Winter Fallow Research Articles

The Impact of Winter Cover Crops on Soil Nematode Communities and Food Web Stability in Corn and Soybean Cultivation.

There is increasing adoption of winter cover crops (WCCs) in corn and soybean production in Canada, primarily to reduce erosion and increase soil organic matter content. WCCs have the potential to influence nematode communities by increasing free-living nematodes and decreasing plant-parasitic nematodes or vice versa. However, the mechanism by which WCCs change nematode community assemblages still remains a key question in soil food web ecology. We tested the hypothesis that the long-term use of rye (Secale cereale), barley (Hordeum vulgare) and oat (Avena sativa) as monocultures or mixtures promotes nematode communities and improves overall soil health conditions compared to winter fallow. The results from this study revealed that the use of WCCs generally promoted a higher abundance and diversity of nematode communities, whereas plant parasitic nematodes were the most abundant in winter fallow. Moreover, the mixtures of WCCs had more similar nematode communities compared to rye alone and winter fallow. The structure and enrichment indices were higher with WCCs, indicating higher nutrient cycling and soil suppressiveness, which are signs of healthy soil conditions. Furthermore, WCCs significantly reduced the populations of root lesion nematode Pratylenchus, although their numbers recovered and increased during the main crop stages. Additionally, mixtures of WCCs promoted the highest abundance of the stunt nematode Tylenchorhynchus, whereas winter fallow had a higher abundance of the spiral nematode Helicotylenchus during the fallow period and the main crop stages. The results show that the long-term use of cover crops can have a positive impact on nematode communities and the soil food web, but these changes depend on the type of WCCs and how they are used.

Winter forage crops influence soil properties through establishing different arbuscular mycorrhizal fungi communities in paddy field

Winter planting is promising for improving the utilization rate of fallow paddy fields in southern China by establishing arbuscular mycorrhizal fungi (AMF) communities. However, the effects of different winter forage crops on AMF community construction remain unknown. The AMF community establishment of different winter planting forage crops were conducted in oat, rye, Chinese milk vetch, and ryegrass, with winter fallow as a control. The AMF colonization rate, soil AMF spore density, community structure and diversity, and soil physicochemical properties were determined. The results showed that the total nitrogen and available nitrogen in winter Chinese milk vetch were 11.11% and 16.92% higher than those in winter fallow (P < 0.05). After planting winter forage crops, the AMF spore density in winter oat, rye, Chinese milk vetch, and ryegrass soil were 127.90%, 64.37%, 59.91%, and 73.62% higher than that before planting, respectively (P < 0.05). Claroideoglomus was the dominant AMF genus in the soil of winter planting oat, rye, and ryegrass. The average membership function value of winter Chinese milk vetch was the highest, indicating that it had the best comprehensive effect on soil physicochemical properties, AMF community structure and diversity, and fresh forage yield. Winter forage crops could increase the spore pool of soil AMF and improve the soil AMF community structure and diversity. Winter Chinese milk vetch in paddy field had the best comprehensive effect on soil physicochemical properties and soil AMF community according to the comprehensive evaluation. These findings provide a theoretical basis for sustainable development and utilization of the southern rice paddy ecosystem.

The communities of arbuscular mycorrhizal fungi established by different winter green manures in paddy fields promote post-cropping rice production1

Winter planting green manures in southern China effectively improve soil properties and rice production through microbial community construction. However, the effects of soil communities of arbuscular mycorrhizal fungi (AMF) from different winter planting green manures on the soil properties and post-cropping rice production remain unclear. In this study, the soil AMF communities of three common winter planting patterns in Southern China, winter fallow, winter ryegrass (Lolium multiflorum L.), and winter Chinese milk vetch (Astragalus sinicus L.), were explored and their effects on post-cropping rice production were investigated. Compared with winter fallow, the winter ryegrass and winter Chinese milk vetch patterns could alleviate soil acidification, significantly increase soil AMF spore density, and improve the soil AMF community structure. Based on sterilized soil, rice production indicators such as thousand-seed weight, theoretical yield, and the grain amylose and total sugar contents of rice inoculated with AMF spores from winter Chinese milk vetch soil were 6.68-53.57% higher than those without AMF inoculation. Rice panicle weight, seed setting rate, and theoretical yield were 15.38-22.71% higher in the treatment with AMF spores from winter ryegrass soil than in the treatments with no AMF inoculation. In addition, the protein, amylose, and total sugar contents of rice grains were 14.92, 104.82, and 802.23 mg kg-1, respectively, which were 31.31, 14.25 and 34.47% higher than those without AMF inoculation. The AMF community dominated by Glomus and Acaulospora in winter Chinese milk vetch had a more positive effect on the improvement of rice yield, while the AMF community dominated by Glomus in winter ryegrass soil was more conducive to rice quality improvement. These findings have revealed the critical role of AMF communities from green manure in rice production, which lays the theoretical basis for a promising strategy to promote the sustainable development of southern winter agriculture.

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.

Roles of Microbial Community and Keystone Taxa in Rice Productivity under Green Manuring in South China

Green manure (GM)–rice–rice rotation is an important management practice for improving soil fertility and rice productivity. The microbiological mechanisms for the increase in grain yield in GM–rice–rice rotation remain unclear. The responses of soil biodiversity, bacterial and fungal communities, and their interactions in the GM–rice–rice rotation were investigated based on two long-term field experiments in Gaoqiao (GQ) and Nanxian (NX) in Hunan Province, south China. Results showed that rice yields were raised by 11.79% and 15.03% under GM in GQ and NX, respectively. GM promoted Shannon diversity and Pielou’s evenness and changed the community structures of bacteria and fungi. The co-occurrence network analysis found that the percentages of negative edges were higher in GM (40.79% and 44.32% in GQ and NX, respectively) than those in the corresponding winter fallow (34.86% and 29.13% in GQ and NX, respectively) in the combined bacterial–fungal networks, suggesting more stable microbial community under GM. Moreover, GM had higher percentages of bacterial–fungal and fungal–fungal edges than winter fallow, indicating that GM increased the interaction between bacteria and fungi and fungi play more essential roles in affecting soil processes under GM. The keystone taxa in GM were positively linked with C metabolism-related enzymes and soil multifunctionality, and were important in improving soil fertility and rice productivity. We concluded that the fungal community was more sensitive to GM application than the bacterial community and that keystone taxa had important influences on soil properties and rice productivity in the GM–double-rice cropping system, which can effectively support the sustainable development of the paddy field ecosystem in southern China.

Integration effects of soil amendments and cover crops on dryland no‐till corn

AbstractA field study was carried out at the Mississippi Agricultural and Forestry Experiment Station near Pontotoc to evaluate the synergistic impacts of broiler litter (BL) and inorganic fertilizer nitrogen (N) with flue gas desulfurization (FGD) gypsum and lignite in the presence of winter cover crops (WCCs) on dryland no‐till corn (Zea mays L.) in Falkner silt loam soil. The experimental design was a split‐plot randomized complete block design with three replications. The main plots were WCC and winter fallow (WF), and the subplots were fertilization treatments. Fertilization treatments included BL, inorganic fertilizer N, FGD gypsum and lignite with BL, FGD gypsum and lignite with inorganic fertilizer N, and an unfertilized control. BL, FGD gypsum, and lignite were applied at the rates of 13.4, 3.4, and 3.4 Mg ha−1, respectively. Inorganic fertilizer N was applied to corn at 168 kg N ha−1. BL increased soil carbon (C), soil infiltration, and resulted in higher corn grain yield compared to both inorganic fertilizer N and unfertilized control in 2020 and 2022. Averaged across fertilization treatments, WCC improved soil moisture, soil C, and soil infiltration by 16%, 19%, and 25% at the 0‐ to 15‐cm depth, respectively, and increased corn grain yield by 25% as compared to WF in 2022. Cover crops boosted corn grain yield during drier years. The combination of FGD gypsum and lignite with BL increased corn grain yield by 15% in 2020 and 13% in 2022 compared to BL alone. This approach can be considered to promote the sustainability of agroecosystems.

Lethality of Simulated UV and Solar Diffuse Radiations to Detached Urediniopores of Phakopsora pachyrhizi

Asian soybean rust (ASR), caused by the fungus Phakopsora pachyrhizi, is the most destructive disease on the crop. This work aimed to generate data to understand the detached uredospores survival during the winter fallow in Mato Grosso state, Brazil. Experiment &amp;lsquo;A&amp;rsquo;&amp;mdash;the detached urediniospores maintained and multiplied on Ativa soybean cultivar, were deposited on soybean estract-agar and kept at 25 oC temperature in closed plastic petri dishes and exposed to UV-C (100-280 nm) radiation, distant 30 cm from the plates surface for &amp;lsquo; 0&amp;rsquo;; 60; 120; 180; 240; 300; 360, 420, 480 and 560 minutes. Experiment &amp;lsquo;B&amp;rsquo;&amp;mdash;was similar to previous experiment but spores were exposed to UV-B (280-320 nm) radiation. In Experiment &amp;lsquo;C&amp;rsquo;&amp;mdash;the urediniospores were deposited into empty plastic petri dishes without lids and exposed to direct diffuse sunlight for 0; 60; 120; 180; 240; 300; 360; 420; and 300 minutes. Solar radiation was measured with a pyranometer (Spectrum Technologies, Inc.). After the exposition time, urediniospores were plated on soybean-extract agar, incubated at 25 oC under dark for 8 h and germination assessed under an optical microscope (400&amp;zwj;&amp;times;). Data were submitted to analyses of variance and regression. All experiments were repeated twice. The detached spores exposed to UV-C were killed with 496 minutes, and under UV-B radiation killed with 962.7 minutes and those submitted to direct diffusion solar radiation killed by 15.6 MJ m-2 dose, or 240 minutes exposition to 1,250 w/m2. It can be inferred that the incident solar diffused radiation in Mato Grosso, during the winter fallow, has the daily potential to kill the detached P. pachyrhizi urediniospores.

Evaluation of organic options for Johnsongrass (Sorghum halepense) control during winter fallow

AbstractJohnsongrass [Sorghum halepense (L.) Pers.] is one of the most problematic perennial grass weed species in row-crop production across the southern United States. Control of this species is especially challenging in organic systems due to a lack of effective options. A field experiment was conducted at the Texas A&amp;M research farm near College Station, TX, from fall 2019 to spring 2021 to evaluate various nonchemical options for managing S. halepense in the fallow season, implemented over 2 yr in the same locations. The treatments included disking once, disking twice, disking + immediate flooding, disking + flush irrigation + flooding, disking twice + flooding after the first frost, periodic mowing, acetic acid treatment, and disking + tarping. Disking + immediate flooding, disking + flush irrigation + flooding, and disking + tarping were the most effective treatments. Compared with the nontreated control plots, these treatments reduced S. halepense aboveground density (&lt;9 plants m−2 vs. 64 plants m−2), aboveground biomass (&lt;80 g m−2 vs. 935 g m−2), rhizome biomass (&lt;4 g m−2 vs. 55 g m−2), rhizome node number (&lt;25 nodes m−2 vs. 316 nodes m−2), and rhizome length (&lt;42 cm m−2 vs. 660 cm m−2). Disking twice + flooding after the first frost did not show a consistent impact. Periodic mowing also reduced S. halepense density (12 plants m−2 vs. 64 plants m−2) and other variables compared with the control plots at the end of the study in spring 2021. Disking alone once or twice each growing season or repeated application of acetic acid failed to control S. halepense. These results indicate that well-timed nonchemical management practices such as tarping and flooding implemented during the winter fallow can be very effective in reducing S. halepense densities.

Green manuring reduces cadmium accumulation in rice: Roles of iron plaque and dissolved organic matter

In southern China, winter green manure is widely used in rice cropping systems for improving grain yields and soil fertility. Cd pollution has recently been reported in some of these paddy fields. Research on the in-depth understanding of how green manuring affects Cd absorption in rice is limited. This study aimed to investigate the impacts of different green manures, including single plantation and mixed plantation on the absorption of Cd by rice and explore the underlying mechanisms. Pot experiments demonstrated that compared with winter fallow–rice, green manuring treatments considerably decreased rice Cd content, promoted the conversion of bioavailable Cd fraction into a more stable form, induced the formation of iron plaque, and increased the content of humic-like fraction (HF) in soil dissolved organic matter (DOM). Treatment with mixed plantation resulted in a greater decrease in rice Cd content and an increase in HF and iron plaque contents than single plantation. Hydroponic experiments confirmed that both iron plaque and green manure-derived DOM significantly reduced the Cd content in rice seedlings. In conclusion, green manure incorporation is an efficient measure for the safe utilization of Cd-contaminated soil, and mixed plantation of different green manures exerts stronger effects.

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.

A modelled quantification of reduced nitrogen fertiliser requirement and associated trade-offs from inclusion of legumes and fallows in wheat-based crop sequences

ContextGlobally there is a need to increase crop production and maintain soil fertility while reducing environmental impact. Intensive wheat production is dependent on synthetic nitrogen (N) fertilisers which represent ∼38% of total on-farm greenhouse gas emissions in Australia and contribute to N pollution. There are four major sources of N available for crop production 1) N mineralised from native soil organic matter (SOM) 2) N derived from biological fixation by legume-associated rhizobial bacteria 3) synthetic N fertiliser 4) N-rich manures, composts, biosolids and other organic wastes. Farmers can emphasise use of these different sources through their management. ObjectivesIn this study we use crop simulation to predict the minimum amount of N fertiliser required for semi-arid wheat crops to achieve economic yield (EY – defined as 80% of water limited potential yield, PYw) when grown in long-term (1991–2020) sequences and at different rotational intensities with either; grain legumes (GL, source 2), legume winter cover crops (CC, source 2) and winter fallow (WF, source 1) compared to continuous wheat (CW, source 3). Results and conclusionsLegume and fallow phases at 25–67% intensity (e.g. one out of four to two out of three crops) reduced the long-term mean fertiliser N application required to achieve EY. For every % area increase of GL and CC, the mean N applied to achieve EY was reduced by 1.3 kg N kg ha-1 (0.43–1.9 N kg ha-1). For every % area increase of WF the mean N applied to achieve EY was reduced by 1.1 kg N kg ha-1 (0.4–1.6 N kg ha-1). Global warming potential emissions from soil (CO2 and N2O) increased compared to CW when legume intensity increased in high rainfall environments with high SOM but decreased at increasing intensity in low rainfall environments with low SOM. Food energy production (kJ ha-1yr-1) was reduced relative to CW by inclusion of CC and WF and to a lesser extent GL in sequences due to reduced total grain production over the study period. However, protein yield increased as GL intensity increased relative to CW. The most profitable sequences over a 30-year period were CW, or GL at different intensities depending on environment. ImplicationsDiversification of wheat-based cropping systems with legumes reduces N fertiliser requirement, but depending on farming system context this benefit can trade off against production, profitability and environmental outcomes. Evaluation and exploitation of appropriate farming system contexts to achieve mutually beneficial outcomes is required to allow farmers and policy makers to make informed decisions on how to increase food production whilst minimising environmental impacts.

Yem bezelyesi çeşitlerinin farklı fenolojik dönemlerdeki verim ve kalite özellikleri

Agricultural areas that rely on a single crop for production experience negative soil characteristics, while the benefits of these locations are further diminished by short-term winter fallows. In the ecological conditions of the Aegean Region, cotton-cotton and maize-maize production patterns can be given as examples of this type of production. With the adoption of a sustainable agriculture approach in recent years, the use of winter annual forage crops is quite important in terms of preventing this situation. The inclusion of forage pea in the production patterns both contributes positively to the soil properties and is a potential source of quality roughage. In line with this information, 8 different forage pea varieties (Kirazlı, Ulubatlı, Ürünlü, Gölyazı, Özkaynak, Töre, Taşkent, GAP Pembesi) were harvested at 3 different phenological stages (10%, 50%, 100% flowering) in Aydın ecological conditions. Some agronomic characteristics such as plant height (cm), stem diameter (mm), herbage yield (kg da-1) were measured in the experiment. After the measurements, ADF (%), NDF (%), ADL (%), protein properties and relative feed value were determined. While lower values were found in terms of yield and fiber values in early mowing, higher values were found in terms of crude protein ratio and relative feed value. At the same time, the variety-environment interactions showed differences in both years. Our results demonstrated that 100% flowering is preferable in terms of yield. Differences were observed among the varieties according to yield and quality characteristics. In terms of herbage and crude protein yields, Töre, Taşkent and GAP Pembesi were the most prominent common varieties. In terms of relative feed value, Ulubatlı and Ürünlü are the varieties with high values.

Semi-arid soil bacterial communities are refined by altered plant selection pressure under conservation management practices

Plants' ability to select for, and refine, their microbiome over time is well known. In soil, the strength of plant selection pressure on microbial composition can result in distinct rhizosphere, and root-zone communities, but may be masked in soils with lower native diversity such as semi-arid soils. Semi-arid soils are also known for their high potential for wind erosion, which may be mitigated by the implementation of cover crops. These cover crops may also alter the microbial composition of the semi-arid soils, but the strength of this effect, and the resulting changes in the composition of the microbiome, are less well known. This study aimed to address whether the implementation of a single-species wheat cover crop in semi-arid agricultural soils would impact the bacterial composition of the cash crop. We investigated three tillage regimes—no-tillage with a winter wheat cover crop, no-tillage winter fallow, and conventional tillage winter fallow—to determine the effects of tillage removal, and cover crop implementation on the soil bacterial community present in the root zone of the cash crop. It was determined that the composition of the bacterial microbiome was similar between cover cropped and non-cover cropped treatments. The similarity of bacterial composition was likely due to the strong effect of environmental selection reducing overall biodiversity in these soils. However, the variability of bacterial community composition was strongly reduced for the cover cropped treatment compared to the two non-cover cropped treatments. The similarity of bacterial communities with cover cropping, without significant soil physicochemical changes, suggests that plant-selection pressure, rather than management-induced changes in soil physicochemical properties, drove the refinement (decreased dissimilarity compared to non-cover cropped treatments) of the bacterial community. The composition of this refined community under cover cropping was determined to contain an enrichment of several genera of interest including N cycling and potential plant-growth promoting bacteria. In summary, the introduction of cover cropping in the nutrient and microbial-poor soil of the semi-arid Southern High Plains strongly refined the bacterial community and selected for organisms with the potential to improve soil functions associated with greater agronomic sustainability.

Comparative analysis of rhizobial and bacterial communities in experimental cotton fields: Impacts of conventional and conservation soil management in the Texas High Plains

Conservative agricultural management strategies pursue long-term ecological benefits through practices such as no-tillage, cover crop, and inherent soil properties management. Farmers, however, are often hesitant to adopt such practices due to lack of experience, initial expense, and concern for low crop productivity. Overcoming this barrier requires novel approaches, such as effectively managing the soil microbiome to attain high productivity at a low cost, especially in a semi-arid region. To study the potential of conservation agriculture, we investigated components of soil bacterial community and rhizobial diversity in long-term experimental cotton fields divided into conventional tillage monoculture systems with winter fallow (CT) and no-tillage with mixed cover crop (M-NT) system on the Texas High Plain (THP). We conducted next-generation amplicon sequencing targeting rpoB gene with collected soil samples from different soil managements and seasons. Our research revealed that although CT had significantly greater bacterial diversity and species richness than the M-NT management, rhizobial diversity and species richness were higher in M-NT than in CT management. Both bacterial and rhizobial diversity and richness were greater in summer than in fall. The abundance of the order Rhizobiales was consistently high in M-NT than in CT fields in both seasons. Soil management altered the dominant rhizobial genus associated with cotton production systems; Rhizobium and Pararhizobium dominated M-NT management, while Bradyrhizobium and Sinorhizobium were dominant under CT management. These outcomes suggest that incorporating legumes into a cover crop in this semi-arid cotton-growing region can initiate beneficial changes to the dynamics of the indigenous rhizobial assemblage. The high prediction accuracy of our machine learning model using bacterial community data classifying the managements as CT or M-NT validates the possibilities of a strong underlying relationship between soil management and the bacterial diversity in the soil.

Winter cropping improves yield, dry matter accumulation and translocation and nitrogen uptake of double-cropping rice

Winter cropping is widely considered as an effective way to increase rice yield. Therefore, this study was performed to find optimal winter cropping patterns in middle and lower reaches of the Yangtze River, China. Five experimental treatments were set up based on the long-term field experiment including winter fallow (CK), Chinese milk vetch winter cropping pattern (CRR), rapeseed winter cropping pattern (RRR), garlic winter cropping pattern (GRR), and winter multiple cropping rotation (ROT). The effects of different winter cropping patterns on the yield, dry matter accumulation and translocation, and plant nitrogen uptake were explored in double-cropping rice. The results showed that compared with CK, winter cropping increased the early and late rice yield by 7.91-10.70% and 3.57-6.89%, respectively. Similarly, compared with CK, winter cropping patterns also increased the number of spikes in early rice by 19.36-25.81% and CRR and ROT increased the effective number of spikes in late rice by 25.58% and 23.26% respectively. The dry matter (DM) translocation by stem and leaf of early rice under CRR was highest, with a 36.2% increase compared with CK, however, DM accumulation after heading in early rice under CRR was lowest. GRR decreased the dry matter translocation by stem and leaf in early rice but increased DM accumulation after heading in early and late rice by 65.28% and 13.44% as compared to CK. Moreover, ROT increased the dry matter translocation by stem and leaf in late rice by 112.63%. Additionally, GRR and ROT treatments increased the stem nitrogen uptake in early rice by 61.76% and 58.61% as compared to control, while CRR increased the nitrogen uptake by stem, leave and spike in late rice by 40.76%, 49.51% and 42.92%. In conclusion, CRR is more beneficial to increase DM accumulation and translocation by stem and leaf in double-cropping rice, and nitrogen uptake by rice plants.

Managing cover crop C:N ratio and subsurface‐banded poultry litter rate for optimal corn yields

AbstractCover crops can be used to provide some of the nitrogen (N) needs of a cash crop to complement mineral fertilizers or manure, but there has yet been limited work to describe corn (Zea mays L.) yield as a function of cover crop quality and N inputs. We investigated the response of corn yield to gradients of both preceding cover crop C:N ratio and poultry litter (PL) application rates in Beltsville, MD during 2012–2014. To achieve different C:N ratios of the cover crops, hairy vetch (Vicia villosa Roth. "Groff") and cereal rye (Secale cereale L. "Aroostook") were seeded in a replacement series of six seeding rate proportions, resulting in shoot C:N ratios of 9.2:1 to 152:1 across years. For each hairy vetch/cereal rye sown proportions, PL was side‐dressed at corn V5–V8 stage in subsurface bands (SSB) at four targeted rates: Zero, P‐based (67 kg plant available nitrogen [PAN] ha−1), N‐based (135 kg PAN ha−1), and excess N and P (269 kg PAN ha−1). We found that corn yield followed a linear‐plateau relationship across these two dimensions. Within the linear region, each unit increase in log‐scaled cover crop C:N ratio resulted in a yield decrease of 2.56 ± 0.26 Mg ha−1 at a given rate of SSB PL. To optimize corn yields, we describe a model where each unit increase in log‐scaled cover crop C:N ratio required an additional 45.9 ± 6.22 kg PAN ha−1 from SSB PL. Yields following winter fallow were typically intermediate to the range of yields observed following the gradient of cover crop C:N ratios. We did not find significant differences in corn yield responses when comparing SSB PL to at‐planting incorporated or broadcast PL; we also found no significant differences between SSB PL and surface‐banded urea ammonium nitrate. Taken together, our approach of modeling yield response across two dimensions can be widely used to guide adaptive N management in subsequent cash crops following winter cover crops, thereby balancing both economic and environmental objectives in cover crop‐based cropping systems.

Relay intercropping cover crop combined with reduced nitrogen application improves subsequent cotton agronomic traits while maintaining yield and quality

AbstractApplying cover crops to reduce nitrogen (N) fertilizer application while ensuring crop productivity is a major challenge for sustainable agricultural production. However, few studies have quantified N fertilizer application reduction through the use of February orchid (Orychophragmus violaceus) cover crops with the goal of ensuring cotton productivity. We conducted field experiments in the Yellow River basin on two cropping systems, monoculture cotton (Gossypium hirsutum L) and cotton/February orchid under four levels of N application (0 [N0], 112.5 [N1], 168.75 [N2], and 225 [N3] kg N·ha−1), to evaluate the impacts of cover cropping on cotton growth parameters, yield, and quality under different N application levels. The results indicated that replacing winter fallow with February orchid prolonged the cotton growth period and increased plant height, leaf area index (LAI), and dry matter accumulation but did not improve cotton yield or fiber quality. The Cotton/February orchid system under a 168.75 kg ha−1 N application rate improved cotton growth, and achieved yield and quality equivalent to those of monoculture cotton under a 225 kg ha−1 N application. Further analysis revealed that February orchid cover crop and N application positively affected lint yield, whereas plant height, LAI, and dry matter accumulation (positively) and phenology (negatively) predicted lint yield and fiber quality. In conclusion, cotton relay intercropping with February orchid in combination with 168.75 kg ha−1 N application is recommended as a suitable cropping system to reduce fallow fields and ensuring cotton productivity in the Yellow River basin and other areas with similar ecological conditions.

Influence of cover crops on soybean yield and partial returns as an alternative to double‐crop soybean in Arkansas

AbstractThe number of hectares dedicated to winter wheat (Triticum aestivum L.) in the southern United States has been trending downward for almost a decade, presenting an opportunity for producers to utilize alternatives in their soybean [Glycine max (L.) Merr.] rotations, such as winter cover crops. A study was established to compare the cover crops to traditional cropping systems by determining the effect each had on a successive soybean crop and to examine partial economic returns. Cropping systems implemented were winter fallow, winter wheat, and seven cover crop treatments, including cereal rye (Secale cereale L.), black‐seeded oat (Avena sativa L.), barley (Hordeum vulgare L.), Austrian winter pea (Pisum sativum L.), blue lupin (Lupinus angustifolius L.), Blend 1 (cereal rye, crimson clover [Trifolium incarnatum L.], seven‐top turnip [Brassica rapa L.]). and Blend 2 (black‐seeded oats and Austrian winter pea). The winter cropping system did not affect the soybean plant population (p = 0.32). Soybean grain yield varied among the different winter cropping systems (p &lt; 0.01) with yields ranging from 3346 to 3906 kg ha−1. The soybean double‐crop system ($1383.02 ha−1) and soybean following winter cover crops ($1239–1380 ha−1) produced similar partial returns but both were greater than soybean following winter fallow ($1217.81 ha−1) (p &lt; 0.01). Soybean yields and partial returns were the highest when following Blend 2. Results of this study showed that winter cover crops can provide an adequate alternative to both winter fallow and traditional winter wheat soybean double‐crop systems in the mid‐southern United States.

Mitigation of greenhouse gases emission affected by no-tillage and winter cover crops in a subtropical paddy rice ecosystem

Paddy rice production based on traditional soil management emits large amounts of methane (CH 4 ) into the atmosphere. This study assessed the potential of no-tillage (NT) and winter cover crops (WCC) to mitigate net greenhouse gas (GHG) emissions in a subtropical paddy rice ecosystem. A long-term (20-yrs) experiment was evaluated regarding the effect of NT combined with winter fallow or three WCC (ryegrass, white oat, and birdsfoot trefoil) on seasonal CH 4 -C and nitrous oxide (N 2 [...]

Soil health tradeoffs may be minimal in phosphorus‐enriched Coastal Plain soils

AbstractSoil health practices can improve soil conditions and provide ecosystem services, but increased risk of phosphorus (P) loss can be an unintended consequence. We investigated conservation tillage and cover crops effects on soil P stratification, P accumulation at depth, and soil aggregation for sandy Coastal Plain soils from the Mid‐Atlantic United States soil cores from 10 agricultural fields with 0–15 years of conservation tillage or cover cropping were analyzed for Mehlich‐3 P and dry aggregate stability. We found no evidence that conservation tillage or cover cropping caused P stratification or accumulation in study fields that were already enriched with P prior to soil health implementation. Annual particulate, dissolved runoff, and leachate P loads decreased when estimated using the North Carolina Phosphorus Loss Assessment Tool assuming no‐till and cover crops (soil health) compared to conventional till and winter fallow (conventional). We suggest that soil health practices are unlikely to exacerbate P losses from high P Coastal Plain soils beyond their initial risk profile.