Browsing by Author "Schipanski, Meagan E., committee member"
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Item Open Access Altering water and nitrogen availability after roadside disturbance to favor native plant species(Colorado State University. Libraries, 2016) Ringer, Lindsay, author; Brown, Cynthia S., advisor; Claassen, Victor P., committee member; Schipanski, Meagan E., committee memberThis study evaluates the use of soil amendments in roadside restoration to promote native species and discourage invasive species establishment through manipulation of water and nitrogen (N) availability. Our goal was to decrease soil N availability and increase soil water content to foster growth of perennial native species on roadsides in Rocky Mountain National Park, Colorado. Roadside construction can increase soil bulk density, reduce aggregation, and cause an initial increase in resource availability, which encourages growth of early successional species. In addition, N deposition from the Front Range of Colorado is increasing nitrate and ammonium availability in this National Park. The study objective was to increase or decrease water and/or N availability with soil amendments to reduce weedy annual species establishment on roadsides. Treatments were hypothesized to 1) increase soil moisture and reduce plant-available N (synthetic polymer incorporation), 2) reduce soil surface temperatures, increase moisture and indirectly decrease N (wood mulch blanket), 3) decrease bulk density by changing soil structure and slowly increase N (yard-waste compost incorporation). These amendments were applied alone and in pairwise combinations to six southeast facing roadsides slopes concurrent with seeding in fall of 2013. Ten perennial grass and forb species were hydro-seeded with tackifier to all roadsides. Plant density, cover, mineral nutrients, soil moisture, total C:N, soil temperature, and rainfall were measured during the growing season in 2014 and 2015. A paired greenhouse study was conducted in spring 2014 with analogue native and non-native grasses. Grass root and shoot biomass, plant height, seedling density, and soil moisture were measured after 9 weeks of growth. On these roadsides, soil moisture, and density of native seeded species was significantly changed by soil treatments through time (p=0.039, p=0.040). Wood mulch alone and combined with compost or polymer increased soil moisture after rainfall in the field (p=0.0007) and after irrigation in the greenhouse (p=0.0001). In the field, seeded species density was highest in mulch/compost treatments in 2014 (p=0.029) and mulch/polymer treatments in 2015 (p=0.003). After one year of decomposition, none of the treatments significantly changed carbon to nitrogen ratios (p=0.27) which averaged 18.7:1, although mulch/compost treatment had the lowest C:N ratio of 13.5:1. Mulch or mulch/polymer treatments combined had much less nitrate than yard-waste compost incorporation (p=0.0002). Mulch blanket immobilized N and decreased non-native density in summer 2015 to 2 plants/m2. In contrast, compost/polymer treatments had 12 non-native plants/m2 (p=0.02). In the greenhouse, nitrate was more limiting than water, and mulch blanket increased native grass growth relative to non-native grasses (p=0.002). Because of the immobilization of N, mulch also decreased germination rates (p=0.001) and biomass (p=0.001) across all species. With higher soil moisture availability in the greenhouse, non-native growth was lower than natives in control (p=0.001), polymer and mulch soil treatments. In contrast, compost incorporation, which increased N availability in the field, drastically increased growth of all species (p<0.0001) in the greenhouse. These results begin to demonstrate how increased soil moisture and decreased soil N favors germination and seedling survival of desirable native perennial species, while simultaneously reducing non-native species establishment. By managing soil resource availability after disturbance, we can achieve resilient plant communities dominated by perennial native species.Item Open Access Cover crops for ecological management of U.S. agricultural systems: quantifying ecosystem services across multiple scales(Colorado State University. Libraries, 2023) Eash, Lisa, author; Fonte, Steven J., advisor; Schipanski, Meagan E., committee member; Trivedi, Pankaj, committee member; Mooney, Daniel, committee memberManaging agricultural systems to provide multiple ecosystem services (ES) beyond food provisioning has gained considerable attention in recent years. The integration of cover crops (CC) into U.S. cropping systems presents an opportunity to support multifunctional agricultural systems, which alleviate negative environmental impacts of agriculture, mitigate greenhouse gas (GHG) emissions and support sustained crop production. However, CC impacts on these ES are variable and depend on management and site characteristics, contributing to uncertainty surrounding to what extent CC can improve ES. Reducing this uncertainty is critical to both identify appropriate environmental and management conditions for CC adoption and improve the estimated potential for CC to improve multifunctionality of U.S. cropping systems. This dissertation aims to quantify CC impacts on ES at multiple scales, exploring benefits to the soil microbiome, at the farm level, and nationally. Throughout this assessment I explore how these effects are influenced by climate and soil characteristics and how management can be leveraged to optimize the provision of ES. Chapter two estimates the potential for widespread adoption of CC to increase soil organic carbon (C) stocks and mitigate GHG emissions in the U.S. Analysis using current U.S. crop management data and a biogeochemical model revealed that the mitigation potential over a 20 year period is lower than previous estimates due to regional variability, decreasing rates of C accrual over time, and limited CC integration. Changes in N2O emissions did not offset C sequestration but introduced large uncertainty surrounding total national mitigation potential. Soil C gains due to CC offer important co-benefits to U.S. cropping systems, but the contribution of CC to achieving U.S. emissions targets will likely be lower than previously anticipated. Our spatially-explicit analysis also highlights regions where adoption of CC can have greater relative contributions to GHG mitigation. I then quantify a larger suite of ES in dryland wheat systems of the semi-arid western U.S., a particularly challenging context for CC due to lower potential productivity and associated economic trade-offs. I used two existing field trials to monitor CC impacts on soil health, cash crop productivity, and economics over a period of six years. No-till, CC planting window, and the sale of CC biomass as forage were also explored as strategies to optimize ES provision and economic viability. Chapters three and four demonstrate that the integration of CC amidst water limitations can benefit erosion control and soil structure, but also present significant productivity and economic trade-offs. The integration of fall-planted CC, no-till management, and the use of CC for forage provided the greatest potential for maximizing ES benefits in an economically viable manner. In Chapter five, I conducted a greenhouse study to examine the impact of CC type and functional diversity on microbial community composition and associated ES. Plant functional types (Poaceae, Brassicaceae, and Fabaceae) were associated with distinct increases in ES proxies, which appear to be mediated by shifts in microbial community composition. Specifically, Fabaceae (legume) CC enhanced the presence of copiotrophic microbes, which were associated with improvements in soil structure and high enzyme activity, a proxy for nutrient cycling. Poaceae and Brassicaceae led to improvements in microbial diversity. Ecosystem service benefits and microbial community shifts were conserved in diverse CC mixtures, contributing to increased multifunctionality. Across studies and scales, CC were observed to support a number of ES that address environmental concerns resulting from modern intensive agricultural practices. However, slight benefits and substantial productivity trade-offs in water-limited systems may limit the extent to which CC can mitigate GHG emissions and restore soil C reserves nationally. Management choices, such as CC composition and diversity, no-till management, and the sale of a portion of CC biomass as forage, can be leveraged to optimize the provision of ES in an economically viable manner. Overall, CC effectively contribute to multifunctional agroecosystems whose ES extend beyond food provisioning.Item Open Access Exploring the role of planned and unplanned biodiversity in the soil health of agroecosystems(Colorado State University. Libraries, 2021) Kelly, Courtland, author; Fonte, Steven J., advisor; Schipanski, Meagan E., committee member; Wallenstein, Matthew, committee member; Hall, Ed, committee memberTo view the abstract, please see the full text of the document.Item Open Access Growing deeper: pathways to enhancing soil organic matter in annual and perennial dryland grain agroecosystems(Colorado State University. Libraries, 2022) van der Pol, Laura Kathryn, author; Cotrufo, M. Francesca, advisor; Schipanski, Meagan E., committee member; Trivedi, Pankaj, committee member; Crews, Timothy E., committee memberThe story of agriculture and human civilization is one of loss: loss of soil structure, soil carbon, ecosystem function, and diversity. As we find ourselves at the nexus of intersecting global challenges of radically altered biogeochemical cycles and anthropogenic climate and productivity influence, we urgently need to alter our relationship with the soil and biosphere that sustain our human systems. In this dissertation I evaluate two management strategies for enhancing soil organic matter (SOM) in dryland, grain fields in the U.S.: legume integration and perennial grains. These strategies have been part of traditional farming practices, but they are not commonly utilized by commodity farmers for reasons I explore in Chapter 5. I conclude with policy recommendations for one way that might lead to systemic change that would value soils and their vital role in our human systems more appropriately. Here I provide a brief synopsis of each chapter: In the introduction (Ch. 1) I provide some historical context of human reliance on grain agriculture and the reasons that legumes and perennials might enhance SOM. I also describe the framework of SOM formation used in this research and provide an overview of the components of SOM I measured in this research. The first study (Ch. 3) is an observational study of conventional, dryland wheat farmers in semi-arid Colorado and Nebraska. I examine the 'soil carbon (C) dilemma' (Janzen 2006): How can SOM be increased, while also increasing the release of nutrients that accompanies decomposition? We specifically tested whether incorporating legumes into a continuous rotation influences the form and amount of SOM as well as productivity in farms of the central Great Plains region of the U.S. by contrasting three, no-till rotation systems: 1) conventional wheat-fallow; 2) continuous grain-only rotations, and 3) continuous grain rotations that incorporate a legume crop. We sampled on-farm fields and experimental agricultural research station plots that had received one of these rotations for at least eight years. We found that intensifying the rotation with continuous grains led to 1.5-fold increase in aggregate size but did not change SOC stocks. Incorporating a legume to the continuous grain rotation resulted in 1 Mg C ha-1 more SOC on average in surface soil compared to wheat-fallow rotations. In chapter 3, I use a similar approach to assess whether conversion from annual to perennial grains such as intermediate wheatgrass Kernza® could sequester soil organic carbon (SOC). We sampled three sites with paired fields under annual grains and converted to Kernza 5-17 years ago to 100-cm and compared their SOC stocks as distributed between mineral-associated (MAOM) and particulate organic matter (POM). POM-C was higher under Kernza cultivation but total and MAOM-C were similar. Our findings suggest Kernza increases SOC at depth as POM. Further study is needed to assess whether this will result in long-term SOC sequestration. In order to quantify the effect of legume incorporation and ability of Kernza to form SOC, I performed a mechanistic study to quantify the formation of SOM from Kernza and alfalfa tissues under contrasting N management (Ch. 4) Using continuously labeled 13C/15N plant residues, we tested the effect of litter inputs of contrasting composition (shoot and root material from Kernza® and alfalfa, a perennial legume) under management of Kernza where N was (1) not added, (2) added as urea, or (3) fixed by an alfalfa intercrop. We selected Kernza for its theoretical potential to build SOM due to deep root systems and long growing season. We hypothesized that the higher quality litter from alfalfa shoots would lead to greater MAOM formation due to its higher density of metabolic components promoting enhanced microbial C use efficiency, while root tissues may more likely become stabilized within aggregates as oPOM due to increased contact with soil surfaces. We predicted that the management with N addition may enhance MAOM-formation by alleviating microbial N-limitation and leading to enhanced microbial C use efficiency. We found that overall Kernza promoted greater SOM formation, in both MAOM and oPOM, with 20% of roots stabilized and 12% of shoot stabilized after 27 mo compared to 10% for alfalfa roots and shoots. Finally, in chapter 5, I propose a pilot crop insurance and research program in the U.S. Northern Plains to promote practices that enhance soil health, farm income, resilience, and mitigate climate change. Such a program could inform nationwide adoption of such practices.Item Open Access Impacts of cropping system and nutrient management on soil health and soil-borne pathogens in smallholder systems of western Kenya(Colorado State University. Libraries, 2024) Mutai, Joyce Chelangat, author; Fonte, Steven J., advisor; Vanek, Steven, advisor; Stewart, Jane E., committee member; Schipanski, Meagan E., committee memberCrop production in smallholder farms is often limited by low soil fertility and the presence of soil-borne pathogens. Both challenges are associated with limited nutrient inputs, low rotational diversity, as well as small land holdings and the associated need for continuous cultivation in many smallholder systems. This dissertation explores the varied ways in which cropping systems and nutrient management strategies influence key soil health parameters and relationships with key soil-borne pathogens. Additionally, this research tests a suite of soil health bioassays to facilitate farmers' understanding of soil-borne pathogen status on their farms. I utilized a mix of observational research, short-term on-farm experiments, and long-term cropping system trials to understand: 1) the potential of simplified soil pathogen tests (for Fusarium, Pythium, and plant parasitic nematodes (PPN)) to provide insight on soil pathogen pressure, 2) the impact of dis- tinct nutrient management strategies (organic vs. synthetic inputs) on key soil health parameters and associated soil-borne pathogens, and 3) effects of cropping system (mono-cropping vs. more complex systems) on key soil health parameters and soilborne pathogens. To address these objectives, I first validated a suite of simplified soil bioassays to screen for PPN (e.g., Meloidogyne, Pratylenchus) and other key soilborne pathogens (Pythium and Fusarium) against formal laboratory methods. I collected soils across eleven on-farm trials in western Kenya (66 plots total), examining the impact organic vs. synthetic nutrient inputs on bean production. The soil nematode bioassays involved counting lesions on soybean roots and galls on lettuce roots and were strongly correlated with the abundance of gall forming, root-knot nematodes (Meloidogyne) and root lesion nematodes (Pratylenchus) recovered in laboratory-based extractions. Effectiveness of a Fusarium bioassay, involving the counting of lesions on buried soybean stem, was validated via DNA sequencing to identify Fusarium taxa and a pathogenicity test of cultured Fusarium strains. Finally, a Pythium soil bioassay using selective media clearly showed presence of the pathogen, with seed rotting and colonies observed. When examining nutrient management impacts on nematode communities, soils amended with manure had fewer PPN and considerably more bacterivores and fungivores compared to soils amended with synthetic N and P. Similarly, Pythium presence was lower in soils amended with manure, and higher levels of Fusarium in the same plots, likely due to the ability of various Fusarium taxa to exist as a saprophyte. Our findings suggested that relatively simple bioassays can be used to help farmers assess soilborne pathogens with minimal costs, thus enabling them to make informed decisions on soil health and pathogen management. In a second study, I used an exploratory approach to examine common cropping systems in western Kenya smallholders including: maize monocultures, maize-legume intercrops, maize in rotation with legumes and vegetables, and horticultural systems based on perennial crops and vegetable production. I sampled 35 farms to understand the impact of cropping system diversity and associated nutrient management on the abundance of Fusarium pathogens and LN. I found that organic inputs led to fewer lesion-causing nematodes compared to the inorganic inputs system, but an inverse relationship with Fusarium pressure was observed. Permanganate oxidizable C (POXC), particular organic matter (POM), total C, and soil pH were highly correlated with each other and negatively associated with LN pressure, while POM was positively correlated with Fusarium pressure. In a third study, I leveraged a long-term (18-year) field trial in western Kenya, testing cropping systems representative of smallholder farms. The long-term trial evaluates three cropping systems: 1) continuous maize monocrop, 2) maize in rotation with the woody legume, Tephrosia (T. candida), and 3) maize intercropping with soybean, and two nutrient management strategies: 1) application of farmyard manure (vs. not), and retention or removal plant residue, with all plots receiving regular fertilizer inputs. I sampled soil from 40 plots and measured soil physical (texture, POM), aggregate stability, bulk density), chemical (pH, total C, available P, POXC), and biological (Fusarium, Pythium, RKN, LN) properties. Results indicated that long-term manure significantly improved soil properties including pH, POXC, POM, total C, and soil aggregation. Moreover, manure significantly reduced Pythium and RKN pressure. Soil pH and POXC were associated with Pythium and RKN, such that plots with low pH and POXC levels had high abundance of these soilborne pathogens. Fusarium abundance on the other hand, was higher with manure and associated variables (aggregation, POXC, total C). In a fourth study, I utilized a long-term trial (45 years) in Kabete, central Kenya focused on integrated soil fertility management in continuous maize-bean rotation and the resulting impacts on soil characteristics was well-suited to this goal. I examined the effects of dry manure application, maize stover management (incorporated vs. removed), and synthetic fertilizers (N and P applied vs. no application) in a full-factorial experiment on a range of soil physical, chemical, and biological properties. Results indicated that application of organic inputs, especially manure, greatly improved soil organic matter (SOM) pools, soil pH, aggregate stability, and decreased bulk density, compared to synthetic fertilizers. At the same time, manure significantly reduced Pythium and LN pressure, while plant residues reduced RKN and Pythium considerably. In summary, the simplified soil pathogen bioassays and soil health analyses considered in this dissertation offer a powerful set of tools to help smallholder farmers and the local research or extension organizations that they work with to monitor and anticipate soil related challenges in their fields, thus supporting agricultural livelihoods and resilience. Additionally, these findings suggest that continuous mining of nutrients and minimal returns of organic matter (i.e. removal of crop residues and no manure application) appears to drive the decline of important soil health properties (pH, POXC, POM, aggregation, and total C), with important implications for soil-borne pathogens.Item Open Access Organic nitrogen fertilizers influence nutritional value, water use efficiency, and nitrogen dynamics of drip irrigated lettuce and sweet corn(Colorado State University. Libraries, 2016) Sukor, Arina, author; Davis, Jessica G., advisor; Schipanski, Meagan E., committee member; Qian, Yaling, committee member; Argueso, Cristiana, committee memberFarmers usually rely on off-farm sources (fish emulsion, feather meal, blood meal) for the additional N needed during the growing season, and they are willing to pay the extra shipping cost. However, there is another fertilizer option being developed that could allow farmers to produce N on-farm, which is cyanobacteria, formerly known as the blue green algae. The general objectives of this study were to assess effects of organic N fertilizer application and N rates on nutritional value, water use efficiency, N dynamics of sweet corn and lettuce. A two-year field study was conducted in the summers of 2013 and 2014 at the Colorado State University Horticulture Research Center, Fort Collins, CO. The fertilizers used in this study were blood meal, feather meal, fish emulsion, and cyano-fertilizer. Both fish emulsion and cyano-fertilizer were supplied in four split applications over the growing season through drip irrigation, while the blood meal and feather meal were subsurface banded prior to planting. Lettuce and sweet corn were used as an indicator to evaluate effects of organic nitrogen (N) fertilizers on nutritional value, water use efficiency, and N dynamics. The aims of this study were to evaluate the effect of different types of organic N fertilizer on nutritional value; β-carotene, iron (Fe), zinc (Zn), marketable yield, water use efficiency (WUE), residual soil nitrate-N, N content, and N use efficiency (NUE) of horticultural crops, particularly lettuce and sweet corn. All fertilizer treatments in 2013 increased β-carotene concentration in leaf tissue compared to control, while only fish emulsion had a higher β-carotene concentration compared to other treatments in 2014. The high indole-3-acetic acid (IAA) applied in the fish emulsion treatment could have increased β- carotene concentration in lettuce in both years. Amount of IAA applied in the fish emulsion treatment was positively correlated with β-carotene concentration in both years. A significant negative correlation was found between marketable yield and β-carotene concentration in leaf tissue in 2014. High salicylic acid (SA) applied in the cyano-fertilizer treatment had a higher total leaf area compared to other fertilizers in both years. In lettuce, the blood meal treatment had a lower leaf Fe and Zn concentrations than other fertilizer treatments at 112 kg N ha-1. The cyano-fertilizer treatment had a higher leaf Fe concentration at 56 kg N ha-1. Leaf N concentration was positively correlated with Leaf Fe and Zn concentrations. Amount of NO3- -N applied in organic N fertilizers was negatively correlated with leaf Fe concentration. The cyano-fertilizer, fish emulsion, and blood meal treatments increased Fe concentration in sweet corn compared to feather meal. Amount of NO3- -N, Fe, and Zn applied in organic N fertilizers were positively correlated with kernel Fe concentration, while amount of NH4+ -N applied was negatively correlated with kernel Fe concentration. There was no N rate or treatment effect on leaf and kernel N concentrations in sweet corn. The amount of phytohormone, Ca, and Fe applied in organic N fertilizers may have affected field water use efficiency (fWUE), instantaneous water use efficiency (iWUE), kernel number, and leaf gas exchange components of sweet corn. Cyano-fertilizer apparently had a higher WUE, likely due to the high amount of SA applied. A positive relationship was observed between the amount of SA applied with iWUE and fWUE. The amount of Fe applied in organic N fertilizers had a positive correlation with leaf VPD and transpiration rate. The amount of Ca applied in the feather meal treatment may have contributed to increasing leaf temperature and decreasing net photosynthetic rate. The amount of NH4+ -N and Ca applied in the feather meal treatments were negatively correlated with both iWUE and fWUE. N rate effect was only observed in lettuce marketable yield and NUE in both years. Blood meal and feather meal fertilizers with higher percentage of N applied as NO3- -N compared to other fertilizer treatments had a higher residual soil NO3- -N concentration in 2013. Greater residual soil NO3 - -N was observed in the 0-30 cm depth compared to the 30-60 cm depth in 2014. Organic growers could achieve higher marketable yield and NUE when applying fertilizers at rates between 28 kg N ha-1 and 56 kg N ha-1 compared with 112 kg N ha-1. In sweet corn, the feather meal and fish emulsion treatments had a higher residual soil NO3- -N compared with other treatments. The fish emulsion, cyano-fertilizer, and blood meal had a higher leaf and kernel N contents and NUE compared with feather meal at 56 kg N ha-1. The cyanofertilizer treatment had a higher marketable ear yield and NUE compared with other treatments at 112 kg N ha-1 in 2014. The amount of C inputs and crop species may have affected soil permanganate oxidizable carbon (POXC) concentration in a single season study. Soil POXC concentration was higher in the cyanofertilizer treatment compared to the control treatment in sweet corn, while the opposite trend was found in lettuce. Depth effect was observed in soil POXC concentration at 0-30 cm compared to 30-60 cm in lettuce. Soil POXC concentration was higher at 112 kg N ha-1 compared to 56 kg N ha-1 in sweet corn, but there was no N rate effect in lettuce. Greater soil POXC concentration and marketable ear yield of sweet corn were observed in the cyano-fertilizer treatment compared to others at 112 kg N ha-1. Overall, our results indicate that organic N fertilizer, particularly cyano-fertilizer influenced soil POXC concentration over a short-term growing season of horticultural crops.Item Open Access Restoring semi-arid lands with superabsorbent polymers under reduced precipitation and threat of Bromus tectorum invasion(Colorado State University. Libraries, 2016) Garbowski, Magda, author; Brown, Cynthia S., advisor; Johnston, Danielle B., advisor; Hardegree, Stuart P., committee member; Schipanski, Meagan E., committee memberRestoration of arid ecosystems in the western United States (US) is often constrained by low and variable moisture and invasion by exotic species. After disturbance, variability in resources as well as inherent soil moisture and temperature regimes may influence the susceptibility of an ecosystem to exotic species invasion. The invasive winter annual grass, Bromus tectorum (B. tectorum), is particularly competitive in disturbed semi-arid areas, has invaded tens of millions of hectares throughout the western US, and its range is projected to expand under predicted climate scenarios. Increasing soil moisture and resources in restoration projects may decrease soil moisture variability and promote establishment of a native plant community that is resilient to disturbance and resistant to invasion of B. tectorum. With their ability to absorb moisture when it is abundant and slowly release it over time, superabsorbent polymers (SAP) may increase overall soil moisture and decrease soil moisture variability during restoration. In this study, we aimed to investigate the interactive effects of precipitation timing, drought, B. tectorum, and SAP on soil resources and developing restoration plant communities. The study was established in 2014 at two climatically distinct sites: one site was located on the Eastern Slope (Larimer County) and one on the Western Slope (San Miguel County) of Colorado. Both sites fall under the mesic soil temperature regime and ustic-aridic soil moisture regime but vary in their susceptibility to invasion largely due to differences in seasonal precipitation patterns. While the Eastern Slope receives most of its growing season moisture in the early spring and summer, the Western Slope site receives most of its growing season moisture in the late summer and early fall. Two levels of three treatments (drought: exclusion of 66% of ambient rainfall or ambient rainfall; B. tectorum presence: 465 seeds m-2 or none; SAP: 26 g m-2 or none) were fully crossed in three blocks at each site resulting in a complete factorial experiment. After one year of monitoring soil moisture, plant available nitrogen (at the Western Slope site), and plant community responses, we observed significant effects of exclusion at both sites on soil resources and the developing plant communities. Independent and interactive effects of drought and SAP at the Eastern Slope site and drought and B. tectorum at the Western Slope site influenced plant communities and soil resources. Overall B. tectorum establishment was low on the Eastern Slope and high on the Western Slope in the first year of the study. At the Eastern Slope site, drought limited seeded species recruitment late in the season and the positive effects of SAP on seeded species were apparent only under ambient precipitation conditions. Total and annual seedling densities were higher under SAP treatments at this site. At the Western Slope site, total seedling densities were lower in drought treatments, and native seedling densities were lower in drought treatments at the end of the growing season. The effects of B. tectorum on seeded annuals at the Western Slope site depended on date and precipitation treatment. Seeded annuals densities were highest in mid-summer in treatments without B. tectorum and ambient precipitation. Interestingly, at the Western Slope site, B. tectorum under ambient precipitation had a stronger negative impact on soil moisture at 30 cm depth than drought treatments regardless of level of B. tectorum or SAP. B. tectorum also decreased soil moisture at 5cm depth early in the season at the Western Slope site while exclusion treatments decreased soil moisture later in the growing season at both sites. Our results demonstrate that drought negatively impacts soil resource availability and native plant community development in restoration. Techniques that improved water and nutrient availability especially under drought conditions are needed to promote native species establishment. While SAP did not improve soil moisture, higher seedling densities were found in SAP treatments at one site, especially under ambient conditions. This suggests that incorporating SAP into the soil may improve plant establishment, but effectiveness is likely affected by antecedent soil moisture and precipitation patterns. In our study, B. tectorum negatively impacted soil moisture and native plant establishment at one site demonstrating the need for management of this species in restoration of semi-arid lands.