Conventional Soybean Production Research Articles

Adaptability and stability of conventional soybean by GGE biplot analysis

ABSTRACT The conventional soybean production has been re-establishing itself every year, due to the fact that the international market has demanded products with high agronomic performance and nutritional quality, free of genetically modified organisms. This study aimed to evaluate the adaptability of conventional soybean genotypes in the southwestern Goiás state (Rio Verde, Montividiu and Santa Helena de Goiás), Brazil, during the 2017/2018 and 2018/2019 crop seasons. A randomized blocks design was used, being tested eight genotypes (the cultivars BRS284, BRS283, BRS232, BRS317, NT11-1277, INT3459 and M6101 and the line NT1478SP). The grain and oil yields, as well as the oil and protein contents, were evaluated. Multi-environment analyses were performed using a heterogeneous residual variance model, and the GGE biplot analysis was used to describe the interrelationships between genotypes and environments. The most adapted and stable genotypes were BRS 317 for grain yield and BRS 283 for oil yield. They also corresponded more closely to the ideotype for the specific region, thus proving to be promising. NT1478SP showed the highest protein content. In the 2018/2019 crop season, Montividiu was more discriminating for the conventional soybean production, regarding grain and oil yields.

Comparison of conventional and transgenic soybean production costs in different regions in Brazil

The soybean crop is one of the most economically important crops in Brazilian agribusiness and in the world, with the expansion of the crop always linked to scientific advances and new production technologies. In view of the above, the objective of this study was to evaluate the production costs of twenty-one producing regions to determine the highest and lowest production costs in the first harvest in three agricultural years and in the summer harvest in two agricultural years, with the conventional and transgenic soybeans, in addition to comparing the cost of production of the cultivation systems. As for technical procedures, a descriptive research was carried out with statistical data provided by the National Supply Company. The agricultural years of 2018, 2019 and 2020 of soybean culture were analyzed in twenty-one Brazilian municipalities, located in the Brazilian states: Bahia, Distrito Federal, Goiás, Maranhão, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Paraná, Piauí , Rio Grande do Sul, Roraima and Tocantins. The region of Primavera do Leste - MT demonstrated a region with a high cost of production in comparison with other producing regions. The lowest costs varied between several regions, depending on the cultivation system employed. The production of transgenic soybeans proved to be the most profitable and promising option due to the lower production cost in relation to the cultivation of conventional soybeans.

Evaluating Soybean Cultivars for Low- and High-Temperature Tolerance During the Seedling Growth Stage

Soybean (Glycine max L.) seedlings may be exposed to low or high temperatures under early or conventional soybean production systems practiced in the US Midsouth. However, a wide range of soybean cultivars commonly grown in the region may inherit diverse tolerance to degrees of temperatures. Therefore, a study was conducted in a controlled-environment facility to quantify 64 soybean cultivars from Maturity Group III to V, to low (LT; 20/12 °C), optimum (OT; 30/22 °C), and high (HT; 40/32 °C) temperature treatments during the seedling growth stage. Several shoot, root, and physiological parameters were assessed at 20 days after sowing. The study found a significant decline in the measured root, shoot, and physiological parameters at both low and high temperatures, except for root average diameter (RAD) and lateral root numbers under LT effects. Under HT, shoot growth was significantly increased, however, root growth showed a significant reduction. Maturity group (MG) III had significantly lower values for the measured root, shoot, and physiological traits across temperature treatments when compared with MG IV and V. Cultivar variability existed and reflected considerably through positive or negative responses in growth to LT and HT. Cumulative stress response indices and principal component analysis were used to identify cultivar-specific tolerance to temperatures. Based on the analysis, cultivars CZ 5225 LL and GS47R216 were identified as most sensitive and tolerant to LT, while, cultivars 45A-46 and 5115LL identified as most tolerant and sensitive to HT, respectively. The information on cultivar-specific tolerance to low or high temperatures obtained in this study would help in cultivar selection to minimize stand loss in present production areas.

Environmental performance of organic farming: Evidence from Korean small-holder soybean production

Organic farming has shown better environmental performance than conventional farming in many studies; however, no systematic study into intensive, smallholder farming practices in Asia has been conducted. In this study, the energy efficiencies (EEs) and greenhouse gas (GHG) emissions of organic and conventional soybean production systems in South Korea, and their major contributing factors, based on life cycle assessments (LCAs) are explored. Multi-level regression analyses and non-parametric comparison tests were applied to the data from 60 soybean farms, 30 of each production system. The results show that conventional farming (1.923 energy efficiency) is significantly more energy efficient than organic farming (1.046 energy efficiency). The energy inefficiency of organic farming is attributed to the excessive use of energy for fuel and mulch film, and smaller crop yields. Greenhouse gas emissions are not significantly different between the organic (2045.11 kg CO2 eq/ton) and conventional soybean-farming systems (1657.55 kg CO2 eq/ton). The surprisingly smaller EE and larger GHG emissions associated with soybean production in Korea, compared with those of large-scale farming, necessitates further research on the environmental performance of smaller farms in Asia.

Palmer Amaranth (Amaranthus palmeri) and Velvetleaf (Abutilon theophrasti) Control in No-Tillage Conventional (Non–genetically engineered) Soybean Using Overlapping Residual Herbicide Programs

AbstractDue to depressed corn and soybean prices over the last few years in the United States, growers in Nebraska are showing interest in no-tillage (hereafter referred to as no-till) conventional (non–genetically engineered [non-GE]) soybean production. Due to the increasing number of herbicide-resistant weeds in the United States, weed control in no-till non-GE soybean using POST herbicides is a challenge. The objectives of this study were to compare PRE-only, PRE followed by (fb) POST, and PRE fb POST with residual (POST-WR) herbicide programs for Palmer amaranth and velvetleaf control and soybean injury and yield, as well as to estimate the gross profit margins and benefit–cost ratio of herbicide programs. A field experiment was conducted in 2016 and 2017 at Clay Center, NE. The PRE herbicides tested in this study resulted in ≥95% Palmer amaranth and velvetleaf control at 28 d after PRE (DAPRE). Averaged across the programs, the PRE-only program controlled Palmer amaranth 66%, whereas 86% and 97% control was obtained with the PRE fb POST and PRE fb POST-WR programs, respectively, at 28 d after POST (DAPOST). At 28 DAPOST, the PRE fb POST herbicide programs controlled velvetleaf 94%, whereas the PRE-only program resulted in 85% control. Mixing soil-residual herbicides with foliar-active POST programs did not improve velvetleaf control. Averaged across herbicide programs, PRE fb POST programs increased soybean yield by 10% and 41% in 2016 and 2017, respectively, over the PRE-only programs. Moreover, PRE fb POST-WR programs produced 7% and 40% higher soybean yield in 2016 and 2017, respectively, compared with the PRE fb POST programs. The gross profit margin (US$1,184.3 ha−1) was highest under flumioxazin/pyroxasulfone (PRE) fb fluthiacet-methyl plusS-metolachlor/fomesafen (POST-WR) treatment; however, the benefit–cost ratio was highest (6.1) with the PRE-only program of flumioxazin/chlorimuron-ethyl.

Fungicide sensitivity and monocyclic parameters related to the Phakopsora pachyrhizi–soybean pathosystem from organic and conventional soybean production systems

The failure of chemical control of soybean rust has been related to the selection of less sensitive isolates, and the infection capacity of such isolates could have implications for the management of the disease. The aims of the present study were to compare the sensitivity to tebuconazole and azoxystrobin and the monocycle of soybean rust using isolates of Phakopsora pachyrhizi from two soybean fields with different production systems (organic and conventional) in 2012/13 and 2013/14 seasons, and to monitor mutations in the CYP51 gene. To assess the sensitivity to tebuconazole and azoxystrobin, detached leaf tests and in vitro germination, respectively, were used. To evaluate the monocycle, detached leaves were inoculated with a urediniospore suspension and evaluated daily by counting the number of uredia. The occurrence of the mutations in CYP51 was investigated by a pyrosequencing assay. In both 2012/13 and 2013/14 seasons, the EC50 to tebuconazole was lower for the population from the organic system (0.41 and 0.10 μg mL−1, respectively) compared to the conventional system (1.60 and 4.44 μg mL−1, respectively), while the EC50 to azoxystrobin was similar for both populations. The lower sensitivity to tebuconazole and azoxystrobin was associated with F120L + Y131H mutations in CYP51, and the F129L mutation in CYTB, respectively. The monomolecular model fitted to monocycle data and parameters related to the maximum asymptote and the AUDPC were superior for organic than the conventional system.

Elicitor-Based Biostimulant PSP1 Protects Soybean Against Late Season Diseases in Field Trials.

Currently, fungicide application in soybean production accounts for an important amount of global pesticide use, and it is therefore most desirable to find new healthier and more environmental friendly alternatives for the phytosanitary management in this crop. In this study, we present convincing evidence for effective induction of disease protection by the agricultural biostimulant PSP1, a formulation based on the plant-defense eliciting activity of the fungal protease AsES (Acremonium strictum elicitor subtilisin), in multiple field trials in Argentina.PSP1 was shown to combine well with commercial spray adjuvants, an insecticide, a herbicide and fungicides used in Argentinian soybean production without losing any defense-inducing activity, indicating an easy and efficient adaptability to conventional soybean production and disease management in the region. Results from multiple soybean field trials conducted with different elite genotypes at several locations during two consecutive growing seasons, showed that PSP1 is able to induce an enhanced pathogen defense which effectively reduced late season disease (LSD) development in field-grown soybean. This defense response seems to be broad-range as disease development was clearly reduced for at least three different fungi causing LSDs in soybean (Septoria glycines, Cercospora kikuchii and Cercospora sojina). It was noteworthy that application of PSP1 in soybean alone gave a similar protection against fungal diseases as compared to the commercial fungicides included in the field trials and that PSP1 applied together with a fungicide at reproductive stages enhanced disease protection and significantly increased grain yields.PSP1 is the first example of an elicitor-based strategy in order to efficiently control multiple fungal diseases under field conditions in the soybean crop. These results show the feasibility of using induced resistance products as complements or even full-good replacements to currently used chemical pesticides, fulfilling a role as important components of a more sustainable crop disease management system.

High Planting Rates Improve Weed Suppression, Yield, and Profitability in Organically-Managed, No-till–Planted Soybean

High soybean populations have been shown to hasten canopy closure, which can improve both weed suppression and soybean yield. In conventional soybean production, the high cost of genetically engineered seed and seed treatments have led growers to plant at lower rates to maximize profitability. For organic farmers, market price premiums are typically double the price received for conventional soybean. Without chemical or mechanical weed management, cultural practices are particularly important for adequate weed suppression in cover crop–based organic no–till planted soybean production. In 2014, an experiment was conducted in Aurora and Hurley, New York, to assess the effects of increasing soybean planting rates on weed suppression, soybean yield, and partial economic return. Five planting rates ranging from 195,000 to 914,000 seedsha−1were arranged in a randomized complete block design. As soybean planting rate increased, weed biomass decreased and soybean yield increased at both sites. An asymptotic model described the relationship between increasing soybean planting rate and yield, and the estimated maximum yield was 2,504 kgha−1in Aurora and 3,178 kgha−1in Hurley. Despite high soybean populations, minimal lodging was observed. Partial returns decreased beyond the predicted economically optimal planting rate of 646,000 seeds ha−1in Aurora and 728,000 seeds ha−1in Hurley as higher seed costs were no longer offset by yield gains. Based on our results, planting rates that are more than double the recommended rate of 321,000 seeds ha−1for wide row (≥76 cm) conventional soybean management in New York can enhance weed suppression, increase yield, and improve profitability in organic no-till planted soybean production.

Comparison of Early and Conventional Soybean Production Systems for Yield and other Agronomic Traits

The early soybean production system (ESPS) was reported to be beneficial for yield compared to the conventional soybean production system (CSPS) and is widely used in the Southern USA. The objective of this study was to compare yield, yield components, root traits, and shoot traits in ESPS (April planting) and CSPS (June planting) in NC Sandhills using a recombinant inbred line (RIL) population, ‘Hartwig’ by ‘Flyer’ (n=92). The population was grown in Spring Lake, NC in 2008 at a density of 16 seeds m-2. The traits measured were days to germination, days to flowering, plant height, seed weight, seed number, pod number, harvest index, root fresh weight, root dry weight, shoot fresh weight, shoot dry weight, maximum root length, and lateral root number. The survival rate ranged from 83.7 to 90.22% for ESPS; however, it was 21.74% for CSPS. Significant differences were observed for almost all traits measured in ESPS (April) compared to CSPS (June) apart from fresh root weight and lateral root number. An average increase in flowering time of 9 days was observed in CSPS compared to ESPS. On the other hand, several traits showed a significant mean decrease in CSPS compared to ESPS as plant height by 41.96%, seed weight by 74.7%, harvest index by 73.3%, pod number by 65.2%, and seed number by 64.9%. The means for root fresh weight, root dry weight, shoot fresh weight, shoot dry weight, maximum root length, and lateral root numbers are shown in Table 2 for both ESPS and CSPS. The results indicated an average decrease of 40.4% in root fresh weight, of 70.2% in root dry weight, of 68.1% in shoot fresh weight, of 80.1% in shoot dry weight, and of 83.3% in maximum root length in CSPS compared to ESPS. However, lateral root numbers increased by an average of 12.7% in CSPS compared to ESPS. Therefore, CSPS may not be appropriate for soybean at least in NC Sandhills.

Evidence for indirect effects of pesticide seed treatments on weed seed banks in maize and soybean

Use of pesticide seed treatments (coating seeds with insecticides and/or fungicides) is a common practice in conventional maize and soybean production. Despite their widespread use, however, little is known about how this practice affects soil food webs and their associated ecosystem services. We conducted a two-year field experiment in central Pennsylvania, USA in which identical genotypes of maize (2013) and soybean (2014) were planted with and without pesticide seed treatments in a completely randomized design with five replications. We sampled the weed seed bank during both the corn (fall 2013) and soybean (summer 2014) phases of the rotation. After each sampling event, soil samples were transported to a temperature-controlled greenhouse facility and weed seed bank composition and density was assessed over a period of four months via the direct germination method. Seed bank data were analyzed with ANOVA and several multivariate techniques to determine the effect of pesticide seed treatments on seed bank density, diversity, and species composition. We hypothesized that pesticide seed treatments reduce the abundance of natural enemies (e.g., soil-dwelling seed predators and pathogens) that damage or destroy weed seeds in the soil, and therefore seed banks in treated plots would be larger and less diverse than those in untreated plots. In accordance with our hypothesis, weed seed banks were significantly less diverse in treated compared to untreated control plots (Shannon and Simpson’s indices of diversity, p<0.05). While not statistically significant, differences in mean germinable weed seed bank density, richness, and evenness were also in the direction that we hypothesized. These data provide the first evidence that we are aware of that weed seed banks, and hence weed populations, may be indirectly affected by pesticide seed treatments. Additional research will be necessary to determine the generality of these responses and their underlying mechanisms.

Comparison of energy consumption and economic performance of organic and conventional soybean production — A case study from Jilin Province, China

Modern agriculture heavily depends on energy consumption, especially fossil energy, but intensive energy input increases the production cost for producers and results in environmental pollution. Organic agricultural production is considered a more sustainable system, but there is lack of scientific research on the energy consumption between organic and conventional systems in China. The analysis and comparison of energy use between the two systems would help decision-makers to establish economic, effective and efficient agricultural production. Thus, the objectives of the present study are to analyze energy inputs, outputs, energy efficiency, and economic benefits between organic and conventional soybean (Glycine max (L.) Merrill) production. A total of 24 organic farmers and 24 conventional farmers in Jilin Province, China, were chosen for investigation in 2010 production year. Total energy input was 71.55 GJ ha−1 and total energy output was 96.18 GJ ha−1 in the organic system, resulting in an energy efficiency (output/input) of 1.34. Total energy input was 9.37 GJ ha−1 and total energy output was 113.4 GJ ha−1 in the conventional system, resulting in the energy efficiency of 12.1. The huge discrepancy in energy inputs and respective efficiencies lies in the several times higher nutrient inputs in the organic compared to the conventional production system. Finally, the production costs ha−1 were 33% higher, and the net income ha−1 25% lower in the organic compared to the conventional soybean production system. It is recommended to improve fertilizer management in organic production to improve its energetic and economic performance.

Initial nitrous oxide, carbon dioxide, and methane costs of converting conservation reserve program grassland to row crops under no‐till vs. conventional tillage

Around 4.4 million ha of land in USDA Conservation Reserve Program (CRP) contracts will expire between 2013 and 2018 and some will likely return to crop production. No-till (NT) management offers the potential to reduce the global warming costs of CO2, CH4, and N2O emissions during CRP conversion, but to date there have been no CRP conversion tillage comparisons. In 2009, we converted portions of three 9–21 ha CRP fields in Michigan to conventional tillage (CT) or NT soybean production and reserved a fourth field for reference. Both CO2 and N2O fluxes increased following herbicide application in all converted fields, but in the CT treatment substantial and immediate N2O and CO2 fluxes occurred after tillage. For the initial 201-day conversion period, average daily N2O fluxes (g N2O-N ha−1 d−1) were significantly different in the order: CT (47.5 ± 6.31, n = 6) ≫ NT (16.7 ± 2.45, n = 6) ≫ reference (2.51 ± 0.73, n = 4). Similarly, soil CO2 fluxes in CT were 1.2 times those in NT and 3.1 times those in the unconverted CRP reference field. All treatments were minor sinks for CH4 (−0.69 ± 0.42 to −1.86 ± 0.37 g CH4–C ha−1 d−1) with no significant differences among treatments. The positive global warming impact (GWI) of converted soybean fields under both CT (11.5 Mg CO2e ha−1) and NT (2.87 Mg CO2e ha−1) was in contrast to the negative GWI of the unconverted reference field (−3.5 Mg CO2e ha−1) with on-going greenhouse gas (GHG) mitigation. N2O contributed 39.3% and 55.0% of the GWI under CT and NT systems with the remainder contributed by CO2 (60.7% and 45.0%, respectively). Including foregone mitigation, we conclude that NT management can reduce GHG costs by ∼60% compared to CT during initial CRP conversion.

Erratum to “Comparative Life Cycle Assessment of Organic and Conventional Soybean Production in Paddy Fields under Rotational Cropping”

Erratum to “Comparative Life Cycle Assessment of Organic and Conventional Soybean Production in Paddy Fields under Rotational Cropping”

Comparison of Weed Control, Yield, and Net Income in Conventional, Glyphosate‐Resistant, and Glufosinate‐Resistant Soybean

Separate field experiments were conducted in central and southeast Missouri during 2009 and 2010 to evaluate the effect of preemergence (PRE) and postemergence (POST) herbicide programs on Palmer amaranth (Amaranthus palmeri S. Wats.) and waterhemp (Amaranthus rudis Sauer) control, soybean [Glycine max (L.) Merr.] yield, and net income in conventional, glyphosateresistant, and glufosinate-resistant soybean production systems. Visual control evaluations 10 wk after emergence at the waterhemp site revealed that all preemergence only applications (PRE-only) and preemergence followed by a postemergence applications (PRE fb POST) provided greater than 92% waterhemp control in either soybean system and at the Palmer amaranth site and all PREonly provided greater than 83% Palmer amaranth control across soybean systems. Averaged across all herbicide programs at both locations, glufosinate-resistant soybean provided the highest grain yield and net return followed by glyphosate-resistant and conventional soybean systems. Furthermore, with the exception of the conventional PRE-only program at the waterhemp site, all glyphosate-resistant soybean herbicide programs provided greater net return than all conventional herbicide programs. Collectively, the results from both trials indicate that programs containing PRE herbicide treatments provide the best opportunity for season-long control of waterhemp and Palmer amaranth and highest grain yields and net returns in conventional, glyphosate-resistant, or glufosinateresistant soybean systems. The results from these experiments also suggest that Palmer amaranth may be particularly difficult to control in conventional soybean systems. Problematic Weeds and Weed Management Systems Palmer amaranth and waterhemp, both members of the Amaranthus family, are two of the most troublesome agronomic weeds in the United States due to their extended period of emergence, rapid growth at high light intensities and temperatures, and prolific seed production (10,14,18,27). In Missouri, the most common pigweed (Amaranthus spp.) species Published in Crop Management DOI 10.1094/CM-2013-0028-RS © Plant Management Network All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Kristin K. Rosenbaum, Graduate Research Assistant, Division of Plant Sciences, 205 Waters Hall, University of Missouri, Columbia, MO 65211; Raymond E. Massey, Extension Professor, Department of Agricultural and Applied Economics, 223D Mumford Hall, University of Missouri, Columbia, MO 65211; and Kevin W. Bradley, Associate Professor, Division of Plant Sciences, 201 Waters Hall, University of Missouri, Columbia, MO 65211. Received 1 Aug. 2013. *Corresponding author (bradleyke@missouri.edu). Abbreviations: 1-pass POST, one-pass postemergence application; 1-pass POST W/Res, one-pass postemergence application with a residual herbicide; 2-pass POST, two-pass postemergence application; ALS, acetolactate synthase; POST, ; PRE, preemergence; PRE fb POST, preemergence followed by a postemergence application; PREonly, preemergence only application; WAE, weeks after emergence.

Soil quality improvement under an ecologically based farming system in northwest Missouri

AbstractEcologically based farming conserves and improves the soil resource and protects environmental quality by using organic or natural resources without the application of synthetic chemicals. Soil quality assessment indicates the ability of management systems to optimize soil productivity and to maintain its structural and biological integrity. Our objective was to evaluate the effect of ecologically based management on biochemical characteristics of soil [soil quality indicators (SQI)] as an assessment of soil quality. The study was conducted on an ecologically based farming enterprise established on gently sloping soils of Sharpsburg silt loam (fine montmorillonitic, mesic Typic Argiudolls) in Clay County, Missouri, which was previously under conventional corn and soybean production. The transition to organic farming began in 1995, which included a primary management strategy to restore soil organic matter consisting of the establishment of native prairie plants and the application of composted vegetative residues and litter from horse and laying hen operations. Soils were collected at 0–10cm depths from sites under organic production (orchard and vegetable), managed prairie/pasture and from adjacent unmanaged fields during 2003–2008 for soil quality assessment. Soil organic carbon (SOC) and water-stable soil aggregates were considerably increased by up to 60 and 72%, respectively, in organic production sites compared with tilled cropland by the fifth year of assessment. Organically managed systems and restored prairie sites significantly increased (P&lt;0.05) soil enzyme activities compared with unmanaged grass and tilled cropland. For example, dehydrogenase and glucosaminidase activities increased by 60 and 73%, respectively, under organic vegetables compared with tilled cropland. Soil enzyme activities were significantly correlated with SOC content (rvalues up to 0.90,P&lt;0.001). The results of the soil quality assessment suggest that ecologically based management successfully restored biological activity of silt loam soils previously under intensive conventional agriculture. The system practiced at the study sites illustrates how resources internal to the farm (i.e., composts) can be used to manage soil productivity.

水田輪作体系における有機・慣行大豆生産の比較LCA

水田輪作体系における有機・慣行大豆生産の比較LCA

Profitability of organic and conventional soybean production under ‘green payments’ in carbon offset programs

AbstractEmphasis on reducing emissions from the greenhouse gases (GHG), carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) has increased in recent years in the USA, primarily for industry, transportation, energy and agricultural sectors. In this study, we utilized on-farm data collected by the USDA-National Agricultural Statistics Service (NASS) Agricultural Resource Management Survey (ARMS), secured under an agreement with the USDA-Economic Research Service (ERS) to analyze the profitability of organic and conventional soybean production, based on changes that ‘green payments’ in a cap-and-trade system would introduce in agricultural markets in the USA. In particular, the analysis focused on establishing whether organic producers would be better positioned to sequester carbon (C) and reap the benefits of the C-offset scheme compared to conventional producers, given the differences in costs, management practices and environmental benefits between organic and conventional production methods. We estimated several changes in profitability of soybean producers according to management practices, incentives for the generation of offset credits, and increase in energy input prices that a potential cap-and-trade system may introduce in future agricultural markets in the USA. Survey data suggested that even with lower yields, conventional producers could profit from converting to organic agriculture, given organic price premiums. In addition, taking into consideration both direct and indirect costs, average cost for conventional-till (CT) organic soybean production was approximately 9% lower than no-till (NT) conventional production. With a C market and payments for soil C sequestration through potential Clean Energy legislation, additional profit could be accrued by organic producers, because organic production would have 28% greater ton CO2 eq. acre−1 yr−1 sequestration than conventional NT. Thus, the environmental benefits from GHG reduction could incentivize increased conversion from conventional to organic production across the USA.

Effects of Silicon Applications on Soybean Rust Development Under Greenhouse and Field Conditions.

Soybean rust (SBR), caused by Phakopsora pachyrhizi, is one of the most destructive fungal diseases affecting soybean production. Silicon (Si) amendments were studied as an alternative strategy to control SBR because this element was reported to suppress a number of plant diseases in other host-pathogen systems. In greenhouse experiments, soybean cultivars inoculated with P. pachyrhizi received soil applications of wollastonite (CaSiO3) (Si at 0, 0.96, and 1.92 t ha-1) or foliar applications of potassium silicate (K2SiO3) (Si at 0, 500, 1,000, or 2,000 mg kg-1). Greenhouse experiment results demonstrated that Si treatments delayed disease onset by approximately 3 days. The area under disease progress curve (AUDPC) of plants receiving Si treatments also was significantly lower than the AUDPC of non-Si-treated plants. For field experiments, an average 3-day delay in disease onset was observed only for soil Si treatments. Reductions in AUDPC of up to 43 and 36% were also observed for soil and foliar Si treatments, respectively. Considering the natural delayed disease onset due to the inability of the pathogen to overwinter in the major soybean production areas of the United States, the delay in disease onset and the final reduction in AUDPC observed by the soil Si treatments used may lead to the development of SBR control practices that can benefit organic and conventional soybean production systems.

Comparison of Early and Conventional Soybean Production Systems for Yield and other Agronomic Traits

The early soybean production system (ESPS) was reported to be beneficial for yield compared to the conventional soybean production system (CSPS) and is widely used in the Southern USA. The objective of this study was to compare yield, yield components, root traits, and shoot traits in ESPS (April planting) and CSPS (June planting) in NC Sandhills using a recombinant inbred line (RIL) population, ‘Hartwig’ by ‘Flyer’ (n=92). The population was grown in Spring Lake, NC in 2008 at a density of 16 seeds m-2. The traits measured were days to germination, days to flowering, plant height, seed weight, seed number, pod number, harvest index, root fresh weight, root dry weight, shoot fresh weight, shoot dry weight, maximum root length, and lateral root number. The survival rate ranged from 83.7 to 90.22% for ESPS; however, it was 21.74% for CSPS. Significant differences were observed for almost all traits measured in ESPS (April) compared to CSPS (June) apart from fresh root weight and lateral root number. An average increase in flowering time of 9 days was observed in CSPS compared to ESPS. On the other hand, several traits showed a significant mean decrease in CSPS compared to ESPS as plant height by 41.96%, seed weight by 74.7%, harvest index by 73.3%, pod number by 65.2%, and seed number by 64.9%. The means for root fresh weight, root dry weight, shoot fresh weight, shoot dry weight, maximum root length, and lateral root numbers are shown in Table 2 for both ESPS and CSPS. The results indicated an average decrease of 40.4% in root fresh weight, of 70.2% in root dry weight, of 68.1% in shoot fresh weight, of 80.1% in shoot dry weight, and of 83.3% in maximum root length in CSPS compared to ESPS. However, lateral root numbers increased by an average of 12.7% in CSPS compared to ESPS. Therefore, CSPS may not be appropriate for soybean at least in NC Sandhills.

Comparison of conventional and no-tillage corn and soybean production on runoff and erosion in the southeastern US Piedmont

Soil erosion on southern Piedmont soils remains a problem without application of sound conservation practices. This study was conducted to compare a no-tillage (NT) system with a conventional-tillage (CT) system in row-cropped land under natural rainfall conditions for six continuous years. Runoff and soil loss were continuously monitored from May 1995 to April 2001 from four erosion plots (7.3 m × 12.2 m [24 ft × 40 ft]) in CT and four plots in NT under a corn (Zea mays L.)-soybean (Glycine max L.) rotation in a Mecklenburg sandy clay loam and Enon clay loam (fine mixed, active, thermic, Ultic Hapludalfs) at a Piedmont location. Runoff was significantly less for NT than for CT in three study years; in the other three years no differences between treatments where found. The NT six-year runoff average was 33% lower than the six-year runoff average of CT. The tolerable soil loss level of 7.0 Mg ha-1 y-1 (3.1 tn ac-1 yr-1) was exceeded in CT in four study years, while annual NT losses were always below 7.0 Mg ha-1 y-1 The six-year soil loss average was 74.7 Mg ha-1 (33.3 tn ac-1) and 2.6 Mg ha-1 (1.2 tn ac-1) for CT and NT, respectively. In CT, most of the soil lost during the six-year study period occurred during rain storms of high intensity. No-till was highly effective at protecting against soil loss during these rain storms.