Perennial Alfalfa Research Articles

Краткая характеристика новых селекционных образцов люцерны в условиях Подмосковья

It is important for Russian agriculture to ensure high sustainability and productivity of natural land and agricultural landscapes, provided that the advanced adaptation of agroecosystems and agricultural landscapes is ready for expected climate and environmental changes. So that the natural vegetation of the agricultural landscape, thanks to controlled, managed and transformed human activities, can be replaced by planting and cultural crops. An adaptive evolutionary-ecological approach to this problem is increasingly being used in scientific breeding science. For all climatic and soil zones of the Russian Federation and various places of plant growth (drylands, floodplain meadows, etc.), it is necessary to create new varieties that would differ in maturity, growth rate of the crop, and also, when used in the early phases of vegetation, could actively accumulate the necessary nutrients for the following alienations. Blue hybrid alfalfa is a legume perennial crop that can be used to produce various types of feed: hay, green pasture feed, grass cutting, herbal protein-vitamin flour, feed pellets and briquettes, haylage, silage and protein concentrate for all types of farm animals and poultry. Scientific studies with this crop were carried out in the Moscow region (Non-Chernozem zone of Russia) on heavy sod-podzolic soils (FNC "VIK named after V.R. Williams") in 2021–2022 in the field crop rotation of perennial alfalfa in three breeding nurseries. The purpose of the research was to obtain new source material and evaluate it. In addition, the identification and involvement in the further breeding process of new biotypes and individual numbers with good indicators of adaptability to the soil and climatic conditions of the Central Non-Chernozem zone of the Moscow region, early spring and friendly regrowth, productive and long-term use, with high productivity and good resistance to alfalfa root rot and other crop diseases. The article presents the research results obtained in the third breeding nursery, at pH = 4.3.

Effects of Perennial Alfalfa on the Structure and Function of Soil Micro-Food Webs in the Loess Plateau.

The Loess Plateau is one of the most vulnerable areas in the world. Numerous studies have been conducted to investigate alfalfa fields with different planting years. Soil microorganisms and nematodes are vital in ecosystem functionality and nutrient cycling. Therefore, comprehending their response to alfalfa fields with varying years of planting is essential for predicting the direction and trajectory of degradation. Alfalfa fields with different planting years (2 years, 9 years, and 18 years) were used as the research object, and farmland was used as the control (CK). High-throughput sequencing and morphological methods determined the community composition of microorganisms and nematodes. Carbon metabolic footprints, correlation networks, and structural equations were used to study soil microorganisms and nematode interactions. Principal component analysis (PCA) results showed that alfalfa fields with different planting years significantly impacted soil microorganisms and nematode community structures. Planting alfalfa significantly increased the nematode channel ratio (NCR) and Wasilewska index (WI), but significantly reduced the soil nematode PPI/MI and dominance (λ). The correlation network results indicated that, for the 2-year and 18-year treatments, the total number of links and positive links are higher than other treatments. Conversely, the 9-year treatment had fewer positive links and more negative links compared to other treatments. Additionally, the keystone species within each network varied based on the treatment years. Structural equation results show that alfalfa planting years directly impact soil fungal community structure and plant-parasitic nematodes' carbon metabolism omnivorous-predatory nematodes. Furthermore, the carbon metabolism of omnivorous-predatory nematodes directly influences soil organic carbon fixation. Moreover, as the duration of alfalfa planting increases, the metabolic footprint of plant-parasitic nematodes decreases while that of omnivorous-predatory nematodes rises. Among treatments varying in alfalfa planting durations, the 9-year treatment exhibited the most incredible energy conversion and utilization efficiency within the soil food web, demonstrating the most stable structure. This study reveals optimal alfalfa planting duration for soil ecosystem stability in the Loess Plateau. Future research should explore sustainable crop rotations and alfalfa-soil-climate interactions for improved agricultural management.

Effect of bio-tillage on the least limiting water range of clayey red soil

Poor soil physical properties related to the least limiting water range (LLWR) limit the productivity of clayey red soil (Ultisol) under a subtropical monsoon climate in southern China. This study evaluated the effects of bio-tillage on LLWR and identified the key factors influencing LLWR through a field experiment. The treatments included no plant, two cultivars of oilseed rape (Brassica napus L. cv. Huashuang 4 and Brassica napus L. cv. Xinan 28), one-year-old and perennial lucerne (Medicago sativa L. cv. Ladino), and one-year-old and perennial vetiver (Vetiveria zizanioides L. cv. Wild), used as cover crops prior to summer maize. Key parameters measured included plant root morphological traits, and soil bulk density, field capacity (FC), wilting point (PWP), available water content (AWC), penetration resistance (PR) and air-filled porosity (AFP) were determined. The two rape cultivars exhibited the shallowest root distribution (limited to 20 cm depth) and the lowest root surface density (RSD, ∼16.61 cm²·cm⁻³) and root volume density (RVD, ∼0.58 cm³·cm⁻³). In contrast, lucerne and vetiver demonstrated greater root development, with deeper root penetration (>60 cm), and higher RSD and RVD, with vetiver showing the highest values (RSD ∼24.01 cm²·cm⁻³, RVD ∼0.96 cm³·cm⁻³). Lucerne and vetiver treatments increased AWC and AFP but reduced PR. Soil planted with vetiver had lower FC (0.35–0.48 cm3·cm−3) and PR (1362–3297 kPa) than soil planted with lucerne, while soil planted with lucerne had a lower PWP (0.25–0.35 cm3·cm−3) than soil planted with vetiver. All crops improved LLWR at 0–20 cm depth, but vetiver increased LLWR below the depth of 20 cm due to its higher root length density (RLD) and RSD. Path analysis revealed that PR had the strongest direct negative effect on LLWR (coefficients from −1.0528 to −1.7642), while redundancy analysis showed a strong correlation between LLWR and the RSD (12.00 %) and RLD (11.33 %) of perennial vetiver, with weaker correlation to root diameter (7.00 %). Bio-tillage reduced PR through root growth, enhancing LLWR particularly at depth of 20–40 cm, with perennial vetiver showing the most significant improvement due to its deeper rooting depth and denser root distribution.

Natural Recovery Dynamics of Alfalfa Field Soils under Different Degrees of Mechanical Compaction

Soil compaction in alfalfa fields has become increasingly severe due to the mechanization of animal husbandry and the increased use of heavy agricultural machinery. Perennial alfalfa land undergoes mechanical compaction several times during the planting period without mechanical tillage. The compacted soil structure may recover through moisture changes, freezing and thawing cycles, and plant growth, but the extent and rate of this recovery remain unknown. In this study, alfalfa plots with two different soil types (medium loam and sandy) in Gansu, China, were selected to address these issues. The areas of the plots were 120 m × 25 m and 80 m × 40 m, respectively. In the third year after sowing, three types of agricultural machinery with grounding pressures of 88 kPa, 69 kPa, and 48 kPa were used to compact the soil one, three, five, and seven times. The interval between replicates was 1 h. Each treatment had one plot of 10 m × 5 m, and the experiment was repeated 4 times, totaling 44 plots. Changes in soil bulk density, soil cone index, and saturated hydraulic conductivity were measured after 1, 4, 8, and 17 weeks, respectively. The results showed that the post-compaction soil bulk density and soil cone index largely influenced the recovery of the compacted soil. Recovery became problematic once the soil bulk density exceeded 1.5 g/cm3. The soil bulk density recovery rate varied across different soil layers, with the top layer recovering faster than more profound layers. The initial state could be restored when the change in post-compaction soil bulk density was minimal. Sandy soil recovered faster than medium-loam soil. The recovery of the soil cone index in each layer of medium-loam soil under lower compaction was more noticeable than that under severe compaction. However, with undergrounding pressures of 88 kPa and 69 kPa, the soil cone index could not fully recover after multiple compactions. The recovery of soil-saturated hydraulic conductivity in both soil types was slower and less pronounced. The recovery of soil-saturated hydraulic conductivity in medium-loam soil was slower than that in sandy loam. After 7 compactions and 17 weeks under a grounding pressure of 88 kPa, the saturated hydraulic conductivity remained below 20% of its initial value of 20 mm/h. In contrast, sandy soils recovered faster, reaching 60 mm/h within a week of each compaction event. This research is crucial for ensuring high and stable alfalfa yields and supporting sustainable agricultural practices.

Morphological and phenological variability within seven oasis populations of perennial alfalfa (Medicago sativa L.) in hyper-arid zone of southern Algeria

Morphological and phenological variability within seven oasis populations of perennial alfalfa (Medicago sativa L.) in hyper-arid zone of southern Algeria

Remote sensing of evapotranspiration for irrigated crops at Yuma, Arizona, USA

A satellite-based vegetation index model that tracks daily crop growth and evapotranspiration (ETc) is developed, tested, and validated over irrigated farms in Yuma irrigation districts of Arizona and California. Model inputs are remotely sensed normalized difference vegetation index (NDVI) images, crop type maps, and local weather. The utility and novelty of the model is a more accurate assessment of ETc than currently provided by the US Bureau of Reclamation’s evapotranspiration modeling system. The model analyzes NDVI time series data from the European Space Agency’s Sentinel-2 satellites using the Google Earth Engine, constructs FAO-56 style crop growth stages from NDVI, and then estimates daily ETc using pre-defined crop coefficients (Kc) and grass reference evapotranspiration (ETos). Four crops were selected to test and evaluate model performance: short-season broccoli, mid-season cotton and wheat, and perennial alfalfa. Comparison of model results showed that Reclamation reports overestimate alfalfa and wheat ETc by 21–25%, cotton ETc by 6%, and underestimate broccoli ETc by 21%. Variability resolved by the model ranged 6–18% of median total ETc. Comparison of model results with those obtained from 13 eddy covariance sites showed validation discrepancies ranging 1–14%: average total actual ETc differences were 12, − 14, 78, and 87 mm/season, respectively, for alfalfa, broccoli, cotton, and wheat. The wide availability of Sentinel-2 data, collected every 5 days or less, and the rapid processing via Google Earth Engine make the vegetation index model implementation fast and practical. Its accuracy and ability to resolve ETc for every field would benefit the Reclamation water accounting system and provide valuable consumptive water use data for any Colorado River stakeholder.

Hot spots and hot moments of greenhouse gas emissions in agricultural peatlands

AbstractDrained agricultural peatlands occupy only 1% of agricultural land but are estimated to be responsible for approximately one third of global cropland greenhouse gas emissions. However, recent studies show that greenhouse gases fluxes from agricultural peatlands can vary by orders of magnitude over time. The relationship between these hot moments (individual fluxes with disproportionate impact on annual budgets) of greenhouse gas emissions and individual chamber locations (i.e. hot spots with disproportionate observations of hot moments) is poorly understood, but may help elucidate patterns and drivers of high greenhouse gas emissions from agricultural peatland soils. We used continuous chamber-based flux measurements across three land uses (corn, alfalfa, and pasture) to quantify the spatiotemporal patterns of soil greenhouse gas emissions from temperate agricultural peatlands in the Sacramento-San Joaquin Delta of California. We found that the location of hot spots of emissions varied over time and were not consistent across annual timescales. Hot moments of nitrous oxide (N2O) and carbon dioxide (CO2) fluxes were more evenly distributed across space than methane (CH4). In the corn system, hot moments of CH4 flux were often isolated to a single location but locations were not consistent across years. Spatiotemporal variability in soil moisture, soil oxygen, and temperature helped explain patterns in N2O fluxes in the annual corn agroecosystem but were less informative for perennial alfalfa N2O fluxes or CH4 fluxes across ecosystems, potentially due to insufficient spatiotemporal resolution of the associated drivers. Overall, our results do not support the concept of persistent hot spots of soil CO2, CH4, and N2O emissions in these drained agricultural peatlands. Hot moments of high flux events generally varied in space and time and thus required high sample densities. Our results highlight the importance of constraining hot moments and their controls to better quantify ecosystem greenhouse gas budgets.

Soil health indicator responses to three years of cover crop and crop rotation in a northern semi-arid region, the Canadian prairies

Increasing crop diversity via cover cropping is considered a powerful strategy to improve soil health; thus, a better understanding of the impacts on soil is crucial. In northern semi-arid regions, cover cropping can be agronomically challenging due to growing condition limitations, and the paucity of cover crop data only exacerbates this challenge. Still, farmers are interested in adopting cover crops to reach their soil health goals. Our study addressed this gap by 1) comparing rotations with versus without cover crops; and 2) comparing different rotational treatments of perennial alfalfa, two-year ‘short’ rotations, to four-year ‘long’ rotations with and without cover crops. After three years, soil health indicators were measured at four sites across the Canadian prairies, including wet aggregate stability (WAS), soil pH, electronic conductivity (EC), evolved soil CO2, soil active C, soil organic carbon (SOC), total carbon (C), N2O production, inorganic N, soil protein, potential mineralized N (PMN), and total N. During a dry period which limited cover crop growth, the cover crops had limited impact on soil health indicators, except for a reduction in spring soil nitrate-N levels at two of the four sites. Surprisingly, the crop phase of the rotation had more differences on soil health indicators than the inclusion of cover crops, but the inconsistency of the changes made it difficult to draw clear patterns. Most notably, soil health indicators (and especially soil CO2) responded to crop rotation treatment. The perennial treatment produced 4.57–8.74 µg g-1 24 hr-1; whereas other rotation treatments respired 25–28%, 44–45%, 22–28%, and 35–36% less CO2. Overall, early indicators of soil health change tended to be related to dynamics of soil inorganic N cycling and CO2 evolution. Our results suggest that a longer-term period of cover cropping and greater biomass accumulation will be needed to substantially impact soil health in this semi-arid environment. Implementing more ‘perennialized’ crop rotations will benefit the early indicators of soil health change in a short timeframe.

Effects of land use-land cover on soil water and salinity contents

Soil salinization due to inadequate land management is considered one of the main threats to the sustainable development of agroecosystems in arid and semiarid regions. Approximately 20% of irrigated areas in the word are threatened by secondary soil salinization. To explore the influence of land use-land cover (LULC) on soil water and salinity in those regions, farmland areas planted with spring-sown wheat (Triticum aestivum L.) or alfalfa (Medicago sativa L.), and bare land (CK) in the Qinwangchuan irrigated region of Gansu Province in China were selected as the research objects. The characteristics of surface vegetation (coverage, height, biomass), surface micro-environmental factors (light intensity, soil temperature) and soil physicochemical properties (moisture and salinity) were measured successively for four years, and their changes and quantitative relationships were analyzed. The results showed that the coverage, height, and biomass of surface vegetation (or stubble) under different LULCs in spring and autumn were significantly different (p < 0.05) and ranked as follows: alfalfa field > wheat field > bare land. With the increasing surface vegetation, the surface light intensity and topsoil temperature at a depth of 5 cm indicated decreasing trends; the water content in the 0–5-cm soil layer showed an increasing trend, while that in the 0–40-cm layers displayed the opposite trend; the salinity at depths of 0–5 and 0–40 cm indicated a decreasing trend. Correlation analysis showed that there was a significant negative correlation between the vegetation characteristics and the salinity in the 0–5- and 0–40-cm soil layers (p < 0.01), while opposite correlations were observed between the vegetation characteristics and the water content in the 0–5- and 0–40-cm soil layers. Regression analysis showed that a 1% increase in vegetation coverage would decrease the salinity at depths of 0–5 and 0–40 cm by 2.5 and 1.0 uS.cm−1, respectively. In summary, farmland planted with spring-sown crops with short growth periods or abandoned in semiarid and arid irrigated regions would gradually experience an increase in soil salinity, whereas the planting of perennial alfalfa could inhibit and lessen soil salt accumulation at depths of 0–5 and 0–40 cm, which is beneficial to improve the soil quality. In addition, this study also revealed the change rule of soil salts under different LULCs in semiarid regions, the fastest increasing stage of topsoil salts, and the importance of surface vegetation and stubble cover in controlling soil salinization.

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.

Assessing perennial alfalfa yield by incorporating physiologically-lucid function into DeNitrification-DeComposition model

Reliable, rapid and timely assessments of forage crop biomass are crucial for managing feed supply and animal husbandry. While process-based models are regularly promulgated in modeling crop and pasture growth and development, the reliability and functionality of such models in simulating alfalfa (Medicago sativa L.) growth remains limited. The purpose of this study was to address deficits associated with simulation of long-term growth dynamics in perennial alfalfa; to assess potential alfalfa yield across the Loess Plateau and dissect key abiotic factors constraining alfalfa yields. We undertook an extensive review of the literature to collate and analyze existing alfalfa biomass data across the entire Loess Plateau in China. We then developed an alfalfa multi-year growth curve using a Gauss-amplitude function; when enacted this algorithm reliably reproduced the rise, peaks and declines in biomass with crop development. To assess the performance of our new function as part of an integrated system, we incorporated a multi-year growth curve into the DeNitrification-DeComposition (DNDC) model to assess longitudinal yields under rain-fed and irrigation conditions. Our adapted model reproduced aboveground trends in biomass more accurately than the original model. The regional simulation results show that alfalfa yield was less than 8000 kg ha–1 in most areas with an annual precipitation lower than 500 mm under rain-fed condition, while the alfalfa yield in most areas was above 8000 kg ha–1 under irrigation condition. Compared with rain-fed alfalfa, there is an increased 69% of yield after irrigation in irrigated areas of the Loess Plateau. The rain-fed alfalfa yield was severely constrained by drought when the aridity index fell below 0.31. Our new model development paves the way for additional refinement of alfalfa crops in process-based models, and provides opportunities for adoption of alfalfa crops in new regions by adjusting the parameters in the Gauss-amplitude function.

Alfalfa in rotation with annual crops reduced nitrate leaching potential.

Rotation of perennial alfalfa (Medicago sativa L.) with annual crops has the potential to reduce nitrate-nitrogen (NO3 -N) in the vadose zone and increase soil organic carbon (SOC) sequestration. The objective of this study was to determine the long-term effects on SOC, NO3 -N, ammonium-N (NH4 -N), and soil water in the 7.2m depth with an alfalfa rotation compared with continuous corn (Zea mays L.). Soils from six pairs of alfalfa rotation versus continuous corn observation points were sampled to 7.2m depth in 0.3m increments. The uppermost 0.3m was divided into 0-0.15 and 0.15-0.30m. For the 0-7.2m depth, the alfalfa rotation compared with continuous corn had 26% less soil water (0.29vs. 0.39g cm-3 ) and 55% less NO3 -N (368vs. 824kg ha-1 ). The cropping system and NO3 -N concentration did not affect NH4 -N in the vadose zone. The alfalfa rotation compared with continuous corn had 47% higher SOC (105.96 Mg ha-1 vs. 72.12 Mg ha-1 ) and 23% higher total soil nitrogen (TSN) (11.99 Mg ha-1 vs. 9.73 Mg ha-1 ) in the 0-1.2m depth. The greater depletion of soil water and NO3 -N with alfalfa rotation was primarily below the rooting zone of corn, suggesting no negative implications for corn following alfalfa but greatly reduced potential of NO3 -N leaching to the aquifer with the alfalfa rotation. Alfalfa rotation compared with continuous corn is a means to greatly reduce the leaching of NO3 -N to the aquifer and improve the surface soil with the potential to increase SOC sequestration.

Assessing trade-offs among productive, economic, and environmental indicators of forage systems in southern Tibetan crop-livestock integration

Fostering crop-livestock integration via crop-forage rotation provides opportunities to cope with land degradation, feed deficit, and agropastoral sustainability. Farmers' preferences for forage options are influenced by economic benefit, environmental preference, and productive performance. However, there is little information available on evaluating multiple trade-offs of forage systems for the design of crop-forage rotations. Here, we performed a comprehensive evaluation to compare the economic, environmental, and productive indicators of five typical forage systems in terms of habitat conditions, soil ecosystem services, economic profit, and forage yield and nutritive value on the southern Tibetan Plateau. Alfalfa pasture and silage corn were mostly cultivated in lower altitudes, with more abundant precipitation, and higher growing degree days. Soil carbon and nitrogen accumulation were significantly higher in perennial alfalfa than in the other forage systems. The relative feed value of alfalfa pasture was also evidently greater than the other forage systems, whereas the yield of silage corn was among the highest. Alfalfa pasture presented superior economic benefits compared to the others. But the alfalfa pasture over six years showed a significant decrease in soil carbon and nitrogen storage, net present value, and yield. Forage systems generally have more soil carbon accumulation, but only forage legumes are more likely to positively affect soil nitrogen retention compared to cereal croplands. The trade-offs among economic, environmental, and productive indicators demonstrated that annual forage systems (silage corn, forage oat, and ryegrass) met productive target rather than environmental and economic objectives, while perennial alfalfa showed synergies among the three goals. These findings indicate that integrating crop-forage rotation, particularly introducing legume forages into farming systems is an adaptive option for crop-livestock integration on the southern Tibetan Plateau. Given the large topographic variation, suitable crop-forage systems should be designed for the heterogeneous Yarlung Zangbo River valleys. Among them, alfalfa-silage corn intercropping is recommended as a promising system to meet both productivity and profitability.

Effects of combined nitrogen and phosphorus application on protein fractions and nonstructural carbohydrate of alfalfa.

Nitrogen (N) and phosphorus (P) fertilization significantly affect alfalfa production and chemical composition; however, the effect of combined N and P application on protein fractions and the nonstructural carbohydrate content of alfalfa is not fully understood. This two-year study investigated the effects of N and P fertilization on the protein fractions, nonstructural carbohydrates (NSC), and alfalfa hay yield. Field experiments were carried out using two nitrogen application rates (N60, 60 and N120, 120 kg N ha - 1) and four phosphorus application rates (P0, 0; P50, 50; P100, 100; and P150, 150 kg P ha - 1), total 8 treatment (N60P0, N60P50, N60P100, N60P150, N120P0, N120P50, N120P100 and N120P150). Alfalfa seeds were sown in the spring of 2019, uniformly managed for alfalfa establishment, and tested in the spring of 2021-2022. Results indicated that P fertilization significantly increased the hay yield (3.07-13.43% ranges), crude protein (6.79-9.54%), non-protein nitrogen of crude protein (fraction A) (4.09-6.40%), and NSC content (11.00-19.40%) of alfalfa under the same treatment of N application (p < 0.05), whereas non-degradable protein (fraction C) decreased significantly (6.85-13.30%, p < 0.05). Moreover, increasing N application resulted in a linear increase the content of non-protein N (NPN) (4.56-14.09%), soluble protein (SOLP) (3.48-9.70%), and neutral detergent-insoluble protein (NDIP) (2.75-5.89%) (p < 0.05), whereas acid detergent-insoluble protein (ADIP) content was significantly decreased (0.56-5.06%, p < 0.05). The regression equations for nitrogen and phosphorus application indicated a quadratic relationship between yield and forage nutritive values. Meanwhile, the comprehensive evaluation scores of NSC, nitrogen distribution, protein fractions, and hay yield by principal component analysis (PCA) revealed that the N120P100 treatment had the highest score. Overall, 120 kg N ha - 1 coupled with 100 kg P ha - 1 (N120P100) promoted the growth and development of perennial alfalfa, increased soluble nitrogen compounds and total carbohydrate content, and reduced protein degradation, thus improving the alfalfa hay yield and nutritional quality.

Adaptive evaluation of green manure rotation for a low fertility farmland system: Impacts on crop yield, soil nutrients, and soil microbial community

Green manure-based rotations have been shown to be an effective sustainable farming practice and were considered a dual solution to resource conservation and crop productivity maintenance. However, our understanding of the adaptations of green manure rotation to the regional agricultural environments lags significantly behind other farming practices. Here, a 6-year field experiment with four green manure cropping treatments and one conventional treatment has been conducted in a typical low fertility farmland in the arid land. Maize yield was significantly increased after green manure was planted, and on a 6-year average, maize grain yield in the green manure intercropping system was 11.7% higher than that in the conventional cropping system. Green manure rotation or intercropping with maize can significantly increase SOM (soil organic matter), TN (total nitrogen), and TP (total phosphorus) in the surface soil layer. Perennial alfalfa planting significantly increased SOM and TN, but significantly decreased TP. Continuous maize planting had no significant effect on TN and TP, but significantly decrease SOM. Green manure planting promoted shifts in soil bacteria composition, with increased the relative abundance of Actinobacteria but decreased the relative abundance of Chloroflexi and Acidobacteria. For fungal abundance, green manure intercropping with maize increased the relative abundance of Ascomycota, but green manure rotation decreased the relative abundance of Mortierellomycota. In summary, our study elucidated that green manure planting especially intercropping with maize can be adopted as the most effective cropping system in the future to decrease environmental stress and enhance agricultural production conditions through improving the crop productivity, increasing soil fertility and nutrients, and regulating soil microbial communities in the low fertility farmland.

Adaptation des génotypes de luzerne pérenne à l’environnement hors oasien en vue d’améliorer les performances de l’agro-système du sud Tunisien

La sélection de la luzerne dans des zones à fortes contraintes abiotiques a peu progressé dans l’amélioration de la productivité et de la tolérance. La difficulté réside dans l’identification et la caractérisation des paramètres liés à la résistance aux différentes pressions climatiques. Divers processus phénologiques, morphologiques, physiologiques et chimiques sont à l’origine des stratégies d’évitement et de tolérance. Le but de ce travail était d’étudier les divergences morpho-physiologiques et chimiques entre huit génotypes de luzerne pérenne d’origines différentes : 3 génotypes locaux (IRA, Gabès, Chenini) et cinq exotiques (Ameristand, Bami, Prosementi, Tamentit et Tata) ayant montré une grande tolérance au bioclimat aride en dehors de l’oasis. Les résultats obtenus ont permis d’identifier deux groupes de génotypes suffisamment homogènes qui pourraient être considérés comme un patrimoine génétique intéressant pour les critères de sélection choisis. Ce pool pourra être le matériel génétique de départ pour la création de variétés synthétiques adaptées aux conditions arides en dehors des oasis caractérisées par des rendements frais et secs plus élevés (Ameristand, Bami, et Tamentit), avec une excellente tolérance à la salinité (Gabès et IRA).

Distinct rhizosphere soil responses to nitrogen in relation to microbial biomass and community composition at initial flowering stages of alfalfa cultivars.

In the long-term growth process, alfalfa rhizosphere forms specific microbiome to provide nutrition for its growth and development. However, the effects of different perennial alfalfa cultivars on changes in the rhizosphere soil characteristics and microbiome are not well understood. In this study, 12 perennial alfalfa cultivars were grown continuously for eight years. Rhizosphere samples were tested using Illumina sequencing of the 16S rRNA gene coupled with co-occurrence network analysis to explore the relationship between alfalfa (biomass and crude protein content), soil properties, and the microbial composition and diversity. Redundancy analysis showed SOC and pH had the greatest impact on the composition of the rhizosphere microbial community. Moreover, microbial diversity also contributes to microbial composition. Soil properties (AP, EC, SOC and pH) exhibited a significant positive correlation with soil bacterial communities, which was attributed to the differences between plant cultivars. Partial least squares path modeling (PLS-PM) revealed that microbial biomass and community composition rather than diversity, are the dominant determinants in the rhizosphere soil nitrogen content of perennial alfalfa. Our findings demonstrate that the soil microbial biomass and composition of rhizosphere bacterial communities are strongly affected by cultivar, driving the changes in soil nitrogen content, and variances in the selective capacities of plants.

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.

Functionally diverse flax-based rotations improve wild oat (Avena fatua) and cleavers (Galium spurium) management

AbstractWild oat (Avena fatua L.) and false cleavers (Galium spurium L.) are currently a challenge to manage in less competitive crops such as flax (Linum usitatissimum L.). Increasing the functional diversity in crop rotations can be an option to improve weed management. Nonetheless, this strategy had not been tested in flax in western Canada. A 5-yr (2015 to 2019) crop rotation study was carried at three locations in western Canada to determine the effect of diverse flax-based crop rotations with differences in crop species, crop life cycles, harvesting time, and reduced herbicides on managing A. fatua and G. spurium. The perennial rotation (flax–alfalfa [Medicago sativa L.]–alfalfa–alfalfa–flax) under reduced herbicide use was found to be the most consistent cropping system, providing A. fatua and G. spurium control similar to the conventional annual flax crop rotation (flax–barley [Hordeum vulgare L.]–flax–oat [Avena sativa L.]–flax) with standard herbicides. At Carman, this alfalfa rotation provided even better weed control (80% A. fatua, 75% G. spurium) than the conventional rotation. Furthermore, greater A. fatua control was identified compared with a conventional rotation in which two consecutive winter cereal crops were grown successfully in rotation (flax–barley–winter triticale [×Triticosecale Wittm. ex A. Camus (Secale × Triticum)]–winter wheat [Triticum aestivum L.]–flax). Incorporation of silage oat crops did not show consistent management benefits compared with the perennial alfalfa rotation but was generally similar to the conventional rotation with standard herbicides. The results showed that perennial alfalfa in the rotation minimized G. spurium and A. fatua in flax-cropping systems, followed by rotations with two consecutive winter cereal crops.

Investigating the Effects of Land Use Change on Subsurface, Surface, and Atmospheric Branches of the Hydrologic Cycle in Central Argentina

AbstractSince the 1970s, land cover in central Argentina has shifted away from perennial crops and grasses toward annual crops, largely soy. In this study, we use observations and modeling to understand how this shift in land use has affected the sub‐surface, surface, and atmospheric fluxes of moisture and energy in a flat agricultural area. We analyze the flux tower data from a paired site at Marcos Juarez in central Argentina during the period of the RELAMPAGO field campaign (2018–2019). When compared to perennial alfalfa, the observations over soy show lower evapotranspiration (ET) and specific humidity, higher sensible heat, higher outgoing shortwave radiation, and soil temperature. Water table (WT) depth is shallower below the soy than the alfalfa sites. To better understand the long‐term temporal behavior from 1970s to present, the Budyko framework is used to show that the trends in ET cannot be explained by climate variables alone. We then use the Noah‐MP land surface model calibrated at both soy and alfalfa sites. Long‐term simulations of the calibrated model suggests that ∼95% of precipitation is evaporated in the alfalfa site with negligible recharge and runoff. Contrarily in the case of soy, ET is about 68% of precipitation, leaving nearly 28% for recharge and 4% for runoff. Observed increases in streamflow and decreases in WT depth over time are likely linked to shifts in land cover. Furthermore, the partitioning of net radiation shifts from latent heat to sensible heat resulting in a 250% increase in Bowen ratio (from 0.2 to 0.7).