Fallow Period Research Articles

The Potential of Three Summer Legume Cover Crops to Suppress Weeds and Provide Ecosystem Services—A Review

Recently, there has been growing interest in the use of summer cover crops that can be grown during summer fallow periods of crop rotation. This study evaluates the potential of sunn hemp (Crotalaria juncea L.), velvetbean [Mucuna pruriens (L.) DC.] and cowpea [Vigna unguiculata (L.) Walp.]. as three annual legumes summer cover crops. The main objective of this review was to conduct global research comparing these summer cover crops to investigate the benefits, challenges, and trade-offs among ecosystems services when implementing these summer cover crops. In European agriculture, there are three main windows in crop rotation when these summer legumes can be grown: Around mid-spring after winter fallow, early summer after harvest of a winter crop, and mid- to late summer after harvest of an early-season crop. All three legumes can suppress weeds while they are actively growing. After termination, their mulch can create unfavorable conditions for weed emergence. Sunn hemp and velvetbean cover crops can cause a reduction in weed biomass of more than 50%. In addition to their ability to suppress weeds, sunn hemp, velvetbean, and cowpea provide a variety of ecosystem services, such as improving soil health, quality, and fertility, controlling pests, and sequestering carbon. The review highlights their promising role in weed suppression and their contribution to sustainable agricultural practices. However, further research is needed to evaluate their performance in weed management and their environmental impact in field trials under different soil-climatic conditions, as cover cropping is an effective practice but highly context-specific.

Topography of a Painting: Carel Weight’s Holborn Circus, 1947

In the modern era, London’s streetscape changes with great rapidity as buildings are demolished and replaced. Carel Weight’s painting, Holborn Circus, 1947, records that fallow period between bombsite and rebuilding that often lasted for years after the war, but now is often only a matter of weeks. Weight had not long returned from ten months in Europe as an official war artist when he painted the scene around Holborn Circus from a friend’s studio flat. It is an image of a London past: almost nothing in this painting still exists, and the streetscape has changed more than once since the 1940s. While there is nothing especially innovative about the painting, it addresses our nostalgia for what was and is no more through the vision of an artist tempered by experience of war-ravaged Italian cities. This article situates Weight’s painting in the context of other depictions of London after the war and describes the fundamental changes to the area wrought by widespread demolition and reconstruction in the post-war era.

Maize Straw and Nitrogen Fertilizer Alter Soil Carbon and Nitrogen Mineralization during the Fallow Period in the Oasis Farmland area

Maize Straw and Nitrogen Fertilizer Alter Soil Carbon and Nitrogen Mineralization during the Fallow Period in the Oasis Farmland area

Effects of aquaculture effluents on the slender sea pen Virgularia mirabilis

This study aims to assess in situ the impact of effluents originating from an Atlantic salmon (Salmo salar) farm on a nearby slender sea pen (Virgularia mirabilis) field. We evidenced (1) the presence and persistence of emamectin residues (i.e. a common chemotherapeutants used for treating ectoparasites in salmons) in V. mirabilis tissue 56 days after treatment and (2) lethal and sublethal responses of V. mirabilis to effluents discharged by the salmon farm. Particularly, sea pens near the fish farm exhibited significant overproduction of mucus, contraction of polyps’ tentacles, and disappearance of associated fauna. Furthermore, sea pens located directly underneath the farm showed substantial tissue necrosis and, in the most severe case, complete tissue loss and mortality. Our results suggest that lethal damages on sea pens occur directly below the farm, and that sublethal effects are visible up to 500 m from the farm. However, the presence of V. mirabilis below the studied farm, which has been active for more than twenty years, suggests that V. mirabilis population possesses the capacity to recover from the impacts of the farm, thereby preventing the complete disappearance from the area. In this context, it would be particularly interesting to run a temporal survey following the health state of V. mirabilis during an entire production cycle to have a more precise overview of fish farm impacts on this species, including during and after the post-production fallowing period.

Assessing Microbial Diversity in Páramo Soils (Multistrategy Analysis): Effects of Potato Farming and Livestock Grazing in Nevados National Natural Park, Colombia

High Andean Páramos are very fragile neotropical ecosystems. Moreover, biodiversity in these areas is threatened by the anthropic activities of agriculture, cattle raising, and mining and has been little studied. Changes associated with potato farming and livestock grazing on microorganisms of Páramo soil of the Nevados National Natural Park (Nevados NNP) were assessed by (1) determination of physical and chemical properties (physicochemical matrix) and enzymatic activities associated (enzymatic activity matrix) with different biogeochemical cycles (C, N, and P); (2) microbial community functional diversity via evaluation of functional groups associated with carbon, nitrogen, and phosphorus cycles using cultivation-dependent techniques (arable functional group matrix and most probable number matrix); and (3) microbial diversity using cultivation-independent techniques that employ the hypervariable V5–V6 region of the 16S rRNA gene and pyrosequencing (16S-454 genus matrix and 16S-454 OTU matrix). Four of the six evaluated matrices (physicochemical, enzymatic activities, most probable number, and arable functional groups) revealed significant differences according to land use. The strategy adopted by the arable functional group matrix, in which the diversity of nitrogen fixation, phosphate solubilization, and cellulolytic compounds was evaluated, showed the most significant impacts of the different factors (land use, season, and elevation), especially those caused by potato cultivation and livestock. These results indicate that the initial impacts of potato farming and livestock grazing on the microbial community in El Bosque Village are better detected by functional diversity analysis than by molecular analysis of the 16S rRNA gene V5–V6 variable region. The results may have been caused by the type of molecular marker used in the analyses and the type of agricultural practices used by peasant farmers, which affect the functional diversity of the soil community. Among these practices are the maintenance of fallow periods greater than 7 years between each potato crop and the small proportion of cattle in relation to the total land area of the village. As the findings can be interpreted as an indicator of the early impacts of potato cultivation and livestock on microbial diversity, the effects of implementing community management plans, applying agroecological models, retaining biocultural memory, and changing agrarian structure are relevant for mitigating future changes.

Waste-Based Vertical Planting System Proposal to Increase Productivity in Sustainable Horticulture; “PETREE”

The problems experienced with the decrease in agricultural areas per capita against the uncontrolled population growth in the World and in Turkey are becoming increasingly evident. Especially the manpower engaged in horticulture is increasingly experiencing the problems of migration, economic reasons, and inefficient production methods. For healthy and efficient production, agricultural lands need a sequential cycle that includes cultivation and fallow periods. Agricultural lands, the salt they contain, etc. When left fallow, the soil area needs to rest to re-establish the mineral balance. It is now vital for small producers, whose production areas are gradually shrinking due to global conditions, to continue production while their lands are resting to produce more continuously and efficiently. In the face of increasing demands, decreasing production amounts and areas, the constantly increasing prices of economically simple agricultural products “fresh vegetables” and affecting the easy accessibility of local products, it has become inevitable to seek new and alternative solutions. This study includes an innovative solution proposal to increase the production efficiency of low-scale producers and individual gardeners, especially those producing in small agricultural areas. Critical problems of large-scale greenhouse systems, interactions of agricultural practices within the framework of urban life, water and energy efficiency in agriculture, and sustainability and waste management of the proposed system are examined. To meet changing conditions and maintain productivity in small areas, it is envisaged that mobile and vertical production stations, which can produce by increasing productivity even in fallow areas while the soil is resting, can be an alternative solution to the problems of small producers. The vertical planting system “PETREE” develops mobile units for sustainable agriculture by collecting 5th LT-PET packages, which have a natural lifespan of about 90 years, and reusing them as plant pots and some recycled plastic pieces as structures. With efficient and environmentally friendly design suggestions, the system also examined the possibilities of more efficient gardening with mobile production stations in small agricultural areas, and efficient and enjoyable gardening that suits the needs of urban consumers “production with local seeds and seedlings” with the increase in environmental awareness and food safety concerns.

Stover removal has minimal impact on pennycress seeded into standing corn

AbstractIn the Upper Midwest, corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] are the most prominent agricultural crops, occupying land for only half the year. Their fallow periods are associated with nutrient leaching and soil erosion, but they also represent an opportunity to establish winter‐hardy crops, like pennycress (Thlaspi arvense L.), that can reduce negative environmental impacts while contributing to farm profitability. A lack of agronomic best management practices remains a barrier to pennycress adoption. The objectives of this study were to evaluate the impact of stover presence on pennycress stand establishment and seed yield after seeding pennycress into R4 corn. This study was conducted over the 2014–2015 and 2015–2016 growing seasons with MN106 pennycress at three locations in Minnesota. At maturity, corn plants were removed from plots in 25% increments between 0% and 100% to simulate stover removal scenarios. Pennycress seedlings were unable to compete with corn for available light resources and did not have enough time following corn harvest to establish a dense stand in the autumn with only 5% and 10% green cover in 2014 and 2015, respectively. Despite poor early season emergence, the average seed yield, 1223 kg ha−1, was high relative to other studies using MN106, indicating that challenges of growing pennycress under adverse conditions may not be a barrier to competitive seed yields. Experimentation on the corn–pennycress system should continue in the future to further explore and establish best management practices for this double crop.

A Typical Small Watershed in Southwestern China Is Demonstrated as a Significant Carbon Sink

Small watersheds are fundamental units for natural processes and social management in Southwestern China. Accurately assessing carbon sinks in small watersheds is crucial for formulating carbon sink management policies. However, there has been a lack of assessment of the dynamics of carbon fluxes in the major ecosystems of small watersheds. Here, we selected the Reshuihe River watershed, which is a typical small watershed in Southwestern China, to measure carbon fluxes using eddy covariance systems for two years (October 2021 to September 2023) from three major ecosystems, namely forest, cropland, and non-timber forest. We compared variations and controlling factors of net ecosystem exchange (NEE), gross primary productivity (GPP), and ecosystem respiration (Re) among different ecosystems, and estimated annual watershed carbon flux based on the land cover areas of the three ecosystems. This study found that three ecosystems were net annual carbon sinks during the study period. Forest was the strongest (−592.8 and −488.1 gC m−2 a−1), followed by non-timber forest (−371.0 gC m−2 a−1), and cropland was the smallest (−92.5 and −71.6 gC m−2 a−1), after taking fallow period into account. Weeds were a significant source of carbon flux in non-timber forest ecosystems. It was also found that variations in daily NEE were controlled by photosynthetically active radiation and soil volumetric water content, with weak effects related to temperature also being observed. However, when the temperature exceeded 21 °C, GPP and Re were significantly reduced in cropland. Finally, it was discovered that the total carbon sink of the three ecosystems in the watershed for one year was −52.15 Gg C. Overall, we found that small watersheds dominated by forest ecosystems in Southwestern China have a strong carbon sink capacity.

Soil fungal communities under slash‐and‐burn system in Mozambique: A metataxonomic approach

AbstractThis study provides a metataxonomic analysis of the fungal communities in soils under slash‐and‐burn agroforestry system and offers new insights into the relationships between fungal populations and soil physicochemical features such as pH, the particle size distribution, easily oxidizable organic carbon, total nitrogen, available phosphorus, and the mineralogical composition. Soils from three locations in central Mozambique—Vanduzi, Sussundenga, and Macate—that are subjected to slash‐and‐burn were considered to assess the effects of the forest fallow length (temporal variation) and of the land use (charcoal kiln, crop field, and forest; meaning horizontal variation) on the fungal community. The fungi of the genetic horizons (vertical variation) were also considered. Most of the detected fungi were decomposers, antagonists of plant pathogens, and plant‐growth promoters; they were differently distributed in relation to the soil's physicochemical properties and the soil use. The variations in the fungi distribution among the locations and between the horizons were considerable, while there were few variations between the different land‐use types. The limited differences between land uses indicate the inability of a forest fallow period shorter than 50 years to improve soil fertility and induce changes in the fungal community. The pedological approach used to identify and sample soil horizons allowed us to clearly distinguish the fungal community of the A horizons, those richest in organics and nutrients, and that of the Bo horizons, which have poor fertility.

Estimating soil N2O emissions induced by organic and inorganic fertilizer inputs using a Tier-2, regression-based meta-analytic approach for U.S. agricultural lands

Consistent methods are essential for generating country and region-specific estimates of greenhouse gas (GHG) emissions used for reporting and policymaking. The estimates of direct N2O emissions from U.S. agricultural soils have primarily relied on the use of emission factors (EFs, Tier-1) and process-based models (Tier-3). However, Tier-1 estimates are relatively crude while Tier-3 calculations can be costly. This work addressed this gap by developing a Tier-2, regression-based approach by leveraging a meta-database containing 1883 field N2O observations together with environmental and management covariates from 139 studies. Our results estimated higher monthly soil N2O emissions (N2Om, kg N/ha) during the growing season (0.38) than the fallow period (0.15), highlighting the importance of considering measurement periods when utilizing meta-databases for analyzing N2O drivers. Significantly different N2Om were found for tillage practices (conventional > no-till: 0.42 > 0.27), fertilizer type (liquid > solid manure: 0.55 > 0.32), and soil texture (fine > coarse: 0.36 > 0.22). The comparisons of the influence of crop type and rotation, water management, and soil order on N2O emissions are complicated by regional data availability and interactions among different factors. Additionally, the finding that N2O emissions reported based on area (N2Om), N input rate (EF), or yield can alter treatment rankings underscores the need to establish transparent criteria for rewarding or discouraging regionally-based management practices using N2O metrics. Finally, we show how General Linear Models (GLMs) can be used to estimate country and regional Tier-2 N2Om using a suite of covariates. Our GLMs identified tillage, water management, N input type and rate, soil properties, and elevation as the most influential covariates for the conterminous U.S. The limited accuracy of regional-scale GLMs, however, suggests the need to further improve the quality and availability of GHG and covariate data through concerted efforts in data collection.

Assessment of the Change in Soil Properties and Aggregates Formation of Freshly Restored Texturally Different Marginally Salt-Affected Soils Under Various Soil Amelioration Strategies

ABSTRACT Climate change and salt-affected soils detrimentally affect crop production in arid regions. Reclaiming these soils for crops and carbon sequestration can mitigate climate change and enhance food security. A laboratory-scale experiment was conducted on a wheat-maize crop rotation system for three consecutive years to check the effectiveness of organic amendments in reclaiming marginally salt-affected soils, improving soil health, sequestering carbon, and improving food grain production. This study included five treatments namely control (T1), gypsum alone at 100% gypsum requirements (G100), and its combinations with different organic amendments and 50% gypsum requirements (farm manure (FYM+G50), poultry manure (PM+G50), and green manure (GM+G50)) were used. Results indicated that sandy clay loam textured soil showed highest potential for its properties improvement after 45 days, i.e., EC decreased up to 3.9 dS m−1, pH 7.9 and, SOC increase up to 0.25%. After the fallow period, three consecutive years of crop production study indicated up to 39 and 70% increase in wheat and maize yields, respectively, compared to inorganic fertilizer alone. Maximum soil aggregation was noted in treatment with gypsum and farmyard manure application in loam soils (50%). The maximum soil organic carbon accumulation over the whole experiment was recorded in farmyard manure application in combination with gypsum (0.44 g kg−1) in both loam and sandy clay loam soil, while 0.31 g kg−1 in the clay loam soil. Based on the results, it was concluded that reclaiming marginally salt-affected soils enhances food crop production and incorporating manures improves soil through aggregation and carbon sequestration, mitigating climate change.

Whole soil fatty acid lipidic signature discriminates agriculture intensification in no-till systems

Argentinean farmers are adopting alternative agricultural systems based on diversification and intensification of crop rotations in no-till agriculture in order to improve soil health and recover degraded soils after years of monocropping. This is achieved by reducing fallow periods, increasing the intensity of crop rotations with maize and soybean in summer, and establishing different winter crops, including cover crops. We evaluated whole soil fatty acids (WSFA) signature in agricultural cropping systems with different levels of intensification in three on-farm experiments in Argentinean Argiudolls soils, along an on-field 8-year assay and measuring at 5 and 8 years after the beginning of the intensification. Contrasted treatments were: typical rotation, intensified rotation with cereals and intensified rotation with legumes. They were compared to an implanted pasture, and a pasture converted to intensified rotation. Eight years after the beginning of the trial, the intensified crop rotations were separated from the typical rotation by multivariate analysis of WSFA. This technique was able to distinguish between agricultural treatments with subtle differences in management, separating the intensified rotations, which later showed higher crop productivity. Conversion of pasture back to agriculture showed a delay of three years before changing the lipidic signature according to WSFA-based indicators. The outstanding conclusion is that mono-unsaturated fatty acids (MUFA) are the most relevant fatty acid functional group for land use discrimination, with a similar potency to the whole lipidic pattern. Within the MUFA group, the fatty acids 16:1w5c and 18:1w5c, appeared as potential biomarkers of these alternative agricultural practices.

Chemical recovery of a fish farm in Jinju Bay of South Korea after cessation of long-term fish farming

The development of aquaculture technology has led to significant increases in aquaculture production, which has deteriorated the coastal environment. This study is the first to conduct sedimentary environment recovery monitoring of an aquaculture environment using chemical indicators in a fallow fish farm in South Korea. The total organic carbon concentration in the surface sediments (≤2 cm) decreased to the control level within 1 year; the acid volatile sulfide concentration was not recovered for 3 years and 10 months. Nutrient and sulfide concentrations were high in deep sediments (≤15 cm) because of continuous fish farming for over 20 years and accumulation of organic matter beneath the cages. Complete chemical recovery of this study area may take a longer time than previously anticipated. Overall, this study provides significant insights for implementing coastal management plans and estimating adequate fallowing periods during long-term fish farming.

Estimating Winter Cover Crop Biomass in France Using Optical Sentinel-2 Dense Image Time Series and Machine Learning

Cover crops play a pivotal role in mitigating climate change by bolstering carbon sequestration through biomass production and soil integration. However, current methods for quantifying cover crop biomass lack spatial precision and objectivity. Thus, our research aimed to devise a remote-sensing-based approach to estimate cover crop biomass across various species and mixtures during fallow periods in France. Leveraging Sentinel-2 optical data and machine learning algorithms, we modeled biomass across 50 fields representative of France’s diverse cropping practices and climate types. Initial tests using traditional empirical relationships between vegetation indices/spectral bands and dry biomass revealed challenges in accurately estimating biomass for mixed cover crop categories due to spectral interference from grasses and weeds, underscoring the complexity of modeling diverse agricultural conditions. To address this challenge, we compared several machine learning algorithms (Support Vector Machine, Random Forest, and eXtreme Gradient Boosting) using spectral bands and vegetation indices from the latest available image before sampling as input. Additionally, we developed an approach that incorporates dense optical time series of Sentinel-2 data, generated using a Radial Basis Function for interpolation. Our findings demonstrated that a Random Forest model trained with dense time series data during the cover crop development period yielded promising results, with an average R-squared (r2) value of 0.75 and root mean square error (RMSE) of 0.73 t·ha−1, surpassing results obtained from methods using single-image snapshots (r2 of 0.55). Moreover, our approach exhibited robustness in accounting for factors such as crop species diversity, varied climatic conditions, and the presence of weed vegetation—essential for approximating real-world conditions. Importantly, its applicability extends beyond France, holding potential for global scalability. The availability of data for model calibration across diverse regions and timeframes could facilitate broader application.

Organic Carbon Storage and Structural-Hydraulic Properties of Ultisol under Agricultural Land Use Systems at Umuahia

The extent and pattern of interaction among organic carbon, structural and hydraulic properties of soils under varying land use systems are of great concern in the overall management of soil fertility and productivity. This study was conducted to examine the relationship among soil organic carbon storage, structural and hydraulic properties of soils under different agricultural land use systems at Umuahia, Abia State. The treatments were the four (4) land use systems (continuously cultivated arable farmland, 3 – year fallow land, oil palm plantation, and forest land) in which nine (9) replicates each of disturbed and undisturbed soil samples were randomly collected to give thirty six observational units laid out in a randomized complete block design. The soil samples were prepared and analysed in the laboratory. Analyses of variance, regression and correlation analyses were conducted on the data collected using Genstat version 14 and SPSS version 20. Results show that organic carbon had significant positive relationship with saturated hydraulic conductivity, macro porosity and total porosity but significant negative relationship with bulk density at all the land use systems. However, the influence of organic carbon on the other parameters was greatest at continuously cultivated arable land followed by the 3 – year fallow land. There is need to increase organic matter input at the continuously cultivated arable land and 3 – year fallow land through increased organic manuring and extension of the fallow period, respectively.

Global cropland nitrous oxide emissions in fallow period are comparable to growing‐season emissions

AbstractCroplands account for ~ one‐third of global anthropogenic nitrous oxide (N2O) emissions. A number of recent field experiments found substantial fallow‐period N2O emissions, which have been neglected for decades. However, the global contribution of the fallow‐period emissions and the associated drivers remain unclear. Based on 360 observations across global agroecosystems, we simulated the ratio of the fallow to the whole‐year N2O emissions (Rfallow) by developing a mixed‐effect model and compiling cropping‐system‐specific input data. Our results revealed that the mean global gridded Rfallow was 44% (15%–75%, 95% confidence interval), with hotspots mainly in the northern high latitudes. For most cropping systems, soil pH was the dominant driver of global variation in Rfallow. Global cropland emission factors (i.e., the percentage of fertilizer N emitted as N2O, EFs) in EF‐based models doubled to 1.9% when the fallow‐period N2O emissions were included in our simulation, similar to EFs estimated by process‐based and atmospheric inversion models (1.8%–2.3%). Overall, our study highlights the importance of fallow‐period N2O emissions in annual totals, especially for single cropping systems and croplands in acidic areas. To accurately estimate N2O emissions for national greenhouse gas inventories, it is crucial to update current EFs with full consideration of the fallow‐period N2O emissions in the Intergovernmental Panel on Climate Change (IPCC) Tier 1 method.

Nitrous Oxide Emissions during Cultivation and Fallow Periods from Rice Paddy Soil under Urea Fertilization

Rice cultivation serves as a significant anthropogenic source of methane (CH4) and nitrous oxide (N2O). Although N2O emissions remain relatively small compared to CH4 emissions, they are remarkably affected by nitrogen-fertilized soil conditions during rice cultivation. While numerous studies have investigated nitrous oxide emissions in response to nitrogen fertilization, existing research assessing nitrous oxide emissions based on nitrogen fertilizer levels has often been limited to cultivation periods. Therefore, there is a need for comprehensive analyses covering the entire year, including the dry periods, to address nitrous oxide emissions as an important source throughout the entire agricultural cycle. In this case study, we investigated the characteristics of N2O emissions in a central region of South Korea, where a single rice-cropping cycle occurs annually over a span of three whole years, from May 2020 to May 2023. We investigated the impact of variations in temperature and soil moisture on N2O emissions during rice cultivation and fallow periods. In this context, we attempted to discover the complex dynamics of N2O emissions by comparing longer fallow periods with the rice cultivation periods and extended non-dry periods with irrigated periods. We discovered that the greater contribution of cumulative N2O emissions during the fallow period made a much greater contribution (up to approximately 90%) to the whole-year N2O emissions than those during the rice cultivation period. During the fallow period from rice harvest to rice planting in the following year, variations in N2O emissions were associated with high-flux events after rainy periods on dry soils. This highlights the considerable influence of soil moisture content and weather conditions on N2O emissions during the fallow period. This affects high emission events, which in turn significantly impact the cumulative emissions over the entire period. We underscore that assessing N2O emissions solely based on the rice cultivation period would underestimate annual emissions. To prevent underestimation of N2O emissions, periodic gas collection throughout a year covering both rice cultivation and fallow phases is required in alignment with the monitoring of different temperature and soil moisture conditions. We captured statistical differences in cumulative N2O emissions due to nitrogen fertilization treatments across the three years. However, no significant difference was observed in the three-year average emissions among the different (one, one-and-a-half, and double) nitrogen fertilization treatments, with the exception of the control treatment (no fertilization). Based on the findings, we recommend at least three whole-year evaluations to ensure the estimation accuracy of N2O emissions under different nitrogen fertilization conditions. The findings from this study could help prepare the further revision or refinement of N2O emission factors from rice cultivation in the national greenhouse gas inventories defined by the inter-governmental panel on climate change (IPCC).

Contrasting effects of soil type and use of cover crops on nitrogen and phosphorus leaching in agricultural systems of the Argentinean Pampas

Agricultural systems of the Argentinean Pampas generally use rotations of summer crops under no-tillage and apply fertilization at rates that do not compensate nutrient exports with grain harvest, resulting in negative balances and soil fertility loss. However, the humid climate, long fallow periods and soil factors enhance nitrogen (N) and phosphorus (P) leaching, which has a negative impact on freshwater ecosystems. We propose to evaluate the effect of soil type and replacement of fallow periods with cover crops on drainage and N and P leaching. We used lysimeters containing two Mollisols of contrasting texture and porosity (a Typic Argiudoll and a Typic Hapludoll), and cultivated between 2014 and 2022 with a maize-soybean rotation with (M-CC-S) and without (M-S) cover crops under no tillage.The amount of drainage varied with rainfall (p<0.01), was similar between soils and higher in M-S than in M-CC-S during the intercropping period (148 vs 96 mm, p<0.05). The correlation between daily rainfall and drainage was higher for the Typic Argiudoll (r=0.46 and 0.42, for M-S and M-CC-S, respectively) than for the Typic Hapludoll (0.28 and 0.23 for M-S and M-CC-S, respectively) when considering same-day events, and it decreased for the Typic Argiudoll (r=0.31 and 0.26, for the M-S and M-CC-S, respectively) but not for the Typic Hapludoll (0.28 and 0.21 for the M-S and M-CC-S, respectively) with a 1-day lag between series. The amount of N and P lost through leaching varied with drainage (p<0.01). Cover crops reduced nitrate leaching to a greater extent in the Typic Hapludoll (from 30.4 to 3.3 kg ha−1 period−1) than in the Typic Argiudoll (from 17.6 to 2.0 kg ha−1 period−1) (p<0.05). Soil type modified P leaching in M-S (0.32 and 0.11 kg ha−1 period−1 for the Typic Argiudoll and the Typic Hapludoll, respectively) and M-CC-S had intermediate P leaching (0.17 and 0.16 kg P ha−1 period−1 for the Argiudoll and Hapludoll, respectively) (p<0.05).We conclude that: 1) water flows through different channels in each soil, the rapid flow of the Typic Argiudoll probably occurs through preferential flow channels (macropores) while the slower flow of the Typic Hapludoll is probably associated to matrix porosity, 2) P leaching is related to soil type (Typic Argiudoll > Typic Hapludoll) and drainage reduction by cover crops off-sets P leaching through macropores in the Typic Argiudoll, and 3) cover crops reduce N leaching, due to drainage reduction and N retention in cover crop biomass.

Beneficial Effects on Winter Wheat Production of the Application of Legume Green Manure during the Fallow Period

Legume green manure (LGM) is an excellent organic amendment conducive to soil quality and nutrient cycling; however, the use of LGM was once repealed in the rain-fed agriculture of northern China. The objective was to investigate the effects that planting LGM would bring and whether it would affect other fertilization regimes regarding the productivity and water and nutrient use efficiencies of succeeding crops. A short-term (2016–2019) field experiment was established with a split-plot design in the Loess Plateau of China, which included ten treatments consisting of two planting systems (main treatments)—conventional winter wheat monoculture (G0) and planting and incorporating LGM followed by winter wheat planting (G)—and five fertilization regimes (sub-treatments)—no fertilization (CK), basal fertilization with chemicals N, P and K (NPK), basal fertilization plus wheat straw return (NPK + S), basal fertilization plus farmyard manure application (NPK + M), and basal fertilization plus wheat straw return plus farmyard manure application (NPK + S + M). The results demonstrated that compared with G0, the G did not remarkably affect the total water consumption (WC) and water use efficiency (WUE) across the three trial wheat seasons. Specifically, during the third wheat season, the winter wheat yield of G increased by 7.5% more than that of G0 (p &lt; 0.05). G primarily increased the N concentration in winter wheat and universally increased the uptake of N, P and K by 18.8%, 11.7% and 18.8%, respectively. The apparent use efficiencies (AUEs) of chemicals N, P and K under G were 88.0%, 102% and 93.2% higher than those under G0 (p &lt; 0.05). In contrast, the wheat yields of NPK, NPK + S, NPK + M and NPK + S + M were 14.3%, 22.2%, 26.4% and 19.5%, respectively, higher than those of CK. The WC and WUE increased under NPK, NPK + S, NPK + M and NPK + S + M relative to the CK (p &lt; 0.05). Compared with CK, the NPK, NPK + S, NPK + M and NPK + S + M primarily increased the N concentration in winter wheat and universally increased the uptake of N, P and K (p &lt; 0.05). The AUEs of N, P and K were increased by 44.3–75.3%, 72.4–103% and 128–160%, respectively, by NPK + S, NPK + M and NPK + S + M compared with CK. In conclusion, the revival of planting LGM during the fallow period was considered an appropriate measure in the Loess Plateau and similar rain-fed regions due to its ability to improve the growth and nutrient utilization of subsequent winter wheat even in the short term, as well as the lack of negative effects exerted on other organic amendments in its effectiveness.

Winter Cover Crops Affect Aggregate-Associated Carbon, Nitrogen and Enzyme Activities from Black Soil Cropland

The thinning, leaning, and hardening of arable land in the black soil region of Northeast China has brought serious challenges to the sustainable development of agriculture. It is of great significance to explore suitable conservation tillage for the conservation and sustainable utilization of black soil resources actively. The topsoil of the cropland in the northeastern part of the Songnen Plain with winter fallow (CK), planted alfalfa, and planted winter wheat was used as the research object to analyze the changes in the soil aggregate composition, nutrients, and enzyme activities before and after freeze–thaw, respectively, and to investigate the effect of winter cover crops on the improvement of the quality of the black soil cropland. Compared with the winter fallow field, (1) planting alfalfa significantly increased the mechanical stability of 1–2 mm and 0.25–1 mm particle size aggregates (about 3 times and 25 times over), and planting winter wheat increased the water stability of 0.25–1 mm particle size aggregates significantly (2.7 times over); (2) planting alfalfa and winter wheat increased the soil C/N ratio of &gt;2 mm and 1–2 mm particle size aggregates, and the increment in the C/N ratio in &gt;2 mm particle size aggregates remarkably increased, by 203.6% and 362.7%, respectively; (3) planting alfalfa significantly enhanced the soil invertase activity and urease activity in &gt;2 mm and 0.25–1 mm particle size aggregates, and planting winter wheat significantly enhanced the catalase activity in 0.25–1 mm particle size aggregates. In conclusion, planting winter cover crops during the winter fallow period can maintain and promote the mechanical and water stability of medium and large (0.25–1 mm,1–2 mm) soil aggregates, increase the carbon content and C/N ratio of larger (1–2 mm, &gt;2 mm) aggregates, and enhance the enzyme activity of small and medium (0.25–1 mm, &lt;0.25 mm) aggregates to varying degrees. The results of the study can provide a reference for the promotion of basic research on and technology for winter cover crops in the black soil region.