Soil phosphorus mobilization in different taxonomic orders

Changes in P fractions using Hedley's sequential fractionation of organic and inorganic soil P, were studied in soils covering a wide range of developmental stages and original materials. A greenhouse experiment was performed in order to make an exhaustive P uptake by Lolium perenne and to study soil phosphorus mobilization from different fractions. Samples were obtained at 30, 60 and 90 days from sowing, with two fertilization rates added as KH₂PO₄. The exhaustion produced by plants resulted in different patterns of mobilization according to soil characteristics. For control soils the contents of inorganic labile fraction (LIP) decreased at the end of the experience in Mollisol (31%), Vertisol (24%) and Andisol (17%). The mobilization of organic P was greater for Ultisol and Andisol (77 and 75% respectively) than for the other soils. Fertilization affected mainly inorganic P, with a significant increase in contents of LIP in Entisol (46%) and moderately resistant inorganic P (MRIP) in Andisol (15%). Inorganic P/organic P relationship tended to increase during the experiment, while labile P/moderately resistant P increased in Entisol and Mollisol.     

接种丛枝菌根真菌和巨大芽孢杆菌的红三叶草对难溶磷的利用

A pot experiment was conducted to investigate the mobilization of sparingly soluble inorganic andorganic sources of phosphorus (P) by red clover (Trghlium pmtense L.) whose roots were colonized by the arbuscular mycorrhizal (AM) fungus Glomus mosseae and in association with the phosphate-solubilizing (PS) bacterium Bacillus megaterium ACCC10010. Phosphate-solubilizing bacteria and rock phosphate hada synergistic effect on the colonization of plant roots by the AM fungus. There was a positive interaction between the PS bacterium and the AM fungus in mobilization of rock phosphate, leading to improved plant P nutrition. In dual inoculation with the AM fungus and the PS bacterium, the main contribution to plant P nutrition was made by the AM fungus. Application of P to the low P soil increased phosphatase activityin the rhizosphere. Alkaline phosphatase activity was significantly promoted by inoculation with either the PS bacterium or the AM fungus.     

生物腐植酸对露天矿排土场黑麦草生长的影响

[目的]研究生物腐植酸对露天矿排土场土壤改良效果的影响,为进一步提高露天矿排土场的土壤质量提供科学参考。[方法]通过盆栽试验,研究不同生物腐植酸含量(0~400kg/hm2)对露天矿排土场不同土地利用类型〔(刺槐(Robinia pseudoacacia)林、榆树(Ulmus pumila)林、荆条(Vitex negundo)林、农田、未复垦土地〕下黑麦草(Lolium multiflorum)生长状况的影响。[结果]刺槐土、榆树土、荆条土、农田土、未复垦土出苗率最大值分别出现在加入生物腐植酸量为200,200,300,300,200kg/hm2的试验盆;5种土壤黑麦草幼苗株高所需生物腐植酸最大量值分别为200,200,200,300,300kg/hm2;5种土壤黑麦草根系长度最大值分别出现在300,100,300,300,300kg/hm2的试验盆;而生物量最大值分别出现在加入生物腐植酸量为200,100,200,300,300kg/hm2的试验盆。随着生物腐植酸量的增加,各土地利用类型条件下种植的黑麦草出苗率、株高、根系长度、生物量均表现出先增加后减小的趋势。[结论]生物腐植酸对露天矿排土场不同土壤植物更新与生长具有剂量效应,表现为"单峰型"变化规律,体现出适量的生物腐植酸对露天矿排土场植被恢复具有促进作用。     

盐碱地塔宾曲霉菌的解磷能力及其对小麦生长的影响

[目的]研发新型解磷生物菌肥,提高黄河三角洲盐碱障碍耕地作物产量。[方法]采用无机磷液体培养基培养的方法,从黄河三角洲盐碱化菜园根际土壤筛选得到一株解磷真菌CT1,即塔滨曲霉菌(Aspergillus tubingensis),对其解磷能力进行了深入研究。[结果]解磷菌CT1的解磷能力随发酵液盐浓度升高降低,当发酵液盐浓度在0.03%~6%时,发酵液中有效磷浓度可维持在523.5~338.5mg/L,且解磷菌的溶磷量与发酵液pH之间存在明显的负相关。解磷菌CT1在葡萄糖作为碳源的培养基上生长状况最好,在(NH_4)_2SO_4作为氮源的培养基上生长状况最好。接入解磷菌15d的小麦与未接菌的小麦相比,茎长增加了16.24%,茎鲜重增加了12.35%,根长增加了21.6%。[结论]解磷菌CT1对盐碱地小麦幼苗生长有一定的促进作用,可作为提高盐碱地作物产量的新型解磷生物菌肥利用。     

The role of the earthworm Lumbricus terrestris in the transport of bacterial inocula through soil

Two laboratory experiments were used to investigate the effect of the earthworm Lumbricus terrestris on transport of genetically marked Pseudomonas fluorescens inocula through soil microcosms. The microcosms comprised cylindrical cores of repacked soil with or without earthworms. Late log-phase cells of P. fluorescens, chromosomally marked with lux genes encoding bioluminescence, were applied to the surface of soil cores as inoculated filter paper discs. In one experiment, 5 and 10 days after inoculation, cores were destructively harvested to determine concentrations of marked pseudomonads with depth relative to the initial inoculum applied. Transport of the bacteria occurred only in the presence of earthworms. In a second experiment cores were subjected to simulated rainfall events 18 h after inoculation with lux-marked bacteria at 3-day intervals over a 24-day period. Resulting leachates were analysed for the appearance of the marked bacteria, and after 28 days cores were destructively harvested. Although some marked cells (less than 0.1% of the inoculum applied) were leached through soil in percolating water, particularly in the presence of earthworms, the most important effect of earthworms on cell transport was through burial of inoculated litter rather than an increase in bypass flow due to earthworm channels.     

Interaction study of biochar with phosphate-solubilizing bacterium on phosphorus availability in calcareous soil

A large proportion of phosphate fertilizer applied to calcareous soils reacts with calcium. Changes in soil phosphorus (P) availability after single application of biochar and phosphate-solubilizing bacteria have been reported. However, interaction of biochar (increasing soil pH) and phosphate-solubilizing bacteria (decreasing soil pH) on P availability in calcareous soil is not well known. An incubation experiment was conducted to study how the interactive effects of biochars (produced from wheat straw and cow manure at 300°C and 500°C with residence time of 1, 3 and 6 h) at different rates (0, 5 and 10 t ha^?1) and phosphate-solubilizing Pseudomonas sp. IS8b2 affected on content of soil available P after 0, 60, 120 and 180 days of incubation (DOI) in a calcareous soil. After 60 DOI, the maximum value of available P (50.31 mg kg^?1) was observed in the compound treatment of Pseudomonas sp. IS8b2 and wheat straw biochar (10 t ha^?1) produced at 500°C with residence time of 3 h. We conclude that the combination use of wheat straw biochar and phosphate-solubilizing bacterium is promising to potentially improve soil P availability in calcareous soil, but further research at field scale is needed to confirm this.     

Phosphate-solubilization activity of bacterial strains in soil and their effect on soybean growth under greenhouse conditions

The efficiency of 13 phosphate-solubilizing bacteria (PSB; four Burkholderia sp., five Enterobacter sp., and four Bradyrhizobium sp.) was assessed in a soil plate assay by evaluating soil phosphorus (P) availability. A commercial argentine strain, Pseudomonas fluorescens, was used for comparing solubilizing activity. Burkholderia sp. PER2F, Enterobacter sp. PER3G, and Bradyrhizobium sp. PER2H strains solubilized the largest quantities of P in the soil plate assay after 60 days as compared with the other strains, including the commercial one. The effect of PSB inoculation on growth and nutrient uptake of soybean plants was also studied under greenhouse conditions. Plants inoculated with Burkholderia sp. PER2F had the highest aerial height and showed an appropriate N/P ratio. However, none of the PSB increased P uptake by plants. This suggests that PSB inoculation does not necessarily improve P nutrition in soybean, nor was there any relationship between P availability in the soil plate assay and P content in the soybean shoot in the greenhouse. We concluded that the selection of efficient PSB strains as possible inoculation tools for P-deficient soils should focus on the integral interpretation of soil assays, greenhouse experiments, and field trials.     

Inoculation of phosphate-solubilizing bacteria Bacillus thuringiensis B1 increases available phosphorus and growth of peanut in acidic soil

Phosphate-solubilizing microorganisms play an important role in plant nutrition by enhancing phosphorus (P) availability to roots through converting the insoluble phosphates into soluble ions. We isolated phosphate-solubilizing bacteria (PSB) from acidic soil (Ultisols) in the field from the layer of 0–150 mm at a tea garden located at 28°38′26″ N and 116°24′27″ E. The capacity of bacterial isolates to solubilize mineral phosphate was tested on aluminum phosphate (AlPO₄) in liquid medium. Among these PSB, isolate B1 (identified as Bacillus thuringiensis) exhibited the maximum P-solubilizing ability and was particularly efficient at solubilizing AlPO₄ (up to 321 mg L^?1) in vitro. The isolate B1 was inoculated to an acidic soil to study its effect on phosphate solubilization and growth of peanuts (Arachis hypogeae). The Olsen-P in the tested soil increased from 14.7 to 23.4 mg kg^?1, with solubilization of 16.4 mg kg^?1 soil of Occluded-P after 14-day incubation. The inoculation by B1 significantly increased plant height (from 37.7 to 45.7 cm), number of branches (from 34.0 to 52.7 per plant), hundred-seed weight (from 42.1 to 46.9 g) and crude protein content (from 243.5 to 268.2 g kg^?1 dry weight). The phosphate-solubilizing B. thuringiensis strain B1 showed potential as a biological phosphorus fertilizer.     

秸秆添加对土壤微生物–根系形态介导的番茄磷吸收的影响

  【目的】  研究了添加秸秆后土壤微生物(包括解磷微生物)丰度、磷有效性的动态变化,以及作物根系的生长发育特征对作物磷吸收的影响。  【方法】  以番茄 (Solanum lycopersicum)为供试作物进行田间试验,设置添加秸秆和不添加秸秆对照两个处理,在番茄移栽后第15、30及45 天,测定了番茄地上部生物量、磷含量和根系形态,同时测定了土壤微生物数量(细菌、真菌、解磷微生物)、微生物生物量磷和速效磷含量,分析了微生物?根系–作物磷吸收的关系。  【结果】  添加秸秆提高了成熟期番茄的地上部生物量,显著提高了叶片和地上部的磷吸收量,地上部(叶+茎+果实)总磷吸收量较不加秸秆番茄增加21.8%。与无秸秆对照处理相比,添加秸秆处理提高了土壤细菌以及具phoD,phoC和pqqC功能基因的解磷微生物丰度,增加了微生物量磷。添加秸秆处理降低了移栽后15 天番茄根系生物量和组织密度,增加了根系比根长,降低了移栽后15到30 天的番茄根系生长。番茄移栽后第30 天到45 天,土壤细菌、真菌丰度下降,微生物量磷降低,丰富的解磷微生物以及微生物量磷降低介导的磷活化,驱动番茄根系生长加快,比根长增加,根系直径降低。根系生长与土壤有效磷(Olsen-P)相关性显著。  【结论】  添加秸秆初期微生物增生导致番茄根系生长缓慢,后期微生物量磷的降低和解磷微生物对磷的活化促进细根的快速伸长。秸秆还田激发微生物量磷活化协同根系高效磷吸收特征,促进成熟期番茄地上部磷吸收的增加。     

Comparison of in vitro solubilization activity of diverse phosphate-solubilizing bacteria native to acid soil and their ability to promote Phaseolus vulgaris growth

To identify plant growth promotion ability of phosphorus-solubilizing native bacteria, we have examined a collection of isolates representing the diversity of culturable phosphate-solubilizing bacteria from acid soils of the northeast of Argentina. Assays in growth medium supplemented with tricalcium phosphate revealed different phosphorus solubilization activity and temporal patterns of solubilization. Acidification of the broth medium coincided with phosphorus solubilization. The isolates were grouped according to their Rep fingerprinting profiles and phylogenetically classified by 16S rDNA and biochemical analyses. These isolates were assigned to the genera Enterobacter, Pantoea, Pseudomonas, Acinetobacter, Burkholderia, and Exiguobacterium. Four isolates showing high phosphorus solubilizing activity in in vitro assays were inoculated on common beans (Phaseolus vulgaris); some of them promoted plant growth and increased photosynthesis and the P and N content of leaves. The results indicated that the ability to in vitro solubilize P is not necessarily associated to the promotion of plant growth.     

Phosphataufnahme und -Verwertung von drei Inzuchtlinien des Welschen Weidelgrases (Lolium multiflorum Lam.) und ihren Hybriden

Uptake and utilization of phosphorus by three inbred lines of Lolium multiflorum L. and their hybrids Three Lolium multiflorum inbred lines A, B and C and their hybrids (AB, AC, BC) were tested for their shoot dry matter (DM) production, P uptake (mg P pot^?1), P utilization (mg DM · mg P^?1) and P influx (P uptake rate per cm root length) by growing in plastic pots for a maximum period of 92 days at two P levels in a loess loam soil. The acid phosphatase activity of roots of inbreds A and C grown in nutrient solutions with 1.10 and 100 μmol P · L^?1 was also determined using the hydrolysis of Nitrophenyl phospate (NPP). Compared to the average of the inbreds DM production of the hybrids was 8 % higher at high and 12 % higher at low P level. With an increase of 14% and 25% DM respectively hybrid BC had the highest heterosis effect. The biomass production corresponded with the P uptake. Therefore, the P utilization efficiency of the hybrids was nearly the same as that of the inbreds. The increase in P uptake of the hybrids was related to the increase of root length. This means that the P uptake efficiency, i.e. the influx per unit of root remained unchanged between the inbreds and their hybrids. It can thus be concluded that the heterosis effect corresponds to an increase of P uptake caused by an increase of the size of the root system. The activity of the root phosphatases increased with declining P status of shoots and being absolutely higher in inbred A than C. Both inbreds responded within 3 days to a decreased P supply (from 100 to 1 μmol P · L^?1).     

砒砂岩中植物促生芽孢杆菌的筛选及其对土壤的改良作用

[目的]筛选砒砂岩土壤中植物促生芽孢杆菌,为微生物强化植物改良砒砂岩土壤的科学设想提供资源和技术基础。[方法]以产生植物激素IAA(indole acetic acid)、铁载体和生物膜为筛选指标,从内蒙古砒砂岩区土壤和植物样品中筛选植物促生芽孢杆菌,采用盆栽试验探究植物促生芽孢杆菌改良砒砂岩土壤特性和促进苜蓿和黑麦草生长的作用。[结果]筛选到的12株芽孢杆菌产生IAA、铁载体和生物膜的能力不同,分别属于Bacillus halotolerans,B.atrophaeus,B.siamensis和B.zhangzhouensis种群。与对照相比,B.halotolerans P75能够显著增加砒砂岩土壤的有机质含量(24.7%)、速效磷含量(11.9%)和速效钾含量(21.0%)等养分指标,每1 g土壤可培养细菌达到7.4 lg CFU,土壤蔗糖酶活性显著增强(58.8%)。接种B.halotolerans P75后,在砒砂岩土壤中生长的苜蓿和黑麦草干重增加22.3%～81.5%,[结论]从生长于砒砂岩土壤的苜蓿根内筛选到B.halotolerans P75,可提高砒砂岩土壤肥力,促进苜蓿和黑麦草生长,具有强化植物改良砒砂岩土壤的潜力。     

Isolation of culturable phosphobacteria with both phytate-mineralization and phosphate-solubilization activity from the rhizosphere of plants grown in a volcanic soil

Chilean volcanic soils contain large amounts of total and organic phosphorus, but P availability is low. Phosphobacteria [phytate-mineralizing bacteria (PMB) and phosphate-solubilizing bacteria (PSB)] were isolated from the rhizosphere of perennial ryegrass (Lolium perenne), white clover (Trifolium repens), wheat (Triticum aestivum), oat (Avena sativa), and yellow lupin (Lupinus luteus) growing in volcanic soil. Six phosphobacteria were selected, based on their capacity to utilize both Na-phytate and Ca-phosphate on agar media (denoted as PMPSB), and characterized. The capacity of selected PMPSB to release inorganic P (Pi) from Na-phytate in broth was also assayed. The results showed that from 300 colonies randomly chosen on Luria–Bertani agar, phosphobacteria represented from 44% to 54% in perennial ryegrass, white clover, oat, and wheat rhizospheres. In contrast, phosphobacteria represented only 17% of colonies chosen from yellow lupin rhizosphere. This study also revealed that pasture plants (perennial ryegrass and white clover) have predominantly PMB in their rhizosphere, whereas PSB dominated in the rhizosphere of crops (oat and wheat). Selected PMPSB were genetically characterized as Pseudomonas, Enterobacter, and Pantoea; all showed the production of phosphoric hydrolases (alkaline phosphatase, acid phosphatase, and naphthol phosphohydrolase). Assays with PMPSB resulted in a higher Pi liberation compared with uninoculated controls and revealed also that the addition of glucose influenced the Pi-liberation capacity of some of the PMPSB assayed.     

Nitrogen fixation and CO2 exchange in soybeans (Glycine max L.) inoculated with mixed cultures of different microorganisms

N₂ fixation, photosynthesis of whole plants and yield increases in soybeans inoculated with mixed cultures of Bradyrhizobium japonicum 110 and Pseudomonas fluorescens 20 or P. fluorescens 21 as well as Glomus mosseae were found in pot experiments in gray forest soil carried out in a growth chamber. The effects of pseudomonads and vesicular-arbuscular (VA) mycorrhizal fungus on these parameters were found to be the same. Dual inoculation of soybeans with mixed cultures of microorganisms stimulated nodulation, nitrogenase activity of nodules and enhanced the amount of biological nitrogen in plants as determined by the ¹⁵N dilution method in comparison to soybeans inoculated with nodule bacteria alone. An increased leaf area in dually infected soybeans was estimated to be the major factor increasing photosynthesis. P. fluorescens and G. mosseae stimulated plant growth, photosynthesis and nodulation probably due to the production of plant growth-promoting substances. Increasing phosphorus fertilizer rates within the range of 5–40 mg P 100 g^-1 1:1 (v/v) soil: sand in a greenhouse experiment led to a subsequent improvement in nodulation, and an enhancement of N₂ fixation and yield in soybeans dually inoculated with B. japonicum 110 and P. fluorescens 21. These indexes were considerably higher in P-treated plants inoculated with mixed bacterial culture than in plants inoculated with nodule bacteria alone.     

Effect of humic preparation on winter wheat productivity and rhizosphere microbial community under herbicide-induced stress

Purpose

The aim of the present work was to study the effect of humic preparation on the yielding capacity of winter wheat, the dynamics of mineral nutrients in the rhizosphere, and the activity of rhizosphere microbial community, as well as the protective properties of humate treatment under the stress caused by the application of a sulfonylurea herbicide.

Materials and methods

The humic preparation BIO-Don is prepared from vermicompost by alkaline extraction. The effect of humic preparation was estimated in a field experiment. The contents of the mobile ammonium and nitrate, exchangeable potassium, phosphorus, and humus were determined. Sampling and nutrient determination were performed in the tillering, booting, and grain maturing stages. Production experiments on the study of the combined effect of the humic preparation and the sunfonylurea pesticide Granstar Pro were performed in 2015 and 2017. The dynamics of mobile phosphorus in soil was studied. The abundance of culturable bacteria in the rhizosphere and bacterial species with different ecological strategies was determined. The dominant bacterial species were identified by MALDI-TOF mass spectrometry.

Results and discussion

The results of a small-plot experiment showed that at the tillering stage, the use of humic preparation has led to significantly higher supply of soil with mobile phosphorus. The winter wheat yield was 32.0 dt/ha in the control and 39.2 dt/ha with humic preparation or 22.5% gain in yield. The results of production experiment show that the application of sulfonylurea herbicide induced a chemical stress on winter wheat plants, but the use of humic preparation reduced this effect and increased the availability of phosphorus compounds. The treatment of plants with pesticides caused the general decrease in abundance of bacteria in the rhizosphere. The effect on quickly growing bacteria is more pronounced, while slowly growing bacteria and fungi are more resistant to this impact.

Conclusions

The application of humic preparation to winter wheat plantations allows to decrease the toxic effect of sulfonylurea herbicide, improve the supply of soil with mineral nutrients, and increase the crop yield. The favorable effects of humic preparation can be related to the active regulation of phosphorus mobilization by plants through the mechanism of root exudates due to the activation of root microbiota.

     

Survival and potential denitrifying activity of Azospirillum lipoferum and Bradyrhizobium japonicum inoculated into sterilized soil

Summary Potential denitrifying activity and population dynamics of Azospirillum lipoferum (137C) and Bradyrhizobium japonicum (G2sp) inoculated into a -sterilized soil were studied for a period of 3 weeks. The denitrifying enzyme potential of soil inoculated independently with each bacterial species was strongly stimulated by the presence of a plant (Zea mays L.). Simultaneous inoculation of both bacteria also produced a higher denitrifying enzyme potential than simple inoculation. Even with double inoculation, the presence of a plant did not modify the evolution of the activity. The response of the population dynamics to these treatments followed a different pattern. The population dynamics of A. lipoferum was not affected by the presence of the plant or by the presence of B. japonicum. In contrast, the presence of both a plant and of A. lipoferum seemed to promote the growth of B. japonicum.     

Interactions of Glomus clarum with Acetobacter diazotrophicus in infection of sweet potato (Ipomoea batatas), sugarcane (Saccharum spp.), and sweet sorghum (Sorghum vulgare)

Summary Spores of the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus clarum obtained from sweet potatoes grown in soil inoculated with this fungus and with an enrichment culture of Acetobacter diazotrophicus contained A. diazotrophicus and several other bacteria, including a diazotrophic Klebsiella sp. Inoculation of micropropagated sweet potatoes with G. clarum and A. diazotrophicus enhanced spore formation in soil compared to VAM inoculation alone. Plants inoculated with VAM spores containing the bacteria showed additional increases in the number of spores formed within roots. A. diazotrophicus infected aerial plant parts only when inoculated together with VAM or when present within VAM spores. Micropropagated sugarcane seedlings inoculated with the same VAM spores containing the diazotrophs also contained much higher numbers of A. diazotrophicus in aerial parts than seedlings inoculated in vitro with the bacteria alone. When grown in non-sterile soil, the sugarcane seedlings again showed the greatest infection of aerial parts after inoculation with VAM spores containing the diazotrophs. This treatment also increased VAM colonization and the numbers of spores formed within roots. Similar effects were observed in sweet sorghum except that the aerial plant parts were not infected by A. diazotrophicus.     

污泥有机肥改良铅锌尾矿对4种草本植物生长和重金属积累的影响

[目的]研究添加不同量的污泥有机肥对生长在铅锌尾矿中的黑麦草、白三叶、草木樨、沙打旺4种植物生长状况和对Pb,Zn,Cu,Cr,Cd累积的影响,以期为合理利用污泥有机肥改良、修复尾矿库提供理论依据。[方法]采用盆栽试验的方法。[结果]20g/kg处理水平下,4种植物株高、根长、地上鲜重、根鲜重均达到最大。施肥处理下,供试的4种植物叶绿素a+b含量均比对照高。随着改良剂含量的增加,黑麦草、白三叶丙二醛含量呈下降趋势。黑麦草、白三叶、草木樨体内Pb,Zn,Cd含量在10g/kg处理水平下达到最大,在20g/kg水平下降低。[结论]随着有机肥添加量的增加,重金属量向植物体内转移减少,有利于缓解重金属的毒害作用。     

Humic substrates application in diluted form enhanced availability of phosphorus (P) and its uptake by tea bushes in the tea-growing soil of Northeast India

Tea (Camellia sinensis L.) is an evergreen perennial crop, which is cultivated for its shoots in acidic soil under sub-tropical humid climatic condition. The availability of phosphorus (P) to plants is naturally limited in acidic tea-growing soils. Humic substrates (HS) are often applied to enhance availability of nutrients, especially P in horticultural and vegetable crop fields. However, its effect on soil of a perennial crop like tea was not studied before. In this study, application of HS enhanced P availability mainly by facilitating growth of phosphate-solubilizing bacteria (PSB) and enhancing phosphatase activity in soil. Application of same amount of HS in diluted form was more effective to enhance PSB population and phosphatase activity, which in turn increased P availability in soil and P uptake by tea bushes. This experiment indicated that application of 1.5 kg HS ha^?1 as 0.3% solution might be applied to enhance P availability to improve P availability and P uptake by plants in tea-growing soil.     

绿肥覆盖对紫色土坡耕地柑橘园氮磷流失的阻控效应研究

为探明紫色土坡耕地不同绿肥覆盖对柑橘园径流和养分流失的阻控效应,在田间径流小区设置黑麦草(Lolium perenne L.)、光叶苕子(Vicia villosa Roth var.)、二月兰(Orychophragmus violaceus)和清耕对照4个处理,定量监测了在自然降雨条件下不同处理的径流及氮磷养分流失...