Characteristics of the microbial communities regulate soil multi-functionality under different cover crop amendments in Ultisol

The use of cover crops is a promising strategy for influencing the soil microbial consortium,which is essential for the delivery of multiple soil functions(i.e.,soil multifunctionality).Nonetheless,relatively little is known about the role of the soil microbial consortium in mediating soil multifunctionality under different cover crop amendments in dryland Ultisols.Here,we assessed the multifunctionality of soils subjected to four cover crop amendments(control,non-amended treatment;RD,radish monoculture;HV,hairy vetch monoculture;and RDHV,radish-hairy vetch mixture),and we investigated the contributions of soil microbial richness,network complexity,and ecological clusters to soil multifunctionality.Our results demonstrated that cover crops whose chemical composition differed from that of the main plant crop promoted higher multifunctionality,and the radish-hairy vetch mixture rendered the highest enhancement.We obtained evidence that changes in soil microbial richness and network complexity triggered by the cover crops were associated with higher soil multifunctionality.Specifically,specialized microbes in a key ecological cluster(ecological cluster 2)of the soil microbial network were particularly important for maintaining soil multifunctionality.Our results highlight the importance of cover crop-induced variations in functionally important taxa for promoting the soil multifunctionality of dryland Ultisols.

Adding Value to Crop Production Systems by Integrating Forage Cover Crop Grazing

In addition to their value as cereal grains, wheat (Triticum aestivum L.) and triticale (× Triticosecale Wittmack) are important cool-season annual forages and cover crops. Yearling steer (Bos taurus) performance was compared in the spring following autumn establishment as for age cover crops after soybean [Glycine max (L.) Merr.] grain harvest. Replicated pastures (0.4 ha) were no-till seeded in three consecutive years into soybean stubble in autumn, fertilized, and grazed the following spring near Ithaca, NE, USA. Each pasture (n = 3) was continuously stocked in spring with four yearling steers (380 ± 38 kg) for 17, 32, and 28 d in 2005, 2006, and 2007, respectively. In 2005, average daily gain (ADG) for steers grazing triticale exceeded the ADG for wheat by 0.31 kghd-1d-1. In 2006, wheat ADG exceeded that for triticale by 0.12 kghd-1d-1. In 2007, steers grazing wheat lost weight, while steers grazing triticale gained 0.20 kghd-1d-1. Based on the 3-year average animal gains valued at $1.32 kg-1, mean net return ($ ha-1 yr-1) was $62.15 for triticale and $22.55 for wheat. Since these grazed cover crops provide ecosystem services in addition to forage, grazing could be viewed as a mechanism for recovering costs and adds additional value to the system. Based on this 3-year grazing trial, triticale was superior to wheat and likely will provide the most stable beef yearling performance across years with variable weather for the western Cornbelt USA.

Near-Surface Soil Chemical Properties as Affected by Cover Crops Over Time in the Lower Mississippi River Valley

Typical row-crop agricultural practices can potentially be harmful to soil health and future sustainability. The use of cover crops (CC) as a mechanism to improve soil health on a wide scale remains underutilized. Soil health remains a major concern for the sustainability of agricultural productivity, therefore, research into CC implementation as a mean to preserve or improve soil health is warranted. The objective of this study was to evaluate the effects of CC on the soils in the eastern Arkansas portion of the Lower Mississippi River Valley (LMRV) over time for various chemical soil parameters, including pH, soil organic matter (SOM), soil elemental contents (i.e., P, K, Ca, Mg, S, Na, Fe, Mn, Zn, Cu, and B), soil respiration, and a generalized soil health score index. Soil pH decreased over time under both CC and no-cover-crop (NCC) treatments, by −0.3 and −0.2, respectively. Soil OM decreased over time under NCC by −0.1%, but did not differ between CC treatments. Soil N availability decreased over time under NCC (−22.6 kg·ha−1), but did not change over time under CC. Soil respiration decreased over time under both CC and NCC, by −76.1 mg·L−1 and −77.3 mg·L−1, respectively, though there was no effect of CC treatment. The Haney soil health score index decreased under CC (−7.0) and NCC (−6.8) without an effect from CC treatment. Results of the study place emphasis on the temporal nature of soil health as influenced by cover crops and their potential to improve soil health.

Modelling the impacts of cover crop management strategies on the water use,carbon exchange and yield of olive orchards

Cover crops have long been proposed as an alternative soil management for minimizing erosion rates in olive stands while providing additional ecosystem services.However,the trade-off between these benefits and the competition for water with the trees makes the definition of optimal management practices a challenging task in semiarid climates.This work presents an improved version of OliveCan,a process-based simulation model of olive orchards that now can simulate the main impacts of cover crops on the water and carbon balances of olive orchards.Albeit simple in its formulation,the new model components were developed to deal with different cover crop management strategies.Examples are presented for simulation runs of a traditional olive orchard in the conditions of southern Spain,evaluating the effects of different widths for the strip occupied by the cover crop(Fcc)and two contrasting mowing dates.Results revealed that high Fccresulted in lower olive yields,but only when mowing was applied at the end of spring.In this regard,late mowing and high Fccwas associated with lower soil water content from spring to summer,coinciding with olive flowering and the earlier stages of fruit growth.Fccwas also negatively correlated with surface runoff irrespective of the mowing date.On the other hand,net ecosystem productivity(NEP)was substantially affected by both Fccand mowing date.Further simulations under future climate scenarios comparing the same management alternatives are also presented,showing substantial yield reductions by the end of the century and minor or negligible changes in NEP and seasonal runoff.

The Effect of Vineyard Cover Crop on Main Monomeric Phenols of Grape Berry and Wine in Vitis viniferal L. cv. Cabernet Sauvignon

This study was conducted to determine the effect of cover crop inter-row in vineyard on main mono-phenol content of grape berry and wine. Three such cover crops, two perennial legumes （white clover and alfalfa） and a perennial gramineous grass （tall fescue） were sown in vineyard. The main phenolic compounds of mature grape berry and wines vinified under the same conditions were extracted with ethyl acetate and diethyl ether and analyzed by high- performance liquid chromatography （HPLC） by comparing to soil tillage. A total of ten phenolic compounds were identified and quantified in the different grape berry and wines, including nonflavonoids （hydroxybenzoic and hydroxycinnamic acids） and flavonoids （flavanols and flavonols）. The concentration of flavonoid compounds （409.43 to 538.63 mg kg^-1 and 56.16 to 81.30 mg L^-1） was higher than nonflavonoids （76.91 to 98.85 mg kg^-1 and 30.65 to 41.22 mg L^-1） for Cabernet Sauvignon grape and wine under different treatments, respectively. In the flavonoid phenolics, Catechin was the most abundant in the different grapes and wines, accounting for 74.94 to 79.70% and 48.60 to 50.62% of total nonanthocyanin phenolics quantified, respectively. Compared to soil tillage, the sward treatments showed a higher content of main mono-phenol and total nonanthocyanin phenolics in grapes and wines. There were significant differences between two cover crop treatments （tall fescue and white clover） and soil tillage for the content of benzoic acid, salicylic acid, caffeic acid, catechin, and total phenolics in the grape berry （P 〈 0.05 or P〈0.01）. The wine from tall fescue cover crop had the highest gallic acid, caffeic acid and catechin. Cover crop system increased the total nonanthocyanin phenolics of grapes and wines in order of the four treatments： tall fescue, white clover, alfalfa, and soil tillage （control）. Cover crop in vineyard increased total phenols of grape berry and wine, and thus improved the quality of wine evidently.

Non-leguminous winter cover crop and nitrogen rate in relation to double rice grain yield and nitrogen uptake in Dongting Lake Plain, Hunan Province, China

Annual ryegrass（Lolium multiflorum Lam.）, a non-leguminous winter cover crop, has been adopted to absorb soil native N to minimize N loss from an intensive double rice cropping system in southern China, but a little is known about its effects on rice grain yield and rice N use efficiency. In this study, effects of ryegrass on double rice yield, N uptake and use efficiency were measured under different fertilizer N rates. A 3-year（2009–2011） field experiment arranged in a split-plot design was undertaken. Main plots were ryegrass（RG） as a winter cover crop and winter fallow（WF） without weed. Subplots were three N treatments for each rice season： 0（N_0）, 100（N_（100）） and 200 kg N ha–1（N_（200））. In the 3-year experiment, RG reduced grain yield and plant N uptake for early rice（0.4–1.7 t ha–1 for grain yield and 4.6–20.3 kg ha–1 for N uptake） and double rice（0.6–2.0 t ha–1 for grain yield and 6.3–27.0 kg ha–1 for N uptake） when compared with WF among different N rates. Yield and N uptake decrease due to RG was smaller in N_（100） and N_（200） plots than in N_0 plots. The reduction in early rice grain yield in RG plots was associated with decrease number of panicles. Agronomic N use efficiency and fertilizer N recovery efficiency were higher in RG plots than winter fallow for early rice and double rice among different N rates and experimental years. RG tended to have little effect on grain yield, N uptake, agronomic N use efficiency, and fertilizer N recovery efficiency in the late rice season. These results suggest that ryegrass may reduce grain yield while it improves rice N use efficiency in a double rice cropping system.

The effect of total carbon on microscopic soil properties and implications for crop production

Soil structure is a dynamic property affected by physical, chemical, and microbiological processes. Addition of organic matter to soils and the use of different management practices have been reported to impact soil structure and crop production. Moderation in soil temperature and increases in microbial activity and soil water retention are often suggested as reasons for the rise in crop yield when organic matter is added to the soil. Less is known about the direct effect of changes in soil structure on crop production. A field experiment was conducted to study the effect of summer cover crop and in-season management system on soil structure. The experiment was a nested design with summer cover crop as the main plot and management system as the subplot. Summer cover crop treatments included cowpea （Vigna unguiculata L. Walp.） incorporated into the soil in the fall （CI）, cowpea used as mulch in the fall （CM）, sudangrass （Sorghum vulgare） incorporated into the soil in the fall （S）, and dry fallow or bare ground （B）. Management systems were organic （ORG） and conventional （CNV） systems. Lettuce （Lactuca sativa L.） and cantaloupes （Cucumis melo L.） were cultivated in rotation in the plots for three consecutive years using the same cover crops and management systems for each plot. Disturbed and undisturbed soil cores were collected at the end of the third year and used for laboratory experiments to measure physical, chemical, and hy- draulic properties. Image analysis was used to quantify soil structure properties using a scanning electron micro- scope on thin sections prepared from the undisturbed soil cores. We found that total soil carbon was correlated with porosity, saturation percentage, and pore roughness. Pore roughness was correlated with crop production in gen- eral and with marketable production in particular. We found that the higher the complexity of the pore space, the more water retained in the soil, which may increase soil water residence and reduce plant water stress.

Explaining farmers'reluctance to adopt green manure cover crops planting for sustainable agriculture in Northwest China

Green manure cover crops(GMCCs)planting has a potential for mitigating greenhouse gas emissions(GHG)in agroecosystems and provides important ecosystem services,thereby achieving the Sustainable Development Goals(SDGs)stipulated by the United Nations.However,the advantages of cultivating GMCCs on arable land are not widely recognized.For example,in the whole of China,the GMCCs planting area is less than 3.5%of total arable land.The aim of this study is to explore reasons for the low adoption rate of GMCCs planting.Using best–worst scaling(BWS)approach,farmers ranked their preferred conservation practices including three types of GMCC cropping systems.Taking Gansu Province in Northwest China as a case study,a survey with 276 farmers was conducted.The findings indicated that three factors are related to the low adoption rate of GMCCs:1)farmers preferred improving farmland irrigation facilities and substituting chemical fertilizers with organic rather than planting GMCCs;2)lack of awareness and understanding of government policy on GMCCs and limited access to training courses;3)financial support and subsidies from the government are insufficient.This study provides insights and strategic implications for policymakers on how to further promote GMCCs in the future.

Effects of Winter Cover Crop and Straw Returning on the Functional Diversity of Rhizosphere Microflora in Double-crop Rice Paddies

The functional diversity of rhizosphere microflora which is also known as the “microbial community” is a sensitive indicator of soil quality subject to the type of winter cover crop and straw returning.In order to evaluate the effects of different winter cover crops and returning patterns on the functional diversity of rhizosphere microflora in double-crop rice paddies,we designed five winter cover crops and straw returning combinations to analyze their effects on the functional diversity of rhizosphere microflora in rice paddies: ryegrass (Lolium multiflorumL.)–double-crop rice (Ry),milk vetch (Astragalus sinicus L.)–double-crop rice (Mv),Rape (Brassica napus L.)–Double-crop rice (Ra), Potato (Solanum tuberosum L.)–double-crop rice (Po),and winter fallow–doublecrop rice (CK,the control).In this paper,the average well color development (AWCD) in Biolog-GN plates indicated the capacity for carbon utilization by the rhizosphere microbial community.We analyzed the rhizosphere microbial community functional diversity of the paddy soils with the above five treatments by using the Biolog-GN system.The results showed that applications of winter cover crop and straw returning caused high increases in AWCD compared with CK,and the AWCD values for samples with Po treatment was greater than those with Ry and CK treatments at the early and late rice maturity stages. It was concluded that applications of winter cover crop and straw returning can cause changes in the carbon utilization efficiency of rhizosphere microflora.There were differences in the genetic diversity of the rhizosphere microflora among different treatments at the maturity stage of early and late rice.The richness,Shannon,and McIntosh Index under different winter cover crop and straw returning treatments were significantly different.The highest indexes were observed in the Po treatment and the lowest in the CK at the maturity stage of early and late rice.The richness, Shannon,and McIntosh Index under different treatments ranked in descending order is as follows: Po>Ra>Mv>Ry>CK.Principal Component Analysis (PCA) of substrate reactions were conducted in this research.The results indicated that the pattern of carbon source utilization varied with winter cover crop treatments,and that carbohydrates and amino acids were the main carbon sources of rhizosphere microorganisms.To conclude,the application of winter cover crop and straw returning to paddy fields could significantly increase the carbon source utilization, species richness,and species evenness of rhizosphere microflora in double-crop rice paddies.

Influence of Tillage and Deep Rooted Cool Season Cover Crops on Soil Properties, Pests, and Yield Responses in Cotton

Soil compaction is a significant problem in the Southeastern USA. This compacted zone or hardpan limits root penetration below this layer and reduces potential yield and makes plants more susceptible to drought induced stresses. Soil compaction in this region is managed using costly annual deep tillage at or before planting and there is a great interest in reducing and/or eliminating annual tillage operations to lower production costs. Deep rooted cool season cover crops can penetrate this compacted soil zone and create channels, which cash crop roots, such as cotton, could follow to capture moisture and nutrients stored in the subsoil. The cool season cover crop roots would reduce the need for annual deep tillage prior to planting, increases soil organic matter, which provides greater water infiltration and available water holding capacity. Field studies were conducted for two years with three different soil series to determine the effects of tillage systems and cool season cover crops on the soil chemical and physical properties, yield responses, and pest pressure. Results showed that cool season cover crops significantly reduced soil compaction, increased cotton lint yield and soil moisture content, reduced nematode population densities, and increased soil available P, K, Mn, and organic matter content compared to the conventional no-cover crop.

Hairy Vetch and Triticale Cover Crops for N Management in Soils

Over-application of fertilizer to cropland adversely affects both environmental and agricultural ecosystems. This study examined whether planting a legume-based winter cover crop mix offsets fertilizer application via natural nitrogen inputs. The influence of the cover crop mixture on available nutrients was also assessed. Hairy vetch (Vicia villosa) and winter triticale (×triticosecale) cover crops were planted in fall and terminated in May. Soil fertility data was collected before and after planting the winter cover crop to determine the effect on fixing nitrogen and soil phosphorus, potassium and organic matter levels. Increases of soil ammonium were observed in plots with cover crop treatments. A triticale-hairy vetch cover crop mix was successful at scavenging P for future crops and appears to hold promise for long-term soil fertility benefits.

Effect of Rye and Mix Cover Crops on Soil Water and Cotton Yield in a Humid Environment

In recent years, the use of cover crops is becoming a popular technology among growers in many regions of the United States, which is expected to deliver various benefits such as improving soil health, increasing soil organic matter, controlling weeds, and helping conserve soil water and nutrients. Although expecting these benefits seems reasonable, it is challenging to know how much of these benefits to expect under specific situations. The potential effect of cover crops on soil water conservation is especially significant because of the documented impact of soil water on crop yield, especially for dryland cropping systems. Some researchers have found that planting a cover crop tended to increase soil water, while others have reported the opposite effect. Information on the impact of cover crops on soil water in cotton (Gossypium hirsutum L.) production systems in South Carolina is currently lacking. Therefore, the objective of this study was to quantify the effect of cover crops on soil water and cotton yield. A field experiment was conducted in South Carolina during winter, spring, and summer of 2015, with three cover crop treatments. The treatments included: 1) rye (Secale cereale L.), planted alone;2) a mix of six cover crop species;and 3) a control treatment with no-cover. The cover crop was established in the winter, terminated in the spring, and cotton was grown during the summer. Soil water was measured at different depths using capacitance probes and a neutron probe. Our results showed no significant differences in soil water and cotton yield among the cover crop treatments. These results suggest that under the humid conditions of this study, any short-term effect of the cover crop on soil water was masked by timely rain.

Cover Crop Effects on Near-Surface Soil Aggregate Stability in the Southern Mississippi Valley Loess (MLRA 134)

The use of cover crops (CC) during the agricultural fallow period has been shown to help alleviate soil compaction and provide stabilizing effects against soil erosion. These benefits are particularly important as many of the silty, loess-derived soils of the major land resource area (MLRA) 134, the Southern Mississippi Valley Loess, have large erosion potentials. This study evaluated the effects of CC and no-cover crop (NCC) treatments on a selection of silt-loam soils in MLRA 134. Treatments were implemented during Fall 2018 and Fall 2019 and consisted of a range of CC species. Soil samples from the top 10 cm were collected to evaluate a suite of soil properties. Soil texture, pH, soil organic matter, and Mehlich-3 extractable Mg, Na, and Ca were unaffected (P > 0.05) by CC treatment. Total water-stable aggregate concentration was unaffected (P > 0.05) by CC treatment and soil depth (i.e., 0 - 5 and 5 - 10 cm). Soil bulk density was greater (P •cm−3) than under CC treatment (1.24 g•cm−3). Water-stable aggregate concentration was unaffected (P > 0.05) by CC treatment and soil depth, but was 21.5 times greater (P •g−1) than in the > 4-mm (0.05 g•g−1) size class. Study results indicate that, even among sites with large variability, CC can have consistent, short-term, positive effects on soil properties, but a long-term commitment to continuous, annual cover crops is necessary for the full realization of potential benefits.

Effects of Direct Sowing under Mulch-Based Cropping System (DMC) on Cotton and Maize Yield and Chemical Characteristics of Ferruginous Soil (Lixisoil) in the South Sudan Area of Burkina Faso

To better understand the effects of direct sowing under mulch-based cropping system (DMC) in Burkina Faso’s cotton production systems, randomized blocks of Fisher experimental design were implemented at Farako-Ba research station from 2010 to 2019. The study was conducted on lixisoil to evaluate DMC effects on biomass production, crops yields and soil chemical properties in a maize and cotton rotation system associated with cover crop. Conventional tillage and direct seeding without cover crop were compared to DMC under B. ruziziensis (GERM. & EVRARD), DMC under B. ruziziensis + M. cochinchinensis mulch and DMC under C. juncea (L.) mulch used in association with maize. Biomass production, crop yields and soil chemistry were evaluated. Results showed that over 10 years, no-till with or without a cover crop provided cotton seed and maize yields that were statistically equivalent to the tillage commonly practiced by farmers. Cover crop has allowed increasing the biomass production compared to Conventional Tillage and Direct Seeding. Maize yield has not varied significantly with the cover crop. After 10 years of maize and cotton rotation, the improvement raised from +27% to +38% for organic matter and from +15% to +29% for nitrogen with DMC including legumes such as M. cochinchinensis and C. juncea compared to Conventional Tillage on 0 - 5 cm depth. No significant differences were found on soil pH like P2O5 and K2O content. Although DMC with C. juncea used as cover crop did not provide the best biomass production, it contributes to increase nitrogen and organic matter and presents better mineral balances in 10 years of rotation. The 5 - 10 cm and 10 - 20 cm were little influenced by DMC systems.

Applying plant-based irrigation scheduling to assess water use efficiency of cotton following a high-biomass rye cover crop

Background:This study addressed the potential of combining a high biomass rye winter cover crop with predawn leaf water potential(ΨPD)irrigation thresholds to increase agricultural water use efficiency(WUE)in cotton.To this end,a study was conducted near Tifton,Georgia under a manually-controlled,variable-rate lateral irrigation system using a Scholander pressure chamber approach to measure leaf water potential and impose varying irrigation scheduling treatments during the growing season.ΨPDthresholds were-0.4 MPa(T1),-0.5 MPa(T2),and-0.7 MPa(T3).A winter rye cover crop or conventional tillage were utilized for T1-T3 as well.Results:Reductions in irrigation of up to 10%were noted in this study for the driest threshold(-0.7 MPa)with no reduction in lint yield relative to the-0.4 MPa and-0.5 MPa thresholds.Drier conditions during flowering(2014)limited plant growth and node production,hastened cutout,and decreased yield and WUE relative to 2015.Conclusions:We conclude thatΨPDirrigation thresholds between-0.5 MPa and-0.7 MPa appear to be viable for use in aΨPDscheduling system with adequate yield and WUE for cotton production in the southeastern U.S.Rye cover positively impacted water potential at certain points throughout the growing season but not yield or WUE indicating the potential for rye cover crops to improve water use efficiency should be tested under longer-term production scenarios.

Cover crops,crop rotation,and gypsum,as conservation practices,impact Mehlich-3 extractable plant nutrients and trace metals

Conservation practices are encouraged to improve soil health and sustain agronomic crop production.Mehlich-3 is often used as a multi-nutrient extractant to determine soil fertility status.A study inves-tigated the impacts of the conservation practices of gypsum,cover crops,and crop rotation on 28 Mehlich-3 extractable elements,of which 11 were considered plant nutrients,from soil at three mid-western US locations.Soil was collected from 0 to 15 and 15-30 cm depths 5 years after implementing the conservation practices.Treatments consisted of(1)with and without cereal rye(Secale cereale L.)winter cover,(2)continuous soybean[Glycine max(L.)Merr.]vs.soybean-corn(Zea mays L.)rotation,and(3)annual gypsum application(0,1.1,and 2.2 Mg ha-1).Differences were observed by site,depth,and conservation practice depending on the element evaluated.Minimal interactive effects were observed among treatments.The most consistent effect was observed for crop rotation across sites.Gypsum only affected the site with the greatest clay content,where more Ca and S were retained,and Mg and Mn displaced.Cover crop only affected elements at this high clay site,where different elements were positively or negatively affected.Results suggest that not one practice fits all,and optimum conservation practices must be tailored for the site.

Environmental benefits and farmers' adoption of winter cover crops in the North China Plain

The introduction of cover crops into monoculture systems to improve soil health has been widely adopted worldwide. However, little is known about the environmental risks and application prospects of different cover crops in spring maize(Zea mays L.) monocultures proposed in the North China Plain. A pot experiment was conducted to evaluate the effects of different winter cover crops on subsequent maize yield, soil fertility, and environmental risks of nitrogen(N) loss, and a questionnaire survey was conducted to examine factors influencing farmers' willingness to adopt cover crops in the North China Plain. Based on the same fertilization regime during the maize growing period, four winter cover crop treatments were set up, including bare fallow, hairy vetch(Vicia villosa Roth.), February orchid(Orychophragmus violaceus), and winter oilseed rape(Brassica campestris L.). The results indicated that winter cover crops significantly increased subsequent maize yield and soil organic carbon, total N, and microbial biomass carbon and N compared with the bare fallow treatment.The incorporation of cover crops led to a negligible increase in nitrous oxide(N_(2)O) emissions and had a very limited effect on ammonia(NH_(3)) emissions.The incorporation of February orchid and winter oilseed rape decreased nitrate leaching compared with the hairy vetch treatment in the maize growing season.The N losses via N_(2)O and NH_(3) emissions and N leaching accounted for 71%–84% of the N surplus. However, yield increase and environmental benefits were not the main positive factors for farmers to accept cover crops. Financial incentive was rated by 83.9% of farmers as an “extremely important” factor, followed by other costs, when considering winter cover cropping. These results indicate that the environmental benefits depend on the type of cover crop. Maintaining high levels of soil fertility and maize yield, providing sufficient subsidies, and encouraging large-area cultivation of cover crops are critical measures to promote winter cover cropping in the North China Plain.

Evaluation of the Effect of Four Levels of Shade on the Growth and Development of Desmodium adscendens with a View to Its Domestication as a Cover Crop in Côte d’Ivoire

Desmodium adscendens is a plant in the Fabaceae family that is very important to man, both agronomically and medicinally. It is an important cover crop that contributes to improving soil fertility, reducing the risks associated with crop pests and weeds. However, very little research has been carried out into its domestication for use as a cover crop in banana plantations in Côte d’Ivoire. The general objective of this study was to evaluate, under semi-controlled conditions, the effect of different levels of shade on the growth and development of Desmodium adscendens. The studies were carried out on the experimental site of the UP-Plant Physiology Laboratory. Four shading levels were evaluated: 0 (NO), 20% (N1), 40% (N2) and 60% (N3) light levels. The Desmodium adscendens cuttings used were collected from a 3-month nursery. For each treatment, 10 tubs containing sterilized soil were used, and 50 cuttings were planted. After planting, growth and development parameters were assessed weekly on 10 plants. In addition, yield and fresh and dry mass were measured. Finally, the reproductive cycle of Desmodium adscendens was determined. The results showed that plant growth and development were greatest in plants grown under the 40% shade level, followed by the 20% and 60% shade levels. In contrast, plants in full light showed poor growth and development. The 40% shade level was the most favorable for growing Desmodium adscendens cuttings, with a cycle length of 67 days. Growing Desmodium adscendens under shade with 20% and 40% light levels could be recommended to farmers.

Long-Term Impacts of Cover Crops, Chicken Litter, and Crop Rotations on Soil Health in No-Till Systems

Identification of management practices that can improve soil health is critical to improving the sustainability of soybean [Glycine max (L.) Merr.] production. The objective of this study was to examine the long-term effects of continuous soybean, corn-soybean, and soybean-cotton rotations with chicken litter and cover crops (hairy vetch, wheat, fallow) on soil health parameters, including nutrient accumulation and soil organic matter dynamics under a split plot design. The depth intervals of soil sampling were 0 - 15, 15 - 30, 30 - 60, and 60 - 90 cm. Chicken litter resulted in 62.1% and 32.8% higher water extractable organic soil N content than fallow and wheat, respectively, in the surface 0 - 15 cm of soil only. However, there was no significant difference in 1-day Solvita respiration, water extractable organic C, C/N ratio, health score, moisture, earthworm, organic matter, pH, or CEC of soil among fallow, hairy vetch, chicken litter, and wheat regardless of soil depth. Unexpectedly, annual application of chicken litter at 4.4 Mg ha−1 as an N source or growing a winter-season cover crop such as hairy vetch or wheat for continuous 16 years did not significantly increase soil organic matter or water extractable organic soil C. Annual application of chicken litter at 4.4 metric tons (Mg) ha–1 for 16 years increased soil nitrate-nitrogen (NO3−-N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), and zinc (Zn) contents by 92%, 400%, 134%, 20%, 43%, 206%, and 430% in 0 - 15 cm depth compared with their initial soil values, respectively, extracted with Haney H3A-2 (2 g L–1 lithium citrate + 0.6 g L–1 citric acid + 0.4 g L–1 malic acid + 0.4 g L–1 oxalic acid) solution. The increases enhanced soil supply of these nutrients to following crops, but also increased the risks of losing them to the environment. Hairy vetch caused higher H3A extracted soil manganese (Mn) content than fallow and chicken litter in 0 - 60 cm. There was no significant difference in 1-day Solvita respiration, water extractable organic C and N, health score, moisture, organic matter, pH, CEC, or population of earthworm of soil among continuous soybean, corn-soybean, and soybean-cotton in any soil depth. Another major finding of this study was that continuous soybean exerted no adverse effect on soil health relative to the commonly used corn (Zea mays L.)-soybean and soybean-cotton (Gossypium hirsutum L.) rotations under no-tillage after 16 years. To mitigate the risks of nutrient runoff and leaching from long-term chicken litter application, we recommend reducing litter application rates and integrating cover crops into crop rotations to enhance nutrient cycling and reduce environmental impacts.

Integrated application of February Orchid(Orychophragmus violaceus) as green manure with chemical fertilizer for improving grain yield and reducing nitrogen losses in spring maize system in northern China

The development of more efficient management systems is crucial to achieving high grain yields with high nitrogen use efficiency（NUE）. February Orchid-spring maize rotation system is a newly established planting system with the benefits of ground cover and potential wind erosion in northern China. A field experiment was conducted to evaluate the effects of integrated application of February Orchid as green manure with reduction of chemical fertilizers（INTEGRATED） on spring maize yield, N uptake, ammonium volatilization, and soil residual mineral N in northern China. Compared to farmers＇ traditional fertilization（CON）, integrated application of February Orchid as green manure with 30% reduction of nitrogen fertilizers（INTEGRATED） increased maize grain yield and biomass by 9.9 and 10.2%, respectively. The 0–100 cm soil residual Nmin at harvest was decreased by 58.5% and thus nitrogen use efficiency was increased significantly by 26.7%. The nitrogen balance calculation further demonstrated that the INTEGRATED approach performed better than CON with lower apparent nitrogen loss（decreased by 48.9%） which evidenced by the ammonium volatilization of top-dressing fertilizer was decreased by 31.1%, the N_（min） movement to the deeper soil layers was reduced, and the apparent nitrogen leaching loss nearly equal to 0 under the INTEGRATED treatment. Therefore, in northern China, integrated application of green manure and chemical fertilizers is an efficient management approach for improving maize yields and NUE simultaneously.