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Objective Our objective was to evaluate the effects of grazing method on beef cattle performance, residue characteristics, and subsequent corn grain yields. Materials and Methods This was a 3-yr study in which strip-grazing (SG), continuous grazing (CG), and ungrazed control (CT) treatments were arranged in a randomized complete block design with 3 replications per year on a continuous corn production system in central Illinois. Strip-grazed plots were divided into subplots (1, 2, 3) in which cattle back-grazed. Thirty-six spring-calving, multiparous, Angus cows were used in the first and second year of the study and 42 winter-calving Angus heifers were used in the third year. Cattle grazed for 42 d each year following corn harvest. Results and Discussion Cattle in SG plots were 9.8 kg heavier (P = 0.05) postgrazing compared with those on CG plots but did not differ (P = 0.77) in final BCS, indicating adequate performance was maintained regardless of treatment. The SG and CG plots had increased ADF (P = 0.03) and decreased CP (P Implications and Applications Both grazing methods resulted in acceptable performance. Grazing corn residue did not affect subsequent crop yields; however, strip differences in yield within strip-grazed paddocks warrant further investigation.

Field research for exploring the impact of winter cover crops (WCCs) integration into cropping systems is resource intensive, time consuming and offers limited application beyond the study area. To bridge this gap, we used the APSIM model, to simulate corn (Zea mays L.) – rye – corn – rye and corn – rye – soybean (Glycine max L.) – rye rotations in comparison to corn – corn and corn – soybean rotations across the state of Illinois at a spatial resolution of 5 km × 5 km from 2000–2020 to study the impact of WCCs on soil organic carbon (SOC) dynamics and crop production. By propagating the uncertainty in model simulations associated with initial conditions, weather, soil, and management practices, we estimated the probability and the expected value of change in crop yield and SOC following WCC integration. Our results suggest that integrating cereal rye into the crop rotations did not incur any yield penalties, and on the contrary, imparted greater yield stability for corn across the state. It was found that the areas with low probability of increase in SOC (p

Brown spot, caused by Septoria glycines Hemmi, is a highly prevalent foliar disease of soybean (Glycine max (L.) Merr.). Despite its wide distribution, the development of Septoria brown spot and it...

Nitrogen (N) fertilization in agricultural soils has been receiving worldwide attention due to its detrimental effects on ecosystem services, particularly on microbial N transformation. However, few studies provide a complete picture of N-fertilization effects on the N transformation cycle within a single agricultural ecosystem. Here, we explored the main steps of the microbial N cycle, using targeted gene abundances as proxies, in relation to soil properties, following 35 years of N-fertilization at increasing rates (0, 202 and 269 kg N/ha) in continuous corn (Zea mays L.) and corn-soybean [Glycine max (L.) Merr.] rotations. We used real-time quantitative polymerase chain reaction (qPCR) for the quantification of phylogenetic groups and functional gene screening of the soil microbial communities, including genes encoding critical enzymes of the microbial N cycle: nifH (N2 fixation), amoA (first step of nitrification), nirK and nirS (first step of denitrification), and nosZ (last step of denitrification). Our results showed that long term N-fertilization increased the abundance of fungal communities likely related to decreases in pH, and an enrichment of Al3+ and Fe3+ in exchange sites at the expense of critical macro and micronutrients. At the same time, long term N-fertilization damaged potential biological N2 fixation by significantly reducing the abundance of nifH genes in both continuous and rotated corn systems, while accelerating potential nitrification activities under continuous corn by increasing the abundance of bacterial amoA. Fertilization did not affect the abundance of denitrifying groups. Altogether, these results suggest that N fertilization in corn crops potentially decreases N2 acquisition by free-living soil microbes and stimulates nitrification activities, thus creating a vicious loop that makes the overall agricultural system even more dependent on external N inputs.

Simple Summary The present study of blood chemical, cytokine and hormone indicators in male and female pigs offered insights into the combined effects of maternal immune activation and weaning stress. Our results indicate that maternal immune activation may grant higher tolerance to anion gap and bilirubin disruptions triggered by weaning stress. Therefore, management practices aimed at minimizing the effects of weaning should consider the interacting effect of immune activation during development. Abstract Weaning stress can elicit changes in the metabolic, hormone and immune systems of pigs and interact with prolonged disruptions stemming from maternal immune activation (MIA) during gestation. The present study advances the characterization of the combined effects of weaning stress and MIA on blood chemistry, immune and hormone indicators that inform on the health of pigs. Three-week-old female and male offspring of control gilts or gilts infected with the porcine reproductive and respiratory syndrome virus were allocated to weaned or nursed groups. The anion gap and bilirubin profiles suggest that MIA enhances tolerance to the effects of weaning stress. Interleukin 1 beta and interleukin 2 were highest among weaned MIA females, and cortisol was higher among weaned relative to nursed pigs across sexes. Canonical discriminant analysis demonstrated that weaned and nursed pigs have distinct chemistry profiles, whereas MIA and control pigs have distinct cytokine profiles. The results from this study can guide management practices that recognize the effects of the interaction between MIA and weaning stress on the performance and health of pigs.

Recent advancements in agricultural metagenomics allow for characterizing microbial indicators of soil health brought on by changes in management decisions, which ultimately affect the soil environment. Field-scale studies investigating the microbial taxa from agricultural experiments are sparse, with none investigating the long-term effect of crop rotation and tillage on microbial indicator species. Therefore, our goal was to determine the effect of rotations (continuous corn, CCC, continuous soybean, SSS, and each phase of a corn-soybean rotation, Cs and Sc) and tillage (no-till, NT, and chisel tillage, T) on the soil microbial community composition following 20 years of management. We found that crop rotation and tillage influence the soil environment by altering key soil properties, such as pH and soil organic matter (SOM). Monoculture corn lowered pH compared to SSS (5.9 vs. 6.9, respectively) but increased SOM (5.4% vs. 4.6%, respectively). Bacterial indicator microbes were categorized into two groups: SOM dependent and acidophile vs. N adverse and neutrophile. Fungi preferred the CCC rotation, characterized by low pH. Archaeal indicators were mainly ammonia oxidizers with species occupying niches at contrasting pHs. Numerous indicator microbes are involved with N cycling due to the fertilizer-rich environment, prone to aquatic or gaseous losses.

La inclusión de cultivos de cobertura invernales (CCI) en un sistema de siembra directa (SD) en reemplazo del barbecho constituye una alternativa promisoria para mejorar la salud del suelo y contribuir a la sustentabilidad ambiental de los sistemas agrícolas. Esta revisión ofrece un panorama integral de los efectos sobre el microbioma del suelo que tiene la introducción de CCI en rotación con cultivos de verano en sistemas de SD vs. el barbecho desnudo. Se realizó una búsqueda sistemática de la literatura que reporta los efectos de los CCI sobre los parámetros de abundancia, actividad y diversidad microbiana del suelo. Combinando 7 criterios de búsqueda se seleccionaron y analizaron 22 trabajos. El conjunto de resultados de esos trabajos muestra que la actividad enzimática del suelo se ve favorecida con la inclusión de CCI en la rotación, principalmente si estos se componen de leguminosas y mezclas de especies. Más de la mitad de esos trabajos reportan una mayor biomasa microbiana con CCI que con barbecho. Además, se advierte que los efectos de los CCI sobre los parámetros microbianos son independientes de la duración de los ensayos. Sin embargo, aún se necesitan más investigaciones básicas que permitan reducir la heterogeneidad entre estudios y comprender las complejas interacciones que ocurren entre los CCI y el microbioma del suelo. The inclusion of winter cover crops (WCC) in no-till (NT) systems in replacement of bare fallow is a promising alternative to improve soil health and consequently, contribute to environmental sustainability of agricultural systems. This review provides a comprehensive evaluation of the effects of the use of WCC in rotation with summer cash crops under NT systems on the soil microbiome versus bare fallows. A systematic literature search was conducted to evaluate the impact of WCC on microbial parameters indicative of abundance, activity and diversity. Twenty-two papers were selected based on seven combined criteria. The results of this review show that enzyme activities in soil are enhanced with the inclusion of WCC in the rotation, particularly those that include legumes and mix of species. In general, more than half of the analyzed papers report higher microbial biomass in soils with WCC than in bare fallow. Interestingly, the effects of WCC on microbial parameters are independent of the duration of the experiments. However, more basic research is necessary to reduce the heterogeneity of the studies and to better understand the complexity of the interactions between WCC and the soil microbiome. Fil: Morales, Marianela Estefania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina Fil: Iocoli, Gastón Alejandro. Universidad Nacional del Sur. Departamento de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina Fil: Villamil, Maria Bonita. University of Illinois. Urbana - Champaign; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Zabaloy, Maria Celina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; Argentina

Modern agricultural systems rely on inorganic nitrogen (N) fertilization to enhance crop yields, but its overuse may negatively affect soil properties. Our objective was to investigate the effect of long-term N fertilization on key soil properties under continuous corn [Zea mays L.] (CCC) and both the corn (Cs) and soybean [Glycine max L. Merr.] (Sc) phases of a corn-soybean rotation. Research plots were established in 1981 with treatments arranged as a split-plot design in a randomized complete block design with three replications. The main plot was crop rotation (CCC, Cs, and Sc), and the subplots were N fertilizer rates of 0 kg N ha−1 (N0, controls), and 202 kg N ha−1, and 269 kg N ha−1 (N202, and N269, respectively). After 36 years and within the CCC, the yearly addition of N269 compared to unfertilized controls significantly increased cation exchange capacity (CEC, 65 % higher under N269) and acidified the top 15 cm of the soil (pH 4.8 vs. pH 6.5). Soil organic matter (SOM) and total carbon stocks (TCs) were not affected by treatments, yet water aggregate stability (WAS) decreased by 6.7 % within the soybean phase of the CS rotation compared to CCC. Soil bulk density (BD) decreased with increased fertilization by 5 % from N0 to N269. Although ammonium (NH4+) did not differ by treatments, nitrate (NO3−) increased eight-fold with N269 compared to N0, implying increased nitrification. Soils of unfertilized controls under CCC have over twice the available phosphorus level (P) and 40 % more potassium (K) than the soils of fertilized plots (N202 and N269). On average, corn yields increased 60 % with N fertilization compared to N0. Likewise, under N0, rotated corn yielded 45 % more than CCC; the addition of N (N202 and N269) decreased the crop rotation benefit to 17 %. Our results indicated that due to the increased level of corn residues returned to the soil in fertilized systems, long-term N fertilization improved WAS and BD, yet not SOM, at the cost of significant soil acidification and greater risk of N leaching and increased nitrous oxide emissions.

Cover crops can supply and recycle soil nitrogen (N) in agroecosystems. With increasing interest in cover crop mixtures, farmers have questions about how N cycling is affected by individual species when planted alone or in mixtures. Field trials were conducted on two organic vegetable farms during the spring and summer of 2014–2016 to quantify biomass tissue N provisioned, soil nitrate (NO3-N) scavenged, and soil NO3-N mineralized from 12 species of cover crops (six spring and six summer species) planted in monoculture or five-way mixtures. All cover crops were compared to weedy and weeded (no cover crops or weeds) controls. Cover crops provisioned 28–33% more biomass tissue N than fallow weeds. Among spring cover crops, field pea produced the most biomass tissue N (131 ± 13 kg N ha−1; mean ± 1 SE) but that benefit disappeared when pea abundance was reduced in mixtures. Soil NO3-N to a depth of 0.2 m was reduced by 50–67% during cover crop and weed growth, regardless of treatment. Soil NO3-N availability approximately 1 month after incorporation of cover crop and weedy residues varied by treatment. Post-incorporation soil NO3-N was 17–19% greater in pea and soybean monocultures compared to mixtures; conversely, soil NO3-N was 17–19% lower following incorporation of buckwheat and sudangrass monocultures compared to mixtures. Results of this study demonstrate that cover crop N recycling services in near-surface soil are largely independent of species or mixture, but N provisioning services require careful management and species selection to ensure maximum biomass tissue N and timely N mineralization.

Balancing efforts to mitigate nitrous oxide (N₂O) emissions from crop production while increasing grain yields is an important challenge for agriculture. The objectives of this study were to assess N₂O emissions, soil inorganic nitrogen (N) concentrations, grain yield, and grain N content for three enhanced-efficiency nitrogen fertilizers (EENFs) compared with anhydrous ammonia in a rainfed corn system in Illinois over 3 yr (2015–2017). Treatments included a control (check) and four N sources applied at 202 kg N ha⁻¹: injected anhydrous ammonia, stabilized urea containing urease and nitrification inhibitors (SuperU, Agrotain International), polymer-coated urea (ESN, Agrium Advanced Technologies), and injected urea-ammonium nitrate (UAN) + nitrapyrin. Significant reductions in N₂O emissions were observed for several EENFs compared with anhydrous ammonia, but results were not consistent across treatments and years. SuperU reduced area- and yield-scaled N₂O emissions in two of three study years compared with anhydrous ammonia, while ESN had no N₂O mitigation benefit. Injected UAN + nitrapyrin had the highest emissions in the first year but significantly decreased emissions in the second 2 yr. No treatment significantly improved yield or grain N content compared with anhydrous ammonia. In light of efforts to broadly promote EENFs in the US Midwest, these results demonstrate there is some promise for N₂O mitigation, but the lack of clear crop productivity benefits combined with inconsistent N₂O mitigation effects do not support the conclusion that EENFs inherently improve agronomic and environmental outcomes.

Metagenomics in agricultural research allows for searching for bioindicators of soil health to characterize changes caused by management practices. Cover cropping (CC) improves soil health by mitigating nutrient losses, yet the benefits depend on the tillage system used. Field studies searching for indicator taxa within these systems are scarce and narrow in their scope. Our goal was to identify bioindicators of soil health from microbes that were responsive to CC (three levels) and tillage (chisel tillage, no-till) treatments after five years under field conditions. We used rRNA gene-based analysis via Illumina HiSeq2500 technology with QIIME 2.0 processing to characterize the microbial communities. Our results indicated that CC and tillage differentially changed the relative abundances (RAs) of the copiotrophic and oligotrophic guilds. Corn&ndash, soybean rotations with legume&ndash, grass CC increased the RA of copiotrophic decomposers more than rotations with grass CC, whereas rotations with only bare fallows favored stress-tolerant oligotrophs, including nitrifiers and denitrifiers. Unlike bacteria, fewer indicator fungi and archaea were detected, fungi were poorly identified, and their responses were inconsistent, while the archaea RA increased under bare fallow treatments. This is primary information that allows for understanding the potential for managing the soil community compositions using cover crops to reduce nutrient losses to the environment.

Agricultural practices of no-till and crop rotations are critical to counteract the detrimental effects of monocultures and tillage operations on ecosystem services related to soil health such as microbial N cycling. The present study explored the main steps of the microbial N cycle, using targeted gene abundance as a proxy, and concerning soil properties, following 19 and 20 years of crop monocultures and rotations of corn (Zea mays L.), and soybean [Glycine max (L.) Merr.], either under no-till or chisel tillage. Real-time quantitative polymerase chain reaction (qPCR) was implemented to estimate phylogenetic groups and functional genes related to the microbial N cycle: nifH (N2 fixation), amoA (nitrification) and nirK, nirS, and nosZ (denitrification). Our results indicate that long-term crop rotation and tillage decisions affect soil health as it relates to soil properties and microbial parameters. No-till management increased soil organic matter (SOM), decreased soil pH, and increased copy numbers of AOB (ammonia oxidizing bacteria). Crop rotations with more corn increased SOM, reduced soil pH, reduced AOA (ammonia oxidizing archaea) copy numbers, and increased AOB and fungal ITS copy numbers. NirK denitrifier groups were also enhanced under continuous corn. Altogether, the more corn years included in a crop rotation multiplies the amount of N needed to sustain yield levels, thereby intensifying the N cycle in these systems, potentially leading to acidification, enhanced bacterial nitrification, and creating an environment primed for N losses and increased N2O emissions. Fil: Behnke, G. D.. University of Illinois; Estados Unidos Fil: Zabaloy, Maria Celina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina Fil: Riggins, C. W.. University of Illinois; Estados Unidos Fil: Rodríguez-Zas, S.. University of Illinois; Estados Unidos Fil: Huang, L.. University of Illinois; Estados Unidos Fil: Villamil, Maria Bonita. University of Illinois; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Cover cropping is a promising sustainable agricultural method with the potential to enhance soil health and mitigate consequences of soil degradation. Because cover cropping can form an agroecosystem distinct from that of bare fallow, the soil microbiome is hypothesized to respond to the altered environmental circumstances. Despite the growing number of primary literature sources investigating the relationship between cover cropping and the soil microbiome, there has not been a quantitative research synthesis that is sufficiently comprehensive and specific to this relationship. We conducted a meta-analysis by compiling the results of 60 relevant studies reporting cover cropping effects on soil microbial properties to estimate global effect sizes and explore the current landscape of this topic. Overall, cover cropping significantly increased parameters of soil microbial abundance, activity, and diversity by 27%, 22%, and 2.5% respectively, compared to those of bare fallow. Moreover, cover cropping effect sizes varied by agricultural covariates like cover crop termination or tillage methods. Notably, cover cropping effects were less pronounced under conditions like continental climate, chemical cover crop termination, and conservation tillage. This meta-analysis showed that the soil microbiome can become more robust under cover cropping when properly managed with other agricultural practices. However, more primary research is still needed to control between-study heterogeneity and to more elaborately assess the relationships between cover cropping and the soil microbiome. Fil: Kim, Nakian. University of Illinois at Urbana; Estados Unidos Fil: Zabaloy, Maria Celina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; Argentina Fil: Guan, Kaiyu. University of Illinois at Urbana; Estados Unidos Fil: Villamil, Maria Bonita. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of Illinois at Urbana; Estados Unidos

Author(s): Yuan, M; Greer, KD; Nafziger, ED; Villamil, MB; Pittelkow, CM | Abstract: The environmental consequences of residue removal practices to support cellulosic biofuel production remain poorly understood. In the U.S. Midwest, corn (Zea mays L.) stover removal combined with no-till practices may increase or decrease soil N2O emissions by influencing soil moisture, temperature, and nutrient dynamics, yet empirical evidence from long-term field experiments is inconsistent. We investigated the effects of residue management (residue retained or removed) and tillage (chisel-till or no-till) on cumulative soil nitrous oxide (N2O) emissions, grain yield, and yield-scaled N2O emissions in a 3-year study initiated 10nyears after treatment implementation in a long-term, continuous corn experiment in Illinois, United States. Crop yields were affected by treatment in only one of three study years, with the combination of residue removal and no-till reducing yields compared to both chisel-till treatments. Cumulative N2O emissions, soil inorganic N concentrations, and yield-scaled N2O emissions differed over the 3-year period and were significantly affected by tillage, with no response to residue management. In 2nyears, no-till decreased cumulative N2O emissions and yield-scaled N2O emissions by an average of 64% and 60%, respectively. Correlations between daily N2O fluxes and soil moisture, temperature, and inorganic N concentrations suggested that the relative importance of these variables changed depending on year and treatment. While more research across a range of sites and management practices is needed, our findings support previous studies which have challenged IPCC methodology assumptions regarding the effects of residue removal on N2O emissions. We conclude there is inherent difficulty in predicting the impacts of residue removal due to the complexity of soil processes underlying N2O emissions coupled with inter-annual weather variability in this rainfed continuous corn system. Future efforts to evaluate the net greenhouse gas emissions of cellulosic biofuel production may benefit from accounting for this uncertainty.

Phosphonates are organic phosphorous (P) compounds frequently detected in the environment due to a very stable CP bond that render them relatively recalcitrant. Glyphosate [N-phosphonomethyl glycine] is the most widely used and best-known synthetic phosphonate, and one of the most concerning herbicides in the world today. Microbial degradation of glyphosate and organophosphonates in general, is the main dissipation mechanism operating in most environments. One microbial metabolic pathway in this process is the CP lyase pathway, entailing an enzymatic complex encoded by about 14 genes (the Phn operon). Our goal was to develop a quantitative polymerase chain reaction (qPCR) assay for a key enzyme, the CP lyase that breaks down the CP bond, via quantification of the codifying phnJ gene. The primers designed in this study fulfill the requirements for a successful qPCR assay, with high efficiency and sensitivity, as well as specific detection of the target sequence in a wide range of taxonomic groups. This is, to our knowledge, the first report of primers designed to target phnJ in both pure cultures and metagenomic DNA from different environmental sources. Direct quantification of phnJ may be a cost-effective proxy to determine glyphosate degradation potential in different matrixes.

Soil organic C (SOC) is significantly affected by changes in climate that control the physical, chemical, and biological processes in the soil. Simulating the impacts of future climate on SOC is challenging due to the limited availability of soil and climate variables required to properly simulate future SOC dynamics. The main objective of this study was to develop a modeling framework to quantify the impacts of future climate on SOC dynamics. The framework was developed for the Model for Nitrogen and Carbon in Agro-Ecosystems (MONICA) using the data collected from three University of Illinois Crop Science Research Centers. Projected precipitation and air temperature, collected from 32 global circulation models, were used to estimate the climate variables and cropping operation schedules required as inputs in MONICA. Six corn ()-soybean [ (L.) Merr.] rotation scenarios were considered in the simulations. Results showed that the total SOC in the upper 30 cm of the soil was expected to decrease from 43 to 70% in 2015 to 2075, with an uncertainty range of 13 to 16% due to the variation in climate prediction. The SOC in corn-soybean rotation schemes did not vary significantly from that of continuous corn scheme. The ability of a model to simulate realistic results depends significantly on the reliability of input data used to parameterize the model. A methodology that comprehensively estimates the impacts of future climatic conditions on SOC allows for realistic model results that can be used as a basis for environmental options, leading to a sustainable agro-production system.

Short-duration summer annual crop rotations are widely used in the Midwest, but their long-term impact on soil quality has not been thoroughly examined. Our goal was to compare soil properties under long-term use of the most common crop rotations around Illinois, and to identify soil quality indicators for rotations in the state. Crop rotations of continuous corn (Zea mays L.) (CCC), corn–soybean [Glycine max (L.) Merr.] (CS), and corn–corn–soybean (CCS) were arranged in a randomized complete block design (RCBD), with three or four replications at each of six locations, with all phases present each year for 12 yr. We measured 21 soil properties on the surface soil and 18 properties at four successive depths, rendering a total of 126 and 504 observations available for the multivariate statistical analyses, including principal component analyses (PCA) and canonical discriminant analysis (CDA) in both data sets. We found that our discriminant rules based on the measured soil properties correctly identified the location of origin of the soil samples in 98% of cases, representing

Field observations of no-till production plots in the southern semiarid pampas region of Argentina question the sustainability of this practice from the soil quality (SQ) standpoint when the amount of residues left by typical crop rotations is not taken into account. Our aim was to evaluate a set of management practices as they have been implemented on farm operations of the region on SQ parameters of the surface soil. The six production systems identified represent the combinations of tillage systems (no − till, NT and reduced till, RT), time since implementation (10 or 15 years), rotations (WW, winter crops; WF, winter crops with extended fallow; WS, winter and summer crops) and soil types (sandy loam or loam to clay loam) found in the agricultural operations of local producers. Composited soil samples at three successive depths (0–5 cm, 5–10 cm and 10–18 cm) were taken in 27 production plots of ∼50 ha in size each, and analyzed for soil chemical, physical and biological properties. Our results showed when including sunflower as summer crops on the dominant sandy loams, that NT production plots had the lowest total organic carbon (TOC) and total nitrogen (TN), and particulate organic carbon and nitrogen (POC, PN), and showed a three-fold decrease in structural stability when compared with NT of only winter crops or with RT managed plots. Furthermore, our canonical discriminant analysis (CDA) showed structural index (SI), TOC, change in the mean weight diameter of aggregates (CWMD), and biological activity (BA) as the best SQ indicators for the study area. The quantified degradation suggests the need to reassess NT implementation in order to make NT a sustainable option for the southern semiarid pampas region.

Growing cover crops is one of the most promising conservation practices with multiple benefits. However, the impacts of cover crops on the productivity of the maize-soybean [Zea mays L. - Glycine max (L.) Merr.] rotation system in the U.S. Midwest still have large uncertainties based on results obtained from field experiments, specifically across different soil properties, climate conditions, and land management practices. Process-based models fully validated with data from field experiments across these diverse conditions provide an effective tool to quantify cover crop impacts on cash crop productivity and optimize the management of cover crops accordingly. In this study, we aim to answer the following questions: (1) What are the impacts of cover crops on cash crop yield in the U.S. Midwest agroecosystems? (2) What are the mechanistic pathways of cover crop to affect cash crop yield (e.g. through influencing soil water, nitrogen and O2 dynamics)? (3) What management practices can be used to mitigate the negative impacts on cash crop yield caused by cover crops? To address these questions, we calibrated and validated a sophisticated process-based agroecosystem model, ecosys, using field experimental data from 2013 to 2018 across Illinois, and then used ecosys to assess the impacts of winter cover crops on maize and soybean yield under different management practices. Our study revealed the following findings: (1) planting non-legume cover crops can cause 3.9 ± 3% yield reduction for maize and no significant impacts on soybean yield, while planting legume cover crops has no significant impact on the yield of either maize or soybean; (2) the maize yield reduction caused by planting cover crops can be mainly explained by nitrogen deficiency induced by increased immobilization, water competition in dry areas, cooler soil surface and oxygen competition; (3) later termination of non-legume cover crops before maize can result in larger maize yield loss due to intensive competition for resources (e.g. water and nitrogen), and the impacts of non-legume cover crops on maize yield reduction can be minimized by optimizing cover crop termination time in the spring. Overall, in the U.S. Midwestern maize-soybean rotation system, we found that although non-legume cover crops cause yield reduction for maize through resource competition, this yield reduction can be minimized through management practices, such as controlling termination time of cover crop and proper fertilizer management.

The long-term implementation of crop rotation and tillage influences the soil environment through inputs and disturbance of the soil, which in turn, impact soil quality (SQ). A vital component of developing sustainable agronomic practices is to evaluate their effect on SQ. The objective of this study is to address the first step in this process by identifying soil parameters that are sensitive to changes in the soil and indicative of soil functions. Soil samples were collected from two Illinois sites with cropping systems and tillage treatments in place for more than 16 years. Crop rotation and tillage were evaluated with separate principal component analyses (PCA) of 20 soil parameters. Six principal components accounted for 74% of variability among rotations. The soil parameters loaded within these components highlighted the strong influence on carbon and nitrogen cycling indicated by greater soil organic carbon, total nitrogen, microbial biomass, and aggregate stability under crop rotations with high C:N residues and biomass production. Other strongly loaded parameters, such as soil pH and nutrient contents, are likely related to the use of nitrogenous fertilizers in grass species. Rotations with only a single contrasting crop were able to be differentiated readily while the multi-species crop rotations were only marginally able to be separated. The PCA for tillage explained 73% of variability with six principal components; of those, three were able to separate no-till from conventional tillage. As with rotation, the choice of tillage practice can have a large influence on the cycling of carbon and nitrogen, as decomposition of residues and soil organic matter are accelerated by tillage. No-till was also associated with stratification of pH and other nutrients. Soil parameters relating to carbon and nitrogen cycling have the greatest potential as SQ indicators while other measures relating to nitrogen fertilization, such as shifts in soil pH and nutrient contents, can also prove useful in comparing SQ under crop rotation and tillage in Illinois.

Soil microbial communities are essential in the cycling of nutrients that affect crop production. Our goal was to characterize the microbial community structure following 34 years of nitrogen (N) fertilization treatments in continuous maize production in highly fertile soils. Using 16S rRNA gene-based analysis of the V4 region via Illumina HiSeq2500 technology with downstream bioinformatics processing and analysis with QIIME 2.0, we aimed to characterize the prokaryotic communities under three increasing N fertilization rates. Factor analyses indicated that a high N level decreased the diversity of soil bacterial and archaeal communities and altered the relative abundance (RA) of the dominant (&gt, 1% RA) and minor (&lt, 1% RA) phyla. Among the 12 major phyla, we determined increases in Gemmatimonadetes, Proteobacteria, and Euryarchaeota, accompanied by reductions in Cyanobacteria, Chloroflexi, Firmicutes, and Planctomycetes with increasing N. Within the 29 minor phyla, N fertilization led to increases in Aquificae, WPS2, Parvarchaeota, AD3, FCPU426, Armatimonadetes, TM7, Chlamydiae, and OD1, along with reductions of Nitrospirae, WS3, Tenericutes, Lentisphaerae, OP3, Synergistetes, Thermotogae, and prokaryotes that could not be reliably assigned to a phylum (classified as Other).

The combined use of biochar and compost as a soil amendment presents benefits to crops and nutrient cycling. Although there are literature reviews regarding biochar and biochar-compost mixtures, a quantitative literature review on the role of co-composted biochar (hereby called COMBI) in plant productivity is currently missing. The goal of this review paper is to find evidence-based measures of the effects of application rates, soil pH, plant types, biochar feedstock, and compost materials, on plant productivity. Plant productivity covers a variety of measurements but mostly refers to grain yield and above-ground biomass. Response ratio was selected as the effect size. Funnel plot showed that the studies were reasonably symmetrically distributed around the mean effect size. Results showed that application rates of 30 t/ha significantly increased plant productivity by 48.3 and 15.7%, respectively, while no significant yield increases were found for the application rates between 20 and 30 t/ha. When data was grouped based on the soil pH, the greatest increase in plant productivity was found to be at acidic soil pH values (pH 4–5), which was expected because the liming effect of biochar is often reported as one of the main mechanisms behind the increased crop yields. When different plant species were compared, cereal grasses grown with COMBI yielded significantly higher grain yields (39.7%). Rice husk biochar yielded the highest increase in productivity but this result was based on only one study. The second highest increase was obtained with wood-based biochars (29.4%) based on ten studies. The effect sizes found with our meta-analyses are based on 14 research works worldwide and represent the most updated information regarding the effects of COMBI on plant production. As more data on COMBI become available, data analyses can be updated to make more robust comparisons.

Brown spot caused by Septoria glycines is a prevalent foliar disease in all soybean production areas. Application of foliar fungicides after bloom reduces the disease severity, yet yield responses are not consistent among locations and years. Our research goal was to determine the effect of different levels of Septoria brown spot on yield. Different levels of disease severity were effectively obtained in the field by weekly application of chlorothalonil for three, six, and nine times after disease inoculation at V3/V4 stage. Fungicide treatments had a significant effect on vertical progress and chlorotic area with no statistically significant effect on yield. Soybean yield was negatively correlated with vertical progress of the disease (r = −0.36). The vertical progress was the best linear predictor of yield. Based on this model, when the vertical progress of brown spot at R6 increased by 10%, the yield decreased by 142.13 kg/ha (3.4%). A variance component analyses of our data showed that location was the most critical factor, illustrating the significant effect of local environmental conditions on the disease. Power analyses indicated that at least eight locations are needed to detect an effect of 269 kg/ha. Our results provide useful information to improve the experimental design for future experiments addressing the yield constrain by late season diseases of soybean.

No-till in continuous corn (Zea mays L.) production helps to keep an important volume of residues on the soil surface, creating management challenges that could be alleviated by residue removal for bioenergy or animal use. Crop residues, however, are essential to stimulate microbial nutrient cycling in agroecosystems. Thus, both residue removal and tillage options need to be fully evaluated for their impacts on ecosystem services related to soil health, including microbial N cycling. We explored the main steps of the microbial N cycle in relation to soil properties by using targeted gene abundance as a proxy following over a decade of residue removal in continuous corn systems either under no-till or chisel tillage. We used real-time quantitative polymerase chain reaction (qPCR) for the quantification of phylogenetic groups and functional gene screening of the soil microbial communities, including genes encoding critical enzymes of the microbial N cycle: nifH (N2 fixation), amoA (nitrification – ammonia oxidation), nirK and nirS (denitrification – nitrite reduction), and nosZ (denitrification – nitrous oxide reduction). Our results showed that long-term residue removal and tillage decreased soil organic matter (SOM), water aggregate stability (WAS), and the relative abundance (RA) of ammonia-oxidizing bacteria (AOB) carrying nitrifying amoA genes. Denitrifiers carrying nirS genes decreased under no-till as crop residue was removed. In addition, our results evidenced strong correlations among soil properties and phylogenetic groups of bacteria, archaea, and fungi. Overall, this study demonstrated limited but definite impacts of residue management and tillage on the soil environment, which could be exacerbated under less resilient conditions. Fil: Kim, N.. University of Illinois; Estados Unidos Fil: Riggins, C. W.. University of Illinois; Estados Unidos Fil: Rodríguez Zas, S.. University of Illinois; Estados Unidos Fil: Zabaloy, Maria Celina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina Fil: Villamil, Maria Bonita. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of Illinois; Estados Unidos

Measures of soil biology are critical for the assessment of soil quality under different agricultural management practices. By modifying soil microclimate, tillage exerts the most important control on soil microbial communities. The objective of this study is to assess the effect of tillage on soil microbial biomass and enzyme activities. A meta-analysis was conducted utilizing 139 observations from 62 studies from around the world; the selected effect size (ES) was logn of the response ratio (RR), the mean of the tilled treatment divided by the mean of the no-till control. This ES was calculated for seven different microbial properties – microbial biomass carbon (MBC) and nitrogen (MBN), metabolic quotient (qCO2), fluorescein diacetate (FDA), dehydrogenase (DHA), β-glucosidase, and urease. Microbial biomass, metabolic quotient and enzyme activities were evaluated due their prevalent usage in evaluation of soil quality and use in soil quality indices. Overall, microbial biomass and all of the enzyme activities were greater under no-till compared to tillage. One exception to this was that under chisel tillage, there was no difference in MBC between the tilled plots and no-till. The qCO2 was greater under tillage than under no-till indicating more active microbes in tilled soil, perhaps compensating for the reduced quantity. In contrast, when looking at only long-term experiments, qCO2 was similar under both tillage and no-till, which may indicate that eventually microbes in no-till plots become as active as those in tilled plots even with the larger microbial community. The findings of this study illustrate that no-till and even reduced tillage, such as chisel tillage, promote larger microbial communities and greater enzymatic activity.

Organic producers often rely heavily on tillage for weed management, which can create compaction, especially in headlands, and favor weed growth. To address Illinois organic grain farmers’ concerns, we explored the effect of cover crops in headland areas of their farms on soil properties, weeds, and yields in a participatory on-farm approach. A split-plot arrangement with two replications at each of four Illinois locations was used in two consecutive years within field areas [FA: headlands – or turn-rows – HL; non-headlands NHL] randomly selected as main plots where four cover crop treatments were randomly assigned (CC: fallow control C; forage radish FR; mix of forage radish and buckwheat FRbw; and mix of forage radish with hairy vetch and cereal rye FRhvr). Collaborating farmers planted soybean [ Glycine max (L.) Merr.] in 2012 and corn ( Zea mays L.) in 2013. Each fall and spring, we measured soil penetration resistance (PR), bulk density (BD), water aggregate stability (WAS), total carbon (TC), nitrate (N-NO 3 ), ammonium (N-NH 4 ), available phosphorus (P), and pH. Additionally, cover crop and weed growth, and cash crop yields were determined each year. Our results indicate HL areas had greater PR (+22%) and BD (+3%), as well as higher WAS (+4%), TC (+10%), P (+36%), and pH (+7%) in comparison to NHL areas on average through the fall and spring seasons. Though FRhvr significantly reduced spring weed biomass (−30%) compared to the controls, higher density of grass weeds (+44%) were present in HL areas through spring and summer regardless of CC treatments. Due to the resilient nature of these particular Illinois soils and extreme weather pattern observations, the cover crop treatments did not alleviate compaction nor influence soil properties for the duration of this project. However, there was a trend toward lower available P in the FRhvr treatments and reduced crop yields in those treatments within the NHL areas. Though the cover crop treatments chosen for this trial did not seem to provide clear benefits, our results point toward a beneficial feedback between the weed community and the soil properties within headland areas in these organic systems.

Two of the most important agricultural practices aimed at improving soil properties are crop rotations and no-tillage, yet relatively few studies have assessed their long-term impacts on crop yields and soil greenhouse gas (GHG) emissions. The objective of this study was to determine the influence of tillage and crop rotation on soil GHG emissions and yields following 15 years of treatment implementation in a long-term cropping systems experiment in Illinois, USA. The experimental design was a split-plot RCBD with crop rotation as the main plot: (continuous corn [Zea mays L.] (CCC), corn-soybean [Glycine max (L.) Merr.] (CS), continuous soybean (SSS), and corn-soybean-wheat [Triticum aestivum L.] (CSW); with each phase of each crop rotation present every year) and tillage as the subplot: chisel tillage (T) and no-tillage (NT). Tillage increased the yields of corn and soybean. Tillage and crop rotation had no effect on methane (CH4) emissions (p = 0.4738 and p = 0.8494 respectively) and only rotation had an effect on cumulative carbon dioxide (CO2) (p = 0.0137). However, their interaction affected cumulative nitrous oxide (N2O) emissions significantly (p = 0.0960); N2O emissions from tilled CCC were the greatest at 6.9 kg-N ha−1-yr−1; while emissions from NT CCC (4.0 kg-N ha−1-yr−1) were not different than both T CS or NT CS (3.6 and 3.3 kg-N ha−1−yr−1, respectively). Utilizing just a CS crop rotation increased corn yields by around 20% while reducing N2O emissions by around 35%; soybean yields were 7% greater and N2O emissions were not affected. Therefore results from this long-term study indicate that a CS rotation has the ability to increase yields and reduce GHG emissions compared to either CCC or SSS alone, yet moving to a CSW rotation did not further increase yields or reduce N2O emissions.

Relationships between greenhouse gas emissions, yields, and soil properties are not well known. Utilizing two datasets from long-term cropping systems in Illinois, USA, our we aim to address these knowledge gaps. The objective of this study was to explore the relationships between the physical and chemical properties and greenhouse gas (GHG) emissions of soil, and cash crop yields over a four-year time-period and following 15 years of treatment implementation in Illinois, USA. The experimental layout was a split-plot arrangement involving rotation and tillage treatments in a randomized complete block design with four replications. The studied crop rotations were continuous corn [Zea mays L.] (CCC), corn-soybean [Glycine max (L.) Merr.] (CS), continuous soybean (SSS), and corn-soybean-wheat [Triticum aestivum L.] (CSW), with each phase being present for every year. The tillage options were chisel tillage (T) and no-tillage (NT). We used an array of multivariate approaches to analyze both of our datasets that included 31 soil properties, GHG emissions (N2 O, CO2, and CH4 ) and cash crop yields. The results from our analyses indicate that N2 O emissions are associated with a low soil pH, an increased Al concentration, the presence of soil nitrate throughout the growing season, an increase in plant available water (PAW) and an increased soil C concentration. Likewise, soil CO2 respiration was correlated with low pH, elevated Al concentrations, low Ca, increased PAW, higher levels of microbial biomass carbon (MBC), and lower water aggregate stability (WAS). Emissions of CH4 were associated with increased levels of MBC. Lastly, the yield index (YdI) was correlated with lower levels of soil Ca and available P and lower values of WAS. The association between high YdI and lower WAS can be attributed to tillage, as tillage lowers WAS, but increases yields in highly productive cropping systems in the Midwest.

Removal of crop residues for use as ethanol production feedstock might deplete soil carbon and nutrient pools in site- and management-specific ways. We investigated the effect of residue removal (RR), tillage (T), and N fertilizer rate (Nr) after five years of continuous corn (Zea mays L.) on total soil carbon (TC) and nutrient stocks at four sites within Illinois. The experimental design was a split–split plot arrangement of treatments in a randomized complete block design with four replications, and all treatments remained in the same place each year. Main plots consist of one of three levels of corn residue removal (RR: full, partial, and none); split plots were two tillage systems (T: chisel tilled and no-till) and split–split plots were four N fertilizer rates (Nr: 67, 134, 201, and 268 kg N ha− 1). The highest TC stocks were found under no-till without residue removal; removing any residue under no-till lowered TC to the levels found under chisel tillage. Removing residue in tilled soils produced higher TC values similar to the levels found with no residue removal and no-till. Residue removal tended to lower P and lowered K and EC in the surface 15 cm soil. Tillage decreased the N and K stocks in the surface soil. Increasing the rate of N fertilizer lowered P, K, and pH, generally in an increasing, curvilinear manner, but the response of EC was concave, increasing at the highest N rate used. These responses were closely related to corn grain yields, indicating that the amount of nutrient removed by harvest of grain and residue and the amount of residue retained after harvest affect TC and nutrient stocks in Illinois soils. This information will help producers and policy makers to make better decisions regarding the feasibility of harvesting corn residue, and on agronomic practices that might accompany residue removal in order to prevent soil nutrient depletion.

A B S T R A C T Harvesting corn (Zea mays L.) residue for use as a biofuel feedstock may alter important chemical and physical properties of soils. Long-term residue removal, linked with tillage and fertilizer practices, could lower soil organic carbon (SOC), as well as increase soil compaction and susceptibility to erosion. A study initiated in 2006 included three levels of residue removal (none, partial, or full removal), two tillage treatments (no-till or chisel plow), and two N application rates (134 and 268 kg N/ha). These experiments were established in continuous corn (CC) at four Illinois sites, with treatments remaining in the same plots each year. In the spring at the beginning of the eighth growing season, we measured total carbon stocks (SOC), water aggregate stability (WAS), soil bulk density (BD), and penetration resistance (PR). Results showed that with all crop residue retained in the field, SOC stocks 13% lower under chisel tillage than in no-tilled plots, but removal of some or all of the residue lowered the SOC levels of no-tilled plots to those of tilled plots. On average for the studied depths, no-till plots had 5% and 39% higher BD and PR, respectively, than tilled plots, and residue removal significantly increased PR under no-till. Regardless of tillage treatment, the highest WAS values were found without residue removal at the lower N rate and with partial removal at the higher N rate. The higher N rate slightly lowered the BD under partial removal of residue for both tillage treatments at both studied depths. Our results indicate that residue harvest generates modest changes in soil properties under continuous corn, likely smaller than the effects of tillage and N fertilizer use in these systems. But as long as residue amount and tillage practices are sufficient to limit losses of soil by erosion to acceptable levels, we believe that corn residue represents a viable feedstock for a sustainable bioenergy industry in the U.S. Midwest.