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1.
The efficiency of filter strips in protecting watercourses against herbicides in run‐off was evaluated in field experiments in western Germany. Surface run‐off caused by natural rainfall and related transport of metolachlor, terbuthylazine and pendimethalin were measured on plots of 40 m length without filter strips (F0), and after passing over three types of herbicide‐untreated field margin: 12 m conservation headland (CH12), 6 m (GF6) and 12 m grass strips (GF12). Run‐off was also measured after simulated rainfall on 7 m long plots without (F0) and with 3 m grass strips (GF3). All three herbicides were transported both in dissolved and in adsorbed forms; the partitioning depended on their water solubility with metolachlor and terbuthylazine mainly translocated in dissolved form (F0: highest mean concentrations for a natural run‐off event 721 and 220 μg L?1, respectively). Pendimethalin was predominantly transported in adsorbed form (maximum mean concentration 11.2 μg L?1). In the sediment, the highest mean herbicide contents in a single natural event (F0) accounted for 2294 μg kg?1 (metolachlor), 1317 μg kg?1 (terbuthylazine) and 5648 μg kg?1 (pendimethalin). The proportions of applied herbicide translocated were 0.3% (metolachlor), 0.2% (terbuthylazine) and 0.06% (pendimethalin; F0, natural rainfall). The extent of herbicide transport decreased with time but within this trend soil sealing, soil moisture and amount and intensity of rainfall increased losses. Compared with the F0 plots, the reduction of herbicide translocation after natural rainfall reached 80–83% (CH12), 80–88% (GF6) and >99% (GF12) over the 3‐year period. The 12 m grass strips allowed only one extreme run‐off event to pass through, thus providing a highly effective watercourse protection against herbicide pollution. 相似文献
2.
草本植被过滤带对径流中泥沙和除草剂的去除效果 总被引：5，自引：1，他引：4
除草剂阿特拉津的大量使用在提高农业生产效率、增加作物产量的同时,也导致了严重的环境污染。该研究通过在土槽上进行浑水冲刷试验,定量研究了禾本科草本植被过滤带（狼尾草Pennisetum alopecuroides (Linn.) Spreng和野古草Arundinella hirta (Thunb.) C. Tanaka）对径流、泥沙、以及阿特拉津的拦截效果。结果表明,禾本科草本植被过滤带能有效拦截径流,拦截率可达88%;并显著降低泥沙和阿特拉津流失量,但其作用效果受泥沙和阿特拉津的进水浓度影响较大。当进水泥沙浓度为20、40、60 g/L时,植被过滤带对泥沙的拦截率分别为95%、93%、85%;当进水阿特拉津浓度为0.3、0.6、0.9 mg/L时,植被过滤带对阿特拉津的拦截率分别为95%、92%、91%。另外,植被过滤带对泥沙和阿特拉津的拦截率随时间延长呈逐渐降低趋势,试验开始后第1、10、20、40、60分钟的泥沙拦截率分别为97%、95%、93%、91%、87%,阿特拉津拦截率分别为97%、93%、90%、86%、84%;同时,阿特拉津出流浓度与径流量有显著相关关系（r1=0.88,r2=0.93,r3=0.94）,表明径流量在一定程度上决定了阿特拉津出流浓度和出流量。研究证实,植被过滤带能有效降低阿特拉津随径流流失量,对阿特拉津引起的农业面源污染具有较好防治效果。 相似文献
3.
J. WANYAMA K. HERREMANS W. MAETENS M. ISABIRYE F. KAHIMBA D. KIMARO J. POESEN J. DECKERS 《Soil Use and Management》2012,28(3):409-418
The effectiveness of tropical grass species in strips of different length in trapping sediment from cropland was assessed, and the influence of filter length was determined. The assessment was made under natural rainfall which induced sheet and rill erosion in run‐off plots and then using simulated run‐off which caused concentrated erosion. The evaluated grasses were elephant grass, lemon grass, paspalum and sugarcane. Run‐off plots were on a 10% slope in a randomized complete block design replicated three times. Filter lengths were 2.5, 5 and 10 m against a 10‐m‐long sediment source area planted with maize on a clay loam soil. The results show that sediment trapping effectiveness (TE) increases nonlinearly with increasing filter length for all grasses. Under natural rainfall, more than 70% of sediment was trapped in the first 5 m, and lengthening the strip to 10 m only resulted in a marginal increase in TE. With concentrated run‐off, more than 70% of sediment was trapped in the first 5 m and lengthening the strip to 10 m resulted in a significant increase in TE. Paspalum and lemon grass performed significantly better than other grasses (P < 0.05), owing to their spreading growth pattern over the soil surface. Paspalum also has the highest root density in the upper 0.3‐m layer of the soil followed by lemon grass, hence offering the greatest resistance to erosion from concentrated flow. The results demonstrate that tropical grass filter strips provide a viable means for reducing the sediment flux from cropland. 相似文献
4.
草地植被过滤带对高含沙坡面流泥沙的拦截效应研究 总被引：1，自引：0，他引：1
To evaluate the effect of vegetative filter strips on sediment trapping, the spatial distribution of deposited sediment, and the size distribution of deposited particles from hyperconcentrated flows, a simulated grass filter strip experiment was conducted with plastic grass using an adjustable slope steel flume. The simulated vegetation cover was 36%, and the inflow sediment concentrations applied were 147, 238, 320, and 429 kg m-3. The sediment concentration in the outflow, and the sediment particle size were determined. The results showed that the grass filter strips trapped most of the sediment from inflow at low sediment concentration. The deposition efficiency decreased with increasing sediment concentration, being 55.2% and 15.7% in the 147 and 429 kg m-3sediment treatments, respectively. Most of the deposited sediments were distributed in the upper flume. In addition, the grass filter strips mainly trapped the coarse sediment （particle size>10 μm）. 相似文献
5.
在我国农业面源污染已经成为水环境质量恶化和湖泊富营养化的重要原因,其中氮磷对地表水富营养化的贡献超过了50%。通过浑水冲刷试验,研究了3种禾本科植被过滤带((黑麦草Lolium perenne Linn.)、偃麦草((京草2号)Elytrigia repens(L.)Nevski)、无芒雀麦(Bromus inermis Leyss.)对径流、泥沙以及氮磷的拦截效果,同时分析了3种植被过滤带拦截氮磷的主要途径。结果表明:(1)与裸地相比,3种植被过滤带均能显著提高径流与氮磷的拦截率。3种植被过滤带之间对径流、氮磷拦截率没有显著差异。黑麦草过滤带泥沙流失量显著低于无芒雀麦过滤带;同时径流、泥沙与氮磷拦截率之间存在显著正相关关系,表明植被对径流和泥沙的拦截一定程度上决定对氮磷的拦截量;(2)径流过程中磷的流失量均低于氮的流失量。氮的流失主要以溶解态氮为主,占总氮流失量的90%以上;磷的流失则主要以颗粒态磷为主;(3)植被过滤带拦截氮磷的途径不同,氮主要通过增加土壤入渗的途径来拦截,磷则主要通过植物茎秆基部进行物理拦截;(4)京草2号对氮的拦截效果优于黑麦草和无芒雀麦,而黑麦草则在磷的拦截方面表现突出。因此在植被过滤带的优化设计方面可以考虑黑麦草与京草2号2者混播以达到最佳的拦截吸附效果。 相似文献
6.
草带措施对坡耕地产流产沙和氮磷迁移的控制作用 总被引：3，自引：0，他引：3
植被在坡面的位置对坡面保持水土的作用是不同的。动态监测澄江抚仙湖一级支流尖山河小流域坡耕地降雨-径流过程及水土流失量,研究草带措施对云南红壤坡耕地产流产沙和氮磷迁移的削减作用。结果表明:草带调控处理下雨季降雨量、总产流次数、径流深和土壤侵蚀量较原状坡面明显减少,次降雨下,宽草带的径流控制率和土壤侵蚀控制率分别为79.19%和64.55%,窄草带的径流控制率和土壤侵蚀控制率分别为85.15%和73.77%,坡耕地土壤侵蚀量变异系数>径流深变异系数>降雨量变异系数,原状坡面变异系数间增幅差异为31.42%,宽草带调控措施作用下变异系数间增幅差异为20.37%,窄草带调控措施作用下变异系数间增幅差异为19.11%,窄草带对坡耕地径流和泥沙的调控能力更强;宽草带和窄草带2种草带作用下,径流氮磷迁移浓度差异不显著,较原状坡面相比,草带措施明显控制氮磷迁移通量,径流总氮迁移通量控制率分别为81.23%和81.68%,铵态氮迁移通量控制率为78.25%和59.50%,总磷迁移通量控制率为71.36%和82.03%;径流泥沙速效养分含量明显增加,较原状坡面相比,草带措施能明显控制径流泥沙氮磷迁移通量,且径流泥沙氮磷迁移控制率较径流氮磷迁移控制率高,径流泥沙全氮迁移通量控制率为98.43%和94.30%,碱解氮迁移通量控制率为98.43%和93.10%,全磷迁移通量控制率为96.43%和89.77%,速效磷迁移通量控制率为90.34%和57.43%。 相似文献
7.
Z. Vryzas E. Papadopoulou-Mourkidou G. Soulios & K. Prodromou 《European Journal of Soil Science》2007,58(5):1186-1199
The adsorption kinetics and adsorption parameters of metolachlor, atrazine, deethylatrazine (DEA), deisopropylatrazine (DIA) and hydroxyatrazine (HA) were investigated in a soil profile in a maize field formed from recent alluvial deposits in a river basin in Greece. We used the batch equilibrium method modified to simulate field conditions as closely as possible for the use and practices related to soil applied pre‐emergence herbicides. Pseudo‐equilibrium times, determined by kinetic studies, were achieved after 16, 16, 24, 24 and 48 hours for metolachlor, DIA, DEA, HA and atrazine, respectively. At pseudo‐equilibrium the percentage of the adsorbed amount increased in the order of DEA (10%) < DIA (14%) < atrazine (27%) < metolachlor (43%) ≪ HA (94%) which indicates that more than 57% of all compounds except for HA are in solution and available for transport to deeper soil layers when conditions similar to those simulated in the laboratory exist in the field. Adsorption isotherms of all compounds and in most of the cases correlated well with the Freundlich model and adsorption coefficients (Kf) decreased with increased soil depth. Principal component and multiple regression analyses confirmed the importance of the soil organic carbon content on the adsorption capacity of soils for all compounds except HA in the plough layers (0–40 cm). In the subsurface soils (40–110 cm) variables such as clay content and pH were more important. For HA, the Kf values determined for the plough and subsurface soil layers were better correlated with clay content and pH. Also in the subsurface soils, the variation in organic carbon content was not correlated with the variation of Kf values. Thus calculated Koc‐f‐values misrepresent the adsorptive capacity of these soils towards the compounds studied. 相似文献
8.
Southwick LM Grigg BC Fouss JL Kornecki TS 《Journal of agricultural and food chemistry》2003,51(18):5355-5361
Atrazine and metolachlor are commonly detected in surface water bodies in southern Louisiana. These herbicides are frequently applied in combination to corn, and atrazine to sugarcane, in this region. A study was conducted on the runoff of atrazine and metolachlor from 0.21 ha plots planted to corn on Commerce silt loam, a Mississippi River alluvial soil. The study, carried out over a three-year period characterized by rainfall close to the 30-year average, provided data on persistence in the surface soil (top 2.5 cm layer) and in the runoff active zone of the soil, as measured by decrease in runoff concentrations with time after application. Regression equations were developed that allow an estimate of the runoff extraction coefficients for each herbicide. Atrazine showed soil half-lives in the range 10.5-17.3 days, and metolachlor exhibited half-lives from 15.8-28.0 days. Concentrations in successive runoff events declined much faster than those in the surface soil layer: Atrazine runoff concentrations decreased over successive runoff events with a half-life from 0.6 to 5.7 days, and metolachlor in runoff was characterized by half-lives of 0.6-6.4 days. That is, half-lives of the two herbicides in the runoff-active zone were one-tenth to one-half as long as the respective half-lives in the surface soil layer. Within years, the half-lives of these herbicides in the runoff active zone varied from two-thirds longer for metolachlor in 1996 to one-fifth longer for atrazine in 1995. The equations relating runoff concentrations of atrazine and metolachlor to soil concentrations contain extraction coefficients of 0.009. Losses in runoff for atrazine were 5.2-10.8% of applied, and for metolachlor they were 3.7-8.0%; atrazine losses in runoff were 20-40% higher than those for metolachlor. These relatively high percent of application losses indicate the importance of practices that reduce runoff of these chemicals from alluvial soils of southern Louisiana. 相似文献
9.
Nitrogen and phosphorus in runoff from grassland with buffer strips following application of fertilizers and manures 总被引：6，自引：0，他引：6
Abstract. We examined whether nitrogen (N) and phosphorus (P) export was enhanced from grassland receiving inorganic fertilizer and manures typical of intensive livestock production. Buffer strips were included in the study to determine if they could reduce nutrient export. Hillslope plots receiving granular inorganic fertilizer, liquid cattle slurry and solid cattle manure (FYM) were compared using rainfall simulation for 4 storms on consecutive days at 22 mm h-1 and 35 minutes duration. The plots were hydrologically isolated in a randomized block layout of 4 treatments × 3 replicates and measured 30 × 5m; the upper 20m received either fertilizer, slurry or FYM, while the lower 10 m acted as an unfertilized grass buffer strip. Nitrogen and P export in surface runoff from grassland receiving inorganic fertilizer exceeded that from FYM or slurry treatments; concentrations up to46mgN1--1 and 15 mgP1–1 were recorded.
Sixty eight % and 62% of the N from FYM and slurry respectively, was exported in organic form. Seventy four % (FYM) and 39% (slurry) of the P was in particulate or dissolved organic form. The buffer strip reduced N export in surface runoff by 94% and P export by 98% from inorganic fertilizer plots. A 75% reduction in N export was recorded from the buffer zone below slurry plots but only a 10% reduction in P, with most P remaining in the particulate or dissolved organic fraction. There was no significant difference in N export from the buffer zone between the inorganic fertilizer treatment and the untreated control. 相似文献
Sixty eight % and 62% of the N from FYM and slurry respectively, was exported in organic form. Seventy four % (FYM) and 39% (slurry) of the P was in particulate or dissolved organic form. The buffer strip reduced N export in surface runoff by 94% and P export by 98% from inorganic fertilizer plots. A 75% reduction in N export was recorded from the buffer zone below slurry plots but only a 10% reduction in P, with most P remaining in the particulate or dissolved organic fraction. There was no significant difference in N export from the buffer zone between the inorganic fertilizer treatment and the untreated control. 相似文献
10.
植被过滤带对地表径流中污染物的净化效果 总被引：18，自引：3，他引：15
植被过滤带是控制非点源污染的“最佳管理措施”之一。为了探讨植被过滤带在中国西北地区的实际应用,该文作者在陕西小华山水库岸坡地建设了3条不同配置方式的植被过滤带,通过试验测定了植被过滤带对地表径流中几种污染物的净化效果,并分析其影响因素。结果表明,植被过滤带对地表径流中的颗粒态氮、颗粒态磷、总氮、总磷和化学需氧量浓度削减率分别达到82.02%、77.13%、46.05%、73.28%和60.48%以上,负荷削减率分别达到89.98%、87.25%、69.93%、85.11%和77.97%以上,并能有效地削减溶解态氮和溶解态磷的负荷量;自然草地过滤带和沙棘-草本过滤带对地表径流中这几种污染物的削减主要发生在前10 m。过滤带内的植被条件、入流流量和入流污染物浓度是影响过滤带净化效果的重要因素。 相似文献
11.
基于VFSMOD模型的黄土坡面生草带产流产沙动态模拟 总被引：1，自引：1，他引：1
利用微型径流小区和人工降雨试验,探讨运用VFSMOD模型评估和预测引入不同草种生草带后黄土坡面产流产沙动态特征的可行性。通过土壤物理性质参数和生草带生长状态参数的差异,模型还原了黄土坡面引入白三叶生草带与百脉根生草带后产流产沙特征的差异及其随生长时期的变化,模拟效果可靠,纳什系数:0.93(径流系数),0.98(修正后产沙量);归一化均方根误差:6.2%(径流系数),10.9%(修正后产沙量)。当生草带在降雨集中期(如本研究中百脉根草带9月上旬)不能保证较好的生长状态和地表覆盖时,其坡面产沙量急剧增大,且明显大于VFSMOD模型模拟值。在实际生草带设计时,应避免该情况发生。综上,VFSMOD模型适用于引入生草带后黄土坡面产流、产沙量的模拟和预测。 相似文献
12.
D. Seghers R. Bulcke D. Reheul S. D. Siciliano E. M. Top † & W. Verstraete ‡ 《European Journal of Soil Science》2003,54(4):679-684
There is an increasing interest in agricultural systems in which the use of herbicides is forbidden. Therefore, soils treated with herbicides atrazine and metolachlor for the last 20 years were compared with soil samples from the same field that had never been treated (control soil). We determined the pollution induced community tolerance (PICT) by evaluating the methane oxidation capacity of soil samples after adding increasing amounts of a methane oxidation inhibitor, 2,4‐dichlorophenoxyacetic acid (2,4‐D). Denaturing gradient gel electrophoresis (DGGE) of 16S rRNA genes assessed whether the soil methanotrophic community differed between the two treatments. Addition of 60 µg 2,4‐D per g soil clearly inhibited methane oxidation in both soils but increased the time needed to oxidize 5% methane in the headspace by 250% for the control soil compared with 175% for the herbicide‐treated soil. This indicates that the soil with a long‐term herbicide history had a greater tolerance to the methane oxidation inhibitor than did the control soil. The DGGE of 16S rRNA genes amplified directly from soil community DNA could also distinguish the two treatments. The banding patterns of the Type I methanotrophs contained fewer bands in the herbicide‐treated soil. It seems that both the PICT approach and DGGE analysis are effective assays to distinguish a long‐term herbicide‐treated soil from an untreated soil. 相似文献
13.
Adsorption of atrazine and metolachlor in three soils from Blue Creek wetlands, Waterville, Ohio 总被引：1，自引：0，他引：1
Atrazine and metolachlor are extensively used pesticides in agricultural activities in northwest Ohio. Adsorption coefficients are often used to model pesticide fate and transport. Many physical-chemical parameters, such as organic matter, clay content, pH, and ionic strength, affect pesticide adsorption. Adsorption kinetics and adsorption isotherms were studied by batch experiment. Effects of humic acid, solution pH, and ionic strength on atrazine and metolachlor adsorption were also approached. After 24 h, both atrazine and metolachlor reached adsorption equilibrium in three local soils. Adsorption isotherms were described by Freundlich equations. The Freundlich coefficient (Kf) ranged from 0.14 to 4.47 (L kg–1) for atrazine, and 0.04 to 5.30 (L kg–1) for metolachlor. Adsorption capacity decreased in the order Sloan loam > Del Rey loam > Ottokee fine sand. Koc values varied considerably for both pesticides: metolachlor > in Sloan loam, atrazine metolachlor in Del Rey loam, and atrazine > metolachlor in Ottokee fine sand. In addition to organic matter content, clay played a key role in adsorption in the Del Rey loam and Ottokee fine sand. Higher adsorption was observed at pH 5 for both pesticides. As pH decreased to 3 and increased to 11, adsorption decreased. Adsorption increased as ionic strength increased. 相似文献
14.
A simple and rapid method based on microwave-assisted extraction (MAE) coupled to gas chromatographic analysis was developed for the analysis of triazine (atrazine, cyanazine, metribuzine, simazine and deethylatrazine, and deisopropylatrazine) and chloroacetanilide (acetochlor, alachlor, and metolachlor) herbicide residues in soils. Soil samples are processed by MAE for 5 min at 80 degrees C in the presence of acetonitrile (20 mL/sample). Mean recovery values of most solutes are >80% in the 10 to 500 microg/kg fortification range with respective RSDs (relative standard deviations) < 20%. The limits of quantification (LOQ) and limits of detection (LOD) are 10 and 1 to 5 microg/kg, respectively. The method was validated with two types of soils containing 1.5 and 3.0% organic matter content, respectively; no statistically significant differences were found between solute recovery values from the two types of soils. The solute mean recovery values from freshly spiked (24 h aging) and spiked samples stored refrigerated for one week before processed were also not statistically different. Residue levels determined in field weathered soils were higher when soils were processed by MAE than with a comparison method based on flask-shaking of soil suspensions overnight. Extracts were analyzed by a gas chromatographic system equipped either with a thermionic (GC-NPD) or a mass spectrometric detector (GC-MS). 相似文献
15.
B. N. Ghosh P. Dogra R. Bhattacharyya N. K. Sharma K. S. Dadhwal 《Soil Use and Management》2012,28(4):635-646
Vegetation strips (VS) along with conservation tillage, application of organic amendments and weed mulching improve crop yields by reducing run‐off and topsoil erosion. To investigate these issues, an experiment was conducted under rainfed conditions using grass VS for four and a half years (June 2007 to October 2011) at Dehradun, Uttarakhand, in the Indian Himalayan region. VS were incorporated in the experimental plots (Entisols) in a randomized complete block design in permanent 100 × 20 m (2000 m2) plots with a 2% slope to evaluate the effects of vegetation strips on run‐off, soil loss and crop yield. Three treatments were evaluated: (i) without VS with recommended NPK under conventional tillage, (ii) panicum as VS with recommended NPK under conventional tillage and (iii) palmarosa+ that consists of palmarosa as VS along with organic amendments (farmyard manure, vermicompost and poultry manure) and weed mulch under minimum tillage. The results show that soil loss and run‐off were significantly lower (P < 0.05) in plots under palmarosa+ than without VS treatment. Mean soil loss of 3.4, 5.2 and 7.1 t/ha was recorded from palmarosa+, panicum and without VS treated plots, respectively. Mean run‐off was 234, 356 and 428 mm from plots under palmarosa+, panicum and without VS, respectively. Maize yield was lower on the plots under palmarosa+ compared with panicum, but significantly higher (P < 0.05) than without a strip. The succeeding rainfed wheat yield was significantly greater in plots under palmarosa+ than in the initial years. The wheat yield equivalent was significantly higher in plots under palmarosa+ followed by panicum and without VS. Thus, vegetation strips are recommended for wider adoption to reduce run‐off and soil loss and to increase crop yield. The long‐term goal is to achieve a palmarosa+ system (palmarosa as a vegetation strip along with organic amendments, farmyard manure, vermicompost and poultry manure) and weed mulch under minimum tillage. 相似文献
16.
径流流量对植被过滤带净化效果的影响 总被引：6，自引：1，他引：5
植被过滤带净化效果的影响因素较多,1次降雨径流过程中植被过滤带的净化效果也会随时间变化。该文通过野外小区试验,分析了暴雨径流过程中流量对植被过滤带净化效果的影响。结果表明:在1场暴雨径流过程中的不同时间段,即不同入流流量下,植被过滤带对悬浮固体、总氮、总磷、颗粒态氮和颗粒态磷的净化效果变化较大,随着入流流量的减小,植被过滤带的净化效果更为显著,其中草地过滤带的净化效果最好;对植被过滤带进出口水流中的颗粒粒径分析也表明植被过滤带对粗颗粒的净化效果较好,植被阻滞水流使粗颗粒沉积是植被过滤带净化的主要方式之一。该研究可为我国西北地区植被过滤带技术的应用提供参考依据。 相似文献
17.
Javier M. Gonzalez Douglas R. Smith Stan Livingston Elizabeth Warnemuende-Pappas Martha Zwonitzer 《Journal of Soils and Sediments》2016,16(7):1921-1932
Purpose
In a 6-year study, we investigated the effectiveness of blind inlets as a conservation practice in reducing pesticide losses compared to tile risers from two closed farmed depressional areas (potholes) in the US Midwest under a 4-year cropping rotation.Materials and methods
In two adjacent potholes within the same farm and having similar soils, a conventional tile riser and blind inlet were installed. Each draining practice could be operated independent of each other in order to drain and monitor each depression with either practice. Sampling events (runoff events) were collected from the potholes from 2008 to 2013 using autosamplers. The samples were analyzed for atrazine, metolachlor, 2,4-D, glyphosate, and deethylatrazine.Results and discussion
The results of this study demonstrated that the blind inlet reduced analyzed pesticide losses; however, the level of reduction was compound dependent: atrazine (57 %), 2,4-D (58 %), metolachlor (53 %), and glyphosate (11 %).Conclusions
Results from this study corroborate previous research findings that blind inlets are an effective conservation practice to reduce discharge and pollutants, including pesticides from farmed pothole surface runoff in the US Midwest.18.
Assessing the effectiveness of manure export plus intensive silage cropping for lowering the Olsen‐P status of P‐enriched grassland 
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下载免费PDF全文 J. S. Bailey 《Soil Use and Management》2015,31(4):438-439
A substantial proportion of farmed grassland soils in Northern Ireland (NI) are overly enriched with P and pose a risk to water quality. To address this problem, manure could be exported rather than recycled to P‐enriched land and the latter intensively cropped with grass silage to deplete soil P. To assess the efficacy of such a strategy, a P‐ and K‐enriched grassland site was intensively cropped over a 6‐yr period with fertilizer N alone supplied to support silage growth. By year 6, soil P had declined from index 5 to index 3, and it was estimated that two more years of this management may bring it into the target index 2 range. Soil K, however, declined rapidly from index 4 to index 1 in just 4 yr, with the result that grass production became limited by K deficiency. It was concluded that nonrecycling of manure to P‐enriched grassland under silage management is probably the most effective strategy for lowering soil P status, but care must be taken to prevent K deficiency occurring. 相似文献
19.
Vegetated buffer strips alongside watercourses are commonly used to counteract diffuse pollution from agricultural activities. If properly designed, they can provide multiple environmental benefits by increasing wildlife habitats and biodiversity. Little attention has been paid to the effects of buffer strips on soil quality. This study was conducted to determine the impact of different buffer designs on soil biochemical parameters and to define relevant quality parameters for soil monitoring. We compared four buffer arrangements: 3 m wide grass buffer; 3 m grass with one tree row; 6 m grass with one tree row; 6 m grass with two tree rows; plus two controls: an adjacent maize crop field and a plot without buffer. Buffers were established 13 years ago at the Padua University Experimental Farm in the Po Valley, north-east Italy. Studied parameters included soil organic matter composition and soil microbial and enzymatic assays. As expected, control plots showed the lowest values for all the studied parameters. Among buffer designs, 3 m grass and 3 m grass with 1 tree row buffers gave the highest values. Multivariate analysis demonstrated that the increase of soil organic carbon content distinguished buffers from controls, whereas soil humic carbon quality parameters such as humic compounds apparent molecular weight, together with acetyl esterase (fluorescein test) enzyme activity, were discriminatory in separating buffer designs. These results are an important contribution to the knowledge base and can help to improve the management of these systems. 相似文献
20.
不同草带覆盖位置条件下坡沟系统侵蚀产沙差异性 总被引：7，自引：4，他引：3
以坡沟系统单元为研究对象,利用室内降雨试验,结合三维激光扫描和微地貌分析技术,研究不同草带覆盖位置下坡沟系统侵蚀产沙差异性。结果表明:一些布设在合适位置的草带能够在p0.05水平上显著影响坡沟系统的径流量和产沙量。植被布设于坡面中下部比布设于坡面上部具有更好的水沙调控作用,植被布设于坡面长度60%时,径流量和产沙量分别减少7.35%和62.93%,直接拦沙功效优于蓄水减沙功效,水土保持功效达到最优。植被布设于坡面下部时,其侵蚀输沙过程的剧烈程度得到了缓解,植被调控侵蚀发育的作用体现。植被布设于坡面中下部时,下垫面仅有52%的区域发生侵蚀,其侵蚀输沙过程的剧烈程度明显减少,植被调控侵蚀作用有效限制了侵蚀发育。植被布设于坡面中部和中上部时,加剧了侵蚀的发育程度。研究结果有助于更好地理解植被优化配置。 相似文献