Agricultural intensification to increase food, feed, and fibre production has also resulted in environmental degradation, including poorer soil quality and high emissions of greenhouse gases (GHGs) like nitrous oxide (N2O). Intercropping, an agroecosystem management practice where more than one crop is planted on the same plot of land at the same time, promotes the complementary use of soil nutrients, and may improve soil quality and increase the retention of inorganic nitrogen (N) in the soil, thereby reducing N2O emissions. An experiment was conducted in Balcarce, Argentina to determine the impact of intercropping maize (Zea mays L.) and soybean (Glycine max (L.) Merr.), (either 1:2 or 2:3 rows of maize to soybean) on soil quality and soil N transformations after six cropping seasons. It was found that intercropping significantly improved soil quality over a six year period, as indicated by the soil organic carbon (SOC), soil total nitrogen (TN), soil light fraction organic matter (LF), and soil microbial biomass carbon (SMB-C). However, the soil quality also significantly improved in the sole crops over this time, and in 2012, only SMB-C was significantly (p<0.05) greater in the 2:3 intercrop than in the sole crops. Intercropping resulted in higher rates of gross nitrogen (N) mineralization than the sole crops, and the 2:3 intercrop resulted in higher rates of gross N immobilization than in the other treatments. However, the high rate of gross N mineralization resulted in a low relative NH4+ immobilization in both intercrops, signifying a lower potential for reducing soil NH4+ concentrations than in the sole crop treatments. Net N immobilization occurred in all treatment plots, which was desired at the end of the fallow period to reduce N losses from the soil. The 2:3 intercrop appeared to perform better than the 1:2 intercrop. However, further research needs to be conducted to determine the seasonal variations in N mineralization and immobilization, and to further examine the intercrop spatial arrangements to increase crop residue yield.

Large stands of Arundinaria gigantea (Walt.) Muhl., called canebrakes, were vital to wildlife and lowland ecosystem functions and historically covered millions of acres in the southeastern United States. Since European settlement, human disturbance (i.e, clearing for agriculture and fire suppression) has caused giant canebrakes to become critically endangered ecosystems. Increasing evidence suggests the loss of canebrakes has directly impacted riparian ecosystems, resulting in increased soil erosion, poorer water quality, and reduced flood control. Cane's ecological importance has led to an increased interest in canebrake restoration in riparian zones. To examine the role that cane plays in nutrient cycling and to attempt to determine targeted restoration sites, a four phase research strategy was designed to determine physical and chemical properties of existing riparian stands of native giant cane and their associated soils. Phase one was a GIS analysis to determine what geographical features may be used in selecting sites within a landscape suitable for canebrake restoration. First, common physical site characteristics for 140 existing southern Illinois canebrakes were determined. Soil taxonomy and pH were used to represent soil characteristics and percent slope was used as a topographic metric. These factors, combined with digital elevation models and land cover in GIS were used to identify the potential suitability of sites within the watershed for canebrake plantings and general riparian restoration. The following soil characteristics were determined to be associated with giant cane success: percentage of area containing slopes of 3 percent or less, fine to coarse-silty textures, pH of 5.3 - 6.7, effective cation exchange capacity of less than 30 units, available water holding capacity greater than 0.12, bulk density of 1.37 - 1.65 g cm-3, and percent clay of 11 - 55. Eighty-percent of existing giant cane sites were found within these slope and soil characteristics. The total area of potential riparian canebrake landscapes based on these parameters is 13,970 hectares (35,600 acres) within the Cache River watershed. The remaining three phases examined the role that cane plays in nutrient cycling. Phase two determined the pools and cycling of nitrogen and carbon in canebrakes and compared those to nearby agricultural and forested riparian areas. Phase three quantified the N2O and CO2 fluxes from canebrakes and adjacent forested areas. Phase four included methods to quantify nutrient content of leaf litter and live leaves from existing canebrakes to estimate the nutrient use efficiency of cane. Further, a decomposition study was conducted to calculate the decomposition rate of cane leaves and to explore the litter quality attributes of giant cane. The primary purpose of phase two was to compare the effects of perennial riparian vegetation (giant cane and forest) and annual crops on soil quality, nitrogen cycling, and physical properties. This was to determine if any of them have a significant influence on giant cane distribution, while focusing on nitrogen dynamics to help determine why giant cane is a successful riparian buffer species. Five study sites in the Cache River watershed that had cane, agricultural fields (corn-soybean rotation), and forested areas adjacent to one another were selected. Data were collected on soil texture, carbon/nitrogen ratios, bulk density, nitrogen content (as ammonia and nitrate), and net nitrogen mineralization rates. The crop sites had significantly lower soil C:N ratios than both forest and cane (9.8:1 vs. 10.9:1 and 10.7:1, respectively), though all sites had ratios less than 25:1, indicating a tendency toward nitrogen mineralization. Forest soils had significantly higher rates of net mineralization than cane (19.0 μg m-2 day-1 and 6.6 μg m-2 day-1, respectively), with crop not significantly different from either cane or forest (8.0 μg m-2 day-1). Cane had higher levels of soil carbon and nitrogen when compared to forest and crop soils. Cane can be successful in wetter areas than previously thought, implying that the range of conditions that will support cane is broader than previously thought. Overall, there were few identifiable soil controls on giant cane distribution, or those that differentiate long-standing canebrakes from the nearby crop and forest land. For Phase three, nitrous oxide and carbon dioxide emissions were measured monthly for one year in riparian canebrakes and forests in southern Illinois to determine the rates of greenhouse gas (GHG) fluxes in bottomland riparian areas. Carbon dioxide emissions had a strong correlation with soil temperature (p < 0.001, r2= 0.54), but not with soil water content (p > 0.05), and were greater during the warmer months. Nitrous oxide emissions had a correlation with soil water content (p=0.470, r2 = 0.11), but no relation with soil temperature (p > 0.05), nor a difference across time. Vegetation type did not appear to influence GHG fluxes. Riparian CO2 and N2O emission rates were higher than documented cropland emissions, indicating riparian restoration projects to reduce NO3 delivery to streams may affect N2O and CO2 emissions resulting in an ecosystem tradeoff between water quality and air quality. Leaf deposition, N resorption efficiency and proficiency, and decomposition rates were analyzed in riparian stands of Arundinaria gigantea in southern Illinois for the first time in Phase four. Leaf litter was collected from five established canebrakes monthly over one year and a decomposition study was conducted over 72 weeks. Live leaves, freshly senesced leaves, and decomposed leaves were analyzed for carbon and nitrogen content. Leaf litterfall biomass peaked in November at twice the monthly average for all but one site, indicating a resemblance to deciduous leaf fall patterns. Nitrogen and carbon levels decreased 48% and 30%, respectively, between live leaves and 72 weeks decomposed. High soil moisture appeared to slow decomposition rates, perhaps due to the creation of anaerobic conditions. Cane leaves have low resorption proficiency and nutrient use proficiency, suggesting that these riparian canebrakes are not nitrogen limited. These results will help improve our understanding of the role that giant cane plays in a riparian ecosystem and help focus cane restoration efforts in southern Illinois.

Riparian buffers have been proven to reduce nutrient and sediment transport to streams in agricultural watersheds. Southern Illinois offers a unique opportunity to study functions of riparian buffers in reclaimed mine soils. In Perry County, Illinois three stream segments of Bonnie Creek, Galum Creek and Pipestone Creek were restored to their approximate original position following mining. Between 1980 and 2000, as part of the restoration, vegetative buffers of grasses and trees were planted along the streams to minimize nutrient and sediment inputs from adjacent restored agricultural land. Our research objective was to determine whether riparian soil function was being restored in the vegetated buffers by comparing multiple soil properties to the adjacent reclaimed soils in agricultural production. Four transects were established on each study site through the buffer and agricultural field. Ten one meter plots were evenly spaced along each transect in each of the land uses. In summers 2010 and 2011, water infiltration rates, bulk density, total carbon concentration, total nitrogen concentration, and C:N ratio measurements were made to assess the restoration of soil function. Soil water infiltration was significantly higher and bulk density was significantly lower in the riparian buffers compared to the adjacent agricultural fields. In the riparian buffer, roots likely helped to break up the soil adding pore space, which reduced the bulk density and increased the water infiltration rates. Soil total carbon, total nitrogen, and C:N ratio were significantly higher in the riparian buffers than the agricultural fields. The additional organic matter inputs from the roots of the riparian vegetation along with incorporation of litter from the soil macrofauna likely helped to increase the soil carbon and nitrogen levels compared to the agricultural fields. Even though the soil C:N ratio was significantly higher in the riparian buffers than the agricultural fields, more time is needed to restore the ratio to levels where nitrogen will be immobilized not mineralized in the riparian soils. Soil function in the riparian areas should continue to develop at a faster rate compared to the agricultural fields due to the impact of the perennial vegetation. Restoration of landscapes is not estimated by the return of structure alone, it also includes the re-establishment of function such as soil quality improvement, water quality improvement, and wildlife habitat restoration.

Submitted by JEFFERSON ANTHONY GABRIEL DE OLIVEIRA null (jeffunesp@yahoo.com.br) on 2016-05-08T22:02:27Z No. of bitstreams: 1 Tese Jefferson Final.pdf: 2156121 bytes, checksum: ef8e9ae3951c0e807526ae02fb2aa5bf (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-05-10T18:08:46Z (GMT) No. of bitstreams: 1 oliveira_jag_dr_ilha.pdf: 2156121 bytes, checksum: ef8e9ae3951c0e807526ae02fb2aa5bf (MD5) / Made available in DSpace on 2016-05-10T18:08:46Z (GMT). No. of bitstreams: 1 oliveira_jag_dr_ilha.pdf: 2156121 bytes, checksum: ef8e9ae3951c0e807526ae02fb2aa5bf (MD5) Previous issue date: 2016-02-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A cultura do feijoeiro (Phaseolus vulgaris L.) constitui-se numa das mais importantes explorações agrícolas tanto pela área cultivada quanto pelo valor de produção. O cultivo agrícola realizado visando a preservação dos atributos físicos, químicos e biológicos do solo é fundamental para a realização de uma agricultura sustentável. O objetivo do trabalho foi avaliar o cultivo do feijoeiro cultivar IAC, sobre diferentes palhadas de plantas de cobertura e doses de nitrogênio, aplicados em cobertura, e sua influência sobre a produção e qualidade de sementes e sobre os atributos físicos e químicos do solo. O experimento foi realizado na Fazenda de Ensino, Pesquisa e Extensão da UNESP - Campus de Ilha Solteira, localizada no município de Selvíria-MS. Os tratamentos foram compostos por 5 doses de nitrogênio (0, 40, 80, 120 e 160 kg ha-1) utilizando-se como fonte a ureia e 6 de palhadas (milho, milheto, Urochloa decumbens, Urochloa ruziziensis, Urochloa brizantha cv. MG5, Urochloa brizantha cv. Marandu), no cultivar IAC Formoso. As parcelas constaram de 6 linhas de 5 m sendo considerado como área útil as 4 linhas centrais a 0,5 m de cada extremidade. Após a colheita foram feitas análises dos componentes de produção do feijoeiro (número de vagens por planta, número de sementes por planta, número de sementes por vagem, massa de 100 sementes e produtividade), qualidade fisiológica de sementes (teste de germinação, teste de primeira contagem, índice de velocidade de germinação, comprimento de plântulas, teste de condutividade elétrica, tese de envelhecimento acelerado e teste de frio sem solo) e atributos físicos e químicos do solo, por meio da avaliação da resistência à penetração e análise química do solo, respectivamente. Conclui-se que: a produtividade do feijoeiro foi influenciada pelas plantas de cobertura nos dois anos, porém nem as maiores Produtividades e nem as menores ocorreram nas mesmas espécies. ara doses de nitrogênio em cobertura ocorreram variações entre os anos, sendo que em um dos anos para massa de 100 sementes foram obtidos ajustes dos dados a uma função linear, não ficando evidenciada nas demais avaliações efeito do nutriente sobre componentes de produtividade e produtividade do feijoeiro provavelmente devido a seca no período; as sementes obtidas apresentaram bom nível de qualidade fisiológica. A resistência à penetração de solo apresentou valores impeditivos ao pleno desenvolvimento da cultura. A as plantas de cobertura não influenciaram os atributos químicos de solo. / The common bean (Phaseolus vulgaris L.) is in one of the most important farms both the acreage and by production value. The agricultural cultivation carried out for the preservation of the physical, chemical and biological soil is essential for the achievement of a profitable and sustainable agriculture. The objective was to evaluate the bean cultivation IAC on different straws cover crops and nitrogen, applied in coverage , and its influence on the production and quality of seeds and about the physical and chemical soil. The experiment was conducted in Fazenda de Ensino, Pesquisa e Extensão da UNESP - Ilha Solteira, located in Selvíria-MS. The treatments consisted of five nitrogen rates (0, 40, 80, 120 and 160 kg ha-1) using as source urea and 6 straws (maize, millet, Urochloa decumbens, Urochloa ruziziensis, Urochloa brizantha cv. MG5, Urochloa brizantha cv. Marandu) in IAC Formoso. The plots consisted of 6 lines of 5 m length. After harvest were made analysis of yield components (number of pods per plant, number of seeds per plant, number of seeds per pod, weight of 100 seeds and productivity), physiological seed quality (germination test, first count, speed germination index, seedling length, electrical conductivity, accelerated aging and cold test without soil) and physical characteristics and soil chemistry, by evaluating the resistance to penetration and chemical analysis of soil, respectively. In conclusion: bean yield was influenced by cover crops in two years, but not the highest productivity and even the smallest occurred in the same species; for nitrogen levels in coverage there were variations between years, and in one year for mass of 100 seeds were obtained settings data to a linear function, not being evidenced in other evaluations effect of nutrient on yield components and bean yield probably due to drought in the period; the obtained seeds showed good level of physiological quality. resistance to soil penetration values presented impede the full development of crop; cover crops did not affect the chemical aspects of soil, with all providing a good nutrient cycling.

Orientador: Marco Eustáquio Sá / Resumo: A cultura do feijoeiro (Phaseolus vulgaris L.) constitui-se numa das mais importantes explorações agrícolas tanto pela área cultivada quanto pelo valor de produção. O cultivo agrícola realizado visando a preservação dos atributos físicos, químicos e biológicos do solo é fundamental para a realização de uma agricultura sustentável. O objetivo do trabalho foi avaliar o cultivo do feijoeiro cultivar IAC, sobre diferentes palhadas de plantas de cobertura e doses de nitrogênio, aplicados em cobertura, e sua influência sobre a produção e qualidade de sementes e sobre os atributos físicos e químicos do solo. O experimento foi realizado na Fazenda de Ensino, Pesquisa e Extensão da UNESP - Campus de Ilha Solteira, localizada no município de Selvíria-MS. Os tratamentos foram compostos por 5 doses de nitrogênio (0, 40, 80, 120 e 160 kg ha-1) utilizando-se como fonte a ureia e 6 de palhadas (milho, milheto, Urochloa decumbens, Urochloa ruziziensis, Urochloa brizantha cv. MG5, Urochloa brizantha cv. Marandu), no cultivar IAC Formoso. As parcelas constaram de 6 linhas de 5 m sendo considerado como área útil as 4 linhas centrais a 0,5 m de cada extremidade. Após a colheita foram feitas análises dos componentes de produção do feijoeiro (número de vagens por planta, número de sementes por planta, número de sementes por vagem, massa de 100 sementes e produtividade), qualidade fisiológica de sementes (teste de germinação, teste de primeira contagem, índice de velocidade de germinação, comprimen... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The common bean (Phaseolus vulgaris L.) is in one of the most important farms both the acreage and by production value. The agricultural cultivation carried out for the preservation of the physical, chemical and biological soil is essential for the achievement of a profitable and sustainable agriculture. The objective was to evaluate the bean cultivation IAC on different straws cover crops and nitrogen, applied in coverage , and its influence on the production and quality of seeds and about the physical and chemical soil. The experiment was conducted in Fazenda de Ensino, Pesquisa e Extensão da UNESP - Ilha Solteira, located in Selvíria-MS. The treatments consisted of five nitrogen rates (0, 40, 80, 120 and 160 kg ha-1) using as source urea and 6 straws (maize, millet, Urochloa decumbens, Urochloa ruziziensis, Urochloa brizantha cv. MG5, Urochloa brizantha cv. Marandu) in IAC Formoso. The plots consisted of 6 lines of 5 m length. After harvest were made analysis of yield components (number of pods per plant, number of seeds per plant, number of seeds per pod, weight of 100 seeds and productivity), physiological seed quality (germination test, first count, speed germination index, seedling length, electrical conductivity, accelerated aging and cold test without soil) and physical characteristics and soil chemistry, by evaluating the resistance to penetration and chemical analysis of soil, respectively. In conclusion: bean yield was influenced by cover crops in two years, but n... (Complete abstract click electronic access below) / Doutor

nÃo hà / This study evaluates the indicators of soil and water and its implications for the public supply of Juazeiro system pollution from interactions between aquifers and soils that makes up part of the drainage area of the stream of the Apes. For this, a characterization of the soils of the area as the physical, chemical and biological aspects was conducted through qualitative indicators of total organic carbon, total nitrogen, basal respiration and C / N ratio. Surface waters were also characterized in terms of COD and BOD parameters and groundwater for the parameters of Ammonia, Nitrite, Nitrate and chloride. The data obtained in the characterization of the soils of the study area were analyzed using multivariate statistical methods Principal Component Analysis and Cluster Analysis Hierarchical Agglomerative; and those obtained in the characterization of surface water were contrasted with the framework set out by the CONAMA Resolution No. 357 for classes of freshwaters. Data from qualitative monitoring of groundwater, provided by CAGECE, were analyzed regarding the classification according to the predominant uses, by Resolution No. 396 of CONAMA and how to meet potability standards, by Ordinance No. 9214 MS. It was found that the soils of the drainage area of &#8203;&#8203;the stream of the Apes are degraded by human interference in the area, standing surface water polluted by sewage to the fullest extent analyzed, not fitting into any of the classes of freshwater, based the parameters analyzed. Of groundwater supply wells included in the study area meet the required legal standards, but already show signs of pollution by domestic sewage. / Este trabalho procura avaliar os indicadores de poluiÃÃo de solos e Ãguas e suas implicaÃÃes no sistema de abastecimento pÃblico de Juazeiro do Norte, a partir das interaÃÃes entre os aquÃferos e os solos que compÃe parte da zona de drenagem do riacho dos Macacos. Para isso, foi realizada uma caracterizaÃÃo dos solos da Ãrea quanto os aspectos fÃsicos, quÃmicos e biolÃgicos, atravÃs dos indicadores qualitativos de carbono orgÃnico total, nitrogÃnio total, respiraÃÃo basal e relaÃÃo C/N. Foram caracterizadas tambÃm as Ãguas superficiais quanto aos parÃmetros de DQO e DBO e as Ãguas subterrÃneas quanto aos parÃmetros de AmÃnia, Nitrito, Nitrato e Cloreto. Os dados obtidos na caracterizaÃÃo dos solos da Ãrea de estudo foram analisados atravÃs dos mÃtodos de estatÃstica multivariada AnÃlise de Componentes Principais e AnÃlise de Cluster Aglomerativa HierÃrquica; e os obtidos na caracterizaÃÃo das Ãguas superficiais foram contrastados com o enquadramento previsto pela ResoluÃÃo n 357 do CONAMA para classes de Ãguas doces. Os dados de monitoramento qualitativo das Ãguas subterrÃneas, fornecidos pela CAGECE, foram analisados, quanto ao enquadramento segundo os usos preponderantes, pela ResoluÃÃo n 396 do CONAMA e quanto ao atendimento aos padrÃes de potabilidade, pela Portaria MS n 9.214. Constatou-se que os solos da Ãrea de drenagem do riacho dos Macacos encontram-se degradados pelas interferÃncias antrÃpicas na Ãrea, estando as Ãguas superficiais poluÃdas por esgotos em toda a extensÃo analisada, nÃo se enquadrando em nenhuma das classes de Ãgua doce, com base nos parÃmetros analisados. As Ãguas subterrÃneas dos poÃos de abastecimento inseridos na Ãrea de estudo atendem aos padrÃes legais exigidos, mas jà apresentam indÃcios de poluiÃÃo por esgotos domÃsticos.

Low microbial activity and associated nutrient cycling are concerns in agricultural problem soils. The objectives of this study were to investigate microbial response on problem soils to amendments, drying-wetting cycles, and the interaction of amendments and drying-wetting cycles. In this laboratory study, soil carbon dioxide (CO2) flux was measured from thermal desorption treated soils and saline soils in response to Proganics, spent lime, and composted beef manure applications. Microbial activity was measured through CO2 flux and its rate of change, permanganate oxidizable C, and residual inorganic nitrogen. Proganics had the greatest ability to elevate and sustain microbial activity on problem soils, but spent lime and compost had the greatest potential to improve microbial mediated nitrogen mineralization. In conclusion, spent lime and compost can be effective amendments for improving soil quality of saline and thermal desorption treated problem soils to increase microbial activity and associated nitrogen cycling.

No description available.

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. / Doctor of Philosophy / 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.

In 2003 eight peanut and cotton crop rotations were established in southeastern Virginia, 4 of which included 2 or 3 years of tall fescue or orchardgrass grown as high-value hay crops. Each crop rotation was evaluated for changes in soil quality indicators including soil carbon and nitrogen, water stable soil aggregates, plant available water content, bulk density, cone index values, and soil moisture. Cotton and peanut growth and yield were also observed to evaluate changes in crop growth associated with differences in soil quality. Soilborne plant pathogens including root-knot nematode, stubby root nematode, ring nematode, stunt nematode, and Cylindrocladium parasiticum microsclerotia were measured in the spring and fall of each year to determine differences associated with crop rotations. Water stable soil aggregates in 2007 were higher in rotations with 3 years of either perennial grass. Soil moisture tended to be the highest at depths 30 - 60 cm in the 3-year tall fescue rotation in August and September 2007. Cotton in 2006 and peanut in 2007 had higher growth and yield where the annual crop directly followed a perennial grass. Root-knot nematode tended to decrease in all rotations over time. Stubby root nematode populations tended to increase in rotations with either duration of orchardgrass. Including perennial grasses in cotton and peanut rotations has the potential to increase growth and yield as demonstrated in this research. / Master of Science