Single Crop Research Articles

Multiple agricultural cropland products of South Asia developed using Landsat-8 30 m and MODIS 250 m data using machine learning on the Google Earth Engine (GEE) cloud and spectral matching techniques (SMTs) in support of food and water security

ABSTRACT Cropland products are of great importance in water and food security assessments, especially in South Asia, which is home to nearly 2 billion people and 230 million hectares of net cropland area. In South Asia, croplands account for about 90% of all human water use. Cropland extent, cropping intensity, crop watering methods, and crop types are important factors that have a bearing on the quantity, quality, and location of production. Currently, cropland products are produced using mainly coarse-resolution (250–1000 m) remote sensing data. As multiple cropland products are needed to address food and water security challenges, our study was aimed at producing three distinct products that would be useful overall in South Asia. The first of these, Product 1, was meant to assess irrigated versus rainfed croplands in South Asia using Landsat 30 m data on the Google Earth Engine (GEE) platform. The second, Product 2, was tailored for major crop types using Moderate Resolution Imaging Spectroradiometer (MODIS) 250 m data. The third, Product 3, was designed for cropping intensity (single, double, and triple cropping) using MODIS 250 m data. For the kharif season (the main cropping season in South Asia, Jun–Oct), 10 major crops (5 irrigated crops: rice, soybean, maize, sugarcane, cotton; and 5 rainfed crops: pulses, rice, sorghum, millet, groundnut) were mapped. For the rabi season (post-rainy season, Nov–Feb), five major crops (three irrigated crops: rice, wheat, maize; and two rainfed crops: chickpea, pulses) were mapped. The irrigated versus rainfed 30 m product showed an overall accuracy of 79.8% with the irrigated cropland class providing a producer’s accuracy of 79% and the rainfed cropland class 74%. The overall accuracy demonstrated by the cropping intensity product was 85.3% with the producer’s accuracies of 88%, 85%, and 67% for single, double, and triple cropping, respectively. Crop types were mapped to accuracy levels ranging from 72% to 97%. A comparison of the crop-type area statistics with national statistics explained 63–98% variability. The study produced multiple-cropland products that are crucial for food and water security assessments, modeling, mapping, and monitoring using multiple-satellite sensor big-data, and Random Forest (RF) machine learning algorithms by coding, processing, and computing on the GEE cloud.

Crotalaria Sowing Times Intercropped with Off-Season Maize in the Variability of Soil Temperature and Moisture

The thermal regime and the dynamics of soil moisture affect crop yield. Therefore, there is a need to understand the extent to which the intercropping system modifies the variability of soil temperature and moisture conditions for optimal growth and yield of the maize crop. This study aimed to evaluate the influence of different sowing times of crotalaria in an intercropping system with irrigated and non-irrigated off-season maize in the variability of soil temperature and moisture. The experiment consisted of twelve treatments, consisting of different cropping systems (intercropping): maize in a single crop (MS); sowing of crotalaria simultaneous with maize (MCS); sowing of crotalaria with maize in the VE stage (MCVE); sowing of crotalaria with maize in stage V2 (MCV2); sowing of crotalaria with maize in stage V4 (MCV4); sowing of crotalaria with maize in stage V6 (MCV6), in irrigated and non-irrigated systems. Soil temperature was monitored at depths of 10, 20, 30 and 40 cm, and soil moisture was monitored at a depth of 20 cm using "K-type" thermocouple sensors and time domain reflectometry (TDR) probes, which were all connected to a Datalogger and programmed to store the collected data at 15-minute intervals. Irrigation was carried out with a uniformity coefficient greater than 80% and a water depth of 10.38 mm h-1 with a sprinkler system. The intercropping of maize with crotalaria provides the soil with a smaller range of soil temperature, with higher values in the system without irrigation compared to the irrigated system. Soil moisture was lower in the single maize treatment, as it increased soil water evaporation compared to the intercropping treatments. In the irrigated system, the soil moisture was higher at 0.010 m3 m-3 in relation to the system without irrigation. The irrigated system obtained better results for maize yield than the non-irrigated system.

The Fits and Starts of Indian Rice Domestication: How the Movement of Rice Across Northwest India Impacted Domestication Pathways and Agricultural Stories

Rice is currently the staple food for over 3.5 billion people and is arguably the most important crop exploited by humans. Understanding how we came to the point where a single crop dominates the lives of almost half of the Earth’s population has major significance for our future, even more so given the climatic instability we face today, as rice is a cereal that is dependent on water to an extreme degree. In this study, the nature of early rice agriculture in South Asia is explored, looking at how this critical crop may have begun to be exploited, cultivated, and then brought under agricultural regimes during the long span between c.6500 and 1500 BC. There is now clear evidence for early Holocene cultivation of rice in the Middle Gangetic plains of northern India, but there is still considerable debate about the timing of when this cultivation began and whether it involved domestication of rice. By 3200 BC, however, rice agriculture was present outside the Ganges in the Indus Civilization. The data show accelerated domestication in the Indus environment and agricultural systems that played a part in later hybridization with the arrival of Chinese rice. Understanding how this move from its place of origin to a new environment may have become entangled in the domestication pathways of South Asia rice prior to the arrival of Chinese rice c.1500 BC are important to the overall rice story, as they play into modern concerns relating to biodiversity and different ways of growing and watering rice.

Economic and energy efficiency of cultivation of alfalfa-cereal herbage

Aim. To establish indicators of economic and energy efficiency in the cultivation of alfalfa-cereal mixtures under the influence of lime and fertilizers. Methods. Field, laboratory, mathematical-statistical, economic-mathematical. Results. The influence of lime and fertilizers on only alfalfa, alfalfa-cereal and only cereal agrophytocenoses was carried out during 2019−2021 in the Forest-steppe zone of Ukraine on dark gray podsolized coarse silt-light loam soil. The results of research on the study of economic and energy efficiency indicators are shown in terms of the cost of gross production, total costs, net profit, profitability per 1 hectare, cost of fodder units and raw protein, payback of total energy costs, gross and exchangeable energy output are calculated per1 ton. Conclusions. The use of symbiotic nitrogen fixed by alfalfa in its single and mixture crops with cereal increases the net profit from 6.9 to 27.1−35.0 or by 20.2−28.1 thousand UAH/ha, profitability − from 114 to 300−343%, KEE − from 5.7 to 10.9−12.4 and BEC − from 3.0 to 6.1−7.1, and the cost of 1 ton of fodder units decreases from 2.6 to 1.2−1.4 thousand UAH, and energy consumption per 1 ton of fodder units from 4.30 to 1.64−2.0 MJ. The annual application of P45K90 reduces net profit by 3.7−4.4 thousand UAH/ha, profitability by 160−168%, KEE by 1.6−2.5 and BEC by 0.6−1.3 and increases the cost price of 1 ton of fodder units − by 763−827 UAH and energy costs per 1 ton of fodder units − by 0.58−1.55 compare that to the option without fertilizers. The application of lime reduces the profitability of cultivation by 25−78%, KEE – by 0.2−1.0 and BEC – by 0.1−0.5 and increases the cost of 1 ton of fodder units – by 143−369 UAH/ha. The combined application of the fertilizers and lime reduces profitability by 55-194%, KEE by 2.1−2.8 and BEC by 1.0−1.5, and increases cost and energy costs per 1 ton of fodder units.

Effect of defoliants on percent defoliation and yield of American cotton (Gossypium hirsutum)

Cotton production is labour intensive in almost all the developing countries where it is picked by hand. However, due to acute labour shortage in recent times, mechanized harvesting is gaining momentum. It requires the application of defoliants, which reduces the cost of labour and maximum cotton can be picked in a single pick (one picking) and consequently provide timely sowing of next crop. The farmers can get benefit of two crops instead of one single long duration cotton crop. Therefore, a two year study conducted at Agricultural College Farm, Bapatla, Andhra Pradesh, during the kharif of 2018–19 and 2019–20 to know the the effect of different defoliants and their time of application on per cent defoliation and seed cotton yield in High Density Planting American Cotton (HDPS).Three defoliants Dropp ultra, mepiquat chloride and etherel and three times of application 80% of boll opening, Node Above Cracked Boll and Node Above White Flower were included in this research in split plot design with four replications. Per cent defoliation was significantly influenced by different defoliant treatments, as well as time of application. At 21 days after defoliant spray, there was significant increase in per cent defoliation with Dropp Ultra 540 SC (Thidiazuron 360 + Diuron 180) @ 250 mL/ha (91.5%) over other defoliants and at 80% Boll Opening (88.3%), which was on par with NACB (86.9%). Higher seed cotton yield was obtained with application of Dropp Ultra @ 250 mL/ha and found on par with Etherel @ 3000 ppm (D3) and regarding times of application, defoliants applied at 80% Boll Opening recorded maximum yield, which was found at par with NACB method.

Chemical Regulation Effect of Water Use Efficiency of Maize Intercropping

In order to solve the practical problems of large water demand and shortage of water resources in traditional wheat/maize intercropping, a planting method of changing stubble retention method is proposed in this paper. This method was used to study the effects of three stubble retention methods of traditional wheat straw incineration, straw return, and straw stubble on grain yield, water use efficiency (WUE), and economic benefits of wheat/maize intercropping. The results showed that, compared with the grain yield of burning and returning, the single cropping of wheat increased by 7.2% and 5.1%, the intercropping of wheat increased by 6.2% and 5.1%, the single cropping of corn increased by 4.7% and 2.5%, and the intercropping of corn increased by 7.2% and 3.3%, respectively; compared with the burned and returned WUE, wheat monoculture increased by 20.4% and 16.2%, respectively, wheat intercropping increased by 17.9% and 14.6%, respectively, corn monoculture increased by 16.7% and 10.9%, respectively, and corn intercropping increased by 11.8% and 17.0%, respectively. In terms of the average value of monoculture wheat, monoculture corn, and wheat/corn, the net benefits of incineration, turning, and stubble treatment are 10946, 11471, and 13454 yuan • hm−2, respectively. Considering the grain yield, water use efficiency, and net income, the standing stubble planting mode is the best planting mode of wheat/maize in this area.

GrapeNet: A Lightweight Convolutional Neural Network Model for Identification of Grape Leaf Diseases

Most convolutional neural network (CNN) models have various difficulties in identifying crop diseases owing to morphological and physiological changes in crop tissues, and cells. Furthermore, a single crop disease can show different symptoms. Usually, the differences in symptoms between early crop disease and late crop disease stages include the area of disease and color of disease. This also poses additional difficulties for CNN models. Here, we propose a lightweight CNN model called GrapeNet for the identification of different symptom stages for specific grape diseases. The main components of GrapeNet are residual blocks, residual feature fusion blocks (RFFBs), and convolution block attention modules. The residual blocks are used to deepen the network depth and extract rich features. To alleviate the CNN performance degradation associated with a large number of hidden layers, we designed an RFFB module based on the residual block. It fuses the average pooled feature map before the residual block input and the high-dimensional feature maps after the residual block output by a concatenation operation, thereby achieving feature fusion at different depths. In addition, the convolutional block attention module (CBAM) is introduced after each RFFB module to extract valid disease information. The obtained results show that the identification accuracy was determined as 82.99%, 84.01%, 82.74%, 84.77%, 80.96%, 82.74%, 80.96%, 83.76%, and 86.29% for GoogLeNet, Vgg16, ResNet34, DenseNet121, MobileNetV2, MobileNetV3_large, ShuffleNetV2_×1.0, EfficientNetV2_s, and GrapeNet. The GrapeNet model achieved the best classification performance when compared with other classical models. The total number of parameters of the GrapeNet model only included 2.15 million. Compared with DenseNet121, which has the highest accuracy among classical network models, the number of parameters of GrapeNet was reduced by 4.81 million, thereby reducing the training time of GrapeNet by about two times compared with that of DenseNet121. Moreover, the visualization results of Grad-cam indicate that the introduction of CBAM can emphasize disease information and suppress irrelevant information. The overall results suggest that the GrapeNet model is useful for the automatic identification of grape leaf diseases.

Expanding the Duty to Rescue to Climate Migration

Expanding the Duty to Rescue to Climate Migration

Optimizing planting density and irrigation depth of hybrid maize seed production under limited water availability

Improvement in seed vigor and yield of hybrid maize is required to ensure food security. Optimal planting density and irrigation depth are critical for hybrid maize seed production in arid areas. Using data from 2012 to 2017, a new integrated model optimized planting density and border irrigation depth for achieving high yield and seed vigor of hybrid maize under limited water availability. For field experiments, a planting density of 9.75 plants m−2 under full irrigation was in the control treatment. The results showed that water deficit decreased yield, evapotranspiration, and aboveground biomass per plant. The highest yield was obtained for the planting density of 12.75 plants m−2 under full irrigation. The single crop coefficient and crop water production function models were modified to simulate evapotranspiration and yield, respectively. Using kernel number per plant and plant growth rate during the flowering stage, a kernel weight model was established. The maximum yield and minimum irrigation depth were weighted and kernel weight was constrained. Three minimum relative kernel weight (RKWmin) options were considered, option 1 with RKWmin= 1.00 (control), option 2 with RKWmin= 0 (unconstrained), and option 3 with RKWmin ranged from 0.60 to 0.90. In option 1, the optimal irrigation depth during the growing season under control planting density decreased by 24.3–39.4% compared to the conventional practices. In option 2, yield increased but average kernel weight decreased by 25% than control. In the option 3, average yield and water use efficiency increased by 9.2% and 6.5% compared to option 1, respectively. The average planting density decreased by 10.2%, yield reduced by 2.0%, and water use efficiency reduced by 1.7%, but kernel weight increased by 9% compared to option 2. Thus option 3 can be recommended for hybrid maize seed production with limited water availability in arid regions of Northwest China. Our research provided a new theoretical method to improve yield, and ensure seed vigor of hybrid maize in arid regions.

Evaluation of New Fall Rye Cultivar ‘Bono’ in Single and Double Cropping Systems

A new fall rye (FR, Secale cereale L.) cv. Bono was investigated as a novel cropping option in Saskatchewan, Canada. In this study, the performance of Bono was compared to Hazlet FR, and both cultivars were compared to winter triticale (WT, Triticosecale Wittm.) cv. Pika in single cropping (SC) or in double cropping (DC) systems with spring barley (Hordeum vulgare L.) was evaluated in the Dark Brown soil zone, 2019–2021. Five replicated (n = 4) treatments were: (i) BonoFR; (ii) HazletFR; (iii) PikaWT; (iv) Barley–BonoFR; and (v) Barley–HazletFR. The first crop of barley was harvested at soft dough stage, followed by the second crop of FR seeded in the same year and harvested between flag leaf to heading emergence the following summer for greenfeed hay. Bono did not differ (p > 0.05) in DMY (1.2 Mg ha−1) or nutritive value from Hazlet, however, both FRs differed (p = 0.01) from WT by higher nitrogen use efficiency (NUE, 41.0 vs. 33.7) and NDF (541.8 vs. 479.3 g kg–1), but lower CP (155.3 vs. 187.1 g kg–1). Double cropping barley with fall ryes increased total DMY, nutrients yield per ha, and minerals uptake by up to 83% and NUE by 35.3%. In conclusion, Bono fall rye could be an equal quality alternative to Hazlet, although the current higher seed price may delay its adoption.

Índices de eficiência bio-agronômica do consórcio de berinjela e tomate

ABSTRACT The successful intercropping with vegetables depends on the type of crops grown and on the proper handling of tested treatments, such as the time of transplanting a crop in relation to transplanting another crop, among others. Thus, the objective of this work was to evaluate the bio-agronomic performance of eggplant and tomato for industry, in intercropping, in relation to their single crops, as a function of the transplanting time of the eggplant in relation to the tomato and of the cultivation season (summer or winter). The experimental design used was a randomized complete block with ten treatments and four replications, implanted in two growing seasons (from February to September and from August to February), where the treatments consisted of ten eggplant transplanting times (-30, -25, -20, -15, -10, -5, 0, +5, +10 and +15 days in relation to tomato transplantation). In each block, plots of eggplant monocultures were planted in each transplanting time, as well as a plot in tomato monoculture in order to obtain the bio-agronomic indices. The competition and bio-agronomic efficiency indices of the crops and of the intercropped systems were evaluated. The variation in the transplanting time of eggplant in relation to tomato significantly interferes in the bio-agronomic performance of both species. Eggplant transplanting performed between -20 and -15 days compared to tomato transplantation reduces the dominance of one crop over the other and the interspecific competition for environmental resources. The intercropped system has greater land equivalent ratio when the eggplant is transplanted at +15 days after transplanting the tomato.

Desempenho produtivo e eficiência agroeconômica do consórcio rabanete-rúcula sob adubação verde e densidade de plantio

ABSTRACT The cultivation of radish with arugula in strip-intercropped systems is growing in semi-arid environments. The great challenge has been to assess whether there is agro-economic efficiency in the intercrops when fertilized with plant biomass of spontaneous species from the Caatinga biome. Thus, the objective of this study was to evaluate the productive and economic viability of radish and arugula strip-intercrops fertilized with Merremia aegyptia and Calotropis procera biomass equitable amounts from the Caatinga biome at different population densities of arugula at two cropping years. The experimental design used was randomized blocks, with the treatments arranged in a 4x4 factorial scheme, with four replicates. The first factor was constituted by four biomass equitable amounts of M. aegyptia and C. procera (20, 35, 50 and 65 t ha-1 on a dry basis), and the second factor by the population densities of arugula plants [40, 60, 80 and 100% of the recommended density for single crop (RDSC)] intercropped with 100% of the radish RDSC. The highest agro-economic advantages of radish and arugula intercropping were obtained for a land equivalent coefficient (LEC) and monetary equivalent ratio (MER) of 0.55 and 1.35, respectively, for M. aegyptia and C. procera biomass amounts of 54.75 and 54.55 t ha-1 added to the soil. The arugula population density of 100% of the RDSC provided the greatest agro-economic efficiency of the intercropped system of radish with arugula with LEC and MER of 0.58 and 1.33, respectively. The use of M. aegyptia and C. procera biomass from the Caatinga biome, proved to be a viable technology for producers who practice the cultivation of radish and arugula in intercropped systems in a semi-arid environment. The concern of the farmer regarding the preservation of natural resources, as well as with the search for a better quality of life, circumvents the possible limitations that the environment may offer in a given intercropping crop. The option by intercropping system can provide to producers viable alternatives to optimize the planted area, in addition to greater productivity and economic stability of activities on the rural property.

Plant available water capacity (PAWC) of soils predicted from crop yields better reflects within-field soil physicochemical variations

Within field variations of plant available water capacity (PAWC) of soil is one of the major causes of spatial yield variability in dryland agriculture systems, as PAWC interacts with pre-season and in-season rainfall and other climatic variables to determine crop growth and final yield. Quantification of such variations helps to better understand the changes in soil texture and subsoil constraints to inform spatially explicit management practice. An inverse modelling approach to estimate PAWC from crop yields was developed as a more cost-effective alternative to traditional soil sampling methods. In this study, we further extend this approach to predict and map in-field variations of PAWC from yield maps of single and multiple crops. Soil PAWC maps were produced based on inversely predicted PAWC using crop yield maps together with in-field management information, and compared with: 1) available water capacity derived using laboratory-measured soil properties, and 2) soil types derived from proximally sensed soil spectra and ground geophysics for four representative farms in Australia. The results show that the predicted PAWC maps matched well with within-field spatial variation of soil types, and well reflected the impact of soil constraints (e.g. salinity), and soil classifications from soil survey and local experience. This demonstrates that the predicted PAWC from crop yield using inverse modelling can reflect the soil physicochemical variations within-field. The generated PAWC maps can be combined with process-based modelling to predict crop yield and yield zones and to inform spatial field management and soil sampling.

Bio-agroeconomic returns in beet-cowpea intercropping by optimization of population densities and spatial arrangements

One of the great challenges of the beet and cowpea cultivation in crop association is to maintain their productivity as that of their sole counterparts in semi-arid environment. In this context, the objective of this work is to assess whether there is bio-agroeconomic return in associations of beet-cowpea by the optimization of population densities and spatial arrangements of the component crops. Experiments were performed in randomised complete block designs with treatments arranged in a 4 × 3 factorial scheme, with four replications. The first factor was the population densities of cowpea (100, 80, 60, and 40% of the recommended population in single crop - RPSC) in association with beet, and the second factor was the spatial arrangements (2:2, 3:3, and 4:4), formed by beet (B) rows alternating with cowpea (C) rows. The competition and agronomic indices evaluated were aggressiveness, competitive ratio, land equivalent ratio, actual yield loss, intercropping advantage and the productive efficiency index. The economic indicators evaluated were gross income, net income, rate of return and profit margin. High agro-economic efficiency can be obtained in the cultivation of beet and cowpea intercropping when well-managing the factors of production, population densities and spatial arrangement of the component crops. The greatest agro-economic return of the cowpea and beet intercropping was obtained in the population densities of 40 and 100% of RPSC for cowpea and beet, respectively. The 2:2 spatial arrangement between beet and cowpea crops was the one with the best productive performance and higher indicators of economic return. The cowpea was the dominant crop while the beet was dominated.

Remote sensing assessment of available green water to increase crop production in seasonal floodplain wetlands of sub-Saharan Africa

Producing more food for a growing population requires sustainable crop intensification and diversification, particularly in high-potential areas such as the seasonal floodplain wetlands of sub-Saharan Africa (SSA). With emerging water shortages and concerns for conserving these multi-functional wetlands, a further expansion of the cropland area must be avoided as it would entail increased use of blue water for irrigation and infringe on valuable protected areas. We advocate an efficient use of the prevailing green water on the existing cropland areas, where small-scale farmers grow a single crop of rainfed lowland rice during the wet season. However, soil moisture at the onset of the rains (pre-rice niche) and residual soil moisture after rice harvest (post-rice niche) may suffice to cultivate short-cycled crops. We developed a methodological approach to analyze the potential for green water cultivation in the pre- and post-rice niches in the Kilombero Valley Floodplain in Tanzania, as a representative case for seasonal floodplain wetlands in SSA. The three-step approach used open-access remote sensing datasets to: (i) extract cropland areas; (ii) analyze soil moisture conditions using evaporative stress indices to identify the pre- and post-rice niches; and (iii) quantify the green water availability in the identified niches through actual evapotranspiration (AET).We identified distinct patterns of green water being available both before and after the rice-growing period. Based on the analyses of evaporative stress indices, the pre-rice niche tends to be longer (~70 days with average AET of 20–40 mm/10-day) but also more variable (inter-annual variability >30%) than the post-rice niche (~65 days with average AET of 10–30 mm/10-day, inter-annual variability <15%). These findings show the large potential for cultivating short-cycled crops beyond the rice-growing period, such as green manure, vegetables, maize, and forage legumes, by shifting a portion of the nonproductive AET flows (i.e., soil evaporation) to productive flows in form of crop transpiration. A cropland area of 1452 to 1637 km2 (53–60% of the total cropland area identified of 2730 km2) could be cultivated using available green water in the dry season, which shows the significance of such change for food security, livelihoods, and resilience of the agricultural community in Kilombero. A wider application of the developed approach in this study can help identifying opportunities and guiding interventions and investments towards establishing sustainable intensification and diversification practices in floodplain wetlands in SSA.

How to enhance the agronomic performance of cactus-sorghum intercropped system: planting configurations, density and orientation

Clarifying cultivation techniques and making production systems more efficient are practices that have been much sought after in agricultural systems in recent decades. In this context, the forage yield, biological efficiency, and competitive ability, of different cultivation strategies for intercropping forage cactus and sorghum were determined in biosaline production systems from 2018 to 2020 in Brazil. Four experiments were carried out, comprising: 1) cropping configurations for the forage cactus-sorghum intercropping system; 2 and 3) planting densities for the forage cactus intercropped with sorghum with an east-west and north-south row orientation, respectively; and 4) planting densities for the forage cactus and sorghum. Each experiment used a randomised block design with four replications. The intercropped forage cactus and sorghum showed higher productivity than the monocropped systems. The indices of biological efficiency (LER, ATER, LEC and SPI with mean values equal to 1.6, 1.8, 0.6 and 29.0, respectively) and competitive ability (ALGY in average 870.6) show better performance under the intercropped system compared to the single crops. The increased planting density resulted in an increase in productivity under the intercropped forage cactus-sorghum system (on average an increase of 69.4% dry matter). In turn, the orientation had no influence on the productivity of the intercropping system but offered better conditions for the forage cactus when cultivation was in an east-west direction (21.7 Mg ha−1 of dry matter) compared to north-south (17.5 Mg ha−1 of dry matter). Intercropping forage cactus and sorghum using biosaline agriculture is an excellent alternative for a production system in semi-arid environments, especially at higher planting densities (50,000 and 100,000 plants ha−1).

Efficiency of control of segetal vegetation in oats in organic agriculture

The article analyzes the results of studies conducted in the stationary experiment of NSC «Institute of Agriculture NAAS» to determine the impact of different systems of basic tillage on weed agrocenosis of oats in single and mixed crops with legumes (oats + diaper). The aim of the research is to establish the influence of different systems of basic tillage on the level of weediness of crops. The technology of growing crops in the experiment is generally accepted and recommended for the research area. The obtained research results convincingly show that from the replacement of fallow plowing by 20–22 cm by autumn disc cultivation by 10–12 cm weediness of oat crops at the time of its tillering increased from 15 to 25 pieces/m2 on average during the research or 40%. It was found that sowing oat-diaper mixture with 25% bean component, regardless of the system of main tillage, is an effective phytocoenotic agro-measure of control of segetal vegetation and reduces by 9–20% weed binary crops compared to monocotyledons. The priority of application of additional agrotechnical measure of control of segetal vegetation in agrocenosis of oats by carrying out spring pre-emergence loosening of soil by non-shelf implements by 6–8 cm was proved, which allowed to significantly reduce weed infestation. In particular, the spring pre-emergence loosening against the background of fallow plowing and autumn shallow disc cultivation weed reduction of oat crops decreased by 18 and 25% and 20 and 26%, respectively.

Bioenergy crop production potential and carbon mitigation from marginal and degraded lands of India

Bioenergy production from marginal and degraded lands is getting worldwide attention due to its potential for renewable energy, land restoration, soil carbon sequestration and also for meeting the United Nations Sustainable Development Goals. However, majority of the literature reported the bioenergy production prospect based on a single bioenergy crop production system. Therefore, the present article utilizes a multi-criteria analysis to identify India's potential marginal and degraded lands (Pml) and their suitability for bioenergy crop production based on a polyculture zonation technique (PZT) with the projections for bioenergy and carbon mitigation potentials. Ten multipurpose bioenergy crops have been studied, out of which seven hardwood tree species were further selected based on ecological and climate suitability. Results suggested that India accounted for 45.13 million ha (Mha) of Pml, and it could produce 96.82 Mt y−1 of biomass and 6.16 Mt y−1 of biofuel, considering half utilization of the plantation areas. Such productions represent 2.22 EJ y−1 (equivalent to 618 TW h y−1) of bioenergy potential. Around 64 Mt C y−1 can also be sequestered by these plantations and additionally help in meeting carbon sequestration over 2800 MtCO2 by 2030, corresponding to India's nationally determined contribution. According to the spatial validation results via centroid coinciding approach, 14 randomly generated points out of 24 coincided on the centroids of randomly identified land parcels, which were further validated through the ortho-imagery from Google Earth. Our study results can be used for framing suitable strategies for exploring bioenergy production from similar agroecological conditions and also for attaining India's national and international commitments related to land restoration and renewable energy production.

Heterogeneity of soil bacterial and bacteriophage communities in three rice agroecosystems and potential impacts of bacteriophage on nutrient cycling

BackgroundAs genetic entities infecting and replicating only in bacteria, bacteriophages can regulate the community structure and functions of their host bacteria. The ecological roles of bacteriophages in aquatic and forest environments have been widely explored, but those in agroecosystems remains limited. Here, we used metagenomic sequencing to analyze the diversity and interactions of bacteriophages and their host bacteria in soils from three typical rice agroecosystems in China: double cropping in Guangzhou, southern China, rice–wheat rotation cropping in Nanjing, eastern China and early maturing single cropping in Jiamusi, northeastern China. Enterobacter phage-NJ was isolated and its functions on soil nitrogen cycling and effect on soil bacterial community structure were verified in pot inoculation experiments and 16S rRNA gene sequencing.ResultsSoil bacterial and viral diversity and predicted functions varied among the three agroecosystems. Genes detected in communities from the three agroecosystems were associated with typical functions: soil bacteria in Jiamusi were significantly enriched in genes related to carbohydrate metabolism, in Nanjing with xenobiotics biodegradation and metabolism, and in Guangzhou with virulence factors and scarce in secondary metabolite biosynthesis, which might lead to a significant occurrence of rice bacterial diseases. The virus community structure varies significantly among the three ecosystems, only 13.39% of the total viral species were shared by the three rice agroecosystems, 59.56% of the viral species were specific to one agroecosystem. Notably, over-represented auxiliary carbohydrate-active enzyme (CAZyme) genes were identified in the viruses, which might assist host bacteria in metabolizing carbon, and 67.43% of these genes were present in Jiamusi. In bacteriophage isolation and inoculation experiments, Enterobacter bacteriophage-NJ reduced the nitrogen fixation capacity of soil by lysing N-fixing host bacteria and changed the soil bacterial diversity and community structure.ConclusionOur results showed that diversity and function predicted of paddy soil bacteria and viruses varied in the three agroecosystems. Soil bacteriophages can affect nutrient cycling by boosting host metabolism through the carried auxiliary metabolic genes (AMGs) and lysing the host bacteria that are involved in biogeochemical cycles. These findings form a basis for better understanding bacterial and bacteriophage diversity in different rice agroecosystems, laying a solid foundation for further studies of soil microbial communities that support ecofriendly production of healthy rice.

Inoculation with Azospirillum combined with nitrogen fertilization in sorghum intercropped with Urochloa in off-season

The objective of this work was to evaluate the management of nitrogen fertilization in grains of sorghum inoculated or not with Azospirillum brasilense in single crop or intercropped with Urochloa brizantha (cv. Paiaguás) in the off-season. The experimental design was a completely randomized block design with four replications, in a 2 x 2 x 3 factorial scheme, with sorghum in single-cropped system or intercropped with grass; sorghum seeds inoculated or not with A. brasilense; and N management (application of 100% of the dose at sowing or only in topdressing or split - 30% at sowing and 70% in topdressing) at a dose of 120 kg ha-1 N. Morphological components and sorghum grain yield and productivity of dry matter of the aerial part of the grass and the sorghum were evaluated. The splitting of nitrogen fertilization did not interfere in the yield of sorghum grain straw intercropped with U. brizantha. The intercropping with U. brizantha did not reduce sorghum grain yield. In dry climate conditions in the off-season, inoculation of sorghum seeds cv. Ranchero with A. brasilense increases grain yield.