Season Soybean Research Articles

Carbon Storage and Carbon Dioxide Emission as Influenced by Long-term Conservation Tillage and Nitrogen Fertilization in Corn-Soybean Rotation

Although agriculture is a victim of environmental risk due to global warming, but ironically it also contributes to global greenhouse gas (GHG) emission. The objective of this experiment was to determine the influence of long-term conservation tillage and N fertilization on soil carbon storage and CO2 emission in corn-soybean rotation system. A factorial experiment was arranged in a randomized completely block design with four replications. The first factor was tillage systems namely intensive tillage (IT), minimum tillage (MT) and no-tillage (NT). While the second factor was N fertilization with rate of 0, 100 and 200 kg N ha-1 applied for corn, and 0, 25, and 50 kg N ha-1 for soybean production. Samples of soil organic carbon (SOC) after 23 year of cropping were taken at depths of 0-5 cm, 5-10 cm and 10-20 cm, while CO2 emission measurements were taken in corn season (2009) and soybean season (2010). Analysis of variance and means test (HSD 0.05) were analyzed using the Statistical Analysis System package. At 0-5 cm depth, SOC under NT combined with 200 kg N ha-1 fertilization was 46.1% higher than that of NT with no N fertilization, while at depth of 5-10 cm SOC under MT was 26.2% higher than NT and 13.9% higher than IT. Throughout the corn and soybean seasons, CO2-C emissions from IT were higher than those of MT and NT, while CO2-C emissions from 200 kg N ha-1 rate were higher than those of 0 kg N ha-1 and 100 kg N ha-1 rates. With any N rate treatments, MT and NT could reduce CO2-C emission to 65.2 %-67.6% and to 75.4%-87.6% as much of IT, respectively. While in soybean season, MT and NT could reduce CO2-C emission to 17.6%-46.7% and 42.0%-74.3% as much of IT, respectively. Prior to generative soybean growth, N fertilization with rate of 50 kg N ha-1 could reduce CO2-C emission to 32.2%-37.2% as much of 0 and 25 kg N ha-1 rates.

Dynamics of Culturable Soil Bacterial Communities During Pre‐Planting and Growing Soybean Season as Evaluated by Community Level Physiological Profiles

The agricultural practices used today for farming produce crops generate major effects on microbial ecosystems. At the same time, soil microbes can stimulate a wide range of impacts on growing crops. Since changes in soil microbial communities may reflect changes in soil quality or differences in soil management practices, we examined the effects of agricultural farming on the dynamics of soil microbial biomass and community structure. Soil samples were collected prior to planting (May 2019) and during the growing season (September 2019) from a non‐tilled agricultural soybean farm in Greencastle, IN. We quantified microbial biomass using phospholipid phosphate and quantified community structure using community level physiological profiling (CLPP) with Biolog EcoPlates. Soil samples were collected from four subplots in the agricultural field and a control sample from an adjacent woods plot. There was not a significant difference in the C/N ratios between the pooled agricultural plots (9.84) and the woods (9.96) in the pre‐planting season. We also did not see significant differences in C/N ratios among the agricultural subplots. Moisture content (Woods: 36.06% to 42.74%; Farm: 20.18% to 15.46%, from pre‐planting to growing season) was higher in the woods with a stable temperature regime. Consequently, there were no significant differences in the microbial biomass from pre‐planting (37.74 nmol PO□ gdw) to the growing season (41.48 nmol PO□ gdw) in the farm plots, but the woods (Pre‐planting: 44.63 nmol PO□ gdw; Growing: 119.57 nmol PO□ gdw) showed much more temporary fluctuation in biomass. In addition, there was a higher microbial biomass in the control plot compared to the agricultural plots during both the sampling periods. It is possible that seasonal changes are not reflected in microbial biomass on the agricultural plots due to the consistent C/N ratio or the agricultural farming of soybeans. The principal component analysis (PCA) of the CLPP indicated a broad scale of different metabolic functions of the soil microbial communities between the agricultural plots and the control. However, we did not observe any significant difference between the microbial communities of the agricultural plots from pre‐planting to the growing season. The dominant bacterial group present in the agricultural plots was Pseudomonadaceae, a common bacteria in soil, while in the control plot, the most dominant bacterial group was Enterobacteriaceae. Our results imply that a consistent organic input (C/N ratio) might sustain a stable microbial community and thus promote soil health, however, diverse factors such as crop growth stage, residue inputs, and soil physical and chemical conditions may contribute to soil quality and microbial communities. In order to determine the effects of root detritus of soybeans after harvest on soil health and microbial communities, it is recommended that sample collection and analysis occur following the harvest of the soybean crop.Support or Funding InformationScience Research Fellows Program; DePauw University

Contrast in soil microbial metabolic functional diversity to fertilization and crop rotation under rhizosphere and non-rhizosphere in the coal gangue landfill reclamation area of Loess Hills.

Very poor reclaimed soil quality and weak microbial activity occur in the reclamation area of a coal gangue landfill in the Loess Hills. The fourth and fifth years after farmland soil was reclaimed were studied, and the changes in and carbon source utilization characteristics of rhizosphere (R) and non-rhizosphere (S) soil microorganisms under organic and inorganic (OF), inorganic (F), and organic (O) fertilizer application and a control treatment (CK) in soybean (S) and maize (M) rotation systems were compared and analysed in Guljiao Tunlan, Shanxi Province, China. Biolog-EcoPlate technology was used to analyse the mechanism of soil characteristic change from the perspective of soil microbial metabolism function to provide a theoretical basis for reclamation and ecological reconstruction in this area. The average well colour development (AWCD) absorption and Shannon-Wiener index values of soybean and maize rhizosphere microorganisms were higher than those of non-rhizosphere microorganisms, and the mean value of the fertilizer treatment was higher than that for CK. Principal component analysis shows the main carbon sources that impact the functional diversity of the soybean rhizosphere and non-rhizosphere soil communities are a-cyclodextrin, a-D-lactose, ß-methyl D-glucoside, and glucose-1-phosphate and L-phenylalanine, while those for the maize rhizosphere and non-rhizosphere soil communities are D-cellobiose, glucose-1-phosphate, ß-methyl D-glucoside, methyl pyruvate, D-galactosate gamma lactone, D-mannitol, N-acetyl-D-glucosamine, D-galactosalonic acid, and L-serine. The comprehensive utilization score of the non-rhizosphere soil carbon source in the maize season increased with respect to that in the soybean season, and the maximum increase was 1.09 under the OF treatment. Redundancy analysis showed that the soil nutrient factors driving the changes in the metabolic function diversity index values of the rhizosphere and non-rhizosphere soil microbial communities in the different crop seasons in the reclamation area differed, but they were all related to the soil organic matter and available phosphorus. This may explain why OF treatment is the most beneficial to soil fertility under the rotation system in mining reclamation areas.

MODELING EVAPOTRANSPIRATION FOR C4 and C3 CROPS IN THE WESTERN LAKE ERIE BASIN USING REMOTE SENSING DATA

Abstract. Growing monoculture impacts not just soil properties and biodiversity but also local hydrology including evapotranspiration (ET). The Midwest region of the U.S. is known for its monoculture trend by growing and producing corn, which commonly replaces other crop types. In addition to large areas covered with corn, the photosynthetic adaptations of corn, being the C4 crop, affects ET differently than other C3 crops such as soybean, wheat, and alfalfa. This study aims to model and compare ET for C3 and C4 crops using remote sensing (Sentinel-2 data) and the Boreal Ecosystem Productivity Simulator (BEPS) model, modified to consider C3 and C4 crops. The study explores the ET rate trend for corn and soybean in an agriculture area situated in the Western Lake Erie Basin, where the balance between evapotranspiration, groundwater level, and surface runoff may play a role in agricultural runoff and Lake Erie’s algal blooms caused by runoff pollution. The results suggest that the monthly average ET rates for both soybean (C3) and corn (C4) reach its maximum at the mid-to-late growing season. However, the ET rate for corn is higher than for soybean in the early season (June) (ET = 121 mm month−1 for corn; ET = 105 mm month−1 for soybean), while the ET rate for soybean becomes higher than for corn soon after (July) and becomes considerably higher in August (ET = 181 mm month−1 for corn; ET = 218 mm month−1 for soybean). It is surmised that the higher ET rate for corn in the early growing season is due to nitrogen-based fertilizer commonly applied to corn parcels at that time, whereas soybean growth is based on biological nitrogen fixation.

Development of method to forecast soybean leaf damage by common cutworm using entomological radar and searchlight trap

To develop a method to forecast soybean leaf damage caused by larvae of the common cutworm, Spodoptera litura (Fabricius), insect dispersion was monitored with an x-band entomological radar and a searchlight trap during the summer soybean season in 2016 and 2017 in western Japan. The insect catch number in the searchlight trap and number of newly damaged leaves in a soybean field were compared to see how much soybean damage the insect's arrival caused. The 2016 results indicated that catch number peaks appeared 3–5 days before the peaks in the number of newly damaged leaves. The time lag corresponded to the egg period. Similar data were found in 2017. However, both the catch number and the number of newly damaged leaves were smaller that year, due to the lower occurrence of the insect. The radar observation showed dispersion at altitudes over the monitoring site when the peaks in insect catch number occurred. The insects often arrived under a northerly wind condition, from the mountainous area to the north. This study suggested that short-term forecasting of soybean leaf damage by radar and searchlight trap may be possible.

Seasonal pattern and change in prices of soybean in Southern Rajasthan

The present investigation was conducted on seasonal pattern of prices of soybean in selected district of Southern Rajasthan. For workout the seasonal pattern, secondary data was collected from 2000 to 2014 from publish government sources. Four markets were selected from four selected district namely Pratapgarh, Chittorgarh, Bhilwara and Banswara. Pearson correlation co-efficient (r) was calculated between market arrivals and prices of soybean for different years. The correlation coefficient between monthly arrivals and prices of soybean were negative in all the markets. This reveals that prices of soybean are governed by factors such as presence of processing units and competition prevailing between purchasers etc. in addition to the arrival of the crop. Correlation co-efficient for all the markets in the corresponding months were significant at 1 or 5 per cent level of significance. Thus, monthly arrivals of soybean and wholesale prices were significantly and negatively correlated in the corresponding months. The pattern of prices of soybean in different seasons showed that farmers got maximum higher price by sale of soybean in lean season over the sale in peak season. Thus, the carrying of soybean to the mid and lean seasons of the year is advantageous for the producer farmers.

Productive Impact of Residual Nutrients (N and P) in Maize and Soybean Rotation

Agricultural intensification has resulted in severe soil nutrient depletion in Africa. Alternative agricultural practices have been promoted to restore and sustain soil fertility. Use of mineral fertilizer alongside different cropping systems has been particularly promising. This study was conducted in the Guinea savannah zone of Ghana during the 2015 and 2016 cropping season (July to November) to assess the performance of soybean and maize in a rotation system. In season one, using randomized complete block design the treatments were, soybean (without treatment), inoculated soybean, soybean with phosphorus application, inoculated soybean with phosphorus application and maize. During the second season, the first season experimental plots served as main-plots and divided into four sub-plots on which maize planted and treated with four nitrogen rates in a split plot design. The results show that soybean production leads to significant increase in residual soil nitrogen content of about 16kg/ha to 55kg/ha, which is about 28 folds higher than that observed in maize fields. The level of Residual N was enhanced with inoculation. Phosphorus application during the first season of maize cultivation led to increases in residual P levels, which had a positive impact on yield of soybean in the second season. Grain yield of maize that followed soybean in a rotation system performed better than maize that followed maize at various fertilizer rates. This shows that, the residual N and P helps maize and soybean respectively in a rotation system which makes it highly economical.

Вплив різних способів обробітку ґрунту на структурно-агрегатний склад чорнозему типового у Правобережному Лісостепу України

The article presents the results of studies of the structural-aggregate composition of chernozem, which is characteristic depending on the tillage in the cultivation of soybeans under various predecessors. It has been established that minimization of processing allowed improving the structural and aggregate composition of typical black soil. The highest content of agronomic value fraction agronomically valuable aggregates is 0–10 cm. On the lunar slope, they were formed into 12–14 cm and 6–8 cm crayons. Surface treatments were 66,2–69,56 %. In the case of untreated machining of bits, their share was 64,54–66,70 %, and in sections 20–22 cm – 62,76–64,69 %. In the variant of direct seeding – 63,77–67,31 %. During the growing season of soybean, an increase in the share of the agronomic red fraction is observed due to a decrease in dust and brylisti. For plowing fate at 20–22 cm. The soil fraction (10–0,25 mm) was 70,8–72,6% of the processing without shredding (chisel up to 20–22 cm) – 71,5–74,0 % by fine tillage (disk harrow 12-14 cm) – 71,6–74,5 %, surface treatment (disk harrow 6–8 cm) – 72,4-75,1 %, direct seeding – 67,9–71,7%. The highest coefficient of structurality of the upper (0-10 cm) layer of soil at the beginning of soybean vegetation was noted on the varieties of shallow and surface soil treatment: preceding crops winter wheat– 2,16 and 2,29, barley – 2,01 and 2,14, corn grain – 1,96 and 2,09, sunflower – 1,98 and 2,03, soybeans – 1,93 and 1,99. Layers of soil at the bottom (10–20 and 20–30 cm) Above this factor in paths without loose rotation due to compaction of these layers as a result of strong contact of individual particles. During the harvesting of the crop in all variants, regardless of the factors studied, the soil structure has improved.

Cover Crop Effectiveness Varies in Cover Crop-Based Rotational Tillage Organic Soybean Systems Depending on Species and Environment

Organic farming relies heavily on tillage for weed management, however, intensive soil disturbance can have detrimental impacts on soil quality. Cover crop-based rotational tillage (CCBRT), a practice that reduces the need for tillage and cultivation through the creation of cover crop mulches, has emerged as an alternative weed management practice in organic cropping systems. In this study, CCBRT systems using cereal rye and triticale grain species are evaluated with organic soybean directly seeded into a rolled cover crop. Cover crop biomass, weed biomass, and soybean yields were evaluated to assess the effects of cereal rye and winter triticale cover crops on weed suppression and yields. From 2016 to 2018, trials were conducted at six locations in Wisconsin, USA, and Southern France. While cover crop biomass did not differ among the cereal grain species tested, the use of cereal rye as the cover crop resulted in higher soybean yields (2.7 t ha−1 vs. 2.2 t ha−1) and greater weed suppression, both at soybean emergence (231 vs. 577 kg ha−1 of weed biomass) and just prior to soybean harvest (1178 vs. 1545 kg ha−1). On four out of six sites, cover crop biomass was lower than the reported optimal (<8000 kg ha−1) needed to suppress weeds throughout soybean season. Environmental conditions, in tandem with agronomic decisions (e.g., seeding dates, cultivar, planters, etc.), influenced the ability of the cover crop to suppress weeds regardless of the species used. In a changing climate, future research should focus on establishing flexible decision support tools based on multi-tactic cover crop management to ensure more consistent results with respect to cover crop growth, weed suppression, and crop yields.

Tillage effects outweigh seasonal effects on soil nematode community structure

Our understanding of tillage effect on soil community structure during the growing season remains limited. This study aims to test the hypothesis that (1) soil community responds specifically to tillage practices and these responses vary with the growing season; (2) the contribution of tillage to soil community is greater than or equal to that of growing season when considering the impact of tillage on soil properties. Therefore, the nematode community usually used as an indicator of soil organisms was investigated under a long-term (initiated in 2001) tillage experiment (CT, conventional tillage; RT, ridge tillage; NT, no tillage) in a Black soil (Typic Hapludoll) of Northeast China. Soil samples were taken in April, June and August of 2015 at 0–5 and 5–15 cm depths during the growing season of soybean (Glycine max Merr.). The results showed that nematodes responded specifically to tillage practices at both soil depths, and there was a consistent succession of specifically enriched genera from Filenchus in CT to Rhabditis in RT and then to Prismatolaimus in NT in 0–5 cm over the growing season. The response of nematodes to tillage was consistent with crop phenology to a certain degree. For example, the highest value of Helicotylenchus relative abundance in RT at 0–5 cm was observed in June, which corresponded with the maximum root activity period for soybeans. Variation partitioning analysis revealed that tillage played a more important role than growing season in constructing nematode community. The contribution of tillage was greatly increased in the model with soil properties as associated variables, indicating that tillage may indirectly affect nematode community through alteration of soil properties, such as pH at 0–5 cm and bulk density (BD) at 5–15 cm. These results provide strong support for our hypothesis and suggest that the effects of long-term conservation tillage on soil nematode community may be maintained throughout the growing season, which might be a cornerstone of conservation tillage benefits in temperate areas of the world.

Evaluasi Perubahan Iklim dan Pengaruhnya terhadap Pola Tanam, Waktu Tanam serta Produktivitas Kedelai (Glycine max L. Merrill) Di Kabupaten Malang Jawa Timur

Herlina et al, 2018. The Evaluation of Climate Change and The Effect to Cropping Pattern, Panting Season and Productivity of Soybean (Glycine max L. Merrill) in Malang Regency, East Java. JSLO 7(2):Climate change is a negative impact due to development activities on Earth. Forests that lose function caused degradation and increases in greenhouse gas concentrations cause global warming and trigger climate change. Climate change is thought to affect cropping pattern, planting time and soybean productivity. The purpose of the study was to evaluate the expected climate change and analyze correlation between climatic elements and the pattern and time of planting and soybean productivity. The research was carried out in March to April 2018 in Kalipare, Donomulyo, Singosari and Dau, Malang Regency, East Java. The tool used is a questionnaire. The material are the climate elements, soybean productivity and interview data. This study uses survey research methods. Total respondents were 40 farmers. Climate change analysis by analyzing mean changes in temperature, rainfall and number of rainy days in period 1 (1988-1997), period 2 (1998-2007) and period 3 (2008-2017). Correlation coefficient analysis is used to determine the correlation between climatic elements and soybean productivity and followed by t test. The results show that climate change has occurred in Malang Regency for the past 30 years. The correlation between temperature, rainfall with soybean productivity showed a "low" correlation, while number of rainy days with soybean productivity had a "very low" correlation. Temperature significantly affected soybean productivity in Malang Regency. Soybean cropping patterns was not affected by climate change, but planting time was influenced by shifting seasons.

Soybean growth and yield responses at third planting season to residual potassium fertilizer in a vertisol

Application of fertilizers on previous crops can leave a residue so that it can be used for the next crops. It is necessary to know the extent to which these residues can affect the growth and yield of soybean crops. The objective of this study was to explore the effect of potassium fertilizer residues on growth and yield of soybean crops at third planting season (PS-III) on a vertisol. The research was conducted at dry season using a vertisol from Nganjuk, East Java. The experiment was designed using a factorial randomized block design with two factors and three replications. The first factor was the dose of potassium fertilizer (KCl) in the first planting season (PS-I) of rice, i.e. 0, 500, 1500, and 2000 kg potassium fertilizer/ha. The second factor was the dose of potassium fertilizer in the second planting season (PS-II) of soybean, i.e. 0, 50, 100, 200, and 400 kg potassium fertilizer (KCl)/ha. The soybean variety used was Sinabung. The results showed that fertilizer residues of planting season I and planting season II affected the growth component and yield component of soybean, but did not affect seed yield of soybean. There was no consistent increase on growth component, yield component, or seed yield of soybean with an increasing residual dose of potassium fertilizer of planting season I or planting season II. The residual treatment of 1500 kg potassium/ha at planting season I gave the highest number of branches per plant (2 branches) and seed weight per plant (3.13 g) of soybean. The residual treatment of 50 kg potassium/ha at planting season II gave the highest root nodule weight per plant of 0.10 g and the highest seed weight per plant of 3.33 g.

Ảnh hưởng của bã cà phê tươi lên sinh trưởng, năng suất một số cây trồng và đặc tính sinh học đất xám bạc màu từ huyện Mộc Hóa, tỉnh Long An trong điều kiện nhà lưới

The study was to evaluate the affect of fresh spent coffee ground (FSCG) on growth and yields of maize, soybean and rice and as well soil microbial properties under the greenhouse conditions. Maize, soybean and rice were rotationally cultivated in the same soil type (grey degraded soil) from Moc Hoa, Long An with 4 replicates and 7 different treatments including the control (no fertilization) and five levels (2, 4, 6, 8 and 10%) of FSCG applied (w/w, based on the soil mass) and the treatment with recommended inorganic NPK fertilizer application. Height of plant, numbers of leaf, tillers of rice, numbers of bacteria and fungi in soil were sampled at day 30, 45 (60), 60 (90) after seedling. Yield of crops and the structure of bacterial community in soil at the end of the study were also collected. The results showed that applying FSCG at doses of 6 and 10% enhanced the growth and yields of soybean and rice, but no maize as compared to the recommended inorganic NPK fertilizer application treatment, increased signicifcantly the numbers of soil bacteria, fungi, nitrogen fixing bacteria and phosphate solubilizing bacteria as compared to other treatments, especially at the end of maize season and during the whole soybean season. Moreover, the structure of soil bacterial community in these two treatments was more diversified than others. Thus, based on the present study it is recommended that fresh SCG can be applied with a dose of 6% or 10% into soil as a soil clean amender to improve soil fertility and crop yield for sustainably agricultural development.

Cover Crops as Affecting Soil Chemical and Physical Properties and Development of Upland Rice and Soybean Cultivated in Rotation

Cover crops can provide changes in soil chemical and physical properties, which could allow a sustainable development of soybean and upland rice rotation in Brazilian Cerrado. The objective of this study was to determine the effects of cover crops (cultivated in the offseason) in the soybean-upland rice rotation (cultivated in the summer season) on the soil chemical and physical properties, yield components and grain yield of the cash crops. The experimental design was a randomized block design in factorial scheme 4×2 with six replications. Treatments were composed by four cover crops: fallow, millet (Pennisetum glaucum)+Crotalaria ochroleuca, millet+pigeon pea (Cajanus cajans), and millet+pigeon pea+Urochola ruziziensis in the offseason with one or two cycles of cover crops, with rice (Oryza sativa) or soybean (Glycine max) in the summer season. Cover crops alone provided no changes in soil chemical properties. However, the rotation cover crops/cash crops/cover crops/cash crops reduced pH, Al and H+Al and increased Ca, Mg, K and Fe contents in the soil. The cover crops millet+pigeon pea and millet+pigeon pea+U. ruziziensis improved soil physical properties in relation to fallow, especially in the 0–0.10m soil layer. In spite of the improvement of the soil physical properties after two years of rotation with cover crops and cash crops, the soil physical quality was still below the recommended level, showing values of macroporosity, S index and soil aeration capacity lower than 0.10 m3/m3, 0.035 and 0.34, respectively. Upland rice production was higher under mixtures of cover crops than under fallow, mainly because of soil physical changes done by these mixtures of cover crops. Soybean grain yield was similar under all cover crops tested, but was higher after the rotation cover crops/upland rice/cover crops than after only one cycle of cover crops.

Impact of straw management on seasonal soil carbon dioxide emissions, soil water content, and temperature in a semi-arid region of China

The use of crop residues as mulching materials or organic fertilizer, instead of burning, can help improve the soil organic carbon (SOC) and crop grain yield. An experiment was conducted for three consecutive seasons from 2013 to 2016, to study the effect of no straw (S0), S1/2 (700 kg/ha soybean straw, and 3000 kg/ha wheat straw), and S1 (1400 kg ha−1 soybean straw, and 6000 kg/ha wheat straw) treatments in wheat-soybean multi-crop system. The randomized complete block design was used with three repeats. Compared with the S0 regime, a significant increase of 0.5%–8.7% and 1.4%–27.7% in soil CO2 emission was observed in the S1 regime during all growth stages of summer soybean and winter wheat, respectively. Soil temperature of S1/2 and S1 was 0.1–1.1 °C and 0.3–1.4 °C higher than that of S0 during the seeding stage and greening stage for wheat, during 2013 to 2016. During wheat season, soil moisture was higher in the S1 than in the S0 treatment. Likewise, wheat, soybean crop resulted the same results. Soil CO2 emissions increase with the increasing in soil temperature, and 73.4–73.9% of the variation could be explained by seasonal variation in soil temperature in wheat season. Similarly, 69.5–74.7% of the variation in soil CO2 emissions is recorded by seasonal variation in soil temperature in summer soybean season. Meanwhile (S1) increased the SOC and grain yield of wheat and soybean when compared to S0. Straw input increasing soil CO2, grain yield and SOC content, considering the benefits of straw inputs to crops yield and SOC content, It is concluded that the addition of straw improve agriculture production. However, the types of straw inputs in order to promote the sequestration of soil organic carbon with the decrease in greenhouse gas emission is the future research direction for agriculture development in Guanzhong region of China.

Molecular identification of Helicoverpa armigera (Noctuidae: Heliothinae) in Amambay Department, Paraguay

The Helicoverpa armigera (Noctuidae: Heliothinae) is a polyphagous and cosmopolitan pest distributed throughout South America. The objective of this research was to identify by PCR-RFLP molecular analysis, the presence of H. armigera in the Amambay region in Paraguay. Delta traps with sexual pheromone were deployed in the 2016/2017 season soybean crop distributed at the following locations: Pedro Juan Caballero, Zanja Pyta, Capitan Bado, Karapa’ĩ and Bella Vista Norte. Sampling cloth was used for collecting caterpillars. The collected specimens were sorted by external morphological characters, individualized in labeled jars containing pure alcohol. 24 samples were sent to the Arthropods Molecular Ecology Laboratory ESALQ/USP for identification by PCR-RFLP molecular analysis. Ten specimens of H. armigera belonging to Fortuna and Zanja Pyta were identified. Ten other specimens were identified as H. zea belonging to Cerro Cora'i, Captain Bado, Cerro Kuatia and Karapa’ĩ. The remaining four samples did not amplify by PCR-RFLP. The analysis revealed the occurrence of H. armigera in soybean and maize crops in the northern region of Paraguay.

Ichneumonids (Hymenoptera) and Tachinid Flies (Diptera) Associated to Leptidopterans in Soybean Crops

Studies on natural enemies are important to find new species and to develop management strategies to preserve them to help control pests in biological control programs. For the state of Mato Grosso, Brazil, which comprises the Amazon, Cerrado, and Pantanal biomes, few studies have been conducted on the diversity of these parasitoids, possible endemic and/or new species, as well as their potential as natural enemies. Thus, the present study was aimed at describing the diversity of parasitoids of the families Ichneumonidae (Hymenoptera) and Tachinidae (Diptera) associated with pest lepidopterans in soybean crops. Weekly sampling of pest lepidopterans was carried out during four soybean seasons (2009/2010, 2010/2011, 2011/2012 and 2012/2013). Parasitoid larvae were observed in the main lepidopteran pest species of soybean during the four soybean seasons. Three genera of the Ichneumonidae family, belonging to the genera Microcharops Roman, Ophionellus Westwood, and Podogaster Brullé. Six genera of the Tachinidae family occur in the state of Mato Grosso in soybean fields. The following genera were recorded: Archytas spp. Jaennicke, Phorocera spp. Robineau-Desvoidy, Gymnocarcelia spp. Townsend, Lespesia spp. Robineau-Desvoidy, Eucelatoria spp. Townsend, Chetogena spp. Rondani. These parasitoids were found parasitizing caterpillars of the Noctuidae (Lepidoptera), in species that had not yet been reported as hosts for the Neotropical region. Further studies are needed on the beneficial entomofauna and their preservation in agricultural environments.

Population Fluctuation and Vertical Distribution of the Soybean Looper (<i>Chrysodeixis includes</i>) in Soybean Culture

The objective of this work was to study the population fluctuation and the vertical distribution of the Chrysodeixis includes (Walker) (Lepidoptera: Noctuidae) in the leaf canopy of soybeans. The experiments were conducted under field conditions in the experimental area of the Embrapa Agropecuaria Oeste during the 2014/2015 harvest. Adult monitoring was performed using Delta-type traps, baited with the pest sexual pheromone. The eggs were collected in the soybean plants and the caterpillars monitored through the beat cloth. The population peaks of C. includes occurred in the reproductive period of the soybean plants, although the adults were also found in the season soybean. Although there was no significant relationship between the trapped adults and the immature forms of C. includes sampled with the beat cloth, a significant linear and positive relationship was found between the egg and caterpillar densities of the pest in the culture. Adults preferentially oviposited on the lower part of the soybean plants, while the caterpillars preferred to position themselves predominantly in the lower and mid region of the plants. However, at warmer temperatures during the day, the caterpillars migrate to the upper areas of the soybean plants.

Impact of soil compaction due to wheel traffic on corn and soybean growth, development and yield

As the size and weight of agricultural equipment have increased significantly in the past few decades, the severity and depth of compacted zone may have increased proportionately. Past research indicates that soil compaction affects crop growth and grain yield. Very few studies have been conducted in North Dakota (ND) to understand soil compaction under the current machinery, and its effect on crop growth and yield. The research was conducted on a no-till crop field at Jamestown, ND, USA for 2013 (corn) and 2014 (soybean) growing season. The objective of this study was to evaluate the effect of wheel traffic on soil strength indices and its impact on crop emergence, development and yield. The study also evaluated the effect of winter freezing-thawing cycle on soil compaction in the study field. The experiment consisted of five soil transects and two traffic conditions based on machinery traffic in the field for both years such as most trafficked (MT) rows and least trafficked (LT) rows, laid out in a randomized complete block design with three replicates in strip-plot with space for corn season in 2013, and for soybean season in 2014. Data collected included soil resistance or cone index (CI), soil bulk density, soil moisture content, plant emergence, plant height and grain yield. The results showed that CI values followed a similar pattern for different soil transects up to 37.5 cm depth and then increased sharply. An average CI of 1.19 MPa was noted over the whole profile at 0–45 cm depth for the study area and not significantly different between MT and LT rows for both years. Moderate compaction resulted in early emergence of corn plants in MT rows by 175% compared to LT rows. The plant height didn’t show any significant difference between MT and LT rows for both years. The yield data showed significant difference between the soil transects, but no difference was observed between MT and LT rows in both 2013 and 2014 season. The interactions between soil transects and traffic conditions were not significantly different for all soil and plant related dependent variables. The freeze-thaw cycle occurred during winter from 2013 to 2014 and 2014 to 2015 alleviated soil resistance over the whole soil profile at 0–45 cm depth. Results show that different crops grown in a no till field are not very much influenced by wheel traffic. The study also suggests that moderate compaction occurred after harvest in a no till field could be alleviated by the effect of freeze thaw cycle.

Soybeans inoculated with root zone soils of Canadian native legumes harbour diverse and novel Bradyrhizobium spp. that possess agricultural potential

An assessment was made of the evolutionary relationships of soybean nodulating bacteria associated with legumes native to eastern Canada to identify potential new sources of soybean inoculant strains.Short season soybeans were used to selectively trap bacteria from root zone soils of four native legume species. Screening of more than 800 bacterial isolates from soybean root nodules by analysis of recA gene sequences followed by analyses of selected genotypes using six core and two symbiosis (nodC and nifH) gene sequences permitted identification of diverse taxa that included eight novel and four named Bradyrhizobium species as well as lineages attributed to the genera Afipia and Tardiphaga.Plant tests showed that symbionts related to four named species as well as a novel Bradyrhizobium lineage were highly efficient with regard to nitrogen fixation on soybeans relative to an inoculant strain.A new symbiovar (sv. septentrionalis) is proposed based on a group of four novel Bradyrhizobium spp. that possess distinctive nodC and nifH gene sequences and symbiotic characteristics.Evidence is provided for horizontal transfer of sv. septentrionalis symbiosis genes between novel Bradyrhizobium spp., a process that rendered recipient bacteria ineffective on soybeans.Diverse lineages of non-symbiotic and symbiotic Bradyrhizobium spp. co-occured within monophyletic clusters in a phylogenetic tree of concatenated core genes, suggesting that loss and/or gain of symbiosis genes has occurred in the evolutionary history of the bacterial genus.Our data suggest that symbiont populations associated with legumes native to eastern Canada harbour elite strains of Bradyrhizobium for soybean inoculation.