Annual Crop Rotation Research Articles

Comparing structural soil properties of boreal clay fields under contrasting soil management

AbstractSoil management significantly affects soil structure. Tillage and grassland renovation may have destructive influences, while conversion of arable land to grassland can improve pore structure and related soil functions. In crop rotations including perennial grasses, soil structure is affected by these counteracting processes. This work aimed to quantify the impacts of different soil management practices on the structure of boreal clay soils. We studied intact topsoil samples taken from two locations by X‐ray computed microtomography, image‐based flow simulations and water retention measurements. At both locations, adjacent field areas with two contrasting soil management histories were compared. Both locations had at least a 30‐year‐old grassland site, which was compared to arable soils either under no‐till management with annual crop rotation or conventional tillage with crop rotation including perennial grasses. Both imaging and water retention measurements showed significant differences in the soil macropore structure between the long‐term grassland and arable no‐till soil such that macroporosity and hydraulic conductivity of the long‐term grassland were higher than those of soil under agricultural production. On the contrary, at the second study location, differences between long‐term grassland and cultivated fields were minor and the long‐term grassland exhibited lower macroporosity. Our results confirm that soil management affects the macropore structure of boreal clay soil and that no‐till annual cropping and periodically tilled crop rotation including perennial phases exert different effects on the soil structure as compared with long‐term grassland.

Potential gains in soil carbon and nitrogen as a result of systems perenniality: Insights from on‐farm experiments and soil organic matter fractions

AbstractUnderstanding soil organic matter (SOM) dynamics along gradients of land intensification is critical to guide conservation goals towards improvements in soil carbon (C) and nitrogen (N) storage. In this study, we clarified (a) how the C and N concentrations within SOM fractions of distinct ecological relevance responded to soil management representing a cropland‐grassland gradient and (b) how these operationally defined fractions affected soil physicochemical and biological properties. We compared sites with annual row crop rotations with and without cover crops (i.e. cropland soils) with perennial grassland sites (i.e. reference soil) by sampling near‐surface soils from statewide on‐farm cover crop experiments replicated across four agro‐ecoregions in Midwest USA. Soil management had a significant main effect on C and N content in SOM fractions, but responses were site‐ and fraction‐specific. We found that C content of free particulate organic matter and water‐extractable organic matter (WEOM) of reference soils were 58%–76% and 31%–59% greater than those of the cropland soils in two of the four sites. Differences in N content of WEOM because of soil management were observed in two of the four sites. These reference soils had between 40% and 60% greater N than cropland soils. Additionally, the N content of aggregate occluded POM (o‐POM) of reference soils was three times greater than those of the cropland soils in one of the four sites. Broadly across bulk and SOM fractions, high declines in cropland C and N relative to reference soils were observed in non‐irrigated and strip‐till sites and coarse‐texture soils. Free and o‐POM C and N were strongly associated with aggregate stability, water infiltration and enzyme activity, whereas C and N contents of WEOM and MAOM were correlated with soil's ability to hold onto essential nutrients (e.g. calcium, magnesium, potassium and sodium). Although the potential of cover crops to drive changes on ecologically meaningful SOM fractions is less pronounced in the short (3 year) term, the findings demonstrate the potential of continuous living cover as an approach to agroecosystem design to improve soil functions closely related to SOM characteristics.

Effects of Continuous Annual Crop Rotation and Fallow on Soil Aggregate Stability and Organic Carbon

In order to explore the effects of continuous annual crop rotation and fallow on aggregate stability and organic carbon content in red soil, the red soil in sloping farmland was taken as the research object, and the water-stable aggregates and organic carbon content were determined using the wet sieve method and potassium dichromate-concentrated sulfuric acid external heating method, respectively. The changes in soil aggregate stability and organic carbon content under the four treatments of maize-vetch-maize rotation (M-V-M), maize-pea-maize rotation (M-P-M), maize-fallow-maize (M-F-M), and annual fallow (F-F-F) from 2020 to 2022 and the relationships between them were analyzed. The results showed that in 2021 and 2022, the contents of > 2 mm aggregates treated with F-F-F, M-V-M, and M-P-M were significantly increased by 67.01%-100.92%, 29.71%-33.67%, and 29.68%-38.07%, respectively, compared with that treated with M-F-M. In 2021 and 2022, the stability parameters of F-F-F and M-V-M were significantly higher than those of M-F-M (P < 0.05). The content of > 2 mm aggregates, geometric mean diameter (GMD), and mean weight diameter (MWD) under the M-V-M treatment and R0.25 (> 0.25 mm aggregate contents), MWD and > 2 mm aggregate contents under the F-F-F treatment increased with the increase in fallow years, whereas the content of 1-2 mm and < 0.25 mm under the F-F-F treatment decreased with the increase in fallow years. Both green manure rotation and fallow treatment could increase the SOC content, and the SOC content of F-F-F and M-V-M treatment increased with the extension in age. Correlation analysis showed that SOC content was significantly positively correlated with R0.25 and GMD under all treatments. R0.25 and GMD under the F-F-F treatment and GMD and MWD under M-V-M were significantly positively correlated with SOC content. The results showed that continuous annual crop rotation and fallow was beneficial to improve the content of soil macro-aggregates, aggregate stability, and SOC content, which could provide theoretical basis for the implementation of reasonable continuous annual crop rotation and fallow patterns and soil erosion control in red soil areas of sloping farmland in southern China.

Soil Fertility and Phosphorus Leaching in Irrigated Calcareous Soils of the Mediterranean Region

To ensure soil quality and soil health, it is necessary to improve fertilization practices while minimizing environmental impacts. The aim of this study was to record the state of the art on soil fertility related to fertilization management (organic and/or mineral) and to detect environmental challenges in highly productive fields. A soil survey was set up in a new irrigated area (c. 20 years old), in the north-eastern part of Spain, which is mainly devoted to double annual crop rotations of cereals and maize. The area also supports an important animal rearing activity. The survey covered 733 ha of calcareous soils, owned by 35 farmers. At each farm, fertilization management was recorded, and soil was analyzed for nutrients and heavy metals. Multivariate analyses were performed. Total N, P, Cu and Zn, and available P, Cu, Zn and Mn soil concentrations were associated to the use of organic amendments. Heavy metals concentrations were below established thresholds. Available P (Olsen-P) was identified as an indicator of the previously adopted fertilization management and of the potential of P leaching towards deeper soil layers. Regression analyses were performed. A displacement of available P from the uppermost layer (0–0.3 m) occurs in the breakpoint of 86 mg P kg−1 soil. Preventative actions might be established from 53 mg P kg−1 soil due to the slowdown in P immobilization. Our results reinforce the importance of setting up P threshold soil levels for best practices of fertilization, as a basis for sustainable agriculture intensification.

Soil microbial biomass carbon and Jatropha curcas yield intecropping with forages and crop species

The domestication of Jatropha curcas L. in the Brazilian territory has been boosted by its great potential in the production of grains, oil and, in particular, its adaptation in different soil and climatic conditions. The aim of this research was evaluate the soil biological quality through the soil microbial biomass carbon and its indices derivate (metabolic and microbial quotient) under J. curcas intercropping with many forages species, legumes and annual crop rotation systems, as well as the accumulated production of J. curcas grains and oil. The experiment was conducted in a commercial area in the randomized blocks experimental design with the treatments arranged in a 12 x 2 factorial design, with four repetitions, resulting in 12 treatments with cropping systems and 2 sampling times (February 2012 and May 2012). Soil sampling was performed in February and May 2012, at 0 at 10 cm layer and four composite samples were collected in each cropping system, from five subsamples in each plot. J. curcas intercropping with B. ruziziensis, favors the maintenance of the community of soil microorganisms compared to the treatment with the species P. maximum cv. Massai and Cajanus cajan, which promoted decreasing in soil organic matter dynamics, when compared to the other cropping systems. The monocropping systems of J. curcas and intercropping in rotation systems 2 and 3 achieved higher yields of J. curcas grains and oil over three seasons.

Effects of Annual Crop Rotation and Fallow on Soil AMF Community and Aggregate Stability

To investigate the effects of crop rotation and fallow on the community composition of arbuscular mycorrhizal fungi (AMF) and the stability of soil aggregates, AMF community and aggregates were measured using Illumina MiSeq high-throughput sequencing and wet screening methods in red soil of sloping farmland. The AMF community and its relationship with soil factors and aggregate stability were studied under the four treatments of vetch rotation corn (V-C), pea rotation corn (P-C), winter fallow corn (F-C), and annual fallow (F-F). The results showed that the aggregate content of >2 mm, R0.25, and MWD in the F-F, V-C, and P-C treatments were significantly higher than those in F-C (P<0.05), and the aggregate content of <0.25 mm was significantly lower than that of F-C (P<0.05). The ACE, Chao1, and Shannon indexes of the F-F treatment were 29.56%, 35.78%, and 45.55% higher than those of the F-C treatment, respectively. Glomus was the dominant genus of AMF communities under all treatments, whereas Scutellospora showed a significant difference among the treatments (P<0.05). PCoA analysis showed that PC1 and PC2 together explained 29.99% and 22.40% of the difference in the AMF community composition, respectively. The correlation analysis showed that there was a significant negative correlation between Scutellospora and alkaline nitrogen (AN) and organic matter (SOM) (P<0.05), a significant positive correlation between Scutellospora and available potassium (AK) (P<0.05), and a significant positive correlation between Glomus and alkaline nitrogen (P<0.05). RDA analysis showed that AMF diversity (Shannon index) and Scutellospora were significantly and positively correlated with aggregate content >2 mm and 2-1 mm, respectively (P<0.05). Therefore, annual fallow and vetch rotation corn were conducive to improving the stability of soil aggregates and changing the composition of the AMF community. The research results provide a theoretical basis and reference for the annual rotation system to improve soil quality and implement a reasonable crop rotation and fallow pattern in southern China.

Grassland management effect on ecosystem services in the livestock system in an oxisol from the Eastern high plains of Colombia

Colombia has a livestock population of approximately 28.2 million heads, of which 20.4% is found in the eastern high plains of the Orinoquia region. The extensive beef cattle system predominates, whose diet is based on native and introduced pastures of the genus Urochloa sp. which is deficiently managed, affecting productive and reproductive indexes due to the low adoption of technology. We evaluated potential sustainable intensive systems for cattle production, which contribute to maintaining the provision of environmental services. Between 2011 and 2015 in Agrosavia’s Research Center at Carimagua (4° 37'N and 71° 19' W) environmental and animal production variables were monitored in the following systems: a) degraded pastures recovered with tillage and fertilization, b) annual crop rotation with pastures, c) forest arrangements in strips, and d) forest remnants in perimeter areas. Productive and reproductive variables were determined in animals such as weight gain, calving interval, among others while the pasture/crop productive variables included yield and forage quality. Regarding soil ecosystem services (ES) the macrofauna biodiversity, biogeochemical cycles, soil physical and chemical variables were considered. Estimation of indicators was carried out through principal components analysis for soil physical, chemical and macrofauna variables to extract the two main components that explain the variance. For climate regulation of ES, measurement of soil organic carbon (SOC) storage at a depth of 20 cm and the annual accumulated greenhouse gas (GHG) emissions were included. The systems that involved lime amendments and fertilizers increased the value in the year of application. Values in the water regulation indicator did not show significant differences among the options implemented during the years. Edaphic macrofauna biodiversity indicator value was sensitive to changes in management practices, with termites being the group with highest abundance. The indicator related to SOC was higher in the forest area compared to the pasture-crop system. Systems under the agroforestry schemes which integrated various practices such as managed and recovered pastures, crop-pasture rotation, patched areas and tree strips contributed to maintain or improve the ES, although each one of the strategies proposed provided improvement in at leas one ES.

Crop rotation and cultivation effects on Convolvulus arvensis population dynamics in small grain organic cropping systems

Convolvulus arvensis L. Scop. (field bindweed) is a difficult weed to manage in organic cropping systems. Convolvulus arvensis suppression often requires intensive tillage and cultivation practices that have negative impacts on soil quality. To improve C. arvensis management in organic, small grain cropping systems, we compared ten cropping system treatments in a field trial from the autumn of 2017 until harvest of 2020 in Corvallis, MT, USA. Cropping system treatments varied along a gradient of tillage and crop competition, with tillage intensity and competition inversely related. High soil disturbance and no competition occurred in two treatments that remained in tilled fallow for two consecutive years. Six cropping system treatments had different combinations of tillage and annual or biennial crops, including wheat and forages. Two treatments had minimal soil disturbance and maximum competition from two consecutive years of perennial alfalfa. Convolvulus arvensis ramet density was counted annually to estimate changes in treatments over time. Differences in soil chemical and physical properties between treatments were also assessed in the final years of the study. In the first two years, there was no difference in C. arvensis ramet density among cropping system treatments. In the final two years of the study, C. arvensis density remained below one ramet per m2 in intensively tilled fallow treatments and perennial alfalfa treatments, but was much more variable in treatments with more diverse annual and biennial crop rotations with minimal to moderate tillage. The only differences between treatments in soil physical and chemical properties was aggregate stability. Soil from the most intensively tilled fallow treatments had lower soil aggregate stability than six other treatments, indicating higher erosion potential. Our results suggest that annual cropping systems can lead to increased C. arvensis density. Incorporating a perennial forage or an intensively tilled fallow period can prevent C. arvensis expansion in small grain organic cropping systems, but the perennial forage can protect and enhance soil quality.

Crop diversification effects on soil organic carbon and nitrogen storage and stabilization is mediated by soil management practices in semiarid woody crops

Crop diversification is a promising strategy to mitigate climate change through soil carbon sequestration while ensuring soil fertility maintenance and food security. Here, we assess the impact of different inter-cropping practices on soil organic carbon (SOC) and nitrogen (N) storage and stabilization under rainfed and irrigated semiarid conditions. Under rainfed conditions, an almond (Prunus dulcis Mill.) monocrop was compared with an almond inter-cropped with caper (Capparis spinosa) or with winter thyme (Thymus hyemalis). Under irrigated conditions, a mandarin (Citrus reticulata Blanco) monocrop was compared with a mandarin inter-cropped with an annual crop rotation (including Hordeum vulgare, Vicia sativa and Vicia faba) or with a triennial crop rotation (including Vicia faba, Portulaca oleracea and Vigna unguiculata L.). The SOC and N stocks, SOC mineralization rates, water-stable aggregates and associated OC and N contents were estimated at 0–10 and 10–30 cm depth in each monocrop and inter-cropping system after three years. Contrasting effects of inter-cropping on SOC and N stabilization were found in the rainfed and irrigated systems. The combination of inter-cropping and no tillage did not affect the SOC stocks or mineralization rates at any soil depth in the rainfed system, while it significantly increased the OC and N contents within the large macro-aggregates in the subsoil. Compared to the irrigated mandarin monocrop, the mandarins inter-cropped with the annual crop rotation showed a significant increase of 10% and 18% in the topsoil and subsoil N stocks, respectively, while the SOC mineralization rates were reduced by 30% at both soil depths. On the contrary, the topsoil SOC stock in the mandarins inter-cropped with the triennial crop rotation were reduced by 38% compared to the monocrop. Significant reductions ranging between 24% and 66% were also observed in the OC and N contents associated to the macro- and micro-aggregates in the topsoil and subsoil of both crop diversifications compared to the monocrop system. Our results highlight the potential of inter-cropping rainfed woody crops with perennials for boosting SOC and N storage and stabilization. In irrigated woody monocrops, inter-cropping with annual crop rotation schemes that include two or more leguminous and reducing tillage frequency operations seems to be more appropriate in terms of SOC and N stabilization.

Soil carbon storage and compositional responses of soil microbial communities under perennial grain IWG vs. annual wheat

The introduction of novel perennial grains into annual row crop rotations is proposed to increase soil ecosystem services and enhance plant-soil-microbial linkages because perennials provide deeper root systems and more continuous ground cover than annuals. While soil microbial communities underpin many ecosystem services, we know little about how soil microbial composition and diversity, and soil carbon storage, differ between soils of annual vs. perennial grain crops. We measured soil fungi: bacteria (F/B) ratios and soil carbon within the novel perennial intermediate wheatgrass (IWG; trademarked Kernza®) and tilled annual wheat and compared soil microbial diversity and community composition within their rhizosphere, shallow bulk soil (0–15 cm) and total bulk soil (0–90 cm). After three years, soil depth explained 30–40% and 12–22% of the variance in bacterial and fungal community composition, respectively, while crop type explained 10% and 9–16% of the variance, respectively. Fungal communities were most impacted by crop type in the rhizosphere and shallow bulk soil and less sensitive to differences in soil depth. In contrast, crop type had a smaller effect on bacterial communities which were more influenced by soil depth. IWG trended higher in soil carbon mass at 0–30 cm (p = 0.22) and had a higher (F/B) ratio than tilled annual wheat at depths below 15 cm, but tilled annual wheat had higher soil carbon concentration (p = 0.12) and soil carbon mass (p = 0.09) at the 60–90 cm soil depth. Our results indicate that fungi were more responsive than bacterial communities to crop type and that IWG has a higher fungal biomass and different fungal community composition than annual wheat at depth. However, despite these distinct differences in fungal communities in IWG compared to annual wheat, the differences did not translate into greater soil carbon mass in IWG at depth.

Linking agricultural diversification practices, soil arthropod communities and soil health

Abstract Soil arthropods comprise a substantial portion of soil biodiversity and regulate processes in the soil ecosystem. Despite this, cropping system diversification designed to improve soil health for agriculture is rarely evaluated for its effects on soil arthropod biodiversity and community structure. As a result, soil arthropods are not usually considered in management decisions. To address this gap, we evaluated the effects of agricultural diversification through rotation on soil arthropods and soil properties using replicated large‐plot field studies representing two climatically distinct agroecological classes (AECs) in the dryland cereal‐growing region of the inland Pacific Northwest, USA. We investigated how different 3‐year annual crop rotations affected soil arthropod biodiversity and community structure. Treatments reflected ‘business‐as‐usual’ rotations in dryland systems and diversified rotations achieved by incorporating novel winter pea (WP) or forage crops (FORs). We also assessed relationships between the Soil Biological Quality index (QBS‐ar), which uses soil arthropods as bioindicators of soil health, and other biological and physiochemical soil health indicators. We collected 710 community samples with 82,509 arthropod specimens across 66 taxa. Novel crops in diversified rotations promoted soil arthropod abundance and biodiversity relative to crops they could replace in rotation. Crop type determined community composition. Most taxa driving differences in community structure were predators and detritivores associated with WP and FORs. In addition to effects on soil arthropods associated with specific crops, effects were also detected across rotations. Incorporating WP into rotations improved QBS‐ar across entire rotations, not just in the WP phases, in both AECs. Links between QBS‐ar and other soil health indicators were complex and varied by AEC. Synthesis and applications: Soil arthropods respond to agricultural diversification and can be used as bioindicators to assess the effects of diversification on soil health. Below‐ground arthropod communities are structured by crop type, suggesting that planting specific crops may promote soil arthropods and their services. We showed that incorporating winter pea and forage crops into dryland cereal rotations supported soil arthropod biodiversity and soil health. Results indicate that soil arthropod assessments can be included in the soil health framework to guide agricultural management decisions.

Combining organic fertilisation and perennial crops in the rotation enhances arthropod communities

Single and combined diversification practices in crop fields and their effects on arthropod predators, decomposers and herbivores have mainly been assessed in small plot and cage experiments. In particular, effects of diversification on arthropod predators and their food resources, such as soil fauna, weed seeds and herbivorous prey in entire crop fields across the growing season, remain unclear. We explored how organic fertilisers, with or without the legacy of perennial ley in the crop rotation, and mineral fertiliser without the legacy of perennial ley, affected below- and aboveground communities in 19 spring cereal crop fields. In each field, we determined the abundance of the soil mesofauna, communities of arthropod prey aboveground and of the predator guilds carabids, staphylinids and spiders. We sampled at three crop stages: tillering, heading and ripening. Weed cover and soil characteristics, such as carbon and nitrogen content, were assessed. For most soil mesofauna groups, the combination of organic fertiliser with the legacy of ley gave highest, organic fertiliser with annual crop rotations intermediate, and mineral fertiliser with annual crop rotations the lowest total abundance. Aboveground arthropod prey abundances were similar across treatments. The legacy of ley increased richness of all aboveground arthropod predators. Staphylinid communities’ abundance increased additively as diversification treatments were combined during tillering of the crop. Increasing organic amendments, alongside the reduced disturbances through inclusion of perennial ley in the rotation, led to more abundant communities below- and aboveground as well as more richness in aboveground predator communities.

Agricultural practices influence biological soil quality indicators in an irrigated semiarid agro-ecosystem

A study was conducted to investigate how soil biological measurements can be used to indicate differences in soil quality in arid and semiarid agroecosystems. The objectives were to assess soil biological quality indicators under different land management practices and at different depths and to explore the relationships between soil microbial community and organic matter fractions. Soil samples were collected from three replicates of six land management systems at 0–5 cm and 5–15 cm soil depths. Four management systems had medium to fine soil texture including a permanent grass field with tall fescue (Lolium arundinaceum [Schreb]; TFC), peach orchard with clover understory (Prunus persica with Trifolium repens L.; PCC), alfalfa field (Medicago sativa; ALF) and conventionally tilled soil with an annual crop rotation (CTC). Two management systems, including a young cottonwood tree orchard (Populus fremontii and Populus deltoides; CWS) and conventionally tilled soil in annual crop rotation (CTS), had coarse soil texture. Management systems had significant impacts on most of the soil biological indicators assessed at the two depths with both depths responding similarly to management practices. For the soil biological indicators that showed differences, the TFC generally had the most favorable indicator measurements compared to other management systems. The principal component analysis showed a clear separation between the management systems and microbial communities at both soil depths. The ordination pattern was structured by soil textural differences between medium to fine-textured soils from TFC, PCC, ALF, and CTC fields and coarse-textured soils (CWS, CTS). Spearman’s correlation coefficients (rs) showed that the soil organic matter (rs = 0.85, P = 0.001) and the permanganate oxidizable carbon (rs = 0.93, P = 0.001) were significantly correlated with the total microbial biomass at 0–5 cm soil depth. Also, the soil organic matter (rs = 0.84, P = 0.001) was significantly correlated with the total microbial biomass at 5–15 cm soil depth. This study suggests that in semiarid agroecosystems, management practices with permanent covers have the potential to improve soil quality, and soil texture may also influence the directional changes in soil quality within this region.

Weed community shifts during the aging of perennial intermediate wheatgrass crops harvested for grain in arable fields

The development of a perennial grain offers opportunities to diversify annual crop rotations, with potential benefits in terms of soil protection. Perennials could also reduce weed development over time through year-round soil cover and longer growing seasons. However, whether weeds would actually decrease remains mainly theoretical, with field data on perennial grains remaining sparse. Qualitative changes might also have an effect, because disturbance and modifications to resource regimes drive shifts in weed communities. Here, we analyzed weed abundance, composition, and traits in three arable fields containing perennial grain over a 4-year period. Specifically, intermediate wheatgrass (IWG) perennial grain (Kernza) was cultivated. IWG grain production was maximal during the first and second growing seasons (899 and 854 kg.ha-1 respectively), with total biomass production peaking in the second year (mean: 11.9 t DM.ha-1). However, reproductive effort noticeably dropped in the third and fourth years. Weed biomass also gradually reduced during the fall of all years (mean: ∼0.4–∼0.03 t DM.ha-1), but remained constant in spring (mean: 1–2 t DM.ha-1). During spring, the community composition of weeds shifted from broadleaves to grass species and, to a lesser extent, from annuals to perennials, with weed species having an earlier phenology than IWG. Thus, relative fitness appeared to be the strongest driver of weed community composition in aging IWG stands. Weed species richness systematically declined over the years. Specific leaf area, height, light, and nitrogen requirement index of weed communities provided poor descriptors of community shifts; however, all weed species with high light requirements were excluded from aging IWG stands. IWG capacity to compete with weeds might have been undermined by its late growing cycle, absence of forage harvest during the growing season, and substantial initial weed development during establishment (first year of growth). Thus, before IWG establishment, initial site conditions and land use history should be considered to implement the best management strategies for each field. Important weed development in perennial grain fields could lead to high weeding requirement, either mechanical or chemical, in conflict with the initial principle of increasing sustainability and reducing inputs.

Effect of alfalfa on subsurface (tile) nitrogen and phosphorus loss in Ohio, USA.

Growing annual crops such as corn (Zea mays L.) can lead to considerable nutrient losses through subsurface drainage in agricultural fields, posing a serious threat to surface water quality in the midwestern United States. Perennial crops have the potential to reduce these nutrient losses. However, more comprehensive data are needed on the nutrient loss effect of perennial crops. We examined the effect of alfalfa (Medicago sativa L.) on nitrate-nitrogen (NO3 - -N), total nitrogen (TN), dissolved reactive phosphorus (DRP), and total phosphorus (TP) in subsurface drainage using a before-after-control-impact (BACI) experimental design with one control field (with annual crops) and one impact field (with alfalfa) each on two farms (Sites A and B) located in northwestern Ohio. The "Before" period (prior to planting alfalfa at the impact field) extended for 4 yr (2013-2017) at Site A and 6 yr (2011-2017) at Site B; the "After" period extended for an additional 2 yr at both sites. Reductions in the mean monthly discharge and loads of NO3 - -N, TN, DRP, and TP were significant at Site A, whereas the only significant change at site B was a reduction in the mean monthly TP load. Significant reductions in NO3 - -N loads were observed during spring and winter at Site A. In addition, alfalfa reduced the variability of discharge and nutrient loads through subsurface drainage at both sites. Our findings suggest that introducing alfalfa into annual crop rotations has the potential to reduce subsurface nutrient loads and increase the resiliency of agricultural systems.

Reductions in soil water nitrate beneath a perennial grain crop compared to an annual crop rotation on sandy soil

Nitrate (NO3--N) leaching into groundwater as a result of high nitrogen (N) fertilizer rates to annual crops presents human health risks and high costs associated with water treatment. Leaching is a particularly serious concern on sandy soils overlying porous bedrock. Intermediate wheatgrass (IWG) [Thinopyrum intermedium (Host.) Barkw. &amp;amp; D.R. Dewey], is a perennial grass that is being bred to produce agronomically and economically viable grain, which is commercially available as Kernza®. Intermediate wheatgrass is a low-input crop has the potential to produce profitable grain and biomass yields while reducing NO3--N leaching on sandy soils compared with common annual row crop rotations in the Upper Midwest. We compared grain yields, biomass yields, soil solution NO3--N concentration, soil extractable NO3--N, soil water content, and root biomass under IWG and a conventionally managed corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] rotation for 3 years on a Verndale sandy loam in Central Minnesota. Mean soil solution NO3--N was 77–96% lower under IWG than the annual crop rotation. Soil water content was greater under annuals compared to IWG early in the growing season, suggesting greater water use by IWG during this time. Interactions between crop treatments and depth were observed for soil water content in Year 3. Root biomass from 0 to 60 cm below the soil surface was five times greater beneath IWG compared to soybean, which may explain differences in soil extractable and solution NO3--N among crops. With irrigation on coarse structured soils, IWG grain yields were 854, 434, and 222 kg ha−1 for Years 1–3 and vegetative biomass averaged 4.65 Mg ha−1 yr−1; comparable to other reports on heavier soils in the region. Annual crop grain yields were consistent with local averages. These results confirm that IWG effectively reduces soil solution NO3--N concentrations even on sandy soils, supporting its potential for broader adoption on land vulnerable to NO3--N leaching.

Long term effects of crop rotation and fertilization on crop yield stability in southeast China

The objective of this study was to determine the effects of different fertilizer treatments and crop rotations on crop yield stability. A 9 years field experiment was conducted from 2013 to 2021 to evaluate the effects of combinations of two annual crop rotations and two methods of applying fertilizer on crop yield stability. Crop rotations were kidney bean–mustard–rice (P–B–O) and kidney bean–mustard–cowpea (P–B–V) each year. Fertilization methods were recommended fertilization (RF) and conventional fertilization (CF). The indexes Wi2 (Wricke’s ecovalance), coefficient of variation (CV), and sustainable yield index (SYI) were used to quantify the long term effects of crop rotation and fertilization on crop yield stability, and a yield change trend model was used to predict future production. For fertilization program RF, average kidney bean and mustard yields in rotation P–B–O increased respectively by 7.47% and 19.37% over P–B–V in the 9 years of the project. For CF, average kidney bean and mustard yields for P–B–O increased respectively by 14.99% and 18.33% over P–B–V. Wi2 indexes of kidney bean and mustard for P–B–O (respectively 116 and 956) were significantly less than for P–B–V (respectively 147.87 and 1259.67). SYI for kidney beans and mustard in P–B–O (respectively 0.63 and 0.57) were significantly greater than for P–B–V (respectively 0.50 and 0.42). The trends of crop average yields for RF and CF show that the average yield trends of kidney bean in P–B–O (respectively 32.41 and 32.34) were greater than in P–B–V (respectively 29.56 and 27.45). The trends of average yields of mustard for RF and CF in P–B–O (respectively 64.18 and 60.87) were greater than in P–B–V (respectively 51.74 and 51.87). The preceding results led to the conclusion that long term annual P–B–O rotation combined with RF considerably increased yield and maintained yield stability, thus establishing the sustainability of this cropping system.

Long-term simulations of Nature-Based Solutions effects on runoff and soil losses in a flat agricultural area within the catchment of Lake Massaciuccoli (Central Italy)

Nature-Based Solutions (NBSs) are implemented worldwide to mitigate the impact of industrial agriculture on sediment and nutrient losses; however, their effectiveness depends on site-specific features such as surficial hydrology, soil permeability and erodability. This study analyzed the effects of vegetative buffer strips (VBSs) and winter cover crops (CCs) in a land reclamation area of the Catchment of Lake Massaciuccoli (Central Italy) by modelling water and soil dynamics at a very detailed scale, using a novel approach based on high-resolution input data. To this aim, SWAT+ was applied on digital terrain models (DTMs) from close-range photogrammetry, land-cover mapping, real crop rotations and a detailed calendar of farming practices. NBSs behaviour was investigated in two test areas, namely the Studiati and the Gioia areas, with uniform geomorphological settings but different soil types and annual crop rotations. NBS effects were compared with a baseline control scenario (without NBSs) and assessed under future climate conditions (RCP 4.5 and RCP 8.5). Specifically, VBSs and CCs showed different capabilities in mitigating runoff and sediment losses, and their combination provided maximum effectiveness. For the current climate scenarios, the implementation of VBSs produced a reduction of runoff depth of about 41% and 64% in the Studiati and Gioia areas, respectively, whereas showing a limited with the CCs implementation. Under the future climate conditions, similar patterns were observed, even if predicting significantly lower runoff depths. The sediment loss reduction was in the order of 79% and 64% in Studiati and Gioia areas, respectively. Concerning soil and water dynamics, the study remarked that slight topographic irregularities on flat morphologies can trigger concentrated flows responsible for high runoff and sediment losses. Furthermore, the differences in soil texture and organic matter content affected soil erodability rate on a local scale, driving the consistency of NBS mitigating effects. Future climate changes scenarios, exhibiting higher temperature and rarer but more concentrated rainfall events, emphasize the impact of different soil types. Results observed at a very local scale, with a spatialization of a few square meters - which clearly relates to the types of crop rotations, NBSs and soil distribution - noticed that SWAT+ is a suitable tool to aid farmers in cropping systems management and design.

Twenty-four years of contrasting cropping systems on a brown chernozem in Southern Alberta: crop yields, soil carbon, and subsoil salinity

Cropping systems with perennial forages and reduced fallow frequency generally increase soil organic carbon and thus subsequent soil health and crop yield. We evaluated the impact of prior cropping systems on subsequent yields and soil properties in a semiarid region by using crop yields as a bioassay of soil health following the termination of a 24-year crop rotation study in the Brown soil zone in Alberta. During 24 growing seasons from 1992 to 2015, the study included three fallow-containing rotations, two annual crop rotations that were cropped continuously, and perennial grass hay, each with two to six fertilizer treatments. During the bioassay period from 2016 through 2020, all plots in the study were uniformly cropped. Compared to unfertilized fallow wheat, soil organic C in the fall of 2015 was 54% higher after 24 years of fertilized grass and up to 14% higher following annual crops in rotations without fallow. The most notable impact of the previous cropping system on yield during the bioassay years was low yield following perennial grass in 2016 and 2018. Soil electrical conductivity measurements showed that subsoil salinity was elevated following perennial grass, demonstrating the importance of subsoil characteristics for healthy soils. Crop yields in the fifth year of the crop bioassay were 10%–20% greater due to reduced fallow frequency or increased crop diversity. The long-term impact of the cropping system on crop yield in this study depended on drought intensity due to counteracting changes in soil organic matter and subsoil salinity.

Modeling Yield, Biogenic Emissions, and Carbon Sequestration in Southeastern Cropping Systems With Winter Carinata

Sustainable aviation fuel (SAF) production from lipids is a technologically mature approach for replacing conventional fossil fuel use in the aviation sector, and there is increasing demand for such feedstocks. The oilseed Brassica carinata (known as Ethiopian mustard or simply carinata) is a promising SAF feedstock that can be grown as a supplemental cash crop over the winter fallow season of various annual crop rotations in the Southeast US, avoiding land use changes and potentially achieving some of the soil carbon sequestration and ecosystem service benefits of winter cover crops. However, carinata may require more intensive management than traditional cover crops, potentially leading to additional soil greenhouse gas (GHG) emissions through increased carbon losses from soil tillage and nitrous oxide (N2O) emissions from nitrogen fertilizer application. In this work, the 2017 version of the process-based DayCent ecosystem model was used to establish initial expectations for the total regional SAF production potential and associated soil GHG emissions when carinata is integrated as a winter crop into the existing crop rotations across its current suitability range in southern Alabama, southern Georgia, and northern Florida. Using data from academic and industry carinata field trials in the region, DayCent was calibrated to reproduce carinata yield, nitrogen response, harvest index, and biomass carbon-to-nitrogen ratio. The resulting model was then used to simulate the integration of carinata every third winter across all 2.1 Mha of actively cultivated cropland in the study area. The model predicted regional average yields of 2.9–3.0 Mg carinata seed per hectare depending on crop management assumptions. That results in the production of more than two million Mg of carinata seed annually across the study area, enough to supply approximately one billion liters of SAF. Conventional management of carinata led to only modest increases in soil carbon storage that were largely offset by additional N2O emissions. Climate-smart management via adopting no-till carinata establishment or using poultry litter as a nitrogen source resulted in a substantial net soil GHG sink (0.23–0.31 Mg CO2e ha−1 y−1, or 0.24–0.32 Mg CO2e per Mg of seed produced) at the farms where carinata is cultivated.