保护性耕作对地表径流及土壤侵蚀的影响

采用人工模拟降雨方法对陇中黄土高原连续实施5a的4种耕作措施：传统耕作（T），传统耕作结合秸秆还田（TS），免耕（NT），免耕加秸秆覆盖（NTS）下豌豆地收获后的径流起始时间、径流量、土壤侵蚀量进行了研究。结果表明，在降雨强度为85mm／h的条件下，NTS可以延缓径流，减小径流强度。与NT，TS，T这3种处理比较，NTS的径流量分别降低了2．4％，12．1％，34．7％。入渗量分别增加了2．7％，13．6％，38．6％。径流出现时间分别延迟1．17，0．83，3．83min。土壤侵蚀量减少了0．3％，17．7％，62．4％。可见，免耕秸秆覆盖的水土保持效应最为明显，传统耕作的方式极易发生土壤侵蚀。     

用人工模拟降雨研究保护性耕作下的地表径流与水分入渗

采用人工模拟降雨试验研究了保护性耕作控制农田地表径流的效果,重点探讨了表土耕作、秸秆覆盖及土壤压实３种因素对地表径流和水分入渗的影响。试验表明,保护性耕作具有明显的处缓径流,增加水分入渗的效果。在土壤干燥,模拟降雨强度为７２ｍｍ／ｈ的条件下,传统翻耕比保护性耕作早１２－１６ｍｉｎ产生径流,入渗率降低６０．９％,总径流量高１１倍。３种试验因素中,秸秆覆盖对径流和入渗的影响最大,压实次之。在本试验中,     

秸秆覆盖对东北黑土区土壤侵蚀及养分流失的影响

利用野外原位模拟降雨试验,研究了秸秆覆盖对东北黑土区坡面土壤侵蚀和养分流失的影响。试验处理包括1个施肥水平(纯N为150kg/hm2;纯P为75kg/hm2),3个秸秆覆盖度(翻耕裸露,低覆盖2kg/m2,高覆盖4kg/m2),1个降雨强度(90mm/h,降雨历时60min)和1个坡度(5°),试验小区长10m,宽1m。研究结果表明,低秸秆覆盖与翻耕裸露处理相比,坡面的径流量和侵蚀产沙量分别减少了87%和99.86%;在高秸秆覆盖条件下,坡面不产生径流。低秸秆覆盖条件下,径流中的NO3-—N和PO34-—P的浓度分别是翻耕裸露处理的5.52倍和4.25倍,但NO3-—N和PO34-—P的流失量与翻耕裸露处理基本相同。同样,低秆覆盖条件下侵蚀泥沙中NO3-—N和PO43-—P的含量分别是翻耕裸露处理的4.38倍和2.93倍,但NO3-—N和PO43-—P的流失量与翻耕裸露处理相比分别减少了99.3%和99.6%。因此,在东北黑土区选取适宜的秸秆覆盖量对保护耕地质量具有重要意义。     

秸秆覆盖对黄土坡面矿质氮素径流流失的影响

利用室内模拟降雨试验，研究了秸秆覆盖对坡面土壤矿质氮素径流流失和入渗的影响。结果表明：秸秆覆盖可使侵蚀量显著减少，减沙效应十分明显。由于秸秆覆盖使坡面径流流速减弱，增加了表层土壤与地表径流的作用强度，使溶解和解吸于径流中的矿质氮素含量增加，但由径流显著减少，矿质氮流失总量仍减少。与裸地相比，秸秆覆盖可显著地增加土壤水分和硝态氮的入渗深度和入渗量。     

人工降雨条件下秸秆覆盖减少水土流失的效应研究

采用人工降雨模拟试验,研究秸秆不同用量对径流、入渗和土壤侵蚀的影响。结果表明：秸秆覆盖有增加入渗和减少水土流失的作用;覆盖率大于40%条件下能有效的控制水土流失,但当覆盖率低于40%时对控制水土流失的作用不明显。在土壤含水量10%,降雨强度120 mm/h的雨强条件下,秸秆覆盖能推迟起流时间1～15min,增加累积入渗量37%～113%,减少径流总量3%～40%,减少土壤侵蚀10%～80%,效果随着覆盖率的增加而增加。     

人工降雨条件下秸秆覆盖减少水土流失的效应研究

采用人工模拟降雨试验,研究秸秆不同用量对径流、入渗和土壤侵蚀的影响.结果表明:秸秆覆盖有增加入渗和减少水土流失的作用;覆盖率大于40%条件下能有效地控制水土流失,但当覆盖度低于40%时对控制水土流失的作用不明显.在土壤含水量10%,降雨强度120 mm/h的雨强条件下,秸秆覆盖能推迟起流时间1～15min,增加累积人渗量37%～113%,减少径流总量3%～40%,减少土壤侵蚀10%～80%.     

黄土高原主要秋作物坡地降雨入渗特征参数研究

为揭示作物覆盖条件下坡耕地降雨入渗特征,以黄土高原3种典型秋作物(玉米、大豆和谷子)为对象,在3°~15°的坡地径流小区上,采用人工模拟降雨和水量平衡的方法,分析了作物全生育期降雨入渗过程中初始入渗率、稳定入渗率、平均入渗率和累积入渗量的数量特征及影响因素。结果表明:(1)作物坡地的降雨入渗过程随降雨历时的延长,入渗量呈由高到低的变化,波动性明显;(2)作物坡地的初始入渗率、平均入渗率和累积入渗量均高于裸坡地,而稳定入渗率除玉米坡地较大外,其余差异不大,4个参数值基本上与降雨强度和叶面积指数的增大成正比,与坡度成反比;(3)基于降雨强度、坡度及叶面积指数,通过多元回归分析建立了土壤初始入渗率、稳定入渗率、平均入渗率和累积入渗量多元回归模型,为入渗过程模拟提供了基础。     

模拟降雨条件下压砂地土壤水分入渗规律研究

为揭示压砂地土壤水分入渗特性,通过室内模拟降雨的方式,选取与野外大田相同配比的砂石覆盖和土壤,以裸地为对照(CK),研究了不均一介质覆盖条件下压砂地种植年限和降雨强度对土壤水分入渗过程的影响。结果表明,压砂地土壤水分入渗过程与CK相似;在相同降雨强度下,压砂地不同种植年限对累积入渗量有显著的影响,相同入渗时间内,压砂地累积入渗量均大于CK,而在不同种植年限压砂地之间,累积入渗量为NGM最大,MGM次之,OGM最小;对同一压砂地,不同降雨强度对累积入渗量也有显著的影响,在相同入渗时间内,随着降雨强度的增大,累积入渗量逐渐增大,随着压砂地种植年限增加,降雨强度的大小对土壤水分累积入渗量的影响将逐渐减弱;在不同种植年限和不同降雨强度条件下,压砂地土壤水分入渗速率的差异均不显著;Kostiakov入渗模型与Philip方程都可描述压砂地土壤水分入渗过程,但Kostiakov入渗模型拟合效果更好。     

秸秆覆盖红壤径流养分流失效益及径流剪切力影响研究

采用模拟降雨试验的方法,研究秸秆覆盖条件下红壤侵蚀效益及动力影响因素。模拟降雨强度2.0mm/min,坡度20°,径流小区(长1.5m,宽0.5m,深0.3m)条件下,供试土壤为赤红壤。结果表明:(1)秸秆覆盖减流效益达到69.3%,减沙效益达到99.2%;明显提高土壤的入渗速率,渗透效益达到了32%,秸秆覆盖有较好的水土保持效益。(2)秸秆覆盖有效减少径流总氮、径流溶解态氮、径流颗粒态氮、径流总磷、径流溶解态磷、径流颗粒态磷的流失,减少径流中氮流失效益均达到74%以上,减少径流中磷流失效益均达到78%以上,径流中元素流失均以溶解态氮磷元素大于颗粒态氮磷元素,秸秆覆盖减少径流中磷养分流失的效益大于氮养分的流失效益。(3)建立单位面积单位时间径流剪切力和产沙率、径流总氮、径流溶解态氮、径流颗粒态氮和径流总磷、径流溶解态磷、径流颗粒态磷流失速率的模型,初步推断径流剪切力是土壤侵蚀的主要动力因素。(4)秸秆覆盖和未覆盖的临界启动径流剪切力分别为2.8N/m2和1.5N/m2。     

玉米秸秆覆盖对坡面产流产沙过程的影响

通过室内土槽模拟试验,研究不同降雨条件下玉米秸秆覆盖对沙坡地产流时间和产流产沙过程的影响。处理分为8种降雨强度和5个水平的秸秆覆盖度:0、15%、30%、60%和90%。40组模拟降雨结果表明:华北保护性耕作研究区域沙壤土条件下的产流时间与降雨强度符合幂函数关系;秸秆覆盖能延缓地表径流的产生,自然降雨(雨强10~80 mm/h)过程中,15%、30%、60%和90%秸秆覆盖较无覆盖分别推迟产流时间1.0~15.4、2.1~22.1、3.4~48.2和5.9~73.6 min;秸秆覆盖对地表径流和产沙影响显著,降雨历时1 h,30%秸秆覆盖减少径流总量17.9~/o~38.7%,减少产沙总量34.1%~48.0%0 30%秸秆覆盖水土保持效果显著,考虑到过多的秸秆覆盖(80%)会造成播种机堵塞,所以在保护性耕作研究实践中,建议保持30%~60%(1 400~3 100 kg/hm~2)的玉米秸秆覆盖,以达到较好的水土保持效果和播种质量,该研究可为保护性耕作研究区域适宜的玉米秸秆覆盖量提供依据。     

Effects of conservation agriculture techniques on infiltration and soil water content in Zambia and Zimbabwe

The adoption of conservation agriculture (CA), based on minimal soil movement, permanent soil cover with crop residues or growing plants and crop rotation has advanced rapidly in the Americas and Australia over the last three decades. One of the immediate benefits of CA in dryland agriculture is improved rainfall-use efficiency through increased water infiltration and decreased evaporation from the soil surface, with associated decreases in runoff and soil erosion. This paper focuses on the effect of CA techniques on soil moisture relations in two researcher-managed trials in Zambia and Zimbabwe. In 2005/2006 and 2006/2007, we found significantly higher water infiltration on both sites on CA fields compared to conventionally ploughed fields. At Henderson Research Station, Zimbabwe, on a sandy soil, a direct seeded CA treatments had a 49% and 45% greater infiltration rate than the conventionally tilled plots after a simulated rainfall in both seasons. At Monze Farmer Training Centre, Zambia, on a finer-textured soil, the same treatment had 57% and 87% greater infiltration rate than the conventionally tilled control treatment in both seasons. Treatments that included reduced tillage and surface residue retention had less water runoff and erosion on runoff plots at Henderson Research Station, Zimbabwe. On average, soil moisture was higher throughout the season in most CA treatments than in the conventionally tilled plots. However, the full potential of CA in mitigating drought was not evident as there was no significant drought period in either season. Results suggest that CA has the potential to increase the productivity of rainfall water and therefore reduce the risk of crop failure, as was apparent at the Monze Farmer Training Centre, Zambia, in 2005/2006 when a period of moisture stress at tassling affected CA treatments less than the conventionally tilled treatment.     

Soil erosion under simulated rainfall in relation to phenological stages of soybeans and tillage methods in Lages, SC, Brazil

Soil tillage may increase vulnerability to water erosion, whereas no tillage and other conservation cultivation techniques are viewed as strategies to control soil erosion. The objective of this research was to quantify runoff and soil losses by water erosion under different soil tillage systems at the Santa Catarina Highlands, southern Brazil. A field study was carried out using a rotating-boom rainfall simulator with 64 mm h⁻¹ rainfall intensity on a Typic Hapludox, between April 2003 and May 2004. Five rainfall tests were applied along successive cropstages. Surface cover was none (fallow) or soybean (Glycine max, L.). Five treatments were investigated, replicated twice. These treatments were conventional tillage on bare soil (BS) as a control treatment and the following treatments under soybean: conventional tillage (CT), no tillage over burnt crop residues on never before cultivated land (NT-B), no tillage over desiccated crop residues, also on never before cultivated land (NT-D) and traditional no tillage over desiccated crop residues on a soil tilled 4 years before this experiment (NT-PT). Water losses by surface runoff seemed to be more influenced by vegetative crop stadium than by tillage system and consequently a wide range of variation in surface runoff was found, following successive cropstages. The most efficient tillage system in reducing surface runoff and soil losses was no tillage, particularly the NT-PT treatment. Sediment losses were more influenced by tillage system than water losses. In the NT-B, NT-D and NT-PT treatments the rate of sediment losses along the crop vegetative cycle showed a tendency to increase from the first to the second cropstages and later to decrease from the third cropstage onwards. In the conventionally tilled treatment (CT) soil losses were greater than in any of the no tillage treatments (NT-D, NT-B and NT-PT) during the initial growth periods, but at the end of the vegetative period differences in sediment rates between tilled and non-tilled treatments tended to be smaller. In the BS control treatment, soil losses progressively increased following the vegetative growth season of soybean.     

粮草豆隔带种植保护性耕作水土流失规律

为有效防治坡耕地水土流失,持续利用坡耕地,于2007-2010年在黄土高原西部坡耕地上研究保护性耕作对水土流失的影响,重点探讨传统耕作与免耕秸秆覆盖2种耕作措施下春小麦、鹰嘴豆、马铃薯与紫花苜蓿间作的水土流失规律。结果表明:(1)各处理8月份的径流量分别占观测时段内总径流量的46.46%～51.29%,侵蚀量分别占观测时段内总侵蚀量的40.10%～61.22%。(2)降雨量与径流量、侵蚀量间呈现多元多项式关系。(3)2007-2010年不同种植模式下径流总量和侵蚀总量的变化趋势是一致的,均表现出NTSPL相似文献   

不同复垦模式下铁尾矿坡面产流产沙与水力特性

为了揭示降雨条件下铁尾矿复垦坡面的产流产沙特征与水力特性,该文采用室内人工模拟降雨方法研究了不同降雨强度(60、90、120 mm/h)和不同复垦模式(T,铁尾矿;TSH,铁尾矿与高比例生土;TM,铁尾矿与菌糠;TSM,铁尾矿、菌糠与生土;TSL,铁尾矿与低比例生土;植被类型均为胡枝子)25°坡度条件下的侵蚀过程。结果表明:1)产流速率在降雨初期迅速增长,中后期趋于稳定。添加菌糠的复垦模式产流速率高于未添加菌糠的复垦模式;2)产沙速率随降雨历时变化呈现两种模式,添加菌糠的复垦模式为减少型,未添加菌糠的复垦模式为增加型,TSL的减沙效果最为显著,T对降雨强度的响应最为敏感且高雨强下产沙量最大;3)所有复垦坡面平均径流深度范围在0.23~0.93 mm,水流流态均为层流,大部分情况下水流流型为缓流,但TSH在中高雨强下以及T在高雨强下为急流。添加菌糠模式的曼宁糙率系数和水流阻力系数高于未添加菌糠的复垦模式,流速低于未添加菌糠的复垦模式,添加菌糠的基质表面粗糙度较大;4)各复垦坡面的侵蚀形式以溅蚀和片蚀为主,高雨强下T出现细沟侵蚀,其余复垦模式未观察到明显细沟侵蚀;5)产流速率与水流功率、雷诺数(R2>0.998)呈极显著的线性关系,产沙速率与水流功率(R2>0.733)、雷诺数(R2>0.744)呈极显著的幂函数、指数函数关系。该研究可为铁尾矿坡面的复垦模式选择提供理论依据。     

不同处理下油松枯落物减流减沙效应试验研究

森林枯落物对坡面土壤侵蚀过程发挥着重要的调控作用,但其控制效应仍待明确。采用室内大型土槽及人工模拟降雨试验探讨油松枯落物的不同铺设方式对坡面产流产沙的影响,试验在4种雨强(30,60,90,120mm/h)和油松枯落物的3种铺设方式(裸坡对照、枯落物直接铺设和枯落物隔网铺设)下进行,设置枯落物隔网铺设方式来研究枯落物降低雨滴动能减少击溅侵蚀作用,设置枯落物直接铺设方式来研究枯落物增大地表粗糙率阻滞拦截作用。结果表明:(1)枯落物存在使坡面初始产流时间延长2.3～5.5倍,且枯落物隔网铺设较直接铺设初始产流时间更长。(2)2种枯落物覆盖坡面与裸土坡面相比,枯落物减小坡面径流流速47.9%～62.3%,雨强越小,枯落物减弱径流流速作用越明显。(3)枯落物显著增加入渗并减小径流,在雨强较小时作用更加明显。(4)枯落物可减少径流泥沙75%以上,直接铺设减沙更加明显,这主要是由于枯落物增大地表糙度减小流速。研究结果为植被坡面土壤侵蚀模型建立提供一定理论基础,为面向水土流失防控的植被构建提供一定科学依据。     

Impact of rainfall and tillage systems on off‐site herbicide movement

Abstract

Ground cover associated with conservation‐ and no‐till cropping systems can alter runoff and herbicide loss from the soil surface. This study was conducted in 1987 and 1988 to evaluate runoff losses of soil‐applied alachlor and imazaquin in five different soybean cropping systems. Cropping systems used were: 1) conventionally tilled monocrop soybean planted in May; 2) conventionally tilled monocrop soybean planted in June; 3) conventionally tilled doublecrop soybean with incorporated wheat stubble; 4) no‐till doublecrop soybean with burned wheat stubble; and 5) no‐till doublecrop soybean planted into standing wheat stubble. Runoff was lower in 1988 due to a lack of precipitation and dry soil conditions. Herbicide loss in both years was greatest in doublecrop soybean with incorporated wheat stubble, which corresponded to higher runoff. Lower herbicide loss in June‐planted monocrop soybean was attributed to a rougher seedbed that retarded runoff. May‐planted monocrop soybean also lost very little herbicide in 1987, although this treatment had the highest runoff. Lower concentrations of alachlor and imazaquin in runoff from this treatment may be attributed to degradation or soil sorption of herbicides between planting and the first runoff event 23 days later. Highest runoff losses of alachlor and imazaquin, as compared to their initial concentration, were approximately 10% in 1987, and less than 0.5% in 1988. Nomenclature: alachlor, 2‐chloro‐N‐(2, 6‐diethylphenyl) N‐(methoxymethyl) acetamide; imazaquin, 2‐[4, 5‐dihydro‐4‐methyl‐4‐(l‐methyl‐ethyl)‐5‐oxo‐1H‐imadazol‐2‐yl]‐3‐quinolinecarboxylic acid; soybean [Glycine max (L.)] Merr.; wheat (Triticum aestivum L.).     

Effects of tillage on soil microrelief, surface depression storage and soil water storage

Conservation of soil water is an important management objective for crop production in the semi-arid tropics where droughts are persistent. Identification of the best tillage methods to achieve this objective is thus imperative. The integrated effects of conservation tillage on soil micro topography and soil moisture on a sandy loam soil were evaluated. The field experiment consisted of five tillage treatments, namely tied ridging (TR), no till (NT), disc plough (DP), strip catchment tillage (SCT) and hand hoe (HH). Data measured in the field included soil moisture content, surface roughness, infiltration and sorghum grain yield. A depth storage model was used to estimate depression storage TR treatment and the higher the surface roughness, the greater the depression storage volume. Regression analysis showed that random roughness decreased exponentially with increase in cumulative rainfall. Higher moisture contents were associated with treatments having higher depressional storage. Infiltration rate was significantly higher in the tilled soils than the untilled soils. The DP treatment had the highest cumulative infiltration while NT had the lowest. The Infiltration model which was fitted to the infiltration data gave good fit. Grain yield was highest in TR and least in NT, whereas DP and HH had similar yields.     

Interactions between soil properties and moisture content in crust formation, runoff and interrill erosion from tilled loess soils

Soil-surface seals and crusts resulting from aggregate breakdown reduce the soil infiltration rate and may induce erosion by increasing runoff. The cultivated loess areas of northwestern Europe are particularly prone to these processes.Surface samples of ten tilled silty loamy loess soils, ranging in clay content from 120 to 350 g kg⁻¹ and in organic carbon from 10 to 20 g kg⁻¹, were packed into 0.5 m² plots with 5% slopes and subjected to simulated rainfall applied at 30 mm h⁻¹. The 120 minutes rainfall events were applied to initially field-moist soil, air-dried soil and rewetted soil to investigate the effect of soil moisture content prior to rainfall. Runoff and eroded sediments were collected at 5 minutes intervals. Aggregate stability of the soils was assessed by measuring particle-size distribution after different treatments.All soils formed seals. Runoff rates were between 70 and 90% by the end of the rainfall event for field-moist plots. There were large differences between soil runoff rates for the air-dried and rewetted plots. Interrill erosion was associated with runoff, and sediment concentration in runoff readily reached a steady-state value. Measurements of aggregate stability for various treatments were in good agreement with sealing, runoff and erosion responses to rainfall. Runoff and erosion were lower for air-dried plots than for field-moist plots, and were either intermediate or lowest for rewetted plots, depending on soil characteristics. Soils with a high clay content had the lowest erosion rate when they were rewetted, whereas the soil with a high organic-carbon content had the lowest erosion rate in air-dry conditions. The results indicate the complexity of the effect of initial moisture content, and the interactions between soil properties and climate.     

暴雨条件下典型红壤区不同恢复方式侵蚀过程与特征分析

采用空间替代时间的方法,探究暴雨条件下典型红壤区不同恢复方式侵蚀过程与特征。选取不同恢复年限的低效林改造(R1)、乔灌草结构(R2)、自然恢复(R3)和对照(DZ)样地,设计1.5mm/min雨强,进行野外模拟降雨试验,分析坡面初始产流时间、径流率、侵蚀率、累积产沙量、入渗率等特征。结果表明:(1)3种恢复方式初始产流时间表现为R2R1R3,且R1、R2样地初始产流时间随治理年限的增加而延长;(2)3种恢复方式径流率、侵蚀率、累积产沙量均表现出R3R1R2,且R1、R2样地径流率、侵蚀率、累积产沙量随治理年限增加呈下降趋势;(3)同一恢复年限,3种恢复方式初始入渗率、累积入渗量、减流减沙效益均表现出R2R1R3;(4)3种恢复方式,恢复年限对侵蚀过程的影响表现为R1R2R3;累积产沙量与累积产流量成幂函数关系。研究结果为揭示典型红壤区不同治理方式的侵蚀过程研究提供参考,为典型红壤区水土流失治理提供科学依据。     

Infiltration and random roughness of a tilled and untilled claypan soil

No-tillage is generally assumed to increase infiltration and reduce runoff, but runoff from a claypan soil in Central Missouri, however, was greater from no-tillage plots than from moldboard plowed plots. The effect of simulated rainfall on infiltration and random roughness of tilled and untilled soil was measured. Four different tillage systems, each with and without surface cover were studied. An exponential decay function describes the change in random roughness for tilled soil exposed to rainfall kinetic energy. Although the differences were not statistically significant, among the uncovered tilled plots those with the highest random roughness had the highest infiltration. The bare no-tillage treatment had the lowest infiltration. Plots protected with shredded foam rubber infiltrated 88–248% more rainfall than similar bare plots.