Nurse cropping with broomcorn millet (Panicum miliaceum L.) is widely practiced to facilitate alfalfa (Medicago sativa L.) establishment on the semiarid Loess Plateau, yet the mechanisms by which row configuration mediates rhizosphere nutrient cycling, microbial community assembly, and metabolite composition remain poorly understood. A field experiment compared alfalfa monoculture with four broomcorn millet nurse cropping row configurations (1P1M, 1P2M, 1P3M, 2P3M). We quantified aboveground yield, land equivalent ratio (LER), soil nutrients, microbial biomass C/N/P, arbuscular mycorrhizal fungal (AMF) and diazotrophic (nifH) communities, and rhizosphere metabolites. All nurse cropping configurations increased land-use efficiency (LER 1.08–1.28). The 1P1M configuration maximized alfalfa yield and microbial biomass while reducing microbial biomass carbon: nitrogen (MBC: MBN) and microbial biomass carbon: phosphorus (MBC: MBP) ratios, indicative of tighter stoichiometric coupling under intensified interspecific competition, which promotes more balanced microbial nutritional needs. However, AMF and nifH α-diversity were significantly reduced under 1P1M. Compared with the 1P1M configuration, the 2P3M configuration maintained comparable productivity, increased soil total N, and supported greater nifH diversity. Structural equation modeling identified AMF abundance (β = 0.743) and putatively annotated rhizosphere 2-aminophenol enrichment (β = 0.567) as significant positive predictors of alfalfa yield, whereas plant-derived C was the primary driver of nifH community composition. Row configuration influenced the balance between short-term productivity and rhizosphere functional indicators in nurse cropping systems. The 2P3M configuration integrates acceptable productivity with enhanced soil N reserves and diazotrophic diversity, offering an ecologically balanced option for alfalfa establishment in semiarid agroecosystems.

The priming effect (PE) is a key process through which exogenous organic matter drives the decomposition of native soil organic matter and has important implications for soil organic carbon sequestration. However, the factors driving soil microbial communities and the PE under grass mulching in orchards remain unclear. In this study, three grass mulching treatments, Trifolium repens L., Lolium perenne L., and Medicago sativa L.+Trifolium repens L., were established, with clean tillage as the control. Using the natural abundance 13C method, Mantel correlation analysis, and PLS-PM, we analyzed soil physicochemical properties, extracellular enzyme activities, and microbial community structure in the 0~20 cm and 20~40 cm soil layers to investigate the effects of grass mulching on the PE and its microbial mechanisms. The results showed that grass mulching promoted the decomposition of native soil organic matter and induced a positive PE. The dominant microbial phyla differed among the grass mulching treatments and exhibited distinct microbial life-history strategy characteristics. PLS-PM showed that, in the 0~20 cm soil layer, grass mulching indirectly drove the PE mainly by improving soil physicochemical properties, enhancing enzyme activities, and promoting mineralization. In the 20~40 cm soil layer, fungal communities indirectly drove the PE by regulating N-acquiring enzyme activities and promoting mineralization. Overall, the PE under grass mulching in apple orchards showed clear vertical differentiation, with the topsoil more likely dominated by co-metabolism and the subsoil more likely driven by the N-mining mechanism. This study provides theoretical support for green grass mulching management in orchards.

Aims Fall dormancy (FD) in alfalfa (Medicago sativa L.) is a physiological adjustment strategy that determines forage yield, winter survival rates and spring regrowth. This study aimed to explore whether FD could drive alfalfa–soil interactions by modulating soil nutrient status and the microbial community. Methods We investigated the root characteristics, soil nutrients and bacterial and fungal communities of alfalfa cultivars (dormant (D), semidormant (SD), and nondormant (ND)) during the growing season and dormant season on the Loess Plateau, China. Results Our results indicated that the total nitrogen (TN), soil organic carbon (SOC) and total phosphorus (TP) contents tended to increase with increasing FD level in the dormant season. The opposite trend was generally observed for TN, sucrase (SUC) activity and protease (PRO) activity in the growing season. Furthermore, our results demonstrated that FD more readily influences soil fungal than bacterial communities; moreover, both bacterial and fungal diversity indices were lower in the dormant season than in the growing season. There were no obvious differences in the microbial co-occurrence network in the growing season, whereas in the dormant season, the percentage of positive interactions increased with increasing FD level, while that of negative correlations decreased. Conclusions Our results, based on the selection of alfalfa cultivars of different FD types, highlight the importance of the FD-driven rhizosphere effects, which further influences nutrient cycling and the soil microbial community, especially during the dormant season. This study provides valuable information for understanding complex FD-driven plant–soil interactions in alfalfa cultivation.

Grass residue decomposition is crucial for nutrient cycling in agro-ecosystems, enhancing nutrient utilization efficiency and supporting sustainable crop management. While grass mulching has been widely studied for improving orchard soil fertility, the role of soil microbial communities in decomposing different plant organs remains unclear. Before decomposition, the aboveground and belowground plant parts were harvested and placed in separate litterbags, which were later used for evaluating the decomposition rate and chemical characteristics of the shoots and roots for 40 days (at 10 days intervals). The changes in soil fertility, soil microenvironment, soil microbial community were measured after 0, 1 and 3 months, alongside analysis of key microbial taxa under different residues treatments. The remaining mass of root litter treatment was significantly higher than that of other treatments by 72.97

Fall dormancy (FD) in alfalfa (Medicago sativa L.) is a physiological adjustment strategy that affects forage yield, winter survival rates and spring regrowth. This study aimed to determine whether FD could drive alfalfa–soil interactions by modulating soil nutrient dynamics and the microbial community structure. We assessed the root traits, soil properties, and microbial communities (bacteria/fungi) of alfalfa cultivars representing dormant (D), semi-dormant (SD), and non-dormant (ND) FD types during both growing and dormant seasons in semi-arid northwestern China. Our results indicated that total nitrogen (TN), soil organic carbon (SOC), and total phosphorus (TP) content increased with FD level during dormancy, whereas TN, sucrase activity, and protease activity generally decreased during the growing season. Furthermore, both the bacterial and fungal diversity indices were lower in the dormant season than in the growing season. Microbial co-occurrence networks revealed that the proportion of positive bacterial-fungal correlations increased with increasing FD level in the dormant season, while negative correlations decreased. During the dormant season, FD exerted highly significant positive effects on soil nutrients, enzymes, and root nutrition but significantly reduced alfalfa biomass and microbial biomass. Conversely, FD positively influenced root nutrients and microbial biomass during the growing season. Our results highlight the importance of FD-driven rhizosphere effects on nutrient cycling and soil microbial communities, particularly during dormancy. This study provides valuable information for understanding complex FD-driven plant–soil interactions in alfalfa cultivation systems.

Arbuscular mycorrhizal fungi (AMF) and rhizobia enhance the ability of crops to access nitrogen (N) and phosphorus (P) and are keystone microorganisms that engage in reciprocal interactions with plants. However, their contributions and impacts in alleviating plant nutrient dependency and mitigating N deposition and P limitation under various N and P additions remain unclear. We hypothesized that co-inoculation with AMF and rhizobia would synergistically enhance crop nutrient absorption and stabilize N:P stoichiometry for mitigating N deposition and P limitation and enhancing biomass. Here, two experimental systems were established: (1) constant low P with three increasing N levels, and (2) constant low N with three increasing P levels. Within each system, we examined the effects of inoculation with AMF alone, rhizobia alone, both AMF and rhizobia, and no inoculation on alfalfa biomass, photosynthesis, nutrient content, and N:P stoichiometry. Results revealed that co-inoculation with AMF and rhizobia significantly increased alfalfa aboveground biomass (AGB) and belowground biomass (BGB) by 88.54 % and 236.96 %, respectively, under low N and low P conditions. Additionally, co-inoculation significantly enhanced the content of photosynthetic pigments, N and P. However, co-inoculation did not significantly affect photosynthetic rate (Pn) or transpiration rate (Tr), while significantly reducing stomatal conductance (Gs). Furthermore, co-inoculation alleviated N limitation in alfalfa, shifting its limitation from N to P by increasing N:P stoichiometry. Notably, co-inoculation buffered leaf N:P stoichiometry against nutrient change, while maintaining the maximum leaf N:P stoichiometry. In contrast, as N or P levels rose, alfalfa BGB, photosynthetic pigments content, Pn, and N content, and P content were inhibited to varying degrees across all inoculation treatments, with increased N limitation. Moreover, partial least squares path modeling (PLS-PM) demonstrated a unique mechanism in the co-inoculation treatment whereby alfalfa AGB and BGB was enhanced through the root N:P stoichiometric regulation. Overall, our findings highlight multifaceted benefits of co-inoculation under low-input conditions, including increased alfalfa biomass, improved nutrient use efficiency, and reduced reliance on exogenous N. These results suggest the potential of co-inoculation with AMF and rhizobia to reduce fertilizer dependency and enhance alfalfa productivity in low-input agricultural ecosystems, promoting sustainable forage crop production.

To investigate the effects of row ratio configurations on intercropping advantages and related rhizosphere microbial communities, a field experiment involving five treatments of different rows of broomcorn millet, i.e., P1M1 (1 row of broomcorn millet intercropped with 1 row of alfalfa), P2M3, P1M2, P1M3 and broomcorn millet alone (SP), was conducted on the Loess Plateau of China. We analyzed the yield, nutritional content of broomcorn millet, the soil nutrient availability and the diversity and community composition of AMF (arbuscular mycorrhizal fungi) and diazotrophs in the rhizosphere of broomcorn millet. The results showed that compared with monocultures, alfalfa-millet intercropping system under different row ratio configurations significantly increased the yield of broomcorn millet and the absorption of PTP and PTK (total phosphorus and potassium of broomcorn millet). In addition, the broomcorn millet-alfalfa intercropping system also improved soil nutrition, with the decrease of the row ratio of broomcorn millet, the changes of TN, NH4+-N and microbial biomass in the rhizosphere of broomcorn millet were consistent, which was opposite to NO3−-N. Moreover, co-occurrence network and PLS-PM (partial least squares path modelling) analysis showed alfalfa-broomcorn millet intercropping system changed the community diversity and composition of soil microorganisms, increased the improvement of soil nutrition (TN, NH4+-N and microbial biomass), and promoted the absorption of different nutrients by plants (N, P and K) mainly through the negative regulation of AMF and the synergistic effect of AMF on diazotrophs, and finally increased crop yield. This shows that broomcorn millet-alfalfa intercropping can increase plant nutrient content by adjusting soil nutrients and soil microbial activities, thereby increasing yield. Furthermore, we found that 1P2M was the best ratio of alfalfa-millet intercropping system, which may provide reliable suggestions and selection basis for future agricultural production practices.

Alfalfa regrowth is a complex process that is frequently constrained by deficits in water and N fertilisers after cutting. However, the transcriptomic regulatory networks and primary metabolic changes during regrowth are largely unknown. The alfalfa regrowth biomass responses to water deficiency and water deficiency supplied with N fertilisers and corresponding transcriptional and primary metabolic changes in new leaves and roots were systematically explored at 9 and 14 d after cutting. Water deficiency significantly decreased the alfalfa regrowth biomass. Integrated transcriptomic and metabolomic analysis demonstrated that osmoprotection related genes, sucrose and starch metabolic pathways, hormone biosynthesis and signalling pathways, and key transcription factors in new leaves and roots are responsible for alfalfa regrowth under water deficiency. Furthermore, alfalfa regrowth biomass was significantly improved in the presence of N fertilisers under water deficiency through multigene network coordination and metabolic pathway rearrangement. Interestingly, differentially expressed genes expression occurred predominantly in roots at 9 d after cutting, while it mainly occurred in the new leaves at 14 d after cutting. This study revealed the complex molecular mechanisms of alfalfa regrowth and provided theoretical support for optimal irrigation and N fertiliser strategies that will achieve maximum biomass of alfalfa in dryland farming areas.

Soybeans can simultaneously form tripartite symbiotic associations with arbuscular mycorrhizal fungi (AMF) and diazotrophs. However, no studies have explored whether soybean genotypes differing in their maturity groups (MGs) may have implications for the recruitment of rhizosphere soil AMF and diazotrophs. We investigated the diversity and community compositions of AMF and diazotrophs in three soybean genotypes differing in their maturity groups (MG) using high-throughput sequencing. The soybean MGs were MG1.4, MG2.2, and MG3.8, representing early, standard, and late maturity, respectively, for the study region. Soil chemical properties and yield-related traits were determined, and co-occurrence network patterns and drivers were also analyzed. The results obtained demonstrated that AMF richness and diversity were relatively stable in the three soybean genotypes, but noticeable differences were observed in diazotrophs, with late maturity being significantly higher than early maturity. However, there were differences in AMF and diazotrophic composition among different MG genotypes, and the changes in the proportion of dominant species in the community were necessarily related to MG genotypes. Co-occurrence network analysis showed that the positive correlation between AMF and diazotrophs gradually decreased in earlier MG genotypes than in the other later MG genotypes. The results of the structural equation model analysis showed that soil organic carbon, AMF, diversity of soil nutrients, and extracellular enzyme activities were important factors driving soybean yield change, with organic carbon accounting for more than 80% of the pathways analyzed. These results suggest that soybean genotype selection based on MG plays an important role in recruiting both AMF and diazotrophic communities, and in comparison to AMF, diazotrophs are more responsive to the different MG genotypes.

The basic principle underlying organic orchards is increased soil nutrient content, particularly organic matter content and increases soil bacterial activity and diversity. A standard organic management strategy significantly improved (p < 0.05) soil alkaline phosphatase, urease, and sucrase activities and soil organic matter, total nitrogen, total phosphorus, and nitrate nitrogen contents. The soils of two orchards mainly contained 32 bacterial phyla, which were dominated by Proteobacteria, Acidobacteria, Actinobacteria, Chloroflexi, and Gernmatirnonadetes. Correlational analysis showed that the bacterial community was mainly influenced by catalase, sucrase, and soil organic matter. Catalase, urease, sucrase, and alkaline phosphatase activities and soil organic matter, total nitrogen, and nitrate-nitrogen contents promoted soil bacterial content. A comprehensive analysis showed that organic orchard management improved soil nutrients and enzyme activities and changed the soil bacterial diversity compared with those of conventionally managed soil.

为研究紫花苜蓿叶片和根系对水分和外源氮(N)添加的响应规律,在温室条件下设置水分胁迫处理(WS)(35％±5％)田间持水量(field water capacity,FWC)和充分灌溉且未渍水(WW)(70％±5％)FWC两个水分梯度,每个水分梯度下设置0、5和10 mmol·L-13个N添加水平(Nn、Nm和Nh),研究了紫花苜蓿叶片和根系膜脂过氧化的程度及C、N特征对不同水分条件和外源N添加的响应规律.结果表明:WS和外源N提高了紫花苜蓿叶片丙二醛(MDA)含量,但对根系没有显著影响.WS和N添加未影响紫花苜蓿叶片C含量,但N添加提高了根系C含量.WS未改变紫花苜蓿叶片N含量,但提高了根系N含量.外源N添加不但提高了叶片N含量,还增加了根系N含量,但叶片N含量在WW处理下对外源N添加较为敏感,而根系N含量在WS处理下对外源N的添加较为敏感,这说明紫花苜蓿叶片和根系C、N状态对N添加的响应受土壤水分条件的调控.紫花苜蓿根系C/N较叶片更高,且对水分和外源N添加的响应更为敏感.WS处理显著提高了根系δ13C,对叶片δ13C无显著影响.外源N添加降低了叶片和根系δ15N,且在WS处理下根系δ15N显著降低,叶片中δ15N在WW处理下显著降低.总之,相比叶片,紫花苜蓿根系生理参数及C、N特征对水分和外源N添加采取了更为积极的策略,在生长中发挥着更重要的作用.该研究结果有助于全面掌握紫花苜蓿各器官对水分和外源N添加的响应策略,为我国旱作农业区紫花苜蓿制定精准的水肥管理制度提供了理论依据.

为比较不同组成的混合干草对奶山羊公羔生长性能、屠宰性能、肉品质和血清抗氧化指标的影响,将24只奶山羊公羔(11.48±0.55)kg随机分为4组,每组3个重复,每个重复2只羊,分别饲喂4种混合干草:苜蓿+燕麦(Ⅰ组)、苜蓿+多年生黑麦草(Ⅱ组)、毛苕子+多年生黑麦草(Ⅲ组),以当地传统混合干草(作物秸秆50％、苜蓿30％和田间杂草20％)为对照组(CK).处理组两种饲草比例均为1:1,各组精料配比一致,精粗料分开饲喂.预饲期15 d,正试期70 d.结果显示:(1)与对照组相比饲喂果园混合干草提高奶山羊平均日增重,以Ⅰ组效果最显著(P<0.05).Ⅰ、Ⅲ组体高显著增加(P<0.05);(2)Ⅰ组羔羊的胴体重、眼肌面积和GR值等指标较其他组有显著提高(P<0.05);(3)Ⅱ组中剪切力显著低于其它处理组(P<0.05),Ⅲ组亮度L*24 h显著高于其他处理组(P<0.05);(4)Ⅱ组血清谷胱甘肽过氧化物酶活性显著升高(P<0.05),较其他组升高16.67％～23.41％,Ⅰ组羔羊血清过氧化氢酶活性显著升高(P<0.05);(5)饲喂果园生混合干草,育肥羔羊的增收和经济效益均显著高于CK组(P<0.05),其中Ⅰ组最高,增收为267.74元/只、经济效益为208.51元/只.综上分析认为,以苜蓿+燕麦(1:1)混合干草对萨能奶山羊公羔的生长性能和屠宰性能最优,饲喂效果最好,经济效益最佳.

为探究不同秋眠类型紫花苜蓿根际与非根际土壤理化性质,本研究调查了关中地区种植5年不同秋眠类型紫花苜蓿再生期和休眠期根际与非根际土壤有机碳(Soil organic carbon,SOC)、全氮(Total nitrogen,TN)、全磷(Total phosphorus,TP)及土壤酶活性.结果表明:根际SOC、TN、土壤酶活性及化学计量比显著高于非根际土壤(P<0.05);TP在根际与非根际土壤中无显著差异(P>0.05);休眠期土壤SOC、TN、TP含量整体变化趋势表现为随着秋眠级数递增,养分含量逐渐升高,即强秋眠(D)<半秋眠(SD)<非秋眠(ND),而再生期的表现趋势正好相反.根际与非根际SOC与T N、蔗糖酶活性呈正相关;根际土壤T N与蔗糖酶、蛋白酶活性呈正相关,与脲酶活性呈负相关;非根际土壤TN与蔗糖酶活性呈正相关,与蛋白酶活性呈负相关.本研究结果将有助于进一步探究不同秋眠类型紫花苜蓿土壤营养物质循环与生产力之间的关系及根际土壤的微生态.

为进一步明确关中地区基于牧草种植和传统农作物生产对土壤理化性质的影响,本试验测定了单播紫花苜蓿(A)、玉米(M)、小麦(W)及套种紫花苜蓿和玉米(AM)四年后土壤碳氮含量、稳定性同位素、微生物生物量及酶活性.结果表明:紫花苜蓿根际土壤全氮(TN)、同位素氮(δ15N)、微生物生物量碳氮(MBC、MBN)及蔗糖酶(SUC)、脲酶(UR)和中性磷酸酶(NP)均显著高于小麦和玉米.此外,AM的根际土壤全碳(TC),TN和MBC显著高于单播作物.土壤TC和TN分别与δ15N,MBC和NP等呈极显著正相关(P＜0.01),且冗余分析中土壤C,N及微生物生物量分别解释了酶活性变化的50.86％和69.81％.因此,关中地区基于豆科牧草紫花苜蓿的种植模式能够实现C,N资源的高效利用与土壤的可持续生产.本研究从土壤理化性质的角度为关中地区落实"粮改饲"等政策,实现农业资源的高效利用提供理论依据.

Soil microorganisms play a key role in soil fertility. Exploring the microbial community composition and diversity in response to cover crops is important for improving soil fertility in orchards. This study investigated how cover cropping can improve soil fertility by altering microbial community composition and the interrelations among soil microorganisms. Soil physicochemical and biological indicators and microbial community composition were evaluated after a 6-years application of cover cropping in an apple ( Malus pumila cv. Fuji) orchard located on the Loess Plateau, China. Three treatments were applied: Trifolium repens treatment (TR), Lolium perenne treatment (LP), clear tillage treatment (CT). The soil of the cover crop treatments had a more complex microbial co-occurrence network than that of the clear tillage treatment; in particular, the correlations among fungi were significantly increased. Cover cropping increased the levels of soil organic matter (SOM), microbial biomass carbon (MBC), and total nitrogen (TN) in orchard soil. Changes in the fungal community were more related to microbial biomass nitrogen (MBN), TN, and carbon-nitrogen ratio (C:N). This indicates that cover cropping not only increases the diversity of soil microorganisms but also increases the interrelations between microbial groups, thereby improving the soil fertility of apple orchards on the Loess Plateau.

为研究紫花苜蓿在叶片和根系水平上响应干旱胁迫的形态和生理的品种特异性规律,在温室内分析了干旱胁迫下WL363HQ和巨能7紫花苜蓿株高、分枝数、生物量及叶片和根系中丙二醛（MDA）、脯氨酸、抗氧化酶类物质、C、N含量、C/N、稳定性C同位素(δ 13 C)和稳定性N同位素(δ 15 N)。结果表明:干旱胁迫显著降低了供试品种地上部分和根系的干重及分枝数（P＜0.05）。干旱胁迫显著降低了巨能7的株高（P＜0.05）,但增加了巨能7的根冠比,而WL363HQ的结果与之相反,这说明干旱胁迫下供试品种的株高和根冠比具有品种特异性的规律。干旱胁迫增加了WL363HQ和巨能7叶片和根系中MDA和脯氨酸的含量及抗氧化酶物质的活性,且在器官水平也具有品种特异性规律。干旱胁迫下巨能7叶片的MDA含量显著增加（P＜0.05）,而在WL363HQ根系中的MDA含量也显著增加（P＜0.05）。干旱胁迫下WL363HQ叶片脯氨酸含量、POD和SOD活性,及根系SOD的活性均显著增加（P＜0.05）,而巨能7仅叶片SOD活性,根系脯氨酸含量、POD活性显著升高（P＜0.05）。尽管干旱胁迫对供试品种叶片和根系C、N含量无显著影响（P＞0.05）,但干旱胁迫显著提高了WL363HQ和巨能7紫花苜蓿根系的δ 13 C（P＜0.05）,且WL363HQ叶片的δ 15 N均显著高于巨能7（P＜0.05）。此外,干旱胁迫均显著提高了巨能7叶片和根系的C/N（P＜0.05）。干旱胁迫下供试品种C、N代谢参数并没有在叶片和根系中表现出较为明显的品种特异性规律,深层次的机制还有待进一步研究。本研究结果将为进一步掌握紫花苜蓿叶片和根系协同抗旱机制及抗旱丰产紫花苜蓿新品种的选育提供理论依据。

为探究果园生草对关中地区有机猕猴桃(Actinidia chinensis)园土壤养分及细菌群落结构的影响,本研究采用LEfSe差异分析、随机森林算法分析、PICRUSt2功能预测分析等方法,对秣食豆(Glycine max,GM)、草木樨(Melilotus off icinalis,MO)、一年生黑麦草(Lolium perenne,LP)三种生草处理后的有机猕猴桃园0～20 cm耕层土壤养分及细菌群落等指标进行测定.结果 表明:生草处理组的土壤有机质含量均显著高于清耕,草木樨与秣食豆处理显著提高了土壤全钾含量、土壤过氧化氢酶和脲酶含量,说明生草处理能够有效提高果园土壤养分.同时,生草提升了土壤细菌β多样性,改变了不同处理间差异代表物种,增加了土壤细菌碳水化合物代谢和能量代谢功能基因丰度,促进土壤养分循环.综上,在关中平原有机猕猴桃园间种植草木樨、秣食豆和一年生黑麦草有助于提高土壤有机质和养分含量,改善土壤微生态环境,是一种适宜当地条件的果园栽培模式.

Grasslands/Rangelands Resources and Ecology ——— Ecology of Grasslands/Rangelands Responses of photosynthetic rate of lucerne and the mechanisms under cutting at different water availabilities Shubin He , H uimin Y ang 倡 ,Guoli L iu , Zhilong Zhang College o f Pastoral A griculture Science and Technology , L anz hou University , L anz hou 730020 , China . 倡 Corresponding author . E‐mail :huimyang@ lz u .edu .cn

Under the control of monoculture silage maize (Zea mays) and the intercropped alfalfa (Medicago sativa) model, we measured the index of soil C, N, P, microbial biomass C (MBC), microbial biomass N (MBN), microbial biomass P (MBP), glomalin-related soil proteins (GRSP), soil fungal diversity, and community structure characteristics in the soil rhizosphere of early-maturing and late-maturing maize. The results illustrated that the total N content in the soil rhizosphere of the two types of maize increased significantly (P < 0.05) in the first year, indicating that intercropping may enhance the activity of soil N fixing microoganism. The intercropping significantly increased the content of MBN, MBP, late-maturing soil MBC, and easily extractable glomalin (EEG) in the soil rhizosphere of early maturing maize (P < 0.05), and the characteristics of the rhizosphere soil fungal communities tended to be similar. This indicated that intercropping may improve soil nutrient supply and promote soil microbial activities, thereby improving soil fertility and promoting plant growth. Therefore, according to the analysis of results of soil physical and chemical properties and fungi in the first year, the alfalfa and silage maize intercropping in the Guanzhong area may effectively improve the efficiency of soil nutrient element utilization.

This study was conducted in the Guanzhong area to study the effects of chemical fertilizer reduction and application of organic manure on the yield and nutritive value of silage maize (Zea mays) and soil microbial activity. The results showed that there were no significant differences (P > 0.05) in the yields between the different treatments in the first year. The single fertilizer treatment (T1) had the highest crude protein content, and the application of organic manure reduced the crude protein content of maize to a certain extent and increased the fiber content. The soil microbial biomass carbon, microbial biomass nitrogen, soil urease, and alkaline phosphatase activity of the T1 treatment were the lowest. With an increase in the ratio of organic manure application, the soil microbial biomass carbon, microbial biomass nitrogen, and soil enzyme activity increased. This preliminarily indicates that the application of organic manure in the Guanzhong area can maintain the maize yield in the first year, and significantly increase the soil carbon/nitrogen reserves and enzyme activities. This study provides a theoretical basis for the development of the silage maize industry, improvement of the soil environment, and improvement of fertilizer utilization efficiency in the Guanzhong area.