Crop Rotation Systems Research Articles

Migration and transformation of Cd in four crop rotation systems and their potential for remediation of Cd-contaminated farmland in southern China

A crop rotation system combining agricultural production with phytoremediation is an economical and sustainable method of remediation of cadmium (Cd)-contaminated farmland. This study focuses on migration and transformation of Cd in rotation systems and the influencing factors. In a two-year field experiment, four rotation systems were evaluated: traditional rice and oilseed rape (TRO), low-Cd rice and oilseed rape (LRO), maize and oilseed rape (MO), and soybean and oilseed rape (SO). Oilseed rape is a remediation plant in rotation systems. Compared to 2020, the grain Cd concentrations of traditional rice, low-Cd rice, and maize in 2021 decreased by 73.8%, 65.7%, and 24.0% (below the safety limits), respectively. However, soybean increased by 71.4%. The LRO system featured the highest oil content of rapeseed (about 50%) and economic output/input ratio (1.34). Removal efficiency of total Cd in soil was 10.03% (TRO) > 8.3% (LRO) > 5.32% (SO) > 3.21% (MO). Crop uptake of Cd was influenced by bioavailability of soil Cd, and soil environmental factors regulated the bioavailable Cd. Redundancy analysis (RDA) indicated that soil nitrate‑nitrogen (NO3−-N) had a dominant impact on bioavailable Cd in soil, with variance contributions of 56.7% for paddy-upland (TRO and LRO) and 53.5% for dryland (MO and SO) rotation systems. The difference reflected that ammonium N (NH4+-N) was a secondary factor in paddy-upland rotations, while it was the available phosphorus (P) in dryland rotations, with variance contributions of 10.4% and 24.3%, respectively. The comprehensive evaluation of crop safety, production, economic benefits, and remediation efficiency revealed that the LRO system was efficient and more acceptable to local farmers, providing a new direction for the utilization and remediation of Cd-contaminated farmland.

Comparison of Integrated Crop Rotation Systems in Western Canada

AbstractResearch has shown the benefits of diversifying crop rotations, yet many Prairie farmers keep their rotations short and simple with cereals and oilseeds or cereals and pulses being intensively grown in two‐year rotations. As western Canadian farms are pressed to increase yields while reducing inputs and the environmental impact of food production, growers need help to determine what crop rotations can help them achieve these goals and remain economically viable. This article reports on research evaluating yield and yield stability, nitrogen use efficiency, and net economic returns of six crop rotations in the Southern Prairies, Northern Prairies, and Red River Valley ecozones of western Canada. Earn 0.5 CEUs in Crop Management by reading this article and taking the quiz at https://web.sciencesocieties.org/Learning‐Center/Courses.

Modelling interactions between cowpea cover crops and residue retention in Australian dryland cropping systems under climate change

Conservation agriculture management practices (e.g., cover crops and residue retention) have been widely promoted to improve soil quality and environmental sustainability. However, little is known about the long-term interactive effects of cover crops and residue retention on yield of the cash crops and environmental outcomes in dryland cropping systems under climate change. We used the pre-validated APSIM model, driven by statistically downscaled daily climate data from 27 Global Climate Models (GCMs) under two Shared Socioeconomic Pathways (SSP245 and SSP585), to assess the combined influences of cowpea cover crops and three residue retention levels on soil water balance, soil organic carbon (SOC), nitrogen (N) dynamics, crop yield and gross margin across six crop rotation systems during the historical period (1985–2020), near future (2021–2056), and far future (2057–2092) in southeast Australia. Our results showed that, on average, cover crops decreased soil moisture on the day of sowing the succeeding cash crop (by 22%), but led to greater SOC stock (21%), reduced N loss through leaching (71%), and enhanced N uptake and yield of cereals, but decreased N uptake and yield of field pea. The effects of cover crops on yield and gross margin became more positive in the far future under both SSPs, which may be attributed to the SOC increase and greater N availability in the long term. These benefits were more evident under residue removal due to the partly compensatory effects from cover crop residues. Furthermore, cover crops were profitable in the wetter parts of the study region (east), but reduced gross margin in the drier west due to depletion of soil water reserves for the next cash crop. We conclude that particularly where residues are removed, the long-term adoption of cowpea cover crops could be a potential practice to sustain crop productivity with environmental co-benefits under climate change in the wetter parts of the dryland cropping region of southeast Australia.

Microbial functional genes within soil aggregates drive organic carbon mineralization under contrasting tillage practices

AbstractSoil organic carbon (SOC) transformation is susceptible to tillage practices. Conservation tillage is known to optimize soil structure, improve microbial community diversity and increase SOC storage. However, how soil aggregate distribution and microbial community structure and function within aggregates affect SOC transformation under long‐term conservation tillage remains unclear. In this study, SOC mineralization dynamics were studied in situ and under laboratory conditions to examine the mechanisms by which C functional genes within soil aggregates of different sizes (i.e., mega‐, macro‐, and micro‐aggregates) influence SOC mineralization under long‐term tillage (i.e., zero, chisel, and plow tillage) in a dryland. The results indicated that in the winter wheat and summer maize rotation cropping system, SOC‐derived CO2‐C emissions were 143.99 and 133.29 g CO2‐C m−2 h−1 lower under chisel and zero tillage than that under plow tillage, respectively. Moreover, after 180 days of laboratory incubation, SOC mineralization in micro‐ and macro‐aggregates was 1.98 and 1.63 mg CO2‐C g−1 d−1 higher than that in mega‐aggregates, respectively. The aggregate‐associated differential modules of bacterial co‐occurring networks may be directly governed by bacterial community diversity and composition, which might play critical roles in driving SOC mineralization in response to different tillage intensities. Moreover, aggregate‐associated functional genes involved in labile and recalcitrant C compositions, which were determined by shotgun metagenomic sequencing, were associated with SOC mineralization and were significantly affected by the legacy effect of tillage intensity and aggregate size. Particularly, partial least squares path modeling revealed that genes involved in simple sugar metabolism exerted significantly positive effects on SOC mineralization, except for the effects of tillage intensity and aggregate size. Overall, this study showed that decreased abundances of labile C decomposition‐related functional genes within aggregates and community composition changes, as elucidated by the differences in bacterial network modules, under conservation tillage inhibit SOC mineralization. These findings may help in the development of adaptive soil tillage strategies for reducing carbon emissions in agroecosystems.

Different composites inhibit Cd accumulation in grains under the rice-oilseed rape rotation mode of karst area: A field study

Ensuring the safe production of food and oil crops in soils with elevated cadmium (Cd) content in karst regions is crucial. We tested a field experiment to examine the long-term remediation effects of compound microorganisms (CM), strong anion exchange adsorbent (SAX), processed oyster shell (POS), and composite humic acids (CHA) on Cd contamination in paddy fields under a rice-oilseed rape rotation system. In comparison to the control group (CK), the application of amendments significantly increased soil pH, cation exchange capacity (CEC), and soil organic matter (SOM) content while markedly decreasing the content of available Cd (ACd). During the rice cultivation season, Cd was predominantly concentrated in the roots. Relative to the control (CK), the Cd content in each organ was significantly reduced. The Cd content in brown rice decreased by 19.18–85.45%. The Cd content in brown rice following different treatments exhibited the order of CM > POS > CHA > SAX, which was lower than the Chinese Food Safety Standard (GB 2762–2017) (0.20 mg/kg). Intriguingly, during the oilseed rape cultivation season, we discovered that oilseed rape possesses potential phytoremediation capabilities, with Cd mainly accumulating in roots and stems. Notably, CHA treatment alone significantly decreased the Cd content in oilseed rape grains to 0.156 mg/kg. CHA treatment also maintained soil pH and SOM content, consistently reduced soil ACd content, and stabilized Cd content in RSF within the rice-oilseed rape rotation system. Importantly, CHA treatment not only enhances crop production but also has a low total cost (1255.230 US$/hm2). Our research demonstrated that CHA provides a consistent and stable remediation effect on Cd-contaminated rice fields within the crop rotation system, as evidenced by the analysis of Cd reduction efficiency, crop yield, soil environmental change, and total cost. These findings offer valuable guidance for sustainable soil utilization and safe production of grain and oil crops in the context of high Cd concentrations in karst mountainous regions.

Dynamics of Micronutrient Uptake and Removal by Three Modern Runner Peanut Cultivars

Micronutrient fertilization is usually neglected by producers, especially for peanut, a crop that is frequently grown in crop rotation systems due to its low perceived nutrient requirements. New peanut cultivars are able to achieve high yields when grown under suitable conditions. However, fertilization recommendation tables are dated and do not consider the need for micronutrients. To support improvements in these recommendations, this study quantified the micronutrient demand (B, Cu, Fe, Mn, and Zn) of three runner peanut cultivars (IAC Runner 886, IAC 505, and IAC OL3) during the biological cycle and the transport of these micronutrients to pods and kernels. The experiment was carried out in a randomized complete block with a split-plot design and nine replications. The whole plots consisted of the three peanut cultivars, and the subplots comprised nine plant samplings (at 14, 28, 42, 56, 70, 84, 105, 126, and 147 days after emergence (DAE)). These modern peanut cultivars exhibited high uptake and accumulation of Fe, but the proportion of Fe removed by pods and kernels was lowest among all analyzed micronutrients. The second-most-accumulated micronutrient was Mn. The maximum requirement for micronutrients of peanut occurred around 84 DAE, and IAC 505 had the highest micronutrient uptake and accumulation among the cultivars (especially at later stages), followed by IAC OL3 and IAC Runner 886. Our results provide new insights into micronutrient requirements for peanut and demonstrate the need for new fertilizer recommendation programs for peanut cultivation.

Economics of Subsistence Farming: A Comparative Analysis of Paddy-wheat and Maize-wheat Rotation Cropping System in Himachal Pradesh

Background: Marginalisation of Indian agriculture, due to increase in marginal and small agricultural households, brings the focus back on subsistence agriculture. Among other things, understanding the economics of subsistence agriculture will go a long way in making its practice viable by making sure the help that these subsistence farmers need are provided. Therefore, the present study attempts to study the economics of paddy-wheat and maize-wheat rotation cropping system practiced by subsistence farmers of Himachal Pradesh whose agriculture sector is known for its diversification towards high value crops. Methods: The study has used survey data collected from 60 randomly selected households from Rait block of district Kangra, Himachal Pradesh. 30 households practicing paddy-wheat rotating cultivation are selected from Boh and Drini village and 30 households doing Maize-Wheat rotating cultivation are from Machhlini, Panjol, Khridi, Rulede and Lahri village. The study is based on primary data which has been collected through a pre-tested schedule. Using the primary data, we have brought out factors other than self-consumption needs that determines choice between two farming systems and also two group of farmers are compared in terms of productivity, cost of cultivation and net returns from cultivation. Result: Our study found that irrigation facilities play an important role in the choice between the two cropping systems. Return from cultivation is negative for both groups of farmers if imputed value of family labour is included. Performance of paddy-wheat farmers is significantly better than maize-wheat farmers in economic terms in the study area.

Constraints Faced by the Farmers in the Adoption of Crop Rotation in Ayodhya District

Crop rotation is an agronomic practice of growing a series of diff erent types of crops in the same area in a sequential season. Crop rotation is one of the most important practises in organic farming and carbon sequestration. It improves the soil’s physical and chemical properties and also changes the biological environment of the soil. Farmers face obstacles to adopt diverse crop rotation systems. Farmers face numerous barriers when it comes to adopt new or unfamiliar practises such as modifi ed crop rotations. These include market and fi nancial barriers, constraints regarding crop insurance and loans, technical and informational barriers and so on. Major constraints faced by the farmers in knowledge and adoption of crop rotation were ‘Estray animal’, ‘Lack of resources’, ‘Small land holding’ ,‘Diffi cult to maintain multiple activity of crop rotation’ etc. Here, ranking technique is used to determine the most important factor infl uencing the response. Main aim of this paper is to identify the barriers in the adoption of crop rotation as well as potential solutions.

The Effect of Farming Management and Crop Rotation Systems on Chlorophyll Content, Dry Matter Translocation, and Grain Quantity and Quality of Wheat (Triticum aestivum L.) Grown in a Semi-Arid Region of Iran

To find suitable farming management approaches in the semi-arid climate of Iran, we set up an experiment combining three farm management practices with four crop rotation systems over four growing seasons (two winter and two summer seasons), from 2018 to 2020. The three farm management practices comprised: intensive (IF, with inorganic inputs, removal of crop residues from the soil, and weeds chemically controlled), organic (OF, with organic inputs, a return 30% of crop residues in the soil, and weeds mechanically controlled), and integrated (INT, with mineral/organic inputs, return 15% of crop residues to the soil, integrated weed control). The four crop rotation systems were: fallow-wheat (F-W), maize-wheat (M-W), sesame-wheat (S-W), and mung bean-wheat (B-W). Treatment effects were assessed by chlorophyll (Chl) content, photosynthetic parameters, and wheat grain quality and quantity measurements. All management practices from the first to the second year resulted in increases in the total Chl content and post-anthesis photosynthesis (PAP). The total Chl content under INT was improved through a greater increase in Chl-b compared to Chl-a. Dry matter remobilisation (DMR) was higher under INT than under IF. The highest (39) and lowest (23) grain number per spike were obtained in IF under B-W and OF under F-W, respectively. B-W produced the highest grain yield (541.4 g m−2). The protein contents in farming with organic matter inputs were higher than that under IF. INT produced an optimum level of wheat yield despite a 50% reduction in chemical inputs, and this was achieved through the fast absorption of chemical elements at the beginning of growth, and having access—at the grain filling stage—to elements derived from organic matter decomposition, and through the utilisation of DMR. Our results indicate that implementing B-W and S-W under INT is a promising strategy for this region. However, the results need to be further evaluated by long-term experiments.

Histological characterization of wild cucumber resistance to Meloidogyne species

Using nematode resistant varieties is one of effective and environmental sound strategies being adopted in the management of economically important Meloidogyne species. Wild cucumber (Cucumis africanus) has been reported to possess resistance to Meloidogyne species. Two mechanism of nematode resistance, pre- and post-penetration resistance, had been identified, with post-penetration mechanism being used in plant breeding programs and crop rotation systems. The objective of this study was to determine the mechanism of nematode resistance in C. africanus to M. incognita and M. javanica. 6 weeks old C. africanus seedlings were separately inoculated with 100 s-stage juveniles (J2) of M. incognita and M. javanica. For 30 days, five seedlings were harvested from both M. incognita and M. javanica experiments every other day. Seedlings’ roots were examined for necrotic spots, rootlet interferences, giant cells and root gall numbers as indicators of successful or unsuccessful nematode penetration. Harvesting times were highly significant (P ≤ 0.01) on necrotic spot, rootlet interference and root gall numbers in both C. africanus—M. incognita and—M. javanica relations, but were not significant for giant cell number in C. africanus—M. incognita. The results suggested that C. africanus have post-penetration nematode resistance to both Meloidogyne species.

A Case Study of Workable Precipitation in a Large-scale Crop Rotation System on Paddy Fields

A Case Study of Workable Precipitation in a Large-scale Crop Rotation System on Paddy Fields

The presence of soybean, but not soybean cropping frequency has influence on SOM priming in crop rotation systems

Legume crops are advocated for integration into crop rotation systems, and cereal-based rotations with the presence of legumes have a substantial effect on improving soil fertility and health. It is not yet clear whether the frequency of legume inclusion in crop rotation systems influences soil biochemical properties and soil organic matter (SOM) mineralization. An incubation experiment was conducted with 13C-glucose addition to evaluate the influences of soybean (Glycine max L.) cropping frequency on SOM mineralization under long-term wheat (Triticum aestivum L.)- and maize (Zea mays L.)-based rotation systems. Phospholipid fatty acids (PLFAs) and 13C-PLFAs were measured to explore microbial biomass, community structure and microbial utilization of glucose in wheat and maize systems. Glucose addition increased native SOM mineralization, i.e. positive priming effect. Compared with less soybean cropping frequency under long-term wheat- and maize-based rotation systems, wheat-soybean-soybean-soybean rotation and maize-soybean-soybean rotation increased the total biomass (PLFAs), fungal biomass and decreased the ratio of bacteria to fungi. Furthermore, the ratio of bacteria to fungi was negatively correlated with PE intensity, indicating that greater fungal biomass played a key role in stimulating SOM priming. That the proportion of 13C-glucose in G- and fungi had a positive relationship with PE intensity also supported this conclusion. The presence of soybean in wheat- and maize-based rotations increased SOM priming, while the soybean cropping frequency had no significant influence on SOM priming. However, in contrast to a maize-based rotation system, the same frequency of soybean in a wheat-based rotation system had lower soil C/N ratio and higher B/F ratio, and resulted in lower PE intensity. Our findings indicated that the presence of soybean in wheat- and maize-based rotation systems increased PE intensity because of higher soil C/N ratio and lower B/F ratio, while the soybean cropping frequency had no significant influence on SOM priming. Furthermore, the presence of soybean in maize system induced more SOM priming than that in wheat system with glucose addition.

Exploring the Possibility of Chickpea (Cicer arietinum L.) Growing as Second Crop under Uşak Ecology

Tends on human nutrition change every day but legumes act significant role for nutrition over the World. Chickpea (Cicer arietinum L.) is a member of Leguminosae family and originated from Asia. Chickpea is rich with protein, carbohydrate, lipid and minerals. It is also sufficient for Daily requirement by view of the essential amino acids – lysine, leucine and arginine. Chickpea is also source of soluble and insoluble fibers. The nutritional fibers have favorable effects on decreasing the time of food passing through intestine, accelerating of weight loss, decreasing of total and LDL cholesterol and balancing of blood sugar level. Sustainability of agriculture is essential for sustainability of life. From this perspective, chickpea is quite important due to various agronomic advantages that may be summarized by main ones are; able to grow as winter crop, lower water requirement, wide adaptation ability to climate and soil, a good alternative for crop rotation systems in addition to health care features. Present research is realized to evaluation of second crop growing facilities in Uşak/Turkey ecology by using 4 chickpea genotypes (Azkan, Hisar, Sarı-98, Yaşa-05) by 4 sowing time (18th June, 02nd July, 16th July, 30th July) by 3 replications. The following measurements were realized; days to emergence, days to flowering, days to harvest, height of plant, number of pod per plant, number of seed per pod, height of first pod, seed yield and weight of hundred seeds. According to the results Yaşa-05 chickpea genotype was determined as the most adaptable in addition to the Azkan chickpea genotype was also obtained as promising to growing as second crop. Deep and long term studies are needed to achievement of more consistent results and providing to sustainability of food security, improvement of soil, better usage of natural sources and contribute to national economy.

Assessing Liquid Inoculant Formulation of Biofertilizer (Sinorhizobium meliloti) on Growth, Yield, and Nitrogen Uptake of Lucerne (Medicago sativa)

Lucerne is regarded as the best legume crop for forage to be cultivated in South Africa. It is commonly used to produce good quality hay. It also plays an important role in soil conservation, regeneration, and crop rotation systems as it supplies substantial amounts of nitrogen to succeeding crops through symbiotic N2 fixation, which makes it the preferable choice for intensive forage production systems. Fertilizer in liquid inoculant formulations has demonstrated to contribute growth and yield increase for leguminous crops. Therefore, the aim of this paper was to determine the effects of Sinorhizobium meliloti liquid formulation inoculation on the growth, yield, and nitrogen content in lucerne. The strain RF14 (Sinorhizobium meliloti) was collected from the Agricultural Research Council at Roodeplaat (Plant Health and Protection located (East), Pretoria (South Africa). The liquid inoculant contained 6.5 × 109 viable cells mL−1. According to the Kooen–Gieger climatic classification, the experiments were conducted on two different climatic zones. The first site was in Bronkhorspruit (Blesbokfontein farm) in the Gauteng province and the second was in Hartbeesfontein (Rietfontein Farm) in the Northwest province. The results showed that lucerne inoculation with liquid inoculant formulation of Sinorhizobium meliloti significantly increased nodule number, size, growth, and yield in both bioclimatic zones. The significantly increased were compared to the negative control. The Sinorhizobium meliloti inoculant increased nitrogen accumulation in all inoculated treatments compared to the control. The finding of this research provides important information on the impact of rhizobium microbial inoculant application in the improvement of soil fertility through nodule formation. In addition, seed vigor improvement was translated in overall growth and yield increase in lucerne plants.

Seed Germination of Three Milk Thistle (Silybum marianum (L.) Gaertn.) Populations of Greek Origin: Temperature, Duration, and Storage Conditions Effects

Milk thistle besides being a highly competitive weed is cultivated as a medicinal plant, and the seeds of which have been clinically utilized in several disorders caused in liver. The present study aims to evaluate the effect of duration and storage conditions, population, and temperature on seed germination. The experiment was conducted in Petri dishes with three replications and three factors: (a) wild populations of milk thistle (Palaionterveno, Mesopotamia, and Spata) originating from Greece, (b) duration and storage conditions (5 months at room temperature, 17 months at room temperature, and 29 months in the freezer at -18 °C), and (c) temperature (5 °C, 10 °C, 15 °C, 20 °C, 25 °C, and 30 °C). All three factors significantly affected germination percentage (GP), mean germination time (MGT), germination index (GI), radicle length (RL), and hypocotyl length (HL) and significant interactions among the treatments were noted. In specific, no seed germination was recorded at 5 °C, while the populations showed higher GP and GI at 20 °C and 25 °C after 5 months of storage. Prolonged storage negatively affected seed germination although, cold storage mitigated this effect. Moreover, higher temperatures reduced MGT and increased RL and HL with the populations reacting differently in storage and temperature regimes. The results of this study should be taken into consideration when proposing the appropriate sowing date and storage conditions of the seeds used as propagation material for crop establishment. Moreover, the effects of low temperatures such as 5 °C or 10 °C on seed germination as well as the high decline rate in germination percentage over time could be utilized in the design of integrated weed management systems thereby indicating the importance of the sowing time and the suitable crop rotation system to weed control.

Integrated weed management strategies in a long-term crop rotation system

Background Diversified crop systems provide several advantages for crop production and the agricultural ecosystem. In contrast, growing the same crop for consecutive years increases weeds, insects, and diseases issues, adding further cost to crop production owing to their management. Objective The objective was to evaluate the effects of six different winter cover crops and compare the impacts of a diversified rotation system in contrast to the succession system, combined with three different post-emergence herbicide management looking up to soybean [...]

Highland Management in Rotation and Mono Cropping Systems of Li Sub-watershed, Lamphun Province

The objectives of this research are: 1) To compare the factors of land tenure, ecological aspects, economic conditions, perception of information and wisdom affecting the selection in highland rotation cropping and mono cropping. 2) To analyze and identify differences in land management between highland rotation cropping and mono cropping. And 3) to analyze and assess the link between the intensive highland rotation cropping and mono cropping with soil management and degradation. There were quantitative and qualitative data collections from farmer groups of both systems by using the tools as questionnaires and in-depth interviews with participant observation including exploring the research area plot. The data were analyzed using descriptive statistical method in the form of frequency distribution, percentage and comparison table. The results showed the land tenure of the two highland cropping systems was not different. There were no documents and rights over the lands. Rotation cropping system focused on intensive commercial agricultural production, whereas mono cropping system focused on subsistence. Both systems used traditional wisdom. The characteristics of rotation cropping were separated rotation cropping with legumes and no legumes, so crops could be grown throughout the year and continuously. Therefore, the soil management was intensive and the soil was not time for resting. The characteristics of mono cropping system involved growing only one type of crop every other year and year after year. There was a one-year soil resting and the mono crops were replanted annually, so there was not the soil resting. There are differences in the use of chemical fertilizers and concentrated chemicals, as well as soil fertility. It could be concluded that both of cropping systems were not different and had moderate fertility The soil erosion in rotation cropping system was very low to moderate level, thus soil condition was sustainable. The soil erosion in mono cropping system was low to very severe level, thus soil condition was not sustainable.The policy and action recommendations, the government should support in terms of alternative agricultural policies and budgets for developing highland areas seriously and comprehensively in accordance with the sufficiency economy.

Efficacy of different amendments and residual effects on nickel toxicity and nutritional quality in wheat/rice continuous system and health risk assessment in Ultisol

ABSTRACT Rice straw (RS), biochar (BC) and lime (LM) have proved to be effective immobilizing agents in acidic contaminated soil. Up-to-date scientific data is lacking regarding residual effects of these amendments in acidic soils and wheat/rice cropping system. The objective was to analyze the efficacy of amendments to improve grain yields, nutritional quality, and reduce Ni bioavailability of wheat/rice rotation system. A pot experiment was conducted to examine the efficacy of RS, BC 10 and 20 g kg−1 and LM 10 g kg−1 application rates on plant growth, nutritional quality and Ni contents in wheat and rice tissues and grain. Amendments enhanced Ni immobilization, declined their uptake by plants and accumulation in the grains of both crops. Rice straw biochar reduced several factors like health risk assessment, Ni uptake and bioconcentration factor. BC 20 g kg−1 increased shoot, root and grain yields, while enhanced essential nutrients in the wheat/rice cropping system compared to untreated soil. Soil amendments significantly decreased toxicity characteristics leaching procedure (TCLP) extractable Ni by 42.25% and 42.62% and simple bioaccessibility extraction test (SBET) by 42.1% and 45.25% in post- wheat/rice crops. This process enhanced the safety of wheat/rice rotation cropping system to be consumed and mitigated security risks.

German Colonies of St. Petersburg Province

Russia of the 18th – 19th centuries faced a crucial challenge of sparsely populated suburbs consolidation through their economic development. Acute shortage of work force to be involved for transformation of Novorossiya, the steppes of the North Caucasus and the Middle Volga region, Siberia and some other regions into the centers of commodity agriculture and industrial production, forced the authorities to turn to the use of European experience and place a bet on foreign colonization. Central Europe, devastated by the Seven-Year War, brought to life tens of thousands of potential colonists, who answered the call of Empress Catherine the Great to move to the unoccupied lands of the Russian Empire. Since 1765, the first colonies (Novo-Saratovka, Srednaya Rogatka, Yamburg and Izhora colonies) were formed near St. Petersburg. Investigation of the history of these settlements in the imperial period is extremely poor in modern historiography. The article examines the initial period of their existence (1765 – 1800s). It took about 30 years for German colonists to adapt to new living conditions. Some colonies (Srednaya Rogatka) became centers of commodity production of agricultural products (potatoes, etc.), sold in the capital-city market, at the beginning of the 19th century already. Experiments on the advanced multi-field system implementation, initiated by Semyon Dzhunkovsky, opened the way to increase productivity and income of the colonists. The new crop rotation system spurted into popularity not only in the colonies, but in the neighboring settlements of Russian peasants as well. The article is intended for specialists engaged in the study of agrarian development, ethnic minorities of Russia in the imperial period.

Impacts of winter wheat and cover crops on soil microbial diversity in a corn–soybean no‐till cropping system in Quebec (Canada)

AbstractIntensive agriculture based on repeatedly plowing a monoculture is known to degrade the structural, chemical, and biological properties of soils. Conservation agriculture is gaining popularity worldwide with practices including reduced tillage, increased plant diversity, and implementation cover crops. The aim of this study was to assess the impact of crop rotation and cover crops on soil microbial communities. The hypothesis was that enhanced plant diversity would boost the diversity of the soil microbiome. Two rotation were tested by adding a cereal (corn [Zea mays L.]–soybean [Glycine max (L.) Merr.] and corn–soybean–wheat [Triticum aestivum L.]), as well as the implementation of cover crops. The enhanced plant diversity had no impact on total molecular biomass. The bacteria/fungi ratio varied across the plots but was not clearly linked to the enhanced plant diversity. Bacterial richness was not influenced by the treatments, whereas eukaryotic richness decreased in the presence of cover crops in one of the sites. Microbial composition was the most sensitive indicator to enhanced plant diversity. Differential relative abundance (log2 fold changes) identified proteobacterial amplicon sequence variants (ASVs) specifically related to each crop rotation system and to the presence of cover crops. There was more ASV of Actinobacteria associated with the three‐crop rotation system and less ASV of Acidobacteria associated with the cover crops system compared to the two‐ and three‐crop rotation systems, respectively. As for eukaryotes, the number of ASVs belonging to Ascomycota and Cercozoa phyla and associated with the three‐crop rotation system is less important than for the two‐crop rotation system. This study shows that conservation agricultural practices can influence soil microbial communities. The variations in some ASVs could have functional implications on organic matter decomposition or plant growth and in terms of soil ecosystem services and field crop sustainability.