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The magnitude of ecosystem services provided by winter cover crops is linked to their performance (i.e., biomass and associated nitrogen content, forage quality, and fractional ground cover), although few studies quantify these characteristics across the landscape. Remote sensing can produce landscape-level assessments of cover crop performance. However, commonly employed optical vegetation indices (VI) saturate, limiting their ability to measure high-biomass cover crops. Contemporary VIs that employ red-edge bands have been shown to be more robust to saturation issues. Additionally, synthetic aperture radar (SAR) data have been effective at estimating crop biophysical characteristics, although this has not been demonstrated on winter cover crops. We assessed the integration of optical (Sentinel-2) and SAR (Sentinel-1) imagery to estimate winter cover crops biomass across 27 fields over three winter–spring seasons (2018–2021) in Maryland. We used log-linear models to predict cover crop biomass as a function of 27 VIs and eight SAR metrics. Our results suggest that the integration of the normalized difference red-edge vegetation index (NDVI_RE1; employing Sentinel-2 bands 5 and 8A), combined with SAR interferometric (InSAR) coherence, best estimated the biomass of cereal grass cover crops. However, these results were season- and species-specific (R2 = 0.74, 0.81, and 0.34; RMSE = 1227, 793, and 776 kg ha−1, for wheat (Triticum aestivum L.), triticale (Triticale hexaploide L.), and cereal rye (Secale cereale), respectively, in spring (March–May)). Compared to the optical-only model, InSAR coherence improved biomass estimations by 4% in wheat, 5% in triticale, and by 11% in cereal rye. Both optical-only and optical-SAR biomass prediction models exhibited saturation occurring at ~1900 kg ha−1; thus, more work is needed to enable accurate biomass estimations past the point of saturation. To address this continued concern, future work could consider the use of weather and climate variables, machine learning models, the integration of proximal sensing and satellite observations, and/or the integration of process-based crop-soil simulation models and remote sensing observations.

1. Plant diversity can increase nitrogen cycling and decrease soil-borne pests, which are feedback mechanisms influencing subsequent plant growth. The relative strength of these mechanisms is unclear, as is the influence of preceding plant quantity and quality. Here, we studied how plant diversity in space and time influences subsequent crop growth. 2. During 2 years, we rotated two main crops (Avena sativa, Cichorium endivia) with four winter cover crop (WCC) species in monocultures and mixtures. We hypothesized that, relative to monocultures, WCC mixtures promote WCC biomass (quantity) and nitrogen concentration (quality), soil mineral nitrogen, soil organic matter, and reduce plant-feeding nematode abundance. Additionally, we predicted that preceding crops modified WCC legacies. By structural equation modelling (SEM), we tested the relative importance of WCC shoot biomass and nitrogen concentration on succeeding crop productivity directly and indirectly via nitrogen cycling and root-feeding nematode abundance. 3. WCC shoot biomass, soil properties and succeeding Avena productivity were affected by first-season cropping, whereas subsequent Cichorium only responded to the WCC treatments. WCC mixtures' productivity and nitrogen concentration showed over- and under-yielding, depending on mixture composition. Soil nitrogen and nematode abundance did not display WCC mixture effects. Soil organic matter was lower than expected after Raphanus sativus + Vicia sativa mixture. Subsequent Avena productivity depended upon mixture composition, whereas final Cichorium productivity was unresponsive to WCC mixtures. SEM indicated that WCC legacy effects on subsequent Avena (R² = 0.52) and Cichorium (R² = 0.59) productivity were driven by WCC biomass and nitrogen concentration, although not by the quantified soil properties. 4. Synthesis and applications. Through understanding plant-soil feedback, legacy effects of plant species and species mixtures can be employed for sustainable management of agro-ecosystems. Biomass and nitrogen concentration of plants returned to the soil stimulate subsequent plant productivity. Winter cover crop quantity and quality are both manipulable with mixtures. The specificity of spatial and temporal diversity effects warrants consideration of plant species choice in mixtures and rotations for optimal employment of beneficial legacy effects.

In agriculture, winter cover crop (WCC) residues are incorporated into the soil to improve soil quality, as gradual litter decomposition can improve fertility. Decomposition rate is determined by litter quality, local soil abiotic and biotic properties. How these factors are interlinked and influenced by cropping history is, however, unclear. We grew WCC monocultures and mixtures in rotation with main crops Avena sativa (oat) and Cichorium endivia (endive) and tested how crop rotation influences WCC litter quality, abiotic and biotic soil conditions, and litter decomposition rates. To disentangle WCC litter quality effects from WCC soil legacy effects on decomposition, we tested how rotation history influences decomposition of standard substrates and explored the underlying mechanisms. In a common environment (e.g. winter fallow plots), WCC decomposition rate constants (k) correlated negatively with litter C, lignin and, surprisingly, N content, due to strong positive correlations among these traits. Plots with a history of fast‐decomposing WCCs exhibited faster decomposition of their own litters as well as of the standard substrates filter paper and rooibos tea, as compared to winter fallow plots. WCC treatments differentially affected soil microbial biomass, as well as soil organic matter and mineral nitrogen content. WCC‐induced soil changes affected decomposition rates. Depending on the main crop rotation treatment, legacy effects were attributed to biomass input of WCCs and their litter quality or changes in microbial biomass. Synthesis and applications. These results demonstrate that decomposition in cropping systems is influenced directly through crop residues, as well as through crop‐induced changes in soil biotic properties. Rotation history influences decomposition, wherein productive winter cover crops (WCC) with low lignin content decompose fast and stimulate the turnover of both own and newly added residues via their knock‐on effect on the soil microbial community. Thus, WCC have promise for sustainable carbon‐ and nutrient‐cycling management through litter feedbacks. Foreign Language In landbouw worden plantenresten van wintergroenbemesters in de bodem ondergewerkt om bodemkwaliteit te verbeteren. De afbraaksnelheid van groenbemesterstrooisel en het daarbij vrijkomen van voedingsstoffen wordt bepaald door strooiselkwaliteit en lokale abiotische en biotische bodemomstandigheden. Echter is het onduidelijk hoe al deze factoren worden beïnvloed door gewasrotatie. In een veldexperiment werden verschillende winterse groenbemesters verbouwd in monoculturen en mengsels, in rotatie met hoofdgewassen Avena sativa (haver) en Cichorium endivia (andijvie). De invloed van gewasrotatie op de kwaliteit van groenbemesterstrooisel, lokale abiotische en biotische bodemparameters en strooiselafbraaksnelheid werd getest. Om bovendien onderscheid te kunnen maken tussen effecten van strooiselkwaliteit en veranderingen in bodemomstandigheden, werden effecten van gewasrotatie ook getoetst op de afbraak van standaard substraten (filterpapier en rooibosthee). In eenzelfde omgeving, zonder specifieke groenbemestergeschiedenis (voormalig winter braak), waren afbraaksnelheden van groenbemesterstrooisels negatief gecorreleerd met concentraties van koolstof‐ (C), lignine‐, en tegen de verwachtingen in, stikstof‐ (N) in het strooisel. Dit resultaat werd verklaard door de onderlinge positieve correlaties tussen N, C en lignine. In vergelijking met voormalig winter braakvelden, toonden proefvelden met een geschiedenis van snel afbrekende groenbemesters een snellere decompositie van zowel eigen strooisels als ook van de standaard substraten. De verschillende erfeniseffecten op afbraaksnelheid konden worden gerelateerd aan de effecten van de groenbemesters op de bodem microbiële biomassa, bodem organische stof en minerale stikstofgehalten. Afhankelijk van het hoofdgewas, konden de erfeniseffecten worden toegeschreven aan de hoeveelheid plantenresten van de groenbemesters, de kwaliteit hiervan, alsmede aan veranderingen in de microbiële biomassa, maar niet aan veranderde abiotische bodemfactoren. Synthese en toepassing. Deze resultaten tonen aan dat decompositie in landbouwsystemen direct wordt beïnvloed door gewasresten en de bodem erfeniseffecten op biotische bodemomstandigheden. De volgorde van gewassen beïnvloedt afbraak, waarbij productieve groenbemesters met snel afbrekende strooisels de decompositie van nieuw materiaal stimuleren via de microbiële bodemgemeenschap en vrijgekomen stikstof. Winterse groenbemesters zijn daarom veelbelovende middelen om C‐ en N‐kringlopen duurzaam te beheren door middel van strooisel‐feedback. These results demonstrate that decomposition in cropping systems is influenced directly through crop residues, as well as through crop‐induced changes in soil biotic properties. Rotation history influences decomposition, wherein productive winter cover crops (WCC) with low lignin content decompose fast and stimulate the turnover of both own and newly added residues via their knock‐on effect on the soil microbial community. Thus, WCC have promise for sustainable carbon‐ and nutrient‐cycling management through litter feedbacks.

Growing cover or winter crops and retaining crop residue on agricultural lands are considered beneficial management practices to address soil health and water quality. Remote sensing is a valuable tool to assess and map crop residue cover and cover crops. The objective of this study is to evaluate the performance of linear spectral unmixing for estimating soil cover in the non-growing season (November–May) over the Canadian Lake Erie Basin using seasonal multitemporal satellite imagery. Soil cover ground measurements and multispectral Landsat-8 imagery were acquired for two areas throughout the 2015–2016 non-growing season. Vertical soil cover photos were collected from up to 40 residue and 30 cover crop fields for each area (e.g., Elgin and Essex sites) when harvest, cloud, and snow conditions permitted. Images and data were reviewed and compiled to represent a complete coverage of the basin for three time periods (post-harvest, pre-planting, and post-planting). The correlations between field measured and satellite imagery estimated soil covers (e.g., residue and green) were evaluated by coefficient of determination (R2) and root mean square error (RMSE). Overall, spectral unmixing of satellite imagery is well suited for estimating soil cover in the non-growing season. Spectral unmixing using three-endmembers (i.e., corn residue-soil-green cover; soybean residue-soil-green cover) showed higher correlations with field measured soil cover than spectral unmixing using two- or four-endmembers. For the nine non-growing season images analyzed, the residue and green cover fractions derived from linear spectral unmixing using corn residue-soil-green cover endmembers were highly correlated with the field-measured data (mean R2 of 0.70 and 0.86, respectively). The results of this study support the use of remote sensing and spectral unmixing techniques for monitoring performance metrics for government initiatives, such as the Canada-Ontario Lake Erie Action Plan, and as input for sustainability indicators that both require knowledge about non-growing season land management over a large area.

The rate of pennycress residue decomposition and mineralization is critical in determining potential nutrient availability for following crops. To better understand pennycress decomposition, we examined biomass, nitrogen, and carbon loss from wild pennycress, gene edited AOP2 knockout pennycress, annual ryegrass, and cereal rye. Biomass was collected from all crops at the time of cash crop planting, and 20 g of biomass was placed in individual mesh forage bags (50 ± 10 mm). We placed 99 bags from each crop between rows of corn (n = 5) on the soil surface of the dominant soil types (SA and DR) at the ISU farm. Replicate bags were collected from each soil type over the following 84 days, weighed for biomass, and analyzed for carbon and nitrogen in the plant residue. Loss of biomass differed by crop and soil type (F = 3.7 3,32 , p = 0.023) with annual ryegrass losing biomass most rapidly followed by cereal rye, wild-type pennycress, and the domesticated low glucosinolate, AOP2 knockout, pennycress. Nitrogen (F = 8.5 3,36 , p < 0.0001) and carbon (F = 67.5 3,36 , p < 0.0001) losses differed by crop and not soil type following a similar trend as biomass loss. Our results suggest that both wild-type and AOP2 knockout pennycress can be expected to decompose similarly to a rye cover crop but with slower nutrient loss. Pennycress has potential to act as an effective short-term nutrient sink in agroecosystems.

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 >2 mm and 1–2 mm particle size aggregates, and the increment in the C/N ratio in >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 >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, >2 mm) aggregates, and enhance the enzyme activity of small and medium (0.25–1 mm, <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.

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.

Cover crop management during the fallow season may play a relevant role in improving crop productivity and soil quality, by increasing nitrogen (N) and soil organic carbon (SOC) accumulation, but has the possibility of increasing greenhouse gas (GHG) emissions from the soil. A year-long consistency experiment was conducted to examine the effects of various winter covering crops on annual nitrous oxide (N2O) together with methane (CH4) emissions in the mono-rice planting system, including direct emissions in the cover crop period and the effects of incorporating these crops on gaseous emissions during the forthcoming rice (Oryza Sativa L.) growing period, to improve the development of winter fallow paddy field with covering crops and to assess rice cultivation patterns. The experiment included three treatments: Chinese milk vetch-rice (Astragalus sinicus L.) with cover crop residue returned (T1), ryegrass (Lolium multiflorum L.)-rice with cover crop residue returned (T2), and rice with winter fallow (CK). Compared with CK, the two winter cover crop treatments significantly increased rice yield, soil organic carbon (SOC) and total nitrogen (TN) by 6.9–14.5%, 0.8–2.1% and 3.4–5.4%, respectively. In all cases, the fluxes of CH4 and N2O could increase with the incorporation of N fertilizer application and cover crop residues. Short-term peaks of these two gas fluxes were monitored after all crop residues were incorporated in the soil preparation period, the early vegetative growth period and the midseason drainage period. The winter cover crop residue application greatly enhanced CH4 and N2O cumulative emissions compared with CK (by 193.6–226.5% and 37.5–43.7%, respectively) during rice growing season and intercropping period. Meanwhile, the mean values of global warming potentials (GWPs) from paddy fields with different cropping crops were T2 > T1 > CK. Considering the advantages of crop productivity together with environmental safety and soil quality, Chinese milk vetch-rice with cover crop residue returned would be the most practicable and sustainable cultivation pattern for the mono-rice cropping systems.

Introduction: Yield and its stability are both vital characteristics to evaluate the viability of cropping systems. However, the current frames of field research hardly allow an accurate evaluation of short-term effect stability. Therefore, over nine German environments (three years and three locations), first crop, maize, total harvested dry biomass yield (DMY), and maize dry matter content (DMC) variability were evaluated through a risk assessment in an organically managed silage maize experiment comprising 18 cropping systems.Material and methods: The treatment factors included first crop group (pure legume, legume–cereal mixture), first crop (winter pea, hairy vetch and their mixtures with rye, control), management—incorporating first crop use and tillage (double cropping system no-till, double cropping system reduced till, double-cropped, mulched system terminated with roller-crimper, control), fertilization and mechanical weed control (yes–no), and row width (75 cm, 50 cm).Results and discussion: The first crop DMY and maize DMC had a positive relationship with its variance, whereas maize DMY and total DMY had a negative relationship. The differences in risks were governed by system (number of crops), management and first crop (group), and followed compatible patterns with what was observed for their influence on the mean of the parameters. The pedological and climatic conditions, especially near maize sowing and establishment, and therefore the length of season are crucial in double cropping and double-cropped, mulched systems. In its current state, the location in the northern region of Germany was not well suited for the studied alternative systems, whereas in the other regions (central and south), double cropping systems with reduced tillage as well as double-cropped systems with pure legume mulches may offer alternative management systems for silage maize. Further optimization of the critical sowing and establishment phase may result in more diversified options for double cropping and double-cropped, mulched systems in the future.

Rotations that include winter cover crops are widely used in agricultural systems and can provide numerous agroecological and economic benefits. However, the effects of winter cover crops on arthropod diversity, specifically rice pests and related natural enemies in rice rotation systems, are still largely unknown. We compared the effects of three winter cover crops, rapeseed, Brassica napus L. (Brassicales: Brassicaceae), Chinese milkvetch, Astragalus sinicus L. (Fabales: Fabaceae), and garlic, Allium sativum L. (Asparagales: Amaryllidaceae), on arthropods species diversity and evenness, densities of populations of major rice pests and major natural enemies, and grain yield in an experimental double cropping rotational rice field in Jiangxi Province, China. We did not observe any effects of cover crops on arthropod species diversity and evenness. The presence of prior cover crops also had no effect on the number of plants infested by the two major rice pests, Chilo suppressalis Walker (Lepidoptera: Pyralidae) and Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae). Our study did not show any effects of rapeseed and Chinese milkvetch on grain yield. However, grain yield was increased in the garlic treatment. Our results suggest that although the winter cover crops we tested in our study do not affect the number of rice plants infected by major rice pests, they do not negatively affect the arthropod community and grain yields in rice rotation systems. Therefore, planting of winter cover crops may increase agricultural land utilization and have an overall economic benefit in rice rotational systems.