Season Soybean Research Articles

Effect of land configuration and sowing date on growth, yield and economics of soybean (Glycine max L.) in Kharif season

Effect of land configuration and sowing date on growth, yield and economics of soybean (Glycine max L.) in Kharif season

Egg parasitoid assemblages and their effectiveness against the Lepidoptera soybean defoliators in Argentina's subtropical production region

AbstractSoybean, Glycine max (L.) Merr. (Fabaceae), is one of the most important crops worldwide, but caterpillars of various species (Lepidoptera) may greatly reduce its annual yield. Nowadays, the main method of controlling these pest species is based on the use of broad‐spectrum insecticides, which are harmful to human health and increase environmental contamination. Therefore, other sustainable methods of control, such as biological control, are in increasing demand. The present study aimed to identify the egg parasitoid species that attack lepidopterans defoliating soybeans in South America's subtropical regions, as well as evaluate their effectiveness at various stages of soybean development. The research was conducted in a commercial soybean field (80 ha) located in Tucumán, Argentina, which was surrounded by wild vegetation as a way to promote biological control. Every week, throughout three consecutive soybean seasons, 20 soybean plants were randomly selected and brought to the laboratory in search of lepidopteran eggs. Over the course of the three crop seasons, the soybean plants were attacked by Anticarsia gemmatalis Hübner (Erebidae), Rachiplusia nu (Guenée), and Chrysodeixis includens (Walker) (both Noctuidae). Six egg parasitoid species were identified, but only three of them were frequently found during the current study. Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) was the most predominant species attacking all lepidopteran pests across all soybean phenological stages. Encarsia porteri (Mercet) (Hymenoptera: Aphelinidae) preferred to attack R. nu eggs, whereas Telenomus cyamophylax Polaszek (Hymenoptera: Scelionidae) parasitized only A. gemmatalis and R. nu eggs. Despite the use of insecticides in the soybean field, the parasitism rates recorded were high. This suggests that using conservation tactics such as native vegetation patches and surrounding alternative crops may result in higher rates of natural control.

Enhancing Soybean and Maize Yields through Improved Nitrogen and Soil Water Use Efficiencies: A 40-Year Study on the Impact of Farmyard Manure Amendment in Northeast China.

The combined application of manure and chemical fertilizers has been recognized as a critical factor driving significant changes in crop yield and nutrient use efficiency, holding the potential to optimize agricultural management to achieve high yields. In this 40-year study, we investigated the effect of manure amendment on soybean and maize yields, water and nitrogen use efficiencies (WUE and NUE), and water and mineral N storage at 0-100 cm soil depths from 2017 to 2018 to explore the optimization of fertilization management strategies for soybean and maize production in Northeast China. To elucidate the impact of chemical fertilizers and manure, twelve treatments-control (CK); single N fertilizer at a low rate (N1) and that at a high rate (N2); N1, phosphorus (P), and potassium (K) fertilizer (N1PK); manure alone at 13.5 and 27 t ha-1 (M1 and M2); and those combined with N, P, or K fertilizer (M1N1, M1N2, and M1N1PK and M2N1, M2N2, and M2N1PK)-were selected and studied. The results showed that long-term amendment with manure significantly increased crop biomass and yield in the soybean-maize-maize rotation system. Combining with manure increased the WUE, the partial factor productivity of N fertilizer (PFPN), and N physiological efficiency (PEN) in both the soybean and maize seasons; conserved soil water (mainly at 40-60 cm); and increased soil N retention (in the upper 60 cm layer), which reduced the risk of N leaching, with a better effect being observed after the application of 13.5 t ha-1 manure. These results provide insight into the potential of using fertilization management strategies that include amendment with 13.5 t ha-1 manure in combination with N, P, and K fertilizer in the maize season and only chemical fertilizer in the soybean season, as these results indicate that such strategies can achieve high yields and be used to implement agricultural sustainable development in brown soil regions in Northeast China.

Effects of applying lime and phosphogypsum in soybean and wheat nutrition

This study aimed to assess the nutritional status of soybean and wheat and the relationship with grain yield and biometric components after lime and phosphogypsum (GY) reapplication. Treatments consisted of two lime application methods, surface liming and incorporated liming, to different levels of base saturation (BS) (44, 70, and 90%), in addition to surface liming to 70% BS associated with a standard dose (70GY1) or double dose (70GY2) of GY. Treatments were applied in 2012 and reapplied in 2016. The results refer to the 2018/2019 soybean season and the 2019 wheat season. Lime + GY treatment increased leaf area, plant height, leaf dry matter, and stem dry matter in soybean but had no effect on specific leaf area (235.4 cm2 g−1), stem diameter (6.08 mm), number of pods per plant (71.7), grain number per plant (165), or thousand grain weight (117 g). Liming to 90% BS reduced leaf manganese contents in both crops and leaf iron content in soybean. GY application improved the calcium status of both crops and the sulfur status of soybean. However, 70GY2 reduced leaf magnesium contents in soybean and wheat. Soil tillage without lime reduced wheat yield by 12% compared with no-till. Soybean yield correlated positively with leaf nitrogen (0.79), leaf phosphorus (0.91), leaf area (0.62), and thousand grain weight (0.65), whereas wheat yield correlated with leaf phosphorus (0.83), calcium (0.75), and sulfur (0.74). For improved soybean and wheat performance, it is preferable to apply lime and GY to the soil surface (70GY1), permanently maintaining no-till practices.

Effect of Different Sowing Dates and Spacing on Soybean Varieties for Seed Quality during Rabi Season

Soybean, the number one oil seed crop in the world has recently occupied an important place in the edible oil and agricultural economy of the country. Lack of good quality seed is one of the major problems encountered in soybean production. Soybean as commercial crop is successful in kharif season as the agro-climatic conditions are found suitable. But climatic conditions may cause the adverse effect on seed production of different soybean varieties in kharif season. Hence, to fulfill the demand of quality soybean seed, efforts has been made to produce the soybean in rabi season.
 The research trial on rabi season soybean seed production was conducted during 2021-22 at the Research Farm, Department of Agronomy, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola. The field experiment was laid out in split-split plot design having three replications. Total nine treatment combinations were there, consist of three sowing dates viz., 16 Dec, 31 Dec and 15 Jan in main plot and three spacing as 30 x 10 cm, 45 x 10 cm and 60 x 10 cm in sub plot and three varieties are AMS 100-39, RSC 10-46 and KDS-753 in sub-sub plot.
 It can be revealed from the experimental results that graded seed yield (kg ha-1) and weight of graded 100 seed (g) were extensively greater in early sown crop of 16 Dec., variety RSC 10-46 and spacing 45 x 10 cm. Sowing date 16 Dec recorded minimum under size seed weight. In variety RSC 10-46 recorded minimum under size seed weight followed by variety AMS-100-39 (44.96 kg ha-1) and spacing of 45 x 10 cm. Treatment combination D1V2(sowing on 16 Dec. and variety RSC 10-46) recorded minimum under size seed yield. Significantly maximum weight of graded 100 seed was recorded by sowing date 16 Dec. (10.44 g) ,variety RSC 10-46 and spacing 45 x 10 cm.

“Effects of soil management, rotation and sequence of crops on soil nitrous oxide emissions in the Cerrado: A multi-factor assessment”

The emission of nitrous oxide (N2O), one of the main greenhouse gases, which contributes significantly to global warming, is a major challenge in modern agriculture. The effects of land use systems on N2O emissions are the result of multiple variables, whose interactions need to be better understood. In this sense, this study analyzed the possible effects of different soil managements, crop rotations and sequences, as well as edaphoclimatic factors causing N2O emissions from soils in the Cerrado biome (scrubland). The following four land-use systems were evaluated: 1) No-tillage cultivation with biennial crop rotations and sequences: legume-grass and alternating grass-legume crops in the second season - NT-SS/MP; 2) No-tillage with biennial rotations and sequences: grass-legume and alternating second crop of legume-grass - NT-MP/SS; 3) Conventional planting with disc harrow and biennial legume-grass rotation-CT-S/M; and 4) Native Cerrado (CE), no agricultural land use. The legume and grass species, planted in the two no-tillage treatments were soybean, followed by sorghum BRS3.32 (Sorghum bicolor (L.) Moench) (SS), and maize, followed by pigeon pea (Cajanus cajan) (MP). Nitrous oxide emissions were evaluated for 25 months (October 2013 to October 2015), and the results were grouped in annual, total, growing and non-growing seasons, as well as yield-scaled N2O emissions. The mean N2O fluxes were 24.14, 15.71, 32.49 and 1.87 μg m−2 h−1 in the NT-SS/MP, NT-MP/SS, CT-S/M and Cerrado areas respectively. Cumulative N2O fluxes over the total evaluation period from the systems NT-SS/MP, NT-MP/SS, CT-S/M and CE, respectively, were 3.47, 2.29, 4.87 and 0.26 kg ha−1. A correlation between N2O fluxes and the environmental variables was observed, with the exception of water-filled pore space (WFPS), but N2O peaks were associated with WFPS values of >65%. In the 2014–2015 growing season, yield-scaled N2O emissions from NT-MP/SS were lower than from CT-S/M. A multi-factor approach indicated that conventional management with main season soybean or maize and no alternating crop sequence intensifies soil N2O emissions in the Cerrado.

Lime and gypsum application to low-acidity soils: Changes in soil chemical properties, residual lime content and crop agronomic performance

Crop yield gains and improvements in surface and subsurface soil chemical properties are evident when agricultural lime and gypsum are used in high-acidity soils. However, there is scarce information on the effects of lime and gypsum application on no-till tropical soils previously treated with these additives (low-acidity soils). The duration of the effects of lime applied to the soil surface varies according to lime rate, product characteristics, soil conditions, and water and thermal regimes. Such residual effects influence the timing of lime reapplication. This study aimed to investigate the effects of surface application of agricultural lime and gypsum on soil chemical properties, soybean and second-crop corn yields, and lime residual contents. The experiment was conducted on a Red Latosol with a very clayey texture in Floresta, Paraná, Brazil. Four rates of dolomitic lime (0.0, 2.6, 5.4, and 8.1 Mg ha−1) and agricultural gypsum (0, 4, 8, and 12 Mg ha−1) were used. The experimental design was a randomized complete block with subplots and four replications. The experiment lasted for four soybean seasons and three second-crop corn seasons. At 6, 12, 24, and 36 months after treatment, soil samples were collected from the 0.00–0.05, 0.05–0.10, 0.10–0.20, 0.20–0.30, 0.30–0.40, and 0.40–0.60 m layers for chemical analysis. No significant interaction effects were observed on soil chemical properties. Liming resulted in soil alkalization, with a consequent reduction in Al3+ and an increase in Ca, Mg, base saturation, and pH. Residual lime was not detected in layers deeper than 0.05 m, suggesting a lack of physical movement of particles in the soil pore space. Residual lime was detected on surface soil (0.00–0.05 m) up to 36 months after application, demonstrating the low reactivity of lime on no-till soils. At 6 months after gypsum application, there was an increase in Ca2+ levels up to the 0.6 m layer, whereas Mg2+ levels were reduced throughout the soil profile for up to 36 months. In no-till soybean–second-crop corn rotation systems, use of agricultural gypsum alone did not provide consistent effects on crop yield and reduced foliar Mg contents. Under the studied conditions of low acidity, liming did not produce significant differences in crop yield but improved soil chemical properties for plant growth under no-till.

Seasonal variation of the rhizosphere soil aggregation in an Oxisol

Soil aggregation is a key process that results in soil structure formation and stabilization and controls several soil functions. The root system and its mycorrhiza symbiosis contribution to aggregate stabilization have been widely studied. However, only a few studies have considered a large variety of cropping systems under different seasons within tropical environments. Our goal was to better understand the response of aggregate stability in the rhizosphere (RS) and bulk soil (BS) to six cropping systems in an Oxisol, in the summer and winter seasons. Readily-dispersible clay and mechanically-dispersible clay were evaluated as aggregate stability indicators. RS and BS were also characterized for soil physical (i.e., water content), chemical (i.e., soil organic carbon, K, P, Ca, Mg, Al, potential acidity), and physicochemical (i.e., pH, ΔpH, and point of zero charge) properties. Dispersible clay was approximately 1.2 times lower (p < 0.05) within the RS than in the BS, which suggests that the crop root systems increased aggregate stability, but their influence on soil aggregation differed among cropping systems. Aggregate stability was approximately 3 times higher (p < 0.05) in the winter compared to the summer season. In general, RS had better chemical and physicochemical soil parameters than BS. Winter season also showed better chemical and physicochemical parameter values. Overall, these results reflect (i) the positive root system influence of the winter crops on soil structure stability, (ii) the negative response of soil structure stability to the addition of high doses of chemical fertilizers to soybean and maize (cash crops) in the summer season, (iii) the minimal influence of soybean and maize root system on formation and stabilization of the aggregates in the summer season, and (iv) the different weather condition in the summer and winter seasons. Thus, better erosion control practices and crops that promote soil aggregation should be adopted in the summer season. Finally, attention should also be given to the root exudates and their relationship with soil, as they can either increase or decrease soil aggregation.

SOYBEAN CROP YIELD PREDICTION BY INTEGRATION OF REMOTE SENSING AND WEATHER OBSERVATIONS

Abstract. The main objective of this study is the in-season forecasting of soybean crop yield using the integration of satellite remote sensing and weather observations. The study was carried out in the Paran´a state of Brazil. The soybean crop in the study region is sown during Oct.–Nov. month and harvested between Feb.–Mar. of the next year. Municipality-level soybean yield data for 15 municipalities was obtained from the AGROLINK portal of Brazil, from the 2005–06 season to the 2020–21 season. The crop yield data constituted yearly municipality-wise yield in kg/ha. Remote sensing-based indicators such as the Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI) and Land Surface Temperature (LST), and Rainfall data from CHIRPS was considered in the study. Regression modelling was carried out between municipality-level yield as the dependent variable and features generated from remote sensing and weather observations as independent variables. Performance evaluation of tuned random forest regression (RFR) and tuned support vector regression (SVR) were performed against multiple linear regression (MLR). A comparison of results in terms of algorithms shows that RFR performed better than SVR and MLR. Further, a rootmean- square-error (RMSE) of 414 kg/ha and an R2 value of 0.748 were achieved by the best RFR model. Validation of developed RFR model was performed on the data from the new soybean season, i.e., 2020–21. We have achieved an R2 value of 0.693 with a RMSE of 585 kg/ha. Although the model performance on the data of 2020-21 season is slightly reduced, R2 and RMSE are in good agreement with test results. This study showed that, integration of remote sensing and weather observations would be useful for in-season yield forecasting of soybean at municipality level.

IN AND END OF SEASON SOYBEAN YIELD PREDICTION WITH HISTOGRAM BASED DEEP LEARNING

Abstract. One sector that feels the effects of global warming and climate change on all levels is agriculture. In order to prepare for possible yield loss, as well as market, storage, and import planning challenges brought on by climate change, businesses can utilise agricultural decision support applications. Within the scope of this study, a crop yield prediction module has been developed that can provide in and end of season estimation of crop yields to be obtained from the determined regions. The Python programming language was used in the creation of the module as a QGIS plugin. The area for which crop yield predictions are to be made is covered by retrieving MODIS SR, MODIS LST, and Daymet data from the Google Earth Engine data catalogue. Histograms obtained from remotely sensed images are used as input data to two deep learning methods (CNN-LSTM and HistCNN). As a result, the HistCNN model outperformed CNN-LSTM for in season soybean yield prediction, with an R2 of 0.72, while the CNN-LSTM model outperformed it for in end of season soybean yield prediction, with an R2 of 0.67.

Investigating the spatiotemporal dynamics of the leaf beetle Cerotoma arcuata in tropical soybean fields

Cerotoma arcuata (Coleoptera: Chrysomelidae) has been a notorious issue in the previous soybean (Glycine max) season in South America. Geostatistical analyses explore insect spatiotemporal dynamics by settling populations’ spatial dependence. Investigating the spatiotemporal dynamic of C. arcuata provides accomplishments about its regulation factors and scouting directions. Hence, this study aimed to determine the spatiotemporal dynamics of C. arcuata in soybean fields through geostatistical tools. For this purpose, C. arcuata populations, climatic elements, surrounding vegetation, and plant stage were monitored in soybean fields for two years. The highest C. arcuata densities occurred in the second year’s dry season at the reproductive stage, and average air temperature regulated its population. The exponential and spherical semivariograms presented spatial dependence ranges of 7.58 and 17.18 m, respectively. Consequently, samples for scouting purposes must be assessed at greater distances than 17.18 m. C. arcuata distribution was clustered when its density was > 1 adult.m−1. In conclusion, this research elucidates the spatiotemporal dynamics of C. arcuata in tropical soybean fields and provides valuable knowledge to draw decision-making plans and control strategies.

Fertilizer 15N balance in a soybean-maize-maize rotation system based on a 41-year long-term experiment in Northeast China.

Global awareness of the need to enhance crop production and reduce environmental issues associated with nitrogen (N) fertilizer has increased. However, studies on how the N fate changed with manure addition are still limited. To explore efficient fertilization management for an improved grain yield, N recovery efficiency, and reduced N residual in the soil or that unaccounted for, a field 15N micro-plot trial in a soybean-maize-maize rotation was conducted to evaluate the effect of fertilization regimes on soybean and maize yields and the fertilizer N fate in the plant-soil system during 2017-2019 within a 41-year experiment in Northeast China. Treatments included chemical N alone (N), N and phosphorus (NP), N, P, and potassium (NPK), and those combined with manure (MN, MNP, and MNPK). Application of manure increased grain yield, on average, by 153% for soybean (2017) and 105% and 222% for maize (2018 and 2019) compared to no manure, with the highest at MNPK. Crop N uptake and that from labeled 15N-urea also benefited from manure addition, mainly partitioned to grain, and the average 15N-urea recovery was 28.8% in the soybean season with a reduction in the subsequent maize seasons (12.6%, and 4.1%). Across the three years, the fertilizer 15N recovery ranged from 31.2-63.1% (crop) and 21.9-40.5% (0-40 cm soil), with 14.6-29.9% unaccounted for, including N losses. In the two maize seasons, manure addition significantly increased the residual 15N recovery in crop attributed to the enhancing 15N remineralization, and reduced that in soil and unaccounted for compared to single chemical fertilizer, with MNPK performing the best. Therefore, applying N, P, and K fertilizers in the soybean season and NPK combined with manure (13.5t ha-1) in the maize seasons is a promising fertilization management strategy in Northeast China and similar regions.

Assessing the impact of sowing dates and ENSO in a drought index-based insurance for soybean

Crop insurance has been an important mechanism used by farmers to protect the economic and yield losses produced by extreme weather events. Alternatively, index-based insurance (IBI) has been evaluated in many parts of the world as a mechanism to avoid moral hazard and adverse selection from traditional crop insurance products. However, there is a lack of knowledge on how the sowing date impacts the IBI triggers and tick size. In addition, few studies have evaluated how the frequency of payouts is affected by climate phenomena such as the El Niño-Southern Oscillation (ENSO). In this study, we aimed to develop a drought index based-insurance for soybean (Glycine max (L.) Merr) in the Southeastern US, where the triggers and payouts were quantified for sowing dates and ENSO phases. Simulated soybean life cycle and grain yield for multiple sites, sowing dates, and maturity groups were used to calibrate the index triggers. The index triggers were assessed based on the period of measurement, sowing time, and ENSO phase. Our results show that the accumulation of water stress between flowering and physiological maturity using quantile regression increased the accuracy of payments. The results also highlighted a higher frequency of payments triggered when soybean seasons in the Southeastern US were under La Niña influence. The results also presented larger payments generated when the soybean was sown during April and May in comparison to later sowing dates. These results could be used by insurance companies and public administration to improve the efficiency of IBI products offered.

INFLUENCE OF PRE-SOWING TREATMENT OF SOYBEAN SEEDS WITH AGROMINERALS ON THE MAIN ECONOMIC AND USEFUL INDICATORS OF THE CROP

In crop production, the usage of various microelements for seed treatment is of great importance, which have a stimulating effect on the growth and development of plants. This article presents the results of the effect of presowing treatment of soybean seeds with agrominerals based on tagan bentonite and fungicidal biostimulants. The agrominerals consist of complexes of succinic acid and ethylenediamine succinic acid with silver or copper ions in combination with a film-forming substance, as a starch, to increase economically useful qualities of the crop. Various effects of agrominerals were revealed, on the growing season of soybean, such as development, yield, weight of 1000 seeds, quantity of beans on plants, protein and fat content in seeds. It has been established that pre-sowing treatment with separate complexes ofSA-Сu, SA-Ag, and Starch-SA-Cu leads to a reduction in the vegetation period by 5-8 days. However, agromineral based onTgn-EDSA-Ag-Starch and Tgn-EDSA-Cu- Starchon the contrary, increases the duration of the vegetation period by 4-7 days. The yield increases of (Nur+) 3.1-3.5 centner/hectar (cwt/ha) and (Progress) 3.0-4.1 cwt/ha in comparison with the control.Also, the influence of agrominerals on the weight of 1000 seeds, the number of beans on plants, the content of protein and fat in seeds were noted.

Comparative assessment of early season soybean cultivars in organic and conventional production system for morphological and agronomic traits

AbstractOrganic production systems differ from the conventional system, especially because of the insect pest, weed, disease, and nutrient management. Therefore, there has been a focus on increasing performance stability in soybean [Glycine max (L.) Merr.] cultivars specifically adapted for organic farms. The objective of this study was to conduct a comparative assessment of Maturity Group 0 soybean genotypes grown in both organic and conventional conditions for several traits important in the organic soybean production system, such as early season canopy development, root morphology, nodule production, and nutrient use efficiency. A soybean panel consisting of 33 cultivars was grown in four environments (two locations × two years) on an organic farm and conventional production system farm in Southern Ontario, Canada. Significant differences among genotypes were observed for root morphology and canopy development in the organic environment only. Early season canopy development, root length, nodule mass, and nutrient use efficiency were related to yield in both environments. In addition, yield rank correlations between genotypes in two locations were significant in 2014 (r = .57) and 2015 (r = .31), and some large crossover effects were observed in both tested years. The principal components analysis for these and other agronomic traits showed that resource acquisition traits such as canopy development, root length, and nodule mass were more closely related to yield in the organic system than nutrient use efficiency. Overall, the results of this study may be useful for soybean breeders interested in developing cultivars adapted to the organic production system.

Physical-chemical properties of spray syrup in tank-mixing multiple pesticides and water sources used in grain farming

This work evaluated physical-chemical properties of spraying syrup formulated with different water types and using or not tank-mixing pesticides. The experimental design was completely randomized in a 4 x 5 factorial scheme (4 water types and 4 pesticide syrups + control, non-sprayed plant) in three sampling times (off-season corn, pre-planting soybean weed control, and soybean season) within one year. Water treatments consisted of deionized, well, river and weir water. Product mixing consisted of herbicide (Glyphosate 925 g a.i. ha-1), herbicide + insecticide (Imidacloprid + beta-cyfluthrin 100+12.5 g a.i. ha-1), herbicide + fungicide (Trifloxystrobin + Prothioconazole 70+60 g a.i. ha-1) and herbicide + insecticide + fungicide. Weir water presented the worst physical quality. Spraying syrup prepared with tank-mixing herbicide, insecticide, and fungicide in various combinations decreased the effectiveness of the pesticide. When associating the three pesticides, less dissolution of the spray syrup and greater risk of syrup incompatibility leads to pesticide ineffectiveness. Highlights: The water type used in tank-mixing multiple pesticides affects spraying syrup quality. Water with the worst physical quality decreases pesticide performance. Less dissolution and greater risk of fungicide ineffectiveness take place when three pesticides are associated. Spraying syrup prepared with tank-mixing pesticides increased in the successive cultivation of soybean/corn.

Performance of 45 Non-Linear Models for Determining Critical Period of Weed Control and Acceptable Yield Loss in Soybean Agroforestry Systems

A family of Sigmoidal non-linear models is commonly used to determine the critical period of weed control (CPWC) and acceptable yield loss (AYL) in annual crops. We tried to prove another non-linear model to determine CPWC and AYL in a soybean agroforestry system with kayu putih. The three-year experiment (from 2019–2021) was conducted using a randomised complete block design factorial with five blocks as replications. The treatments comprised weedy and weed-free periods. Non-linear models comprised 45 functions. The results show that the Sigmoidal and Dose-Response Curve (DRC) families were the most suitable for estimating CPWC and AYL. The best fitted non-linear model for weedy and weed-free periods in the dry season used the Sigmoidal family consisting of the Weibull and Richards models, while in the wet season the best fit was obtained using the DRC and Sigmoidal families consisting of the DR-Hill and Richards models, respectively. The CPWC of soybean in the dry season for AYL was 5, 10, and 15%, beginning at 20, 22, and 24 days after emergence (DAE) and ended at 56, 54, and 52 DAE. The AYL in the wet season started at 20, 23, and 26 DAE and ended at 59, 53, and 49 DAE.

Влияние биопрепаратов на показатели биологической активности чернозема типичного слабоэродированного

Abstract. The purpose is to study the effect of biological preparations based on Trichoderma viride and Pseudomonas aureofacieens, nitrogen fertilizers (N10 kg a. v. per 1 t of straw) on the surface incorporation of crushed by-products into the soil on the indicators of biological activity of typical slightly eroded chernozem. Methods. The studies were carried out in 2018-2020 in field experiments with biological preparations of FGBNU “Kursk FANTS” (Kursk region, Medvensky district, Panino village) on typical poorly eroded chernozem in the grain (barley – buckwheat – fodder beans) and grain-tilled (sunflower – barley – soybean) crop rotation. The indices of biological activity (C-CO2 production by soil, cellulolytic activity of typical chernozem) are presented for the vegetation period of 2020 in soybean and fodder bean crops. Results. It was found that the use of biopreparations based on Trichoderma viride and Pseudomonas aureofacieens, provided an increase in carbon dioxide emissions on average for the growing season of soybean by 43 % and by 65 % for forage beans in relation to the control. It was revealed that the highest activity of microorganisms participating in mineralization of by-products was observed in soybean during shoots: when nitrogen fertilizers were applied by 7.5 kg/h/ha and when they were mixed with biopreparations by 4.6 kg/h/ha relative to the control. For forage beans, the process of soil C–CO2 emission was more intense in the variant with the application of biopreparations by 3.8 kg/h/ha and their combined use with nitrogen fertilizers by 4.7 kg/h/ha compared to the control. It was shown that a significant proportion of the contribution to the variation of cellulolytic activity in soybeans belonged to nitrogen fertilizers – 80.6 %. For forage beans the main share of participation in variation of cellulosic decomposition intensity was determined by biopreparations, which was 3 times higher in relation to nitrogen fertilizers.

Seasonal agricultural wetlands act as potential source of N2O and CH4 emissions

Seasonal wetlands and depressions in agricultural fields that accumulate nutrients from runoff water might act as hotspots of nitrous oxide (N2O) and methane (CH4) emissions. However, the spatiotemporal pattern of these gases from different parts of agricultural fields had not been compared. A two-year field experiment was conducted in Ontario, Canada, to test whether field locations with higher wetness act as N2O and CH4 hotspots. The objectives included, i) to classify agricultural field using topographical wetness index (TWI), ii) to determine the spatiotemporal patterns of N2O, CH4, and soil properties from TWI classes; and iii) to determine the impact of soil variables on N2O and CH4 emission prediction. The field was divided into four classes based on TWI, i) low TWI (C1; steep slopes), ii) medium TWI and slopes (C2), iii) Higher TWI (C3; low slopes), and iv) very high TWI (C4; seasonal wetlands and depressions). Each TWI class had six sampling points as replicates to collect soil and gas samples during corn (2019) and soybean (2020) seasons. TWI classes had a significant impact on N2O and CH4 emissions. Mean maximum and minimum N2O emissions were observed during corn season from C4 (153 ± 34) and C1 (69 ± 35 µg N2O-N m-2h−1), respectively. However, during soybean season, C1 had higher (70 ± 1), and C4 had lower average (26.5 ± 8 µg N2O-N m-2h−1) emissions. Higher mean CH4 emissions were observed from C4 and C1, respectively, during corn (1264 ± 778) and soybean (60 ± 44 µg CH4-C m-2h−1) seasons. Regression analysis revealed that N2O emissions were mainly controlled by nitrate, electrical conductivity, and moisture during corn and ammonium, pH, and nitrate during soybean season. Similarly, CH4 emissions were regulated by moisture and clay during corn season and ammonium and pH during soybean season. These relationships could help upscale greenhouse gas emissions at regional levels and formulate mitigation strategies.

Relation between Helicoverpa armigera (Hubner) (Lepidoptera/Noctuidae) mortality and entomopathogenic fungi persistence in soybean leaflets

​BackgroundEntomopathogenic fungi have low persistence in the field because of UV light, high temperatures and low humidity. Thus, this study's objective was to correlate the persistence of Beauveria bassiana and Metarhizium anisopliae in soybean leaf by measuring the mortality and sub-lethal effects of Helicoverpa armigera (Hubner) (Lepidoptera/Noctuidae). In the 2017–2018 and 2019–2020 soybean seasons, the experiments were conducted on plots subdivided in a completely randomized design. After spraying each plot with the fungal, either B. bassiana or M. anisopliae, leaves were collected hourly for 8 h after application and transferred to the laboratory. The local air temperature was recorded each time. For persistence assessment, the fungal suspension was prepared from the leaf disks; thereafter, 150 µl of the suspension was removed and poured into a plate. After 72 h of inoculation, colony-forming units (CFUs) were counted. For the mortality test, the leaf disks were placed individually in pots and offered to second instar larvae of H. armigera. The surviving larvae were evaluated for sub-lethal effects and biological parameters.ResultsBeauveria bassiana was more persistent than M. anisopliae, which persisted for 3 h in the first year and 5 h in the second year when temperatures were milder; B. bassiana persisted throughout the evaluation period (8 h). The mortality of H. armigera decreased with an increase in the time since application fungal suspension, presenting a range of 86–30% for B. bassiana and 78–4.2% for M. anisopliae.ConclusionAssessments of sublethal effects showed an inverse correlation between CFUs and parameters such as fertility and weight.