biomass, and shorter crop cycle. Seasonal irrigation water use was simulated to either increase or decrease in the future depending on the rainfall projection of a GCM. Adaptation strategies considered in this study included using ideotypes with a longer maturity, higher yield potential, and greater heat tolerance than the reference cultivar, and shifting of planting dates. The ideotypes were created by modifying thermal times from emergence to end-of-juvenile phase, thermal time from silking to maturity, maximum kernel number per plant, radiation use efficiency (RUE), and optimum and failure temperature thresholds during relative grain filling. The planting dates considered were 16 April, 1 May, 16 May (reference), 1 June, and 16 June. By increasing the reproductive period by 13 days, grain yield could increase by 40 %, but that could increase seasonal irrigation water requirement by 10 %. Grain corn yield increased by 13 % on average when the maximum number of kernels per plant or RUE were increased by 15 %, with minor changes in seasonal irrigation water requirement. Heat tolerant ideotypes showed yield advantage over the reference cultivar without much change in irrigation. Delayed planting increased grain yield in the future. Overall, grain yield could decline under climate change without adaptation. Ideotypes with greater silking to maturity period, potential number of kernels per plant, RUE, and heat tolerance during grain filling, showed yield benefits in the future.

Conversion of Conservation Reserve Program land back to cropland: Changes in soil carbon and nitrogen dynamics during the first five years

In the United States, Texas has one of the largest areas of land enrolled as well as expiring from the Conservation Reserve Program (CRP), and most of these restored grasslands are in the Southern High Plains region. Crop market forces and agency reductions in the number of hectares that can reenroll in CRP have resulted in many farmers considering recultivating this land. Converting grasslands to conventionally tilled annual croplands could reverse the accumulated benefits afforded from perennial grasslands. Three soil profile depths (0 to 10, 0 to 30, and 0 to 50 cm) from three long-term (&gt;23 years) CRP and three converted CRP (C-CRP) sites were assessed annually from 2012 to 2015 (representing one to five years following conversion). Soil health indicators related to soil carbon (C) and nitrogen (N) dynamics were evaluated including soil organic C (SOC), total N (TN), particulate organic matter C and N (POM-C and POM-N), permanganate oxidizable C (POXC), microbial biomass C and N (MBC and MBN), in situ soil carbon dioxide (CO₂) efflux, and metabolic quotient (<i>q</i>CO₂). Redistribution of C following CRP conversion was detected in the MBC stock in 2012 with values higher in C-CRP than CRP at 0 to 30 cm and 0 to 50 cm profiles but not at 0 to 10 cm. The increase was short-lived with lower MBC in C-CRP than CRP in subsequent years. Most C and N stocks were lower in C-CRP compared to CRP across all depth profiles. The greatest losses of soil C and N stocks occurred at 0 to 10 cm, with the magnitude of loss varying by indicator and soil depth profile. Five years following conversion, SOC was reduced 2.7 Mg ha^–1 at 0 to 10 cm, and averaged across all sample years, SOC was reduced by 4.3 Mg ha^–1 at 0 to 50 cm. Drought stress was present from 2011 to 2014 and exerted an additional pressure to both systems, but the CRP system responded more positively to increased precipitation in 2014 and 2015. In CRP, the <i>q</i>CO₂, an indicator of microbial stress, remained below 1.0 throughout the study, and MBC increased by 81% from 2012 to 2014, when drought stress was lessened. In contrast, MBC decreased and <i>q</i>CO₂ doubled under C-CRP from 2012 to 2014. Overall, this study showed negative impacts on soil C and N stocks within five years after CRP to C-CRP conversion.

Evaluation of Surface Drip Irrigation Systems on Water-Use Efficiency in High-Value Vegetable Production in the Semi-Arid, Windy, Texas High Plains

Evaluation of Surface Drip Irrigation Systems on Water-Use Efficiency in High-Value Vegetable Production in the Semi-Arid, Windy, Texas High Plains

Estimation of Specific Yield for Regional Groundwater Models: Pitfalls, Ramifications, and a Promising Path Forward

AbstractSpecific yield (Sy) is one of the most important aquifer parameters in groundwater models with large storage changes. However, it has received limited attention from the modeling community and there are few, if any, approaches that can be widely applied for determination of Sy at the scale required for regional aquifer studies. Despite the limitations of parameter estimation methods and of direct measurements of aquifer storage properties in the field, the large uncertainty in model Sy values is typically ignored and Sy is incorrectly assumed to be a known quantity. These practices can introduce errors into model predictions of aquifer budget components, such as recharge and storage depletion. In turn, aquifer management and planning can be greatly impacted, as estimates of aquifer responses to pumping changes are highly dependent on those simulated budget components. In this work, we use a groundwater model of a portion of the High Plains aquifer in the central United States to illustrate the impacts of inappropriately large Sy values on model predictions and the related water management ramifications. Building on our recent work, we propose a data‐driven approach for determining specific yield for regional groundwater models. Results demonstrate that this new approach can improve model reliability and lead to more robust predictions of aquifer responses to management scenarios.

Structural and functional landscape connectivity for lesser prairie‐chickens in the Sand Shinnery Oak Prairie Ecoregion

AbstractThe lesser prairie‐chicken (Tympanuchus pallidicinctus) is a species of conservation concern on the Southern High Plains of Texas and New Mexico, USA. Because fragmentation and isolation have increased since pre‐settlement, dispersal through this heterogeneous landscape may be constrained, with serious implications for conservation and management of this species. Our objectives were to quantify landscape connectivity for lesser prairie‐chickens within a patch network of potentially isolated leks (breeding display grounds), and examine effects of land use change on modeled lesser prairie‐chicken movements through the landscape. We used graph theory to quantify structural landscape connectivity and circuit theory to quantify functional landscape connectivity for lesser prairie‐chickens in the Sand Shinnery Oak Prairie Ecoregion of the Southern High Plains. There was a high degree of clustering among leks (n = 1,023 leks), with a 41.9‐km coalescence distance of the network. We identified 3 leks as cutpoints within the network, meaning if the habitat patches containing these leks were fragmented, the remaining leks would become isolated from each other. We also identified several leks that were important for maintaining overall population connectivity for lesser prairie‐chickens on the Southern High Plains. Conservation Reserve Program land was important for maintaining connectivity among leks to the north and west of the main lek core area located in New Mexico, but wind energy development constrained pathways to the north and south of this main lek core area. Our results suggest that landscape connectivity was reduced by row‐crop agriculture and energy production and facilitated by the Conservation Reserve Program within the Sand Shinnery Oak Prairie Ecoregion.

PLAYA DYNAMICS AND SALINITY: A STUDY OF YELLOW LAKE ON THE HIGH PLAINS OF TEXAS

Saline playas on the Southern High Plains are almost always located on large cattle ranches but they are of limited value to the herds of cattle grazing around their outer margins. Saline playas are often without water for extended periods and, after inundation, they experience considerable evaporative loss leading to hypersaline conditions. The primary goal of this study was to develop a quantitative method that combines the transitory nature of playa lakes and the variability of salinity into a set of parameters that can be used to compare playas or other surface water sources. Regarding water quality, a variable was developed that describes the fraction of observations with salinity levels below the salt tolerance threshold for cattle. With regard to water availability, water depth measurements were used to compute the fraction of time that a playa contains water. These two variables are combined to form a new variable that represents the fraction of time that water is both available and of acceptable quality. To demonstrate the utility of this method, data was collected at Yellow Lake, a large saline playa located on the Yellow House Ranch northwest of Lubbock, Texas. Results suggest that the playa contained water 50.8% of the time over a five-year period but the fraction of water samples with acceptable salinity was only 6.5%. The resulting fraction of time that water was both available and of acceptable quality was only 3.3%. This technique could be used to compare other ephemeral surface water sources in the region.

Soil Moisture Retention on the High Plains of North America via Compost Amendments: A Longitudinal Field Study

Water is a finite but vital resource, and the volume of water used in arid and semi-arid regions must be managed to its fullest and best use. Irrigation water is approximately 37% of the total water used in the United States by volume annually. Thus, this area of water use is critical for local and national water conservation. Irrigation is primarily used to increase soil water content above that which precipitation can supply. Soil structure and associated effects on drainage and evapotranspiration, however, largely control soil water content, no matter the amount of applied water. Therefore, improving soil structure to hold more water decreases the amount of water needed for irrigation, which frees that water for other uses. In this paper, organic compost amendments are studied to determine the change in soil structure and accompanying improvements in soil water content over a 4-year period. A uniform field site was selected for this research in the high plains of South Dakota, where irrigation water was available for crop growth. The test site was divided into two equal area fields; one without compost and a field with compost amendments added to 20 cm depth. Compost was incorporated into the treated field at rates of 5% and 10% by weight. Both fields received the same tillage, seed, fertilizer, weather and irrigation. Weekly to monthly in-situ water content measurements from both fields were recorded at the surface and the depths of 20, 40 and 60 cm from 2017 to 2020. Precipitation and applied irrigation water were recorded at the site. No irrigation occurred in 2019 and 2020, and moisture content was dependent on natural precipitation in those years. Results of water content and soil structure show significant differences in the water contents of the soils with the compost amendments compared to baseline, with higher compost content resulting in higher water contents without the soil becoming over-saturated. These results were consistent at all depths and across all growing seasons. This work demonstrates the efficacy of compost soil amendments in regulating soil moisture, which has profound impacts on crop yields, topsoil erosion losses, carbon sequestration, and water conservation.