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Munda, Bruce, Tim C. Knowles, Art Meen, Vic Wakimoto, and Bill Worthy. "Winter Forage Cover Crop Trials." College of Agriculture, University of Arizona (Tucson, AZ), 1998. http://hdl.handle.net/10150/208283.
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Several crops were evaluated at Worthy farms, near Marana, AZ, Wakimoto farms, Mohave Valley, near Bullhead City, AZ, and the Tucson Plant Materials Center for use as a winter cover crop following cotton with potential to reduce wind erosion and produce one to two hay cuttings. Hairy vetch (Vicia villosa), 'Lana' woolypod vetch (Vicia villosa ssp. varia), 'Papago' pea (Pisum sativum), and 'Biomaster' pea (Pisum sativum) were sown at the Tucson Plant Materials Center. Species sown at Worthy farm were: Papago pea, Lana vetch, and Biomaster pea. Species sown at Wakimoto farm were: Biomaster pea, Lana vetch, 'Seco' barley (Hordeum vulgare), and 'Multi-cut' berseem clover (Trifolium alexandrinum). Forage yield varied between locations due to sowning date, number of irrigations, and soil textures. Biomaster pea, Papago pea, and Lana vetch performed well at all three locations. However, Biomaster yields were more consistent and due to its shorter growing season may be the better choice as a winter cover between cotton crops. Additional trials are scheduled for the fall of 1998.
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Ess, Daniel R. "Cover crop residue effects on machine-induced soil compaction." Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06062008-164819/.
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Arnet, Kevin Broc. "Cover crops in no-tillage crop rotations in eastern and western Kansas." Thesis, Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/4086.
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Christenson, Andi Marie. "Cover crops for horseweed [Conyza canadensis (L.)] control before and during a soybean crop." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/19230.
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Master of Science<br>Department of Agronomy<br>J. Anita Dille<br>Kraig Roozeboom<br>Increasing numbers of herbicide-resistant weed species require alternative methods of weed suppression to be examined. This study quantified the interaction between various cover crop or herbicide systems and horseweed [Conyza canadensis (L.)] growth. Fall cover crops of winter wheat [Triticum aestivum (L.)], winter rye [Secale cereal (L.)], barley [Hordeum vulgare (L.)] and annual ryegrass [Lolium multiflorum (L.)] were seeded in November 2012 and 2013. Spring cover crop of oat [Avena sativa (L.)] was seeded in April 2013 or rye was seeded in March 2014. All cover crops were no-till seeded into grain sorghum stubble [Sorghum bicolor (L.) Moench]. Four herbicide treatments were fall or spring applied, with and without residual. The spring non-residual treatment was also applied to plots of winter rye. Cover crop plots were split and terminated with a roller crimper or glyphosate application prior to soybean [Glycine max (L.) Merr.] planting to determine the effect of termination method on treatment performance. Soybean was planted in June 2013 and May 2014 and mechanically harvested in October of both years. Horseweed density, biomass accumulation, and soybean yield data were quantified. Horseweed height, whole plant seed production, and seed subsamples were recorded in the untreated fallow control, winter wheat, and winter rye plots in 2014. Horseweed suppression by winter rye approached 90%, levels similar to suppression by herbicide systems. In both years, herbicide plots had less than half the horseweed biomass than any of the cover crop systems. In 2013, soybean yields in herbicide plots were at least 1,500 kg ha[superscript]-1, nearly more than double yields in cover crop plots. Soybean yields in 2014 were more consistent across treatments; barley and spring rye plots achieved yields equal to or greater than 2,000 kg ha[superscript]-1. Winter rye and winter wheat reduced horseweed seed production by 60% compared to the untreated fallow control, with no effect on individual seed weight. Seed production varied across
plants, with the untreated control producing the greatest number of seeds. Cover crops were successful at reducing horseweed biomass, suppressing horseweed pressure, preserving soybean biomass, and protecting soybean yields when compared to a fallow untreated control.
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Davis, Cathryn Joyce. "Cover crops for soil health and forage." Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/34537.
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Master of Science<br>Department of Agronomy<br>DeAnn R. Presley<br>Cover crops have numerous benefits and while cover crops have been used for centuries, currently there are few producers in Kansas growing them and so there is a need for additional research on how cover crops affect soil properties, and on the potential for utilizing cover crops as forage. Two studies are presented in this thesis. The first study evaluated the use of cover crops in a vegetable production system as compared to a fully tilled control. This study evaluated soil physical properties in the form of wet aggregate stability and infiltration, and microbial properties by soil microbial biomass carbon (MBC). Over the three year study, the most pronounced differences observed were in the wet aggregate stability between the cover crop and control treatments where the cover crop treatments had better soil aggregation compared to the control. At the conclusion of the study, there was not a difference between fall and spring planted cover crop treatments. The second study evaluates species composition and forage quality of various combinations of multi-species cover crop mixtures. This study evaluated sixteen treatments, each consisting of a three-way mixture of a brassica (turnip or radish), grass (rye, wheat, barley, oat), and a legume (berseem clover or Austrian winter pea). Species composition analysis found that the brassica species dominated the mixtures (60-80% by mass on a dry weight basis) in 2014 while the grass species were dominant (62 – 67%) in 2015. Overall all treatments produced prime quality forage (as compared to hay values), however some treatments cost significantly more to plant than others. Therefore an economic analysis compared the treatments and found that the treatments containing turnips and oats generally provided the best return on investment given that both of these species were among the cheapest to plant and produced moderate to high biomass compared to the other treatments. The results of these projects point to the potential benefits that cover crops can have for producers interested in improving soil or utilizing cover crops for forage.
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Kern, James D. "Water Quality Impacts of Cover Crop/Manure Management Systems." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/40385.
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Crop production, soil system, water quality, and economic impacts of four corn silage production systems were compared through a field study including 16 plots (4 replications of each treatment). Systems included a rye cover crop and application of liquid dairy manure in the spring and fall.
The four management systems were: 1) traditional, 2) double-crop, 3) roll-down, and 4) undercut. In the fourth system, manure was applied below the soil surface during the undercutting process. In all other systems, manure was surface-applied. In the third system, the rye crop was flattened with a heavy roller after manure application.
Simulated rainfall was applied within 48 h of manure application. Measured constituent concentrations in runoff were compared with water quality criteria. Costs and returns of all systems were compared. The undercut system reduced loadings of all nutrients, but increased total suspended solids (TSS) concentration as compared with all other systems. The mean volume of runoff from the undercut system was less than half that from any other system, which influenced all constituent loadings. Mean TSS concentration in runoff from the undercut system was over three times the mean of any other system. The roll-down system had no significant effect on water quality as compared to the traditional system. The undercut system was reasonably effective in keeping phosphate phosphorus levels below the criterion set for bathing water. None of the systems generally exceeded nitrate nitrogen concentration criteria.
However, total phosphorus, orthophosphate, fecal coliform and e. coli criteria for drinking, bathing, shellfish harvest, and aesthetics were regularly exceeded by all of the systems. There were no differences among the treatments in effects on bacterial concentrations. The double-crop system produced significantly higher net returns than all other systems only if the value of the rye crop was $92.31/Mg or more. There were no significant differences in net returns of the traditional, roll-down, or undercut systems.<br>Ph. D.
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Abel, David Scott. "Cover crop effects on soil moisture and water quality." Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/34650.
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Master of Science<br>Department of Agronomy<br>Nathan O. Nelson<br>Eutrophication of freshwater lakes and streams is linked to phosphorus (P) fertilizer loss from agriculture. Cover crops could help mitigate P loss but producers are concerned that they may use too much water. This study was conducted to better understand the effects cover crops have on soil moisture and P loss. Volumetric water content (θ) was measured at the Kansas Cover Crop Water Use research area at 10 depths throughout a 2.74 m soil profile in 5 cover crop treatments and compared to θ measured from a chemical fallow control. Total profile soil moisture in sorghum sudangrass (1.02 m) and forage soybean (1.03 m) did not significantly differ from chemical fallow (1.05 m) at the time of spring planting. However, water deficits were observed in double-crop soybean (1.01 m), crimson clover (0.99 m), and tillage radish (0.99 m). At the Kansas Agricultural Watersheds, runoff was collected and analyzed for total suspended solids, total P, and DRP from 6 cover crop/fertilizer management treatments over two years. In the first water year the cover crop reduced runoff, sediment, and total P loss by 16, 56, and 52% respectively. There was a significant cover by fertilizer interaction for DRP loss. When P fertilizer was broadcasted in the fall with a cover crop, DRP loss was reduced by 60% but was unaffected in the other two P fertilizer treatments. Results were different in the second water year. The cover crop reduced sediment loss (71% reduction), as was seen in year one, but neither the cover crop nor the fertilizer management had a significant effect on runoff volume or total P loss overall. Contrary to the 2014-2015 results, cover crop increased DRP load by 48% in 2015-2016. DRP load was 2 times greater in the fall broadcast treatment than it was in the spring injected treatment but there was not a significant fertilizer by cover crop interaction. In order to determine the long term effects of cover crops and P fertilizer management P loss parameters should be tracked for several more years.
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Collins, Amanda Shea. "Leguminous cover crop fallows for the suppression of weeds." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0007018.
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Wang, Guangyao (Sam), and Kurt Noite. "Summer Cover Crop Use in Arizona Vegetable Production Systems." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2010. http://hdl.handle.net/10150/147024.
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4 pp.<br>Summer cover crops can add nitrogen to the soil, build up and maintain soil organic matter, suppress pest populations, mitigate soil erosion, and reduce nutrient leaching when they are used in Arizona vegetable systems. However, careful management is required since cover crops can modify the availability of soil nitrogen and other critical nutrients. The ratio between carbon to nitrogen (C:N) in decomposing cover crop biomass is a critical indicator of the overall process of breakdown and eventual release of nutrients. This article introduces five cover crops that could improve vegetable systems in Arizona. The mixtures of a legume and a non-legume cover crop species can also be planted to obtain desired C:N ratios to optimize the benefits of cover crops.
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GABBRIELLI, MARA. "MEASURING AND MODELLING COVER CROP GROWTH AND AGRONOMIC EFFECTS." Doctoral thesis, Università degli Studi di Milano, 2022. https://hdl.handle.net/2434/949531.
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Cover crops are cultivated during the bare soil period between the harvest of a cash crop and the sowing of the next one. Their cultivation puts into effect the permanent soil organic cover principle of conservation agriculture and exerts several agro-ecological services, among which the most relevant are nitrate leaching reduction, weed growth control, soil organic matter increase, soil structure and water infiltration improvement. In temperate climates when crop rotations include summer cash crops (such as maize or soybean), autumn-winter cover crops are sown between late July and October and terminated from March to April of the following year. When sown in autumn, frost-sensitive cover crops may also be terminated efficiently by frost damage: this termination method is frequently called ‘winterkill’. Black oat (Avena strigosa Schreb.) and white mustard (Sinapis alba L.) are two of the most interesting and widespread frost-sensitive cover crops due to their adaptability to various environmental conditions and cropping systems. Even if these species are widely adopted as cover crops, there is a lack of information concerning both crop management and agronomic effects, as well as winterkill termination occurrence frequency and efficiency in temperate climates. Dynamic cropping systems simulation models can be used to determine crop management scenarios convenience for a wide range of weather and soil conditions, while the field trial assessments require large resource investments. However, the application of a simulation model to white mustard and black oat cover crops presents several knowledge gaps, as the limited number of studies focused on winterkilled cover crops growth and agronomic effects carried out in northern Italy. Furthermore, an integrated simulation model dealing both with cover crop growth and winterkill termination, and its consequent effect on the crop-soil system, including cover crop residue degradation on soil surface, is lacking.
This work aimed at representing, within the ARMOSA cropping system model framework, frost sensitive cover crop species growth, development, and agronomic effects by enriching the simulation model with two additional modules, dealing respectively with winterkill events and cover crop superficial residue decomposition. The model was calibrated for white mustard and black oat cover crops using experimental data deriving both from a three-year field trial, from a commercial field monitoring campaign and from previous experiments, carried out in the region of interest. During the three-year field trial, white mustard, black oat and their mixture with purple vetch (Vicia benghalensis L.) have demonstrated a good aboveground biomass production potential (2-3 t DM ha-1), particularly when planted before the first half of September. Their nitrogen uptake (45 kg N ha-1 on average, up to 148 kg N ha-1) follows the biomass accumulation patterns, while their weed species control ability has proven to be consistently high. Overall, the improved ARMOSA model correctly simulated these species development (RRMSE equal to 27.3 and 29.5% respectively for black oat and white mustard), as well as soil water content and temperature (RRMSE equal to 8.4% and 19.2%). The employment of the new ARMOSA version to simulate black oat and white mustard cultivation, generally improved significantly both aboveground biomass simulation (RRMSE was decreased by 56.3% in comparison to the use of the original model version), leaf area index (RRMSE reduction of 31.6%) and C:N ratio simulations (RRMSE reduction of 8.8%). The convenience of the new model version employment was assessed in a wide range of sites (six sites of several provinces of Lombardy region in northern Italy), pedological conditions (soil textures from sandy-loam to silty-clay), weather conditions (calibration seasons ranged from 2019/2020 to 2021/2022) and management practices (minimum and no till seed bed preparation, slurry application, early and late sowing dates). To summarize, the new model version was able to successfully capture the main crop-related variables trends over time, as well as to correctly reproduce soil water content and temperature dynamic.
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Subedi-Chalise, Kopila. "Impacts of Crop Residue and Cover Crops on Soil Hydrological Properties, Soil Water Storage and Water Use Efficiency of Soybean Crop." Thesis, South Dakota State University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10265200.
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<p> Cover crops and crop residue play a multifunctional role in improving soil hydrological properties, soil water storage and water use efficiency (WUE). This study was conducted to better understand the role of crop residue and cover crop on soil properties and soil water dynamics. The study was conducted at the USDA-ARS North Central Agricultural Research Laboratory, located in Brookings, South Dakota. Two residue removal treatments that include low residue removal (LRR) and high residue removal (HRR) were established in 2000 with randomized complete block design under no-till corn (Zea mays L.) and soybean (Glycine max L.) rotation. In 2005, cover crop treatments which include cover crops (CC) and no cover crops (NCC) were integrated into the overall design. Soil samples were collected in 2014, 2015 and 2016. Data from this study showed that LRR treatment resulted in lower bulk density (BD) by 7 and 9% compared to HRR in 2015 and 2016, respectively, for 0-5 cm depth. Similarly, LRR treatment significantly reduced soil penetration resistance (SPR) by 25% in 0-5 cm depth compared with HRR treatment. In addition to this, LRR treatment significantly increased soil organic carbon (SOC) concentrations and total nitrogen (TN) by 22 and 17%, respectively, in 0-5 cm. Similarly, CC treatment resulted in lower BD and SPR by 7% and 23%, respectively, in 0-5 cm depth in 2015 compared with NCC treatment. The LRR significantly increased soil water infiltration by 66 and 22% compared to HRR in 2014 and 2015, respectively. Similarly, the CC treatment significantly increased infiltration by 82 and 22% compared to the NCC in 2014 and 2015, respectively. The significant impact of a crop residue was observed on soil water retention (SWR) in 2014 and 2015 for the 0-5 cm depth. The LRR and CC treatments increased the soil volumetric moisture content (VMC) and soil water storage (SWS) on the surface 0-5 cm depth. However, the trend was not always significant during the growing season. The CC treatment significantly impacted the soybean yield by 14% and WUE by 13% compared with NCC treatment. Some interaction of residue by cover crops was observed on BD, SPR, VMC, and SWS, which showed that the use of cover crops with LRR can be beneficial in improving the soil properties.</p>
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Hänninen, K. (Kaarina). "Tree - cover crop interactions: birch growth, competition and soil properties." Doctoral thesis, University of Oulu, 2002. http://urn.fi/urn:isbn:9514267184.
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The main objective of this thesis was to investigate tree - cover crop interactions and soil response in an intercropping system, in which leguminous and grass cover crops were used with birch (red-leaved Downy birch Betula pubescens L.). The investigation was conducted in two field experiments in a nursery and in a greenhouse experiment. In the latter the effect of the water supply in interspesific competition was also investigated. The cover crops in the field experiments were perennial clovers Trifolium pratense L., T. repens L. and T. hybridum L. and annual clovers T. incarnatum L., T. resupinatum L. and T. subterraneum L. and perennial Festuca rubra L. The height, stem diameter, leaf area and nutrient status of the birch were determined, as well as soil nutrient status and microbial characteristics. The cover crops in the greenhouse experiment were T. repens, T. subterraeum and F. rubra. The biomass, height, leaf area, leaf area index, specific leaf area and N concentration of the birch, the biomass and N concentration of the cover crops were measured, and soil N and microbial characteristics, as well. Bare ground was the control in all the experiments.
The perennial clovers and Festuca strongly decreased the birch growth and nutrient status, but the annual clovers sown in midsummer in the field experiments provided about as good growth as bare ground. In the greenhouse experiment all cover crops were effective competitors with the birch. The soil NO3-N was, in general, the highest on bare ground and second highest in the annual clover plots. Though there were, in general, only minor differences in the soil nutrient concentrations between the treatments, there were significant differences in the tree growth and nutrient concentrations. The interspecific competition in this kind of intercropping system is mainly belowground. The growth reduction in the birch was mainly due to competition for nitrogen but water seems to play an important role in regulating the competitive interaction between the birch and cover crops. The competition for these resources seems to be most crucial at the beginning of the growing season. The microbial biomasses and soil respiration were greatest in the Festuca and perennial clover treatments, which may indicate that microorganisms together with these cover crops may seriously compete with birch for nutrients.
Intercropping system is complex and comprises both negative and positive influences. In order to minimize negative competition effects, the cover crop should be non-competitive or the ground should be kept free of vegetation at the beginning of the growing season. By improving soil microbial characteristics, the vegetative ground covers make this cropping system one possiblity towards sustainability in the long-term.
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Vollmer, Emily R. "Cover Crop Mulches for No-till Organically Managed Onion Production." NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-11062008-105026/.
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Combining the environmentally sound practices of reduced tillage and cover crop use with organic vegetable production systems requires management choices that are tailored to specific climate and crop combinations. In the southeastern U.S. summer cover crops can be grown through the fall until desiccation by frost. At this time a cash crop such as bulb onions (Allium cepa L.) can be grown using reduced tillage for over winter production. Field experiments were conducted on first year transitional (non-organic) land in 2006-07 and 2007-08. Cover crops of foxtail millet âGerman Strain Râ [Setaria italica (L.) Beauv.] and cowpea âIron & Clayâ [Vigna unguiculata (L.) Walp.] were grown as monocrops (MIL, COW) and biculture mixtures and compared to a bare ground control (BG). Mixtures of cowpea and millet consisted of seeding rates aimed at producing 70%, 50%, and 30% millet per total biculture biomass (MIX-70, MIX-50, MIX-30). Cover crop residue treatments were evaluated for weed suppression and N contribution to no-till organic onion production. Supplemental N in the form of surface applied soybean meal [Glycine max (L.) Merrill] was applied to cover crop treatment subplots at three rates: 0, 105, and 210 kg Nâha-1. Onion yields increased linearly from 0 to 210 kg Nâha-1 rates of soybean meal. Cover crop treatments COW and BG had the greatest total marketable onion yield and were statistically equivalent both years. Losses in marketable yield were primarily due to mortality in MIL and MIX in 2006-07 and bolting across all cover crop treatments, which averaged 28% in 2006-07 and 72% in 2007-08. Onion mortality was over 50% in MIL and MIX treatments in 2006-07 and was attributed to physical properties of thick surface mulch. Onion mortality in 2007-08 was highest on MIL compared to all other cover crop treatments but remained below 20%. Weed interference during onion production was highest in COW and lowest in treatments with millet (MIL, MIX) in 2006-07. Nitrogen rates of 105 and 210 kg Nâha-1 increased soil mineral N (NO3- and NH4+) on BG plots two weeks after surface application of soybean meal at the end of November each year but generally ceased to have an effect on soil mineral N by February or March. The 105 kg Nâha-1 soybean meal rate appeared to be more than sufficient for use as a starter fertilizer. Split applications of soybean meal could be an important improvement in N management to avoid N leaching and better meet increased N uptake demand during bulb initiation and growth in the spring. Overall, this study shows that cowpea cover crops grown preceding an over-wintered no-till allium crop is feasible with appropriate management, and provides onion yield comparable to bare ground production.
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Hänninen, Kaarina. "Tree-cover crop interactions : birch growth, competition and soil properties /." Oulu : Oulun Yliopisto, 2002. http://herkules.oulu.fi/isbn9514267184.
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Sciarresi, Cintia Soledad. "OPTIMIZING COVER CROP ROTATIONS FOR WATER, NITROGEN AND WEED MANAGEMENT." UKnowledge, 2019. https://uknowledge.uky.edu/pss_etds/122.
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Winter cover crops grown in rotation with grain crops can be an efficient integrated pest management tool (IPM). However, cover crop biomass production and thus successful provisioning of ecosystem services depend on a timely planting and cover crop establishment after harvest of a cash crop in the fall. One potential management adaptation is the use of short-season soybeans to advance cover crop planting date in the fall. Cover crops planted earlier in the fall may provide a greater percentage of ground cover early in the season because of higher biomass accumulation that may improve weed suppression. However, adapting to short-season soybeans could have a yield penalty compared to full-season soybeans. In addition, it is unclear if further increasing cover crop growing season and biomass production under environmental conditions in Kentucky could limit nitrogen and water availability for the next cash crop. This thesis combines the use of field trials and a crop simulation model to address the research questions posed.
In Chapter 1, field trials evaluating yield and harvest date of soybean maturity group (MG) cultivars from 0 to 4 in 13 site-years across KY, NE, and OH, were used to calibrate and evaluate the DSSAT crop modeling software (v 4.7). The subsequent modeling analysis showed that planting shorter soybean maturity groups (MG) would advance date of harvest maturity (R8) by 6.6 to 11 days per unit decrease in MG for May planting or by 1 to 7.3 days for July planting. The earliest MG cultivar that maximized yield ranged from MG 0 to 3 depending on the location, allowing a winter-killed cover crop to accumulate between 257 to 270 growing degree days (GDD) before the first freeze occurrence when soybean was planted in May, and between 280 to 296 GDD when soybean was planted in July. Winter-hardy cover crops could accumulate 701 to 802 GDD following soybean planted in May and 329 to 416 GDD after soybean planted in July.
In Chapter 2, a two-year field trial was conducted at Lexington, KY to evaluate the effect of a soybean – cover crop rotation with soybean cultivars MG 1, 2, 3 or 4 on cover crop biomass and canopy cover, and on weed biomass in the fall and the following spring. Results showed that having cover crops was an efficient management strategy to reduce weed biomass in the fall and spring compared to no cover treatment. Planting cover crops earlier in the fall after a short-season soybean increased cover crop biomass production and percentage of ground cover in the fall, but not the following spring. Planting cover crop earlier after a short-season soybean did not improve weed suppression in the fall or spring compared to a fallow control with full-season soybean. Having a fall herbicide application improved weed control when there was a high pressure of winter annual weeds. By the spring, delaying cover crop termination increased cover crop biomass but also did weed biomass.
In Chapter 3, a soybean – cover crop – corn rotation was simulated to evaluate the effect of different soybean MG and cover crop termination, as well as year to year variability on water and nitrogen availability for the next corn crop in Lexington, KY. Simulations showed that when cover crops were terminated early, they did not reduced soil available water at corn planting. However, introducing a non-legume cover crop reduced total inorganic nitrogen content in the soil profile by 21 to 34 kg ha-1 implying 15 to 30 kg ha-1 less in corn nitrogen uptake. Cover crop management that was able to maintain similar available water values than fallow treatment while minimizing nitrogen uptake differences was cover crops planted after soybean MG 4 with an early termination. However, the best management strategies that will maximize ecosystem services from cover crops as well as cash crop productivity may need to be tailored to each environment, soil type, irrigation management, and must consider year-to-year variability.
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Malnou, Cathy. "A canopy approach to nitrogen recommendation for the sugar beet crop." Thesis, University of Nottingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288992.
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Peterson, Alan Tollof. "Intersowing Cover Crops Into Standing Soybean in the Upper Midwest." Thesis, North Dakota State University, 2019. https://hdl.handle.net/10365/31688.
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In order to reduce nutrient losses and soil erosion in the United States Upper Midwest following soybean [Glycine max (L.) Merr.], cover crops can be intersown into standing soybean. The objective of this study was to determine the establishment of intersown cover crops and their impacts on a soybean-wheat (Triticum aestivum L.) rotation. Four cover crops, winter camelina [Camelina sativa (L.) Crantz], winter pea [Pisum sativum ssp. arvense (L.) Poir], winter rye (Secale cereale L.), and radish (Raphanus sativus L.), were directly sown into the ground at the R4 and R6 stages of soybean at two locations, Prosper and Fargo, ND in 2016-2018. Results indicated intersowing cover crops have no impact on soybean yield, can produce above ground biomass which ranged from 0.44 to 3.04 Mg ha-1, and show potential to mitigate soil nitrate losses in areas that grow soybean as a cash crop.
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Grindlay, Douglas J. C. "Principles governing the ability of cover crop species to trap nitrate." Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294723.
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Wittenberg, Alex Shawn Robert. "Optimizing Winter Camelina Production as a Cover Crop In North Dakota." Thesis, North Dakota State University, 2020. https://hdl.handle.net/10365/31735.
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Winter camelina [Camelina sativa (L.) Crantz] has gained particular interested from producers and researchers in the northern Great Plains and local production information is critical. Without a correct sowing date plant stand establishment can be challenging. Morphological differences between winter- and summer-biotypes of camelina can allow producers and researchers to distinguish the two biotypes. Visible and non-visible seed differences can offer effective means to distinguish the two biotypes. Seed quality of camelina is crucial. Sowing in September until the first week of October had similar seed yield. Morphological differences in the upper most developed leaves of camelina seedling can be used to distinguish the two biotypes. Field grown samples of camelina can be analyzed to determine if the seed is winter or summer biotype or a mix of both and we developed a near infrared spectroscopy protocol to determine seed composition of intact camelina seeds.
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Sievers, Taylor Jo. "Cover Crop Characteristics and Impacts on Agronomic Systems in Southern Illinois." OpenSIUC, 2016. https://opensiuc.lib.siu.edu/theses/2001.
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AN ABSTRACT OF THE THESIS OF Taylor J. Sievers, for the Master of Science degree in Plant, Soil, and Agricultural Systems, presented on May 13, 2016, at Southern Illinois University Carbondale. TITLE: COVER CROP CHARACTERISITICS AND IMPACTS ON AGRONOMIC SYSTEMS IN SOUTHERN ILLINOIS MAJOR PROFESSOR: Dr. Rachel L. Cook Midwestern farmers face the dual challenge of increasing crop production while reducing environmental impacts. Best management practices to decrease nutrient and soil loss in agronomic systems has fueled the resurgence of the cover cropping practice, but many growers are uncertain about the effects that different cover crop species may have in their fields or how combinations of tillage and cover crops may influence yields or soil characteristics. Different cover crop characteristics, such as above and belowground biomass production, nitrogen content, and decomposition may affect both soils and crop yields. Field experiments were conducted across two sites in southern Illinois from 2013 to 2015 to study characteristics of cover crops and the impact of cover crops and tillage on soils, nutrient availability, and agronomic field crop performance. Specifically, these studies 1) determine the effects of cover crops on soil nitrogen, 2) quantify above and belowground biomass production of cover crops, 3) quantify the grain yield and belowground biomass of the following crops of corn (Zea mays L.) and soybeans (Glycine max L. Merr.), and 4) evaluate cover crop decomposition and nutrient release of a leguminous and non-leguminous species. In both field sites, Hairy vetch (Vicia villosa Roth) treatments produced the most biomass and accumulated the most nitrogen of all cover crop treatments. Cover crop establishment was a problem for the 2014−2015 field season. Cover crops, for the most part, did not have an influence on corn or soybean grain yields, except that corn following Hairy vetch treatments tended to be higher in grain yields than corn following Annual ryegrass treatments. Soybeans following Annual ryegrass treatments tended to be higher in grain yield than soybeans following Canola treatments. Root biomass production was higher for cover cropped plots than non-cover cropped plots (weed root biomass), and corn or soybean root biomass was more affected by tillage practices rather than the main effect of cover crop. Tilled treatments were typically higher in soil nitrate and total inorganic nitrogen compared to No-till treatments, and Annual ryegrass treatments were consistently lower in soil nitrogen compared to other cover crop treatments. Hairy vetch and cereal rye (Secale cereale L.) decomposition and nutrient release was monitored over a 16 week period, with litterbag and intact root core collections at 2, 4, 6, 8, 12, and 16 weeks. Decomposition and nitrogen release data were fit to a single exponential decay model with an asymptote. Cereal rye aboveground (k = 0.14) and belowground (k = 0.19) biomass decomposed more gradually compared to hairy vetch aboveground (k = 0.45) and belowground (k = 0.68) biomass. The same trend developed for nitrogen release with cereal rye aboveground (k = 0.07) and belowground (k = 0.19) biomass releasing nitrogen slower and more gradually compared to hairy vetch aboveground (k = 0.61) and belowground (k = 0.61) biomass. Most of the hairy vetch nitrogen was released around Week 2, but the corn crop did not reach the V6 growth stage until Week 8, therefore cover crop nitrogen release and cash crop uptake may have not been synchronized. Plant Root Simulator™ ion exchange resin membrane probes also captured significantly more nitrogen in hairy vetch plots compared to cereal rye plots at weeks 2, 4, 6, 8, and 12, which indicates that hairy vetch could increase the readily plant available total nitrogen (nitrate + ammonium) in the soil throughout the bulk of cover crop decomposition. Farmers should decrease the time between cover crop termination and cash crop planting in order to increase the likelihood of crop synchrony. This research will help farmers develop better management practices regarding inclusion of cover crops into traditional agronomic production systems.
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Andersen, Bryce James. "Integrating Faba Bean (Vicia faba Roth) into Cropping Systems as a Cover Crop, Intercrop, and Late-Season Forage Compared with Other Legume Cover Crops in the Upper Midwest." Thesis, North Dakota State University, 2019. https://hdl.handle.net/10365/31542.
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Faba bean (Vicia faba Roth) is grown worldwide as a protein source for food, used for animal feed, and is a common cover crop in Europe, but is underutilized in Midwest farming systems. Faba bean, field pea (Pisum sativum L.), and forage pea were evaluated for biomass and chemical composition when sown after wheat. Faba bean, forage pea, balansa clover (Trifolium michelanium Savi), red clover (T. pratense L.), and rye (Secale cereale L.) were evaluated similarly when intersown into maize. Cover crops after wheat had no significant biomass differences, averaging 1210 kg ha-1, enough to support 1.5 animal unit month (AUM) ha-1 for a 450 kg cow with calf. Rye yielded the greatest (374 kg ha-1) of the intercrops with faba bean averaging similarly and other intercrops averaging significantly less. Intercrops did not affect maize yield. Faba bean has similar potential as other commonly used cover crops in the Midwest.
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Sigdel, Sailesh. "Seeding Time and Interseeded Cover Crop Species Influence Sugarbeet Yield and Quality." Thesis, North Dakota State University, 2020. https://hdl.handle.net/10365/31884.
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Field experiments were conducted to evaluate cover crop interseeding time and species effect on sugarbeet production during 2018 and 2019 growing seasons. Cover crops were first interseeded in June and second interseeding was done in late June or early July. Four cover crops species, Austrian pea (Pisum sativum L.), winter rye (Secale cereale L.), winter camelina [Camelina sativa (L.) Crantz], and brown mustard (Brassica juncea L.), were examined. First interseeding resulted in significantly higher cover crop biomass than second interseeding. In 2018, the highest recoverable sugar yield was observed with pea (13.9 Mg ha-1) and camelina (6.6 Mg ha-1) first-interseeded, at Ada and Downer, MN, respectively. In 2019, camelina (11.2 Mg ha-1) at Ada, MN, and pea (12.4 Mg ha-1) at Prosper, ND both second-interseeded, had the highest recoverable sugar yield. Cover crops had no negative impacts on sugarbeet, but the selection of species and planting time are critical.
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Stout, Breanna. "Short term effects of annual ryegrass, red clover and hairy vetch cover crops on various indicators of soil health." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/18716.
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Master of Science<br>Department of Biological and Agricultural Engineering<br>Philip L. Barnes<br>The world’s population has passed 7 billion and is expected grow to more alarming numbers by the year 2050. The increase in human life on the planet ushers the need to responsibly and sustainably grow more food. In order to meet the demand necessary, it is crucial that soil remains healthy and crop yields continue to increase in efficiency. Irresponsible or ill-informed practices can lead to depleted resources and degradation of fertile soils that may limit a producers’ ability to sustainably grow food. Cover crops are a tool that can be used to address issues the modern producer may face. Cover crops have been shown to increase cash crop productivity, improve soil health by improving soil physical and chemical properties as well as providing protection from soil erosion runoff or nutrient leaching.
A study was conducted in 2014 to examine the short term effects associated with cover cropping systems. The effects of ryegrass, red clover and a cover crop cocktail (mixture of ryegrass, red clover and hairy vetch) compared to bare tilled and bare control plots were studied. The five treatments were replicated three times in a completely randomized study and analyzed. Soil physical health indicators such as bulk density and porosity were calculated. Soil and cover crop nutrient use, as well as, soil moisture content data was collected and analyzed using excel and ANOVA statistical procedures.
In the short term, the study found that there was only statistically significant differences between cover cropping regimens, tilled and control plots in regards to biomass production and biomass nutrient concentrations (α=0.05). The cocktail mix provided more biomass, N and P than the ryegrass and clover plots alone. Observable differences in cover crop volumetric soil moisture and water used between plots demonstrated that cover crops utilize soil moisture in the short term, which must be considered in areas experiencing water stress. Although more long-term data is needed to truly quantify how cover crops effect various aspects of soil health, this study demonstrated how cover crops have the potential for providing numerous benefits such as increased erosion control, lower reliance on anthropogenically created nutrients and the reduction of weeds. Overall the benefits associated with cover crops are still being researched and while adoption of cover cropping systems has been slow, a push towards agricultural sustainability while increasing food production will increase the amount of producers utilizing cover crops in the coming years.
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Avila-Segura, Laura M. "Potential benefits of cover crop based systems for sustainable production of vegetables." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0015763.
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Gardner, Megan Bates. "Cover Crop Root Contributions to Soil Quality in an Organiz Maine Agroecosystem." Fogler Library, University of Maine, 2005. http://www.library.umaine.edu/theses/pdf/GardnerMB2005.pdf.
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Koivisto, Jason M. "Semi-leafless peas : a cover crop for establishing lucerne or red clover." Thesis, Coventry University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246331.
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Omwega, Asenath Kwamboka. "Crop cover, rainfall energy and soil erosion in Githunguri (Kiambu district), Kenya." Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257360.
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McClung, Tamara Nicole. "Sweet Corn Germination, Growth, and Yield After a Rye Winter Cover Crop." Thesis, The University of Arizona, 2013. http://hdl.handle.net/10150/311795.
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Odhiambo, Jude Julius Owuor. "Effect of cereal/grass and legume cover crop monocultures and mixtures on the performance of fall-planted cover crops, soil mineral nitrogen and short-term nitrogen availability." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ34601.pdf.
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Samson, Roger A. (Roger Anthony). "On-farm evaluation of cultivation, cover crops and chemical banding for crop and weed management in integrated farming systems." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55700.
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Bilek, Meredith K. "Winter annual rye cover crops in no-till grain crop rotations impacts on soil physical properties and organic matter /." College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/7268.
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Thesis (M.S.) -- University of Maryland, College Park, 2007.<br>Thesis research directed by: Dept. of Natural Resource Sciences and Landscape Architecture. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Johnson, Jennifer. "Residual Nutrient Removal by a Winter Cover Crop From Broiler Litter Amended Soils." TopSCHOLAR®, 2007. http://digitalcommons.wku.edu/theses/424.
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Poultry production throughout Southern Kentucky is becoming a major agricultural enterprise. Rapid spread of the industry has led to many agricultural advances as well as concerns. One primary concerns is the possible nutrient build-up in pasture and cropland as a result of broiler litter application. Studies were conducted at Western Kentucky University using sorghum sudangrass (Sorghum bicolor (L.) Moench) as a forage to possibly remove excess nutrients. This project led to a consideration of using a cover crop to further remove nutrients from broiler litter amended soils. This study's objective was to assess total nutrient removal by sorghum sudangrass followed by a rye (Secale cereale L.) cover crop compared to single crop of sorghum sudangrass as a tool for preventing excess soil nutrient accumulation. A randomized complete block experiment was established in 2005 with four replications and four treatments was conducted: litter applied at recommended nitrogen [Litter-N] rate; litter applied at the recommended P rate with commercial nitrogen [Litter-P+N]; litter applied at the recommended P rate [Litter-Pj; and soil amended with inorganic fertilizer [INORG], Sorghum sudangrass was seeded in the spring and rye planted after the last harvest of the season. Forage acid detergent fiber (ADF), neutral detergent fiber (NDF), crude protein (CP), P, Cu, Fe, and Zn were determined, as well as soil nutrient levels. After analyzing the data from one year, 2005, it was determined that, although differences were noted, the rye cover crop did not mitigate available soil P, Cu, and Zn.
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Looker, Wayde. "Effect of Relative Maturity on Soybean Yield and Cover Crop Biomass Evaluation Methods." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1554894697089079.
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Seman-Varner, Rachel Nicole. "The role of cover crops in agroecosystem functioning." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/83232.
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Current interest in cover cropping is focused on enhancing ecosystem services beyond soil conservation. Cover crop (CC) species function uniquely in their effects on ecosystem services when grown in monoculture or mixtures. This research integrated field experiments and a literature synthesis to evaluate the role of cover crops in improving nitrogen (N) management and simultaneously providing multiple ecosystem services. Legume CC fertilized with poultry litter (PL) could replace 101 to 117 kg N ha-1 of fertilizer in corn (Zea mays L.) production. Rye (Secale cereale L.) CC fertilized with PL had a negligible effect on corn production. Biculture fertilizer equivalence ranged between -12 to +75 kg N ha-1. Fertilizer equivalence of legume-containing treatments increased across time. Without CC, fall-applied PL failed to supply N to corn. Ecosystem services of CC and PL illustrate complex species functions. Bicultures produced more total biomass than monocultures in year 1 but less than rye in year 2. Bicultures were as effective in suppressing weeds as rye, produced corn yield similar to legume, and by the second year had similar amounts of available soil N as the legume. Poultry litter effects and interspecific effects cover crop species biomass differed. Rye yield increased, while legume yield decreased slightly in biculture. Poultry litter increased legume N content and a decrease in legume C:N, while rye N content and C:N were unaffected. The synthesis corroborates that mixed and biculture cover crops yield more than the individual component species. Overyielding was transgressive in 60% of cases studied. Mixture effects varied by species: rye and brassica yield increased, while legume decreased in mixtures. The effect of mixed CC on crop yields varied by crop species and management practices, though generally crops increased 8 to 18% overall. This work can be applied to the design of complex CC and PL systems that optimize individual species functions to enhance ecosystem services.<br>Ph. D.
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Boglaienko, Daria. "Buckwheat as a Cover Crop in Florida: Mycorrhizal Status, Soil Analysis, and Economic Assessment." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/921.
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This thesis analyses buckwheat as a cover crop in Florida. The study was designed to demonstrate: soil enrichment with nutrients, mycorrhizal arbuscular fungi interactions, growth in different soil types, temperature limitations in Florida, and economic benefits for farmers. Buckwheat was planted at the FIU organic garden (Miami, FL) in early November and harvested in middle December. After incorporation of buckwheat residues, soil analyses indicated the ability of buckwheat to enrich soil with major nutrients, in particular, phosphorus. Symbiosis with arbuscular mycorrhizal fungi increased inorganic phosphorus uptake and plant growth. Regression analysis on aboveground buckwheat biomass weight and soil characteristics showed that high soil pH was the major limiting factor that affected buckwheat growth. Spatial analysis illustrated that buckwheat could be planted in South Florida throughout the year but might not be planted in North and Central Florida in winter. An economic assessment proved buckwheat to be a profitable cover crop.
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Finney, Denise McKinney. "Evaluation of sorghum sudangrass as a summer cover crop and marketable hay crop for organic, no-till production of fall cabbage." NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-03282005-141749/.
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The development of organic and conservation tillage-based vegetable production systems will offer growers in the southeastern United States new economic opportunities and promote resource conservation. The purpose of this research project was to assess the impact of incorporating a summer crop that serves as both cover crop and marketable hay crop in an organic fall vegetable production system. Sorghum sudangrass [Sorghum bicolor (L.) Moench X S. sudanense (Piper) Staph] is commonly cultivated as a forage crop in the Southeast and has the potential to produce abundant biomass, suppress weeds, and decrease soil compaction as a summer cover crop. Field studies were conducted to determine the effects of sorghum sudangrass cutting frequency and biomass removal as hay on cover crop biomass production, weed suppression by cover crop residues, and cover crop re-growth in a subsequent cabbage (Brassica oleracea L. var. capitata) crop under conventional and no-till management. Field and greenhouse studies were undertaken to identify potential negative interactions between cover crop residues and cabbage transplants. Transplant dry weight and head weight of the indicator species, cabbage, were used to assess the impact of cover crop management and tillage system on crop growth and development. Results suggest that a sorghum sudangrass hay crop can be harvested without compromising weed suppressive qualities of the cover crop. In this study, however, the presence of sorghum sudangrass led to reductions in cabbage transplant growth and head weight. Sorghum sudangrass may not be suitable as a cover crop immediately prior to conventional or no-till fall vegetable production due to its propensity to re-grow and allelopathic potential.
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Kelley, Tracy. "Efficacy, Phytotoxicity, and Cover Crop Response of Herbicide Combinations in Dark Fire Cured Tobacco." TopSCHOLAR®, 2000. http://digitalcommons.wku.edu/theses/724.
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Field studies were established during the summer of 1999 at the Agricultural Research and Education Complex of Western Kentucky University to evaluate efficacy, phytotoxicity, and cover crop response of herbicide combinations in dark fire cured tobacco. A randomized complete block design was used with nine treatments replicated three times. Hydroponic tobacco transplants (c.v. 'TND950') were established on May 20,1999 in a conventionally tilled system on a Pembroke silt loam (Mollic Palleudalf) with a pH of 5.8 and an organic matter content of 1.2%. The transplants were established at a population of approximately 10,278 plants/ha. Herbicide treatments were applied on May 19, 1999 with a CO2 backpack sprayer. Sulfentrazone as Spartan 75DF was applied in all nine treatments at a rate of 0.47 kg pr/ha. Six of the nine treatments included various rates of clomazone as Command 3ME. Two of the nine treatments included napropamide as Devrinol 50DF. Visual evaluations of crop phytotoxicity due to herbicide application were recorded at 21 and 44 days after treatment (DAT). Weed control was evaluated at 21, 29, 44, and 58 DAT for the following species: Ipomoea hederacea L. (Ivyleaf morningglory), Amaranthus hybridus L. (smooth pigweed), and Eleusine indica L. (goosegrass). Crop injury and weed control evaluations were recorded on a 0-100% scale with 0 representing no injury and/or no control and 100 representing plant death. After crop removal, two types of tillage were performed to examine wheat injury effects due to tillage. One subplot was moldboard plowed and disked while the other subplot was disked. Following tillage operations, winter wheat (Triticum aestivum) was planted on October 30,1999 at a rate of 134.68 kg pr/ha. Visual wheat chlorosis evaluations of each subplot were recorded and based on a scale of 0-100%. Stand counts were taken in the subplots to examine stand loss due to treatment. Wheat aboveground biomass was harvested from each subplot to evaluate the relationship between wheat growth and herbicide rate. Sulfentrazone alone provided >66% control of Eleusine indica, >96% control of Ipomoea hederacea, and >88% of Amaranthus hybridus at all evaluation dates. When combined with 0.584 L pr/ha clomazone, sulfentrazone provided >82% control of all weed species 58 DAT. Sulfentrazone combined with > 1.17 L pr/ha clomazone provided > 86% Eleusine indica control, >60% Ipomoea hederacea control, and >84% Amaranthus hybridus control. Sulfentrazone combined with 1.12 kg pr/ha napropamide provided >71% control for all weed species at all evaluation dates. However, sulfentrazone plus 2.24 kg pr/ha napropamide provided only >55% control of species at all evaluation dates. Wheat chlorosis was affected by increased rates of clomazone combined with sulfentrazone at both 25 and 41 DAP (days after planting). Fresh weight also exhibited a trend of decreased mass as clomazone application rate increased. Addition of >1.75 L pr/ha clomazone decreased stand count at both evaluation dates, as compared to the sulfentrazone treatment. There were no differences in stand count between napropamide rates in either stand count evaluation. Wheat chlorosis 25 and 41 DAP was greater in plots that were not moldboard plowed. Areas moldboard plowed and disked exhibited less chlorosis, but tillage had no significant effect on wheat biomass or stand count.
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Treadwell, Danielle Dion. "Tillage and cover crop management influence weeds, insects, soil and crop nutrients, crop development and yield in organically managed North Carolina sweetpotato Ipomoea batatas (L.) Lam. systems." NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-06182005-181203/.
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In 2004, North Carolina supplied 46% of the nations' sweetpotato and generated 79 million dollars for the state but of the 16,000 ha in production that year; only 405 ha were managed according to federal organic standards. A three-year field experiment was initiated in 2001 to evaluate organic sweetpotato ?Beauregard? production systems that varied in cover crop management and tillage. Three organic systems including 1) compost and no cover crop with tillage (Org-NC), 2) compost and cover crop incorporated prior to transplanting (Org-CI), and 3) compost and cover crop with reduced tillage (Org-RT) were compared to a conventionally managed tilled and chemical control (Conv) production system using a randomized complete block design with six replications. All sweetpotato tissue macro and micronutrient concentrations were within sufficiency ranges defined by North Carolina Department of Agriculture & Consumer Services. Sweetpotato N (4.6%), P (0.5%), and K (4.3%) tissue concentrations were greater in Org-CI compared to remaining systems at 60 DAP in 2004. Monocot and dicot weed density and biomass were similar between Org-NC and Org-CI each year, and with few exceptions were similar to Conv. In Org-RT, high monocot weed density limited sweetpotato vine above ground biomass (154 g m<sup>-2</sup>) and total yield 11.2 Mg ha<sup>-1</sup>) in 2002. In 2001, the percentage of No. 1 grade roots was at least 19% greater in Org-CI (65 %) and Org-NC (62 %) than Conv (50 %). In 2002, the percentage of No. 1 roots was similar among Org-CI (74 %), Org-NC (71 %) and Conv (67 %) and similar among systems in 2004. Root quality was assessed based on degree of insect damage by wireworm-Diabrotica-Systena (WDS) complex. In 2001, Org-RT had the highest percentage of marketable roots (68 %) compared to remaining systems (19-43 %). The number of marketable roots was similar among systems in 2001 and 2004, but reduced in Org-RT (1.3 Mg ha<sup>-1</sup>) compared to remaining systems. Means of wireworm (Melanotus and Conoderus spp.) densities per trap were significantly correlated with degree of root damage. Overall, organic systems performed as well as the conventionally managed system in at least one or more areas.
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Hackman, Jacob James. "THE EFFECTS OF COVER CROPS ON THE SOIL MICROBIOME: A METAGENOMICS STUDY." OpenSIUC, 2018. https://opensiuc.lib.siu.edu/theses/2401.
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To our knowledge, this metagenomics study is the first of its kind to determine how cover crops and tillage management practices affect the soil microbiome in southern Illinois. Seven different cover crops were used over the course of two years from 2014 to 2015, and two different forms of tillage were used: Conventional Tillage (CT) and No-Tillage (NT). Four barcodes were used to generate libraries for the phylogenetic identification of fungi, bacteria, oomycetes, and fusaria: the ITS1, EF1a (Elongation Factor 1-a), and the V4 region of the 16s rRNA subunit. Targeted amplicon sequencing using 250 base pair Paired End (PE) reads yielded 14 x 106 base pair reads in total. Using these amplicons, we successfully unveiled the fungal and bacterial constituents of the studied field plots (database limitations considered) using the QIIME and NCBI Blast protocols. Specifically, this study had three goals 1) to determine if cover crops or tillage had a significant impact on the overall microbial diversity found in bulk soil samples taken from cover crop plots; 2) to determine if the incidence and abundance of individual bacterial or fungal taxa were affected by the cover crop or tillage treatment; 3) perform a bioinformatics methodology comparison for fungal identification using the ITS1 region between Qiime, and MEGAN protocols. Our results indicate many instances of cover crop or tillage interacting with one or more groupings of taxa. Significant whole community differences could be detected to the species (P=0.0335) and family (P=0.0001) taxonomic ranks of fungi using with the three most abundant families based on assigned reads being Mortierellaceae, Trichocomaceae, and Botryosphaeriaceae. Significant whole community interactions between tillage types and year at the level of phylum were observed between bacteria and archaea. Three main phyla constituting bacterial reads were Proteobacteria, Actinobacteria, and Acidobacteria. The primary driver in individual differences in bacterial populations appeared to be the year in which samples were taken either 2014 or 2015 (P=0.0001). This was attributed in part due to drastic fluctuations in weather from November 2014 to November 2015. Whole community differences and shifts could be observed based on cover crop down to the species level using both QIIME and NCBI BLAST protocols. The different dispersions and taxa found between cover crops imply that there is a relationship between certain organisms and the type of plant matter present. Tillage type, year, and cover crop were all found to have some degree of clustering based on reads taken from the four amplicons used. For comparison between NCBI and QIIME methodologies using the ITS1 region, the NCBI BLAST protocol provided the most overlap between taxa at the Order and Class taxonomic rankings. An upwards of 70% complementarity of taxa was found comparing the results after using the NCBI or the QIIME protocols. Whole community analysis using PERMANOVA revealed complementarity shifts based on treatment types when comparing both QIIME and NCBI protocols for taxonomic assignments visualized using PCoA plots. This comparison between the two methods for fungal community analysis using the ITS region, highlights the significant discrepancies as well as the complementarity of the two methodologies when analyzing fungal microbiomes.
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Smith, Joshua Dwayne. "Impacts of Cover Crops on Carbon Dioxide and Nitrous Oxide Flux from a Row Crop Agricultural Field in Central Illinois." OpenSIUC, 2014. https://opensiuc.lib.siu.edu/theses/1391.
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In the United States, there is renewed interest in incorporating cover crops into agricultural systems to provide a variety of potential benefits related to soil quality, water quality, and greenhouse gas emissions. This study focused on assessing whether cover crops influence N2O and CO2 emissions in a central Illinois agricultural research field over two years (2011-2013) of cover crop growing seasons. Three winter cover crop systems, annual ryegrass (Lolium multiflorum), cereal rye (Secale cereale), and a cereal rye (2011)/ hairy vetch (Vicia villosa) (2012) rotation were planted after fall 2011 and 2012 harvests. The field included a total of eight main plots, two of each treatment, and two no cover crop control plots. Soil carbon dioxide (CO2) and nitrous oxide (N2O) fluxes were measured from the plots in a single corn (Zea mays) - soybean (Glycine max) system for two cover crop growing seasons. Fluxes of CO2 and CO2 were measured in March 2012, August 2012, and February 2013. The CO2 flux measurements were performed by using an infrared gas analyzer. The N2O fluxes were analyzed from samples collected at 0, 10, 20, 30 min intervals from the same closed dynamic chamber system. Both CO2 and N2O fluxes were computed from respective gas concentrations over time. Data were analyzed with a repeated measures mixed model procedure. N2O fluxes from the cereal rye/hairy vetch plots were greater than the no cover control and annual ryegrass plots, suggesting that cover crops may not decrease N2O fluxes immediately after being incorporated into a cropping system. In contrast, CO2 fluxes did not significantly differ among the treatments, but the cereal rye/hairy vetch plot sequestered ~100 kg C ha-1 of soil organic carbon (SOC). Overall, it was observed that some cover crop plots can have higher N2O fluxes than plots without cover crops, but cover crops have the long-term potential to sequester C in croplands demonstrating that their use should still be considered a sustainable agriculture practice.
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Hagarty, Brooke Danielle. "The Impacts of Cover Crops and Tillage on Nitrate-N Concentrations in Soil Water in Southern Illinois Row Crop Agriculture." OpenSIUC, 2019. https://opensiuc.lib.siu.edu/theses/2502.
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Nitrate, as a water contaminant, can have many detrimental impacts on ecosystem and human health. With agriculture as one of the largest contributors to nitrate pollution in streams, the need to adapt agricultural practices that are less harmful to the environment is crucial. Furthermore, the need for optimizing agriculture production, while decreasing the impacts of nitrate leaching, becomes more critical as the world population grows. The purpose of this research was to evaluate methods for reducing nitrate leaching from agricultural fields and to determine the effectiveness of cover cropping systems for providing plant-available nitrogen that coincides with cash crop demands. Reductions of nitrate leaching have been documented from the incorporation of cover crops into field rotations, but more research is needed to understand what cover crops (legume vs. non-legume) along with what tillage system (conventional-till vs. no till) are the most effective at reducing nitrate losses. The four treatments for this two-year study were as follows: cover crop, no till; cover crop, conventional-till; no cover crop, no till; and no cover crop, conventional-till. The crop rotations for Season 1 were hairy vetch followed by corn, oats/radish followed by corn, no cover crop followed by corn. The crop rotations for Season 2 were cereal rye followed by soybean and no cover crop followed by soybean. Two tension lysimeters were installed in spring 2015 in each of the 18 treatment plots at 0.46 m deep and 0.91 m deep. Lysimeters were sampled every two weeks throughout the year except during January and February, where they were only sampled once a month. Impacts on soil health were also monitored. Soil samples were collected three times over the course of this study, in the spring of 2015, fall of 2015, and spring of 2016. Soil bulk density, infiltration rates, net nitrogen mineralization, and corn yield were also compared among treatments.
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Askew, Matthew Carter. "Rapeseed (Brassica napus L.) Termination and Integration of Halauxifen into Virginia Cotton (Gossypium hirsutum L.) Production." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/86786.
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Cover crops have become an important part of cropping systems in the United States, especially in the Mid-Atlantic region. Rapeseed is a popular choice due to its deep growing taproot which creates soil macropores and increases water infiltration. If not properly terminated rapeseed can become problematic due to its pod-shattering tendency and its difficulty to terminate with herbicides once it enters reproductive growth. Results indicate termination of rapeseed is most effective when the cover crop is small. Combinations that successfully terminated rapeseed include glyphosate plus 2,4-D and paraquat plus 2,4-D. Halauxifen-methyl is a new Group 4 herbicide marketed for preplant burndown horseweed (Conyza canadensis L.) control. Previous research indicates that halauxifen effectively controls glyphosate-resistant horseweed. However, little is known about control of other common winter annual weeds by halauxifen. Results indicate halauxifen has a narrow spectrum of control providing adequate control (>80%) of horseweed, henbit (Lamium amplexicaule L.), and purple deadnettle (Lamium purpureum L.), while failing to control cutleaf evening-primrose (Oenothera laciniata Hill), curly dock (Rumex crispus L.), purple cudweed (Gamochaeta purpurea L. Cabrera), common chickweed (Stellaria media L.), and mousear chickweed (Cerastium L.). Little is known of cotton (Gossypium hirsutum L.) tolerance to halauxifen applied preplant burndown. Results indicate cotton is more tolerant to halauxifen than 2,4-D or dicamba when the interval between preplant application and cotton planting is less than 30 days.<br>Master of Science in Life Sciences<br>Cover crops are an important part of cropping systems in the United States, especially in the Mid-Atlantic region. Producers utilize cover crops to aid in weed suppression, reduce soil erosion, as well as to increase soil health. Cereals, legumes, and Brassicaceae species are popular cover crops planted either as monocultures or mixtures. Rapeseed can become problematic due to its difficulty to terminate once it enters reproductive stage, as well as its podshattering characteristic. Experiments were conducted to evaluate various herbicides and herbicide combinations for rapeseed termination two application timings. At three locations where rapeseed averaged 12 cm in height at early termination, and 52 cm in height at late termination, glyphosate + 2,4-D was most effective, controlling rapeseed (96%) 28 days after early termination (DAET). Paraquat + atrazine + atrazine (92%), glyphosate + saflufenacil (91%), glyphosate + dicamba (91%), and glyphosate (86%) all provided at least 80% control 28 DAET. Paraquat + 2,4-D (85%), glyphosate + 2,4-D (82%), and paraquat + atrazine + mesotrione (81%) were the only treatments to provide at least 80% control 28 days after late termination (DALT). At one location where rapeseed was much taller (41 cm early termination; 107 cm late termination), herbicides were much less effective, as no herbicide treatments provided greater than 80% control. Results indicated that rapeseed size at time of termination was more critical to successful termination than herbicide choice. Prior to the development of glyphosate-resistant horseweed, producers were able to control horseweed and other weeds with glyphosate applied preplant burndown. Producers now rely on auxin herbicides tank mixed with glyphosate and a residual herbicide to control horseweed and other winter weeds prior to cash crop planting. Experiments were conducted to evaluate halauxifen-methyl, a new Group 4 herbicide, for control of horseweed and other commonly encountered winter annual weeds. Halauxifen (89%) controlled small horseweed (<5 cm in height at time of application) similar to dicamba (91%), while providing better control of large horseweed (79%) (>15 cm in height at time of application) than either dicamba (77%) or 2,4-D evaluated (64%). Halauxifen provided adequate control (>80%) of henbit (Lamium amplexicaule L). and purple deadnettle (Lamium purpureum L.), while failing to effectively control of cutleaf evening-primrose (Oenothera laciniata Hill), curly dock (Rumex crispus L.), purple cudweed (Gamochaeta purpurea L. Cabrera), common chickweed (Stellaria media L. Vill.), and mousear chickweed (Cerastium L.). Results indicate that halauxifen has a narrow spectrum of control and should be tank mixed with 2,4-D or glyphosate in order to control weeds other than horseweed and henbit. Glyphosate plus dicamba or 2,4-D plus a residual herbicide is typically applied prior to cotton planting. Previous research has shown that as long as rainfall requirements and rotation intervals are met, no adverse effects on cotton is observed from 2,4-D or dicamba herbicides. Little is known of cotton tolerance to halauxifen applied preplant burndown. Experiments were conducted to determine if halauxifen applied sooner than the labeled 30-day rotation interval would injure cotton. Very little injury was observed from halauxifen (9%) applied at-planting, however dicamba (26%) and 2,4-D (21%) applied at the same timing did injure cotton. Auxin herbicides applied earlier in the season resulted in little injury (<2%). Early season injury was transient as cotton recovered later in the season and seedcotton yield was unaffected.
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Henry, David Christopher. "Nitrogen Contribution from Red Clover for Corn Following Wheat in Western Ohio." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1293556551.
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McNairn, Heather Elizabeth. "Radar response to crop residue cover and tillage application on post-harvest agricultural surfaces." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0017/NQ47579.pdf.
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Barona, Elizabeth. "Identifying the role of crop production in land cover change in Brazil, 1990-2006." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32278.
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Crop production in Brazil has changed significantly over the last decade. New crops are being cultivated to satisfy the world's growing demand for Brazilian export products —a demand that has caused substantial changes in land use and cover, mainly characterized by the increase in large-scale mechanization of agriculture, deforestation, and intensification of agricultural land use. Brazil currently provides crop production information at the municipality level. This information was analyzed using Geographic Information Systems (GIS) to examine changes in the spatial distribution of the production of various crops and livestock in Brazil for 1990-2006. In addition, to better understand the relationship between agricultural expansion and deforestation, spatial data on agricultural expansion and deforestation over the Legal Amazon were statistically analyzed for 2000-2006. The results indicate that changes in the spatial patterns of crops have indeed taken place in central and northeastern Brazil as well as in the southern Amazon region. The areas to crops such as soybean and sugarcane expanded, surpassing the total area planted to domestic food crops, which, in turn, recorded a significant decrease in area. This crop expansion has exerted pressure on other crops and livestock, pushing them further into the Amazon forest region during 1990-2006. In the same period, pasture was the predominant land use in the Legal Amazon; however, results indicate that the area planted to soybean increased whereas the area under pasture decreased. Statistical analyses revealed that, in those areas with over 50% forest, deforestation was strongly related to agricultural expansion. Defore<br>La production agricole du Brésil a changé significativement durant la dernière décennie. De nouvelles cultures ont été adoptées afin de répondre à la croissance de la demande mondiale pour des produits d'exportation brésiliens – une demande qui a occasionné des changements substantiels au niveau de l'utilisation et de la couverture du sol, principalement caractérisés par l'accroissement à large échelle de la mécanisation de l'agriculture, de la déforestation et de l'intensification de l'agriculture. Le Brésil met à disposition de l'information concernant la production agricole au niveau municipal. Cette information a été analysée par le biais d'un Système d'Information Géographique (SIG) afin d'étudier les changements dans la distribution spatiale de la production de différentes cultures et d'élevage au Brésil de 1990 à 2006. De plus, afin de mieux comprendre la relation entre l'expansion agricole et la déforestation, des données spatiales ont été analysée statistiquement pour l'Amazone Légale pour une période allant de 2000 à 2006. Les résultats indiquent que des changements dans les patrons spatiaux ont en effet pris place au centre et au nord-est du Brésil ainsi qu'au sud de la région amazonienne. Les zones prévues pour cultiver le soja et la canne-à-sucre ont augmenté, surpassant même les surfaces semées pour des cultures vivrières qui ont par ailleurs enregistrées une diminution significative. L'extension de ces cultures a exercé une pression sur les autres cultures et sur les élevages bovins, les poussant à l'intérieur de la forêt amazonienne durant la période 1990-2006. Au cours de la même période, alors q
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Jacobs, Addison Denae. "Influence of Cover Crop Species on Soil Physical Properties in a Corn-soybean Rotation." Thesis, Arkansas State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10831039.
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<p> As crop land decreases and population increases, soil quality is becoming a concern. Utilizing cover crops in cropping systems could improve soil quality. This study examined 16 treatments of single-species cover crops, cover crop mixes, and two control treatments on a silt-loam soil, in a corn (<i> Zea mays</i> L.) - soybean (<i>Glycine max</i> L. <i> Merr</i>.) crop rotation under no-tillage, to determine their effect on soil physical properties. Cover crop biomass differed (p<0.10) among treatments and produced a maximum of 15.6 Mg ha<sup>-1</sup> of biomass in the crimson clover treatment. Water infiltration rates increased as much as 282% in the complete-mix treatment compared to the fallow control. Differences in infiltration rates due to cover crop species were shown in two-years. However, these results suggest that it may take more time for cover crops to affect change in bulk density and aggregate stability.</p><p>
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Wolters, Bethany Rose. "To Mix or Not to Mix: Performance and Management of Diverse Cover Crop Mixtures." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/96592.
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Cover crops (CC) are planted in between cash crops to improve soil quality and to supply nitrogen (N) to cash crops through biological N fixation or soil N scavenging. Most producers use single species CC, in part because potential benefits of using mixtures of three or more CC species are poorly understood. A three-year study was initiated at Painter, Virginia to observe effects of CC mixtures on a no-till (NT) corn (Zea mays), wheat (Triticum aestivum L.), and soybean (Glycine max) rotation to measure CC performance, N cycling, cash crop yield, and soil quality in a sandy, low organic matter soil. Twelve treatments were created with conventional tillage (CT), NT, no CC control, and monoculture or CC mixtures of 3 to 9 species. Corn was grown in year 3 in all 12 treatments and four N rates were applied (0, 56, 112 and 156 kg N ha-1). Cover crop biomass, N accumulation, CC C:N ratio, and corn and soybean yield were measured annually. Soil bulk density, compaction, infiltration rate, pH, electrical conductivity, soil respiration, earthworm counts, soil microbial respiration, and soil microbial biomass carbon (C) after three years of CC. Cover crop biomass production varied significantly each year (5633 kg ha-1 in year 1, 755 kg ha-1 in year 2, 5370 kg ha-1 in year 3) due to climate and agronomic parameters, but a CC mixture always produced the highest biomass at termination. Nitrogen accumulation was strongly correlated with biomass production (R2= 0.94) and followed the same trend due to all CC having C:N < 30:1. Corn and soybean yields in years 1 and 2 were not significantly different, but corn yield was significantly affected by treatment and N fertilizer rate in year 3. After 3 years, soil respiration, earthworm populations and soil microbial biomass C increased in CC compared to CT without CC. However, infiltration rate, bulk density, microbial respiration, pH did not improve or declined compared to CT. In conclusion, adding CC mixtures to crop rotations shows promise for producing high CC biomass, accumulating N, and increasing crop yields, while improving some soil quality parameters on sandy low organic matter soils.<br>Doctor of Philosophy<br>Cover crop (CC) are planted in between cash crops to protect the soil from erosion, improve soil quality, and supply N to next cash crop through biological N fixation or soil N scavenging. Traditionally, CC were single species, but new CC methodologies utilize mixtures of three or more species planted together to protect soils as well as produce high biomass to suppress weeds, conserve soil moisture, and improve soil quality. A long-term study was initiated in fall 2014 in Painter, VA to observe CC mixture effects on no-till (NT) corn (Zea mays), wheat (Triticum aestivum L.), and soybean (Glycine max) rotations on CC performance, N cycling, cash crop yield, and soil quality of a sandy, low organic matter soil. Twelve treatments were created that compared NT rotations with CC monocultures, CC mixtures of 3-9 species, and without CC. In the third year corn was grown in all 12 rotations and four N rates were applied (0, 56, 112 and 156 kg N ha-1). To evaluate CC mixture performance in rotations, CC biomass, CC N accumulation and corn and soybean yield was measured over three years. To evaluate changes in soil quality, nine soil physical, chemical and biological soil properties were measured after three years of NT and CC. Biomass production varied significantly each experimental year (5633 kg ha-1 in year 1, 755 kg ha-1 in year 2, 5370 kg ha-1 in year 3) due to climate and agronomic differences, but CC mixtures were the highest biomass producing CC each spring and accumulated the highest amount of N. Cover crop mixtures had equal corn and soybean yield as CC monocultures. In year 3 corn yield and was greater in treatments with CC than in treatments without CC and was greater in legume dominated monocultures and mixtures than majority grass CC mixtures and monocultures. After 3 years of CC and NT, some soil quality parameters improved. Indicators of soil biology (soil respiration, earthworm populations, and soil microbial biomass C) increased in CC treatments. However, some soil physical and chemical properties (infiltration rate, bulk density, pH and EC) did not improve. In conclusion, adding CC mixtures to crop rotations shows promise for producing high CC biomass, accumulating N, and increasing crop yields, while also improving some soil quality parameters that are important for agricultural systems.
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Trott, Donna M. "Assessing near-field naturally occurring isothiocyanates emissions after mustard green manure cover crop incorporation." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Summer2009/d_trott_071609.pdf.
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Thesis (M.S. in environmental science)--Washington State University, August 2009.<br>Title from PDF title page (viewed on Aug. 7, 2009). "School of Earth and Environmental Sciences." Includes bibliographical references.
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Couedel, Antoine. "Analysis of performances of crucifers-legumes cover crop mixtures to provide multiple-ecosystem services." Thesis, Toulouse, INPT, 2018. http://www.theses.fr/2018INPT0097/document.
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Les cultures intermédiaires multi-services (CIMS) implantées en interculture entre deux cultures de rente permettent de produire de nombreux services écosystémiques. Parmi les familles d’espèces utilisées comme CIMS, les crucifères réduisent efficacement la lixiviation de nitrate et de sulfate en captant l’azote (N) et le soufre (S) minéral du sol (services de piège à N et à S). Les crucifères ont aussi la capacité de contrôler les pathogènes via des composés biocides issus de l’hydrolyse de métabolites secondaires appelés glucosinolates (GSL). L’objectif de nos travaux de recherche est d’évaluer les performances en termes de services écosystémiques liés à l’azote, au soufre et au potentiel de bio-contrôle d’une grande diversité de mélanges bispécifiques de crucifères et de légumineuses en comparaison aux CIMS pures. Nous avons réalisé des expérimentations sur 2 sites contrastés (région de Toulouse et Orléans, France) et sur 2 années pour tester les performances de mélanges crucifère-légumineuse en comparaison aux espèces pures. Les espèces testées sont i) pour les crucifères : colza, moutarde blanche, moutarde brune, moutarde éthiopienne, navet, navette, radis, roquette, et ii) pour les légumineuses : trèfle Egyptien, trèfle incarnat, vesce commune, vesce pourpre, vesce velue, pois, soja, féverole et lupin blanc. Nos travaux de recherche montrent que les mélanges crucifère-légumineuse peuvent produire simultanément divers services écosystémiques avec un haut niveau d’expression, allant de 2/3 (production de GSL, engrais vert à N et S), à quasiment 100% (piège à N et S) du service produit par la famille d’espèce pure la plus performante. La concentration et les types de GSL ne changeant pas en mélanges, les interactions des crucifères avec leurs pathogènes restent identiques. Via une revue de littérature nous concluons également que le service de bio-contrôle des cultures pures de crucifères peut être maintenu en mélanges crucifère-légumineuse sur une grande diversité de pathogènes et adventices tout en réduisant les potentiels dis-services sur les auxiliaires et sur le cycle de l’azote<br>Multi-services cover crops (MSCC) grown during fallow period between two cash crops provide various ecosystem services. Among species used as MSCC, crucifers can efficiently prevent nitrate and sulphate leaching by catching residual soil mineral nitrogen (N) and sulphur (S) afterthe preceding cash crop (N and S catch crop services). Crucifers also have a unique capacity to suppress pathogens due to the biocidal hydrolysis products of endogenous secondary metabolites called glucosinolates (GSL). The aim of our study was to assess the provision of various ecosystem services linked to N, S cycles and biocontrol potential for a wide range of bispecific crucifer-legume mixtures in comparison to sole cover crops of legume and crucifer. We carried out experiments in 2 contrasted sites (Toulouse and Orléans regions, France) during 2 years in order to assess these services and the compatibility of various bi-specific crucifer-legume mixtures. We tested a great diversity of species, such as i) crucifers : rape, white mustard, Indian mustard, Ethiopian mustard, turnip, turnip rape, radish and rocket, and ii) legumes: Egyptian clover, crimson clover, common vetch, purple vetch, hairy vetch, pea, soya bean, faba bean, and white lupin. Our study demonstrated that crucifer-legume mixtures can provide and mutualize various ecosystem services by reaching from 2 thirds (GSL production, S and N green manure) to the same level ofservice (N and S catch crop) than the best sole family of species. GSL profile and concentration did not change in mixtures meaning that crucifer-pests interactions were identical. Through a literature review we also illustrated that biocontrol services of crucifers could be largely maintained in crucifer-legume mixtures for a wide range of pathogens and weeds while reducing potential disservices on beneficials and increasing N related service
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Schmitt, Mattie Bree. "Factors Affecting Establishment and Growth of Cover Crops in a Corn-Soybean Rotation." Thesis, North Dakota State University, 2020. https://hdl.handle.net/10365/31758.
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In the Midwest, it can be beneficial to interseed cover crops into corn (Zea mays L.) since there is a limited time for them to establish and grow after corn harvest. Research conducted in four environments in North Dakota quantified the impacts of planting method and time of planting when grown with or without corn competition on the establishment, and development of three cover crop species. Limited light intensity (less than 20%) under the corn canopy drastically reduced cover crop development. Soil water can also constrain cover crop establishment. Model simulations suggest soil water is more limiting for cover crop establishment in August compared with June or July. Interseeded cover crops had no effect on corn yield or the following soybean (Glycine max (L.) Merr.] crop due to minimal amounts of biomass produced.