Alfalfa Fields Research Articles

Alfalfa Weevil (Coleoptera: Curculionidae) Resistance to Lambda-cyhalothrin in the Western United States.

Forage alfalfa (Medicago sativa L. [Fabales: Fabaceae]) is a key agricultural commodity of the western region of the United States. The key insect pest of alfalfa, Hypera postica Gyllenhal (Coleoptera: Curculionidae), has developed resistance to the most common class of insecticide used to manage its damage. Alfalfa weevil samples from 71 commercial alfalfa fields located in Arizona, California, Montana, Oregon, Washington, and Wyoming were assayed for susceptibility to lambda-cyhalothrin during 2020-2022 using a laboratory concentration-response assay. Seventeen field sites representing all six states were highly resistant to lambda-cyhalothrin (resistance ratios > 79.6) and bioassay mortality often did not exceed 50% even at the highest concentration tested (3.30 µg/cm2 in 2020 and 10.00 µg/cm2 in 2021-2022). Field sites assayed with more than one pyrethroid active ingredient indicated likely cross-resistance between lambda-cyhalothrin and zeta-cypermethrin (type II pyrethroids) and variable and/or limited potential cross-resistance to permethrin (type I pyrethroid). Thirty-two field sites representing five states were susceptible to lambda-cyhalothrin (resistance ratios ranging from 1 to 20). While resistance is widespread, integrated resistance management strategies including rotating mode of action groups, applying chemical control tactics only when economic thresholds have been met, and utilizing cultural control tactics can be employed to slow the further development of resistance.

Allelopathic Toxicity of Cyanamide Could Control Amaranth (Amaranthus retroflexus L.) in Alfalfa (Medicago sativa L.) Field.

The inclination toward natural products has led to the onset of the discovery of new bioactive metabolites that could be targeted for specific therapeutic or agronomic applications. Despite increasing knowledge coming to light of allelochemicals as leads for new herbicides, relatively little is known about the mode of action of allelochemical-based herbicides on herbicide-resistant weeds. Cyanamide is an allelochemical produced by hairy vetch (Vicia villosa Roth.). This study aimed to detect the toxicity of cyanamide to alfalfa and amaranth. Seed germination experiments were carried out by the filter paper culture, and the seedling growth inhibition experiment was carried out by spraying alfalfa (Medicago sativa L.) and amaranth (Amaranthus retroflexus L.) seedlings with cyanamide. The results showed that when the concentration of cyanamide was 0.1 g·L-1, the germination of amaranth seeds could be completely inhibited without affecting the germination of alfalfa seeds. At the concentration of 0.5 g·L-1, cyanamide could significantly inhibit the growth of the root and stem of amaranth seedlings but did not affect the growth of alfalfa. This effect was associated with the induction of oxidative stress. The ascorbate peroxidase (APX) and catalase (CAT) activity of amaranth decreased by 6.828 U/g FW and 290.784 U/g FW, respectively. The malondialdehyde (MDA) content, peroxidase (POD), and superoxide dismutase (SOD) activity of amaranth firstly increased and then decreased with the increasing concentration of CA. These enzyme activities of amaranth changed more than that of alfalfa. Activities of the antioxidant enzymes APX, CAT, POD, and SOD and the content of MDA varied dramatically, thereby demonstrating the great influence of reactive oxygen species upon identified allelochemical exposure. In addition, cyanamide can also inhibit the production of chlorophyll, thereby affecting the growth of plants. From the above experiments, we know that cyanamide can inhibit the growth of amaranth in alfalfa fields. Thus, the changes caused by cyanamide described herein can contribute to a better understanding of the actions of allelochemical and the potential use of cyanamide in the production of bioherbicides.

A survey and molecular diagnosis of flower fly species (Diptera : Syrphidae) in Central of Iraq

A survey study was conducted to find out the species of flower flies and aphids in the alfalfa field from Abu Ghraib region - Iraq for the season 2018-2019. The survey results were eight species from seven genera belonged to two subfamilies (Syrphinae and Eristalinae). Syrphinae included five species: Eupeodes corollae, Episyrphus balteatus, Syrphus baltitus, Ischiodon scutellaris and Sphaerophoria scripta, while Eristalinae included three species: Eristalis pertinax, Eristalinus aeneus and Eristalinus sepulchralis. The highest population density was for E.corollae, followed by E.balteatus then S.scripta, which reached 3.1, 1.6, and 1.1 adult /trap, respectively. Four species of aphids on the alfalfa plant were also recorded in this study, these are Therioaphis maculata, Aphis fabae, Aphis craccivora and Myzus persicae. The results of Polymerase Chain Reaction (PCR) showed the ability of primer ITS2-4 to diagnosis the species of flower flies E.corollae and E.balteatus. It was able to replicate the DNA segments with a molecular weight (450) bp, after it showed a percentage of 100% nucleotide matching with the genetic region located between the ribosomal RNA gene 5.8S and 28S ribosomal RNA. Moreover, the bank number MN648194 and MN648193 were recorded for Eupeodes corollae and Episyrphus balteatus respectively, for the first time in Iraq. Molecular diagnosis is matching with the morphological identify of the two species.

Soil nematode community characteristics of alfalfa field with different growing ages in the semi-arid Loess Plateau of Central Gansu, Northwest China

To clarify the impacts of long-term alfalfa plantation on the soil nematode community, soil samples were collected from different alfalfa growing ages (2 a, 9 a, 18 a) in the semi-arid area of Loess Plateau in Central Gansu by Illumina Miseq sequencing technology. The main controlling factors affecting its community change were also explored. The results showed that soil nematode belongs to 2 classes, 7 orders, 16 families and 21 genera. Among them, Chromadorea was the dominant group (44.6%-81.4%), the relative abundance of which decreased with alfalfa growing ages. Paratylenchus, Helicotylenchus, Xiphinema, Pristionchus, Ditylenchus, Panagrolaimus, Longidorus, Aprutides, Isolaimium and Aglenchus were the special nematode species of alfalfa, among which Paratylenchus (54.1%), Helicotylenchus (23.9%) and Xiphinema (21.9%) were the dominant nematodes in 2 a, 9 a and 18 a alfalfa soil respectively. Plant-parasitic nematode was the dominant group in alfalfa soil (31.8%-67.1%), and its relative abundance decreased at first and then increased with alfalfa growing ages. Results of redundancy analysis showed that soil available phosphorus and total nitrogen were the dominant environmental factors affecting community structure of soil nematodes in the region.

A roadmap for ladybird conservation and recovery.

Ladybirds (Coleoptera: Coccinellidae) provide services that are critical to food production, and they fulfill an ecological role as a food source for predators. The richness, abundance, and distribution of ladybirds, however, are compromised by many anthropogenic threats. Meanwhile, a lack of knowledge of the conservation status of most species and the factors driving their population dynamics hinders the development and implementation of conservation strategies for ladybirds. We conducted a review of the literature on the ecology, diversity, and conservation of ladybirds to identify their key ecological threats. Ladybird populations are most affected by climate factors, landscape composition, and biological invasions. We suggest mitigating actions for ladybird conservation and recovery. Short-term actions include citizen science programs and education, protective measures for habitat recovery and threatened species, prevention of the introduction of non-native species, and the maintenance and restoration of natural areas and landscape heterogeneity. Mid-term actions involve the analysis of data from monitoring programs and insect collections to disentangle the effect of different threats to ladybird populations, understand habitat use by taxa on which there is limited knowledge, and quantify temporal trends of abundance, diversity, and biomass along a management-intensity gradient. Long-term actions include the development of a worldwide monitoring program based on standardized sampling to fill data gaps, increase explanatory power, streamline analyses, and facilitate global collaborations.

Effects of Continuous Cropping on Seed Germination and Seedling Growth, Physiological Characters of Alfalfa

Background: Alfalfa crops are subject to intercalation when grown continuously on the same field, and autotoxicity appears to be another factor in this thinning. Alfalfa fields are often thinned out and have lower yields during consecutive production, and autotoxicity is increasingly found to be a major reason. Hence, Therefore, understanding the seed germination and seedling growth and physiological mechanisms of the alfalfa under continuous cropping system becomes important for sustainable the use of alfalfa grassland. Methods: The leaves, stem, root and rhizosphere soil of alfalfa (Medicago sativa L. cv ZhongMu No.1) were collected to determine the seedling growth germination index (GI) and vigor index(VI), physiological characters malondialdehyde (MDA), proline, Soluble sugar (SS), Soluble protein (SP), Superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD). Result: The germination rate, germination potential, germination index (GI) and vigor index decreased with the increasing extract contents, particularly in leaf extracts. In the extract of plant and soil, the concentration of malondialdehyde altered indistinctly, while the contents of osmo-regulatory substances and the activities of anti-oxidative enzymes generally decreased. Furthermore, the extract increased the seedling length of alfalfa and GI was negatively correlated with seedling growth characteristics.

Landscape Composition and Management History Affect Alfalfa Weevil but not its Parasitoid.

It is widely recognized that both local and landscape-scale factors can be important drivers of crop pests, natural enemies, and biocontrol services. However, recent syntheses have found that landscape effects are inconsistent across study systems, highlighting the need for system-specific research to guide management decisions. In particular, studies conducted in perennial crops and that examine landscape configuration, not just composition, are especially lacking. We studied the impact of local and landscape factors on alfalfa weevil Hypera postica and its parasitoid Bathyplectes curculionis. Although classical biological control efforts have largely suppressed H. postica in the eastern United States, it remains problematic in the western United States. We sampled 20 production alfalfa fields in southeastern Wyoming to estimate H. postica density, parasitism rates by B. curculionis, and vegetation at local scales. We used remotely sensed imagery to characterize both landscape composition and configuration surrounding each sampled field. We used a hypothesis-driven modeling approach to determine which model was most predictive of H. postica and parasitism rate by B. curculionis. Landscape composition was the best model to predict H. postica densities. Host density was the best predictor of parasitism rates by B. curculionis. Production fields that had received insecticide applications in the last 5 years had higher weevil densities than fields that had not received insecticide applications. Stand age was not associated with weevil density or parasitism rate. In conclusion, we found local, landscape, and management components to be important in this system.

Effects of Temperature and Wildflower Strips on Survival and Macronutrient Stores of the Alfalfa Leafcutting Bee (Hymenoptera: Megachilidae) Under Extended Cold Storage.

Megachile rotundata (F.) is an important pollinator of alfalfa in the United States. Enhancing landscapes with wildflowers is a primary strategy for conserving pollinators and may improve the sustainability of M. rotundata. Changing cold storage temperatures from a traditionally static thermal regime (STR) to a fluctuating thermal regime (FTR) improves overwintering success and extends M. rotundata’s shelf life and pollination window. Whether floral resources enhance overwintering survival and/or interact with a thermal regime are unknown. We tested the combined effects of enhancing alfalfa fields with wildflowers and thermal regime on survival and macronutrient stores under extended cold storage (i.e., beyond one season). Megachile rotundata adults were released in alfalfa plots with and without wildflower strips. Completed nests were harvested in September and stored in STR. After a year, cells were randomly assigned to remain in STR for 6 months or in FTR for a year of extended cold storage; emergence rates were observed monthly. Macronutrient levels of emerged females were assessed. FTR improved M. rotundata survival but there was no measurable effect of wildflower strips on overwintering success or nutrient stores. Timing of nest establishment emerged as a key factor: offspring produced late in the season had lower winter survival and dry body mass. Sugars and glycogen stores increased under FTR but not STR. Trehalose levels were similar across treatments. Total lipid stores depleted faster under FTR. While wildflowers did not improve M. rotundata survival, our findings provide mechanistic insight into benefits and potential costs of FTR for this important pollinator.

The impacts of climate change and cropping systems on soil water recovery in the 0–1500 cm soil profile after alfalfa

Alfalfa (Medicago sativa L.) has played an important role in the “Grain-for-Green” program across the Chinese Loess Plateau but has characteristically high water consumption. Long-term growth significantly reduces soil water storage in the 0–1500 cm profile and results in an obvious decline of alfalfa yield. Fields planted with alfalfa for more than 8 years are often converted to annual crops (winter wheat or corn), but these annual crops planted after alfalfa suffer from low yield due to the reduced soil water content. The objectives of this study were to determine the time required for soil water recovery in the 0–1500 cm profile after fields cropped for 15 years with alfalfa are converted to annual crops and to evaluate the impacts of cropping systems, inter-annual climatic variation, and future climate change on the recovery time. Hydraulic parameters for six soil materials in the 0–1500 cm soil profile were calibrated using the measured soil water content in alfalfa fields from 2005 to 2020 and validated using soil water stable isotopic measurements in 2020. Using the calibrated soil hydraulic parameters, the Hydrus-1D model was used to simulate soil water dynamics in the 0–1500 cm profile and determine the recovery time in two cropping systems (alfalfa-wheat and alfalfa-corn) with 53 climatic realizations generated using random non-repeat sequences drawn from 53 years of observed climatic data (1968–2020) and 20 future climate data series projected by 10 GCM models under RCP 4.5 and 8.5 scenarios (2021–2100), respectively. The results showed that, under the 53 climatic realizations, the recovery time ranged from 14 to 44 years with a median of 27 years for the alfalfa-wheat system and from 11 to 31 years with a median of 18 years for the alfalfa-corn system. Under the RCP 4.5 and 8.5 scenarios, the median recovery times were 37.5 and 42.5 years for the alfalfa-wheat system and 30 and 31.5 years for the alfalfa-corn system, respectively. Considering the long-term effects of alfalfa growth on land productivity, planting areas and growing time of alfalfa should be restricted to maintain sustainable agriculture in the study region.

DEVELOPMENT DYNAMICS OF PESTS IN THE ALFALFA BIOTOPE, MEASURES TO CONTROL THE DOMINANT SPECIES

As a result of research, it was observed that phytonutrients, alfalfa saplings, alfalfa sap, alfalfa seeds, along with rodents and locusts, which are specialized in alfalfa fields, cause great damage to plants. The distribution areas of these pests during the growing season, the dynamics of development, the degree of damage were studied and control measures were developed. KEYWORDS. Alfalfa plant, vegetation period, agrobiocenosis, environmental conditions, pest, yield, dominant species, phytonomus, control measures.

Genetic Diversity of Phymatotrichopsis omnivora Based on Mating Type and Microsatellite Markers Reveals Heterothallic Mating System.

Phymatotrichopsis omnivora is a member of Pezizomycetes and causes root rot disease on a broad range of dicotyledonous plants. Using recently generated draft genome sequence data from four P.omnivora isolates, we developed simple sequence repeat (SSR) markers and identified both mating type genes (MAT1-1-1 and MAT1-2-1) in this fungus. To understand the genetic diversity of P.omnivora isolates (n = 43) and spore mats (n = 29) collected from four locations (Oklahoma, Texas, Arizona, and Mexico) and four host crops (cotton, alfalfa, peach, and soybean), we applied 24 SSR markers and showed that of the 72 P.omnivora isolates and spore mats tested, 41 were distinct genotypes. Furthermore, the developed SSR markers did not show cross-transferability to other close relatives of P.omnivora in the class Pezizomycetes. A multiplex PCR detecting both mating type idiomorphs and a reference gene (TUB2) was developed to screen P.omnivora isolates. Based on the dataset we tested, P.omnivora is a heterothallic fungus with both mating types present in the United States in a ratio close to 1:1. We tested P.omnivora spore mats obtained from spatially distinct disease rings that developed in a center-pivot alfalfa field and showed that both mating types can be present not only in the same field but also within a single spore mat. This study shows that P.omnivora has the genetic toolkit for generating sexually diverse progeny, providing impetus for future studies that focus on identifying sexual morphs in nature.

Identifying a suitable revegetation method for soil organic carbon, nitrogen, and phosphorus sequestration: A 16‐year in situ experiment on abandoned farmland in a semiarid area of the Loess Plateau, China

AbstractLegume pasture species have been widely used to re‐establish vegetation cover and control soil erosion in semiarid degraded ecosystems. Nevertheless, the long‐term effects of revegetation on aboveground biomass (AB) and the soil properties under different topographies remain unclear. We conducted a 16‐year in situ experiment to evaluate soil properties and biomass dynamics under fallow, sweet clover (Melilotus officinalis L.) and alfalfa (Medicago sativa L.), in northeast‐facing, southeast‐facing, and horizontal landscapes from 2003 to 2018. After 16 years of revegetation, soil organic carbon (SOC), soil total nitrogen (TN), soil total phosphorus (TP) concentrations were higher in alfalfa fields in the northeast‐ and southeast‐facing landscapes and greater in sweet clover fields in the horizontal landscape alongside soil profiles. In the 0–20 cm, the SOC, TN, and TP concentrations in alfalfa fields increased at rates of 0.322, 0.034, and 0.010 g kg−1 yr−1 in the northeast‐facing landscape and at rates of 0.189, 0.022, and 0.011 g kg−1 yr−1 in the southeast‐facing landscape. The SOC, TN, and TP concentrations in sweet clover fields increased at rates of 0.129, 0.023, and 0.009 g kg−1 yr−1 in the horizontal. Alfalfa introduction is recommended for northeast‐facing landscapes whereas alfalfa and fallow are recommended in southeast‐facing landscapes, introduce sweet clover is recommended in a horizontal landscape to improve the soil nutrient concentrations at mid‐long time. These results suggest that topography influences vegetation restoration by affecting plant growth and soil nutrient and should be considered during the revegetation process to ensure revegetation success and sustainable land use.

Detection of Weeds Growing in Alfalfa Using Convolutional Neural Networks

Alfalfa (Medicago sativa L.) is used as a high-nutrient feed for animals. Weeds are a significant challenge that affects alfalfa production. Although weeds are unevenly distributed, herbicides are broadcast-applied in alfalfa fields. In this research, object detection convolutional neural networks, including Faster R-CNN, VarifocalNet (VFNet), and You Only Look Once Version 3 (YOLOv3), were used to indiscriminately detect all weed species (1-class) and discriminately detect between broadleaves and grasses (2-class). YOLOv3 outperformed other object detection networks in detecting grass weeds. The performances of using image classification networks (GoogLeNet and VGGNet) and object detection networks (Faster R-CNN and YOLOv3) for detecting broadleaves and grasses were compared. GoogLeNet and VGGNet (F1 scores ≥ 0.98) outperformed Faster R-CNN and YOLOv3 (F1 scores ≤ 0.92). Classifying and training various broadleaf and grass weeds did not improve the performance of the neural networks for weed detection. VGGNet was the most effective neural network (F1 scores ≥ 0.99) tested to detect broadleaf and grass weeds growing in alfalfa. Future research will integrate the VGGNet into the machine vision subsystem of smart sprayers for site-specific herbicide applications.

Wastelanding Arabia: America's ‘Garden of Eden’ in Al Kharj, Saudi Arabia

In the late 1930s, the American oil company Aramco helped Saudi Arabia's King Ibn Saud develop his royal farm outside Riyadh. On the king's request, Aramco introduced new technology to tap the Al Kharj region's rich aquifer water and establish vast fields of wheat, alfalfa, and other water-intensive crops. Saudi Arabia's aquifers have since been pumped dry in service of the ‘Garden of Eden’ idyll promised by American advocates, who boasted of their ability to reclaim thousands of acres of ‘desert wasteland.’ This article draws on Traci Voyles' formulation of ‘wastelanding’ to interrogate the agricultural spectacle of Al Kharj in the 1930s–50s. The project was an early exemplar what came to be an established pattern of wastelanding Arabia, built on the unsustainable use of groundwater and social inequalities to create an ‘Eden’ in the desert. Agricultural wastelanding has unique spatial and temporal dimensions that set it apart from other extractive industries, like the uranium mining that Voyles examines in Diné lands. But as this article shows, desert greening projects draw on and produce similar structures of social and environmental violence – with America's ‘Garden of Eden’ in central Arabia being just one case among many of wastelanding across space and time.

Long-term effects of land use type and management on sorptivity, macroscopic capillary length and water-conducting porosity of calcareous soils

Soil hydraulic properties are often influenced by agricultural activities. Knowledge of such properties is needed to understand the effect of agricultural practices on the soil water regime and catchment hydrology. In the present study, we investigated the effects of three land use types including orchard field, OF (without plowing), annual cultivated field, ACF (with seasonal plowing), and perennial alfalfa field, PAF (without plowing) on the soil’s water-conducting porosity at equivalent pore radius interval a to b, ε(a, b), sorptivity at applied tension ψ, Sψ, and macroscopic capillary length at tension interval ψi to ψi+1, λ(ψi, ψi+1) of calcareous soils. The mentioned hydraulic attributes were calculated from infiltration data obtained from tension-disk infiltration measurements at six tensions of 0–15 cm at 75 experimental locations (25 replications per land use). In general, it can be concluded that more macropores are present in the soils of PAF than in those of ACF and OF land uses, probably due to high organic matter content, long-term no-till conditions, positive effects of alfalfa root systems, low machinery/livestock traffic, and low soluble sodium content. In ACF, conventional tillage and high machinery traffic, and in OF excessive use of Na-rich manure fertilizers and high livestock traffic resulted in less macropores compared to PAF.

Improved Daily Evapotranspiration Estimation Using Remotely Sensed Data in a Data Fusion System

Evapotranspiration (ET) represents crop water use and is a key indicator of crop health. Accurate estimation of ET is critical for agricultural irrigation and water resource management. ET retrieval using energy balance methods with remotely sensed thermal infrared data as the key input has been widely applied for irrigation scheduling, yield prediction, drought monitoring and so on. However, limitations on the spatial and temporal resolution of available thermal satellite data combined with the effects of cloud contamination constrain the amount of detail that a single satellite can provide. Fusing satellite data from different satellites with varying spatial and temporal resolutions can provide a more continuous estimation of daily ET at field scale. In this study, we applied an ET fusion modeling system, which uses a surface energy balance model to retrieve ET using both Landsat and Moderate Resolution Imaging Spectroradiometer (MODIS) data and then fuses the Landsat and MODIS ET retrieval timeseries using the Spatial-Temporal Adaptive Reflectance Fusion Model (STARFM). In this paper, we compared different STARFM ET fusion implementation strategies over various crop lands in the central California. In particular, the use of single versus two Landsat-MODIS pair images to constrain the fusion is explored in cases of rapidly changing crop conditions, as in frequently harvested alfalfa fields, as well as an improved dual-pair method. The daily 30 m ET retrievals are evaluated with flux tower observations and analyzed based on land cover type. This study demonstrates improvement using the new dual-pair STARFM method compared with the standard one-pair STARFM method in estimating daily field scale ET for all the major crop types in the study area.

The success of a habitat specialist biological control agent in the face of disturbance

AbstractNatural enemies that can use multiple habitats are thought to better withstand disturbances in agricultural systems than natural enemies that are habitat specialists. This is because habitat generalists have populations in multiple habitats that can serve as sources of immigrants into an agricultural crop following a disturbance. In contrast, the dynamics of habitat specialists are tightly coupled with those of one agricultural crop. Nonetheless, some habitat specialists are successful in highly disturbed environments. To test how the magnitude of within‐field disturbance affects biological control agents, we conducted a large‐scale field manipulation in alfalfa fields and monitored the response of pea aphids, habitat‐generalist predators, a habitat‐specialist parasitoid (Aphidius ervi), and hyperparasitoids of A. ervi. The manipulation involved three treatments: harvesting normally (intermediate disturbance); spraying insecticide immediately after harvesting (high disturbance); and harvesting in strips (low disturbance). As a group, the habitat‐generalist predator species showed a range of responses to disturbances, from no response to decreases in abundance in the high‐disturbance treatment, indicating differences in their response to the density of pea aphids following disturbances. Surprisingly, percentage parasitism by the habitat‐specialist parasitoid was little affected by experimental disturbance manipulations. Furthermore, two of the four hyperparasitoids of A. ervi were negatively affected by the magnitude of disturbance, suggesting that disturbance could have an indirect positive effect on A. ervi. These results suggest that a habitat specialist can overcome the detrimental effects of disturbances without using alternative habitats. In addition, disturbance can sometimes benefit biological control agents by disproportionally negatively affecting their enemies from the fourth trophic level.

Green Corridors May Sustain Habitats for Earthworms in A Partially Converted Grassland

Permanent grasslands provide a healthy and undisturbed environment. We investigated how mulching altered the soil physicochemical parameters, earthworm abundance, biomass, species composition and vegetation cover compared to grassland and cultivated alfalfa field. Microplots (2 × 2 m) were mulched with either weed control fabric (WF) alone or WF combined with straw (WF + S) on a grassland to grow tomato in Ősagárd (Nógrád county, Hungary) between 2018 and 2021. We had two other microhabitats: a conventionally cultivated alfalfa field (CA) and grassland (GR). We measured soil parameters (physical: soil moisture content (SMC), soil penetration resistance (SPR); chemical: pH, soil organic matter; and biological: earthworm abundance, biomass, species composition and vegetation). SMC was significantly higher on covered plots (WF; WF + S) compared to CA and GR. SPR values were the highest in CA and GR at 20 cm depth. The abundance and biomass of earthworms were the highest in GR and lowest in CA in all seasons. Plant abundance was highly influenced by season and habitat. Despite the higher compaction and lower SMC figures, grass vegetation still provided a more suitable environment for earthworms than mulched plots (WF, WF + S). Therefore, where there is agricultural production on grassland, we suggest leaving uncultivated and uncovered patches as biodiversity corridors.

Management of a Mediterranean Forage/Cereal-Based Cropping System: An Ecosystem Service Multisectoral Analysis in the Perspective of Climate Change

Within Mediterranean cropping systems, legume forage crops that last up to 6 years or more (e.g., alfalfa) are replaced with cereal crops (e.g., wheat). The change from forage to cereal crops has negative climate and environmental impacts that must be addressed with mitigation actions. This study evaluated the synergies and tradeoffs between the ecosystem services provided by three management systems after forage legume. A field trial was set up from October 2017 to September 2019 on a 6-year-old alfalfa field subjected to the following management systems: (i) alfalfa termination followed by wheat for 2 years (WW, control); (ii) alfalfa termination followed by single amendment with 60 Mg ha−1 recalcitrant biochar and then by wheat for 2 years (WWB60); and (iii) extension of alfalfa for 2 years (AEXT). A range of regulating, supporting, and provisioning ecosystem services were assessed during the 2018 and 2019 cropping seasons. The results highlight that WWB60 can guarantee carbon sequestration without causing tradeoffs with other services, while AEXT can enhance soil conservation while not increasing soil greenhouse gas emissions. Future policies should support the WWB60 system if the goal is to increase the supporting services. Conversely, the AEXT system should be used if the goal is to increase the regulating and provisioning services.

Weeds in the Alfalfa Field Decrease Rhizosphere Microbial Diversity and Association Networks in the North China Plain.

The competition between weeds and crops for soil nutrients is affected by soil microorganisms, which drive diverse ecological processes and are critical in maintaining the stability of agroecosystems. However, the effects of plant species identity, particularly between forage and weed, on soil microbial diversity, composition, and association are not well understood. Here, we investigate the soil physicochemical properties and bacterial/fungal communities in an agroecosystem with native alfalfa [Medicago stativa (Ms)] and five common weed species (Digitaria sanguinalis, Echinochloa crusgalli, Acalypha australis, Portulaca oleracea, and Chenopodium album) in the North China Plain. The five weeds had a lower plant carbon content than Ms. while the opposite was true for plant nitrogen and phosphorus concentrations. The Shannon diversity of bacterial and fungal communities of the five weeds were significantly lower than in Ms. Soil pH and PO43−-P were identified as the most important factors in shaping the relative abundances of bacteria (Sphingomonadaceae) and fungi (Pleosporaceae), respectively. Importantly, the weeds greatly inhibited the growth of pathogenic fungi (Nectriaceae and Pleosporaceae). Bacterial co-occurrence networks depended on specific species, indicating that Ms. harbored co-occurrence networks that were more complex than those in the bacterial communities of other weed groups. Our study examines how soil nutrients and the soil microbial community structure of five weed species changed in an Ms. field. This analysis of the microbial ecological network enhances our understanding of the influence of weeds on the soil microbiome in agroecosystems.