Die Erodibilität ausgewählter Böden der bayerischen Schichtstufenlandschaft

Erodibility of Selected Soils in the Bavarian Scarpland A laboratory rainfall simulator was used to determine the erodibility (K-factor of the USLE) of 6 soils. 3 of the soils were developed from mesozoic sediments (an Ochrept and an Udipsamment from sandstones, an Udorthent from shale), an Udalf and an Udorthent of loessial origin, and an Udorthent, that was developed from a silty-loamy cover. The measured K-values of the loessial soils agreed well with the calculated. But the calculated K-factors for the 3 Jurassic soils underestimated their erodibility. The erodibility of the silty-loamy soil was overestimated. It could be shown that the measured erodibilities agreed better with field data than the calculated.     

Erodibility of agricultural soils on the Loess Plateau of China

Soil erodibility is thought of as the ease with which soil is detached by splash during rainfall or by surface flow. Soil erodibility is an important factor in determining the rate of soil loss. In the universal soil loss equation (USLE) and the revised universal soil loss equation (RUSLE), soil erodibility is represented by an erodibility factor (K). The K factor was defined as the mean rate of soil loss per unit rainfall erosivity index from unit runoff plots. Although high rate of soil loss from the Loess Plateau in China is well known and widely documented, it is remarkable that there is little systematic attempt to develop and validate an erodibility index for soils on the Loess Plateu for erosion prediction. Field experimental data from four sites on the Loess Plateau were analyzed to determine the K factor for USLE/RUSLE and to compare with another erodibility index based on soil loss and runoff commonly used for the region. The data set consists of event erosivity index, runoff, and soil loss for 17 runoff plots with slope ranging from 8.7 to 60.1%. Results indicate that the K factor for USLE/RULSE is more appropriate for agricultural soils on the Loess Plateau than the erodibility index developed locally. Values of the K factor for loessial soils range from 0.0096 to 0.0269 t h/(MJ mm). The spatial distribution of the K value in the study area follows a simple pattern showing high values in areas with low clay content. For the four sites investigated, the K factor was significantly related to the clay content, (K=0.031−0.0013 Cl, r²=0.75), where Cl is the clay content in percent. The measured values of the K factor are systematically lower than the nomograph-based estimates by a factor of 3.3–8.4. This implies that use of the nomograph method to estimate soil erodibility would considerably over-predict the rate of soil loss, and local relationship between soil property and the K factor is required for soil erosion prediction for the region.     

秸秆覆盖和有机质输入对紫色土土壤可蚀性的影响

以紫色土坡耕地为研究对象开展野外径流小区定位监测试验,设置有机质(OM)、秸秆覆盖(SW)、有机质+秸秆覆盖(OM+SW)和对照(无秸秆覆盖,不增施有机质,CK)4个处理,对2014年侵蚀性降雨条件下不同处理小区径流及产沙特征进行分析,以单位径流冲刷侵蚀量(K_w)作为土壤可蚀性指标,研究四川省中江县紫色土区秸秆覆盖和有机质输入对坡耕地土壤可蚀性的影响。结果表明:秸秆和有机质输入能显著降低紫色土区坡耕地产流量,4个处理减小径流的效果表现为OM+SWSWOMCK;有机质、秸秆覆盖均显著降低单位径流侵蚀量,从而减小土壤可蚀性,OM、SW、OM+SW处理对土壤可蚀性的平均消减率分别为22.30%、29.76%、35.04%,秸秆覆盖处理(SW)对土壤可蚀性的减小效应略高于有机质处理(OM),但二者差异不显著。综合分析得出,增施有机质的同时进行秸秆覆盖可作为紫色土区坡耕地减小土壤可蚀性的有效措施。     

Anwendung des Agrarökosystemmodells EPIC zur Prognose des Wasser- und Nährstoffhaushaltes von landwirtschaftlich genutzten Flächen auf Sandböden in Ost-Brandenburg

Predictions of water and nutrient dynamics from agricultural sites on sandy soils in East- Brandenburg The validity of the agroecosystem model EPIC was tested for two agricultural sites on sandy soils without groundwater located at the moraine landscape in East-Brandenburg. Measurements of soil moisture, soil nitrate, above ground plant biomass and yield from these two agricultural investigation sites were compared with the corresponding simulation results of the model. The calculations of the soil water balance show a good fit between simulated and observed soil moisture values. The comparison between simulated and measured above ground plant biomass presents an underestimation of biomass by the model at the beginning of crop growth in spring and an overestimation at the end of the vegetation period. EPIC shows also an overestimation of yield in this study. The observed and the simulated soil nitrate values show no fit. Probably one reason for this fact might be the kind of process modeling included in EPIC, which was designed for long term calculations up to 50 years. Another possible reason could be the over estimation of N-uptakes of plants in comparison with estimates of the N-demand of plants based on the simulated yields. However a clear reason for the insufficient calculations of soil nitrate status by the model could not be found in this study. Further analysis of mineralization, N-uptake of plants and N-Ieaching in EPIC must be done in future.     

不同土壤抗蚀性能研究

该对四川省农业科学院资阳水土保持试验所布设的７种土壤试验小区，用模拟降雨装置进行了土壤抗蚀性能的初步试验研究，结果表明：（１）７种土壤的抗蚀能力大小依次为：冷沙黄泥＞棕紫泥＞红棕紫泥＞灰色潮土＞红紫泥＞黄红紫泥＞暗棕紫泥；（２）７种土壤的么径流过程累积量与降雨历时、产沙过程累积量与降雨历时，径流过程累积量与产沙过程累积量之间均有显的线性相关关系，以及６种土壤的土壤含水量与开始产流时间之间有非常     

Räumliche Variabilität von Stoffkonzentrationen am Grundwasserspiegel bei einem grundwasserfernen Sandstandort unter Kiefern

Spatial variability of groundwater solute concentrations at the water table under a pine stand on sandy soil with deep groundwater Aim of the study was to prove the evidence of a direct influence of solute input pattern (induced by canopy throughfall) on the pattern of groundwater solute concentration at the water table even at sites with groundwater table of 4–5 m below surface. The test site was a weakly buffered sandy soil with groundwater table ca. 4.3 m below surface (Podzol soil with some features of former gley process) under a cultivated pine stand (age ca. 60 years). Groundwater at the water table was sampled in between two rows of trees along a 30 m transect at 0.5 m intervals. As example, the results for sulfate concentration (the key solute of soil and groundwater acidification) show rather high variation along the transect. But a thorough stochastic analysis of empirical data sets reveals cyclic oszillations occurring synchronous and with same period length for sulfate concentration at the water table and for canopy coverage of the ground (and therefore for solute input). An additional long-periodic oscillation is strongly superimposing in the case of sulfate concentration. Thus the results indicate a direct influence of the pattern of canopy throughfall on the pattern of sulfate concentration at the water table. However, this influence is rather weakly pronounced at this deep groundwater site compared to corresponding shallow groundwater sites.     

Differential hydrological response of biological topsoil crusts along a rainfall gradient in a sandy arid area: Northern Negev desert,Israel

Drylands are regarded as highly sensitive to climatic change. The putative positive relationship between average annual rainfall and runoff, assumed for areas between 100 and 300 mm ignores the fact that climatic change in drylands is not limited to climatic factors alone, but is often accompanied by a parallel change in surface properties. Data on rainfall, runoff and soil moisture regime were collected at five monitoring sites in a sandy area, along a rainfall gradient from 86 to 160 mm. Despite the uniform sandy substratum the frequency and magnitude of runoff declined with increasing annual rainfall. Under wetter conditions a thick topsoil biological crust develops. This crust is able to absorb and retain large rain amounts, limiting the depth to which water can penetrate, and therefore water availability for the perennial vegetation. In the drier area, the thin crust can absorb only limited rain amounts, resulting in surface runoff and deeper water infiltration at run-on areas. Our findings demonstrate the important role played by different types of biological soil crusts along the rainfall gradient considered, and question the generally held belief that higher rainfall necessarily leads to deeper water infiltration in sandy arid areas; and higher water availability for the perennial vegetation.     

滇池流域农田土壤氮素流失影响因子研究

本试验采用田间原位模拟降雨并结合多元线性回归(逐步)的统计分析方法,分别在滇池流域的6个点位研究了旱季和雨季农田土壤的理化性质与氮素流失的关系。结果表明:各点位进行的模拟降雨的产流起始时间、产流历时和平均出水速度,在径流和渗漏两种流失方式下差异显著;两次径流试验中,质地为砂质黏壤土的C-2点(大渔乡元宝村)的初始产流强度和平均产流强度均最大。渗漏是氮素流失的主要方式,流失的形态主要是与NO3--N为主。土壤的孔隙度与降雨平均入渗率呈显著正相关,与径流中总氮(TN)和铵态氮(NH4+-N)的流失量呈负相关。0～20 cm的土壤硝态氮含量与地表径流和渗漏中总氮(TN)、硝态氮(NO3--N)的流失量呈极显著的正相关,是影响氮素流失的最重要因子,且0～20 cm土壤有机质含量与氮素的流失量呈正相关,土壤pH、5～20 cm的土壤含水量均与TN及NO3--N的流失量呈负相关。0～5 cm土壤铵态氮与NH4+-N的流失量呈正相关。     

冻融条件下土壤侵蚀阻力影响因素

为揭示季节性冻融区土壤侵蚀阻力的变化机制，确定影响土壤侵蚀阻力主控因子，通过室内冻融模拟、水槽冲刷和土壤抗剪试验，对黄绵土(SM粉质壤土)、风沙土(WS砂壤土)和黑土(KS黏壤土)侵蚀阻力影响因素进行研究。结果表明：(1)随着冻融循环次数增加，细沟可蚀性值逐渐升高，而临界剪切力降低。经历10次冻融循环后，SM粉质壤土、WS砂壤土和KS黏壤土的细沟可蚀性分别增加76%,63%,11%,临界剪切力分别减小37%,13%,91%。(2)细沟可蚀性随土壤抗剪强度、黏聚力和内摩擦角增大而减小，临界剪切力则呈相反趋势。与内摩擦角相比，黏聚力更适合用来表征土壤侵蚀阻力。采用黏聚力对SM粉质壤土、WS砂壤土和KS黏壤土的细沟可蚀性进行预测，决定系数(R²)分别为0.42,0.78,0.50,平均为0.57;对临界剪切力的预测效果较差，决定系数(R²)分别为0.16,0.14,0.18,平均仅为0.16。(3)根据皮尔逊相关分析结果，基于土壤的初始含水率、冻融循环次数、力学特性以及土壤参数等分别建立细沟可蚀性(R²=0.85)和临界剪切力...     

沙区旱垄作对油菜生长环境的影响

垄作是沙区旱作农田常用的集水防风耕作技术。本文通过野外试验观测和土壤样品分析,对不同结构的垄作与平作下油菜生长环境进行了研究。结果表明,垄作相对于平作增加了生长季内土壤耕作层水分含量,降低了其波动幅度,改变了土壤水分在垂直剖面上的分布,使湿润锋位于耕作层,有利于油菜对土壤水分的吸收,对缓解干旱对作物生长的胁迫有积极作用。垄作下土壤易蚀性颗粒含量降低,地表粗糙度和垂直风速梯度增大,有效降低了土壤可蚀性和近地表风速,对防治土壤风蚀和保护作物幼苗有重要作用。不同结构的垄作比较,垄高15 cm、垄沟比1/12和垄高25 cm、垄沟比1/24的两种垄作在油菜生长季内集水效果较优,而垄高25 cm、垄沟比1/6的垄作在农田休闲期内防治风蚀效果较好。故结构合理的垄作是沙区旱作农田微观土地利用结构调整的有效措施。     

Using rainfall simulation and site measurements to predict annual interrill erodibility and phosphorus generation rates from unsealed forest roads: Validation against in-situ erosion measurements

The measurement of soil erosion rates under natural rainfall conditions is costly and time consuming. Data provided by rainfall simulation and static site measurements can be used to predict erosion rates under natural conditions, however the accuracy of this method is largely untested. This is especially true for erosion rates from unsealed forest roads. In this study, the values for a range of erodibility indices calculated from rainfall simulation experiments are compared to observed erodibility index values from 1 year of detailed in-situ erosion monitoring of seven different forest road types. The prediction of phosphorus generation rates from rainfall simulation and/or soil sampling was also evaluated. The results showed that a series of commonly used erodibility indices such as sediment per unit rainfall, sediment per unit runoff, sediment per unit EI₃₀, and sediment per unit rainfall energy were poorly predicted from the rainfall simulation experiments. Five of the six indices tested substantially overpredicted the observed erodibility at one site, a gravel road subjected to minimal traffic. For the other six road sites predictions were poor and highly variable, the coefficient of efficiency ranging from − 13.32 to 0.17 for these erodibility indices. A modified index, the ratio of sediment per unit rainfall energy to the mean rate of rainfall energy input, was able to predict annual erosion rates from six different road surfaces using rainfall simulation data with a coefficient of efficiency of 0.9. The results indicate that existing erodibility indices are not suitable for predicting observed erosion rates on forest roads using rainfall simulation data as collected in this study. It is argued that the modified index is more suited to sites (such as compacted roads) where interrill processes dominate, and erosion rates are less sensitive to peak flows. With respect to nutrient generation rates, rainfall simulation was able to accurately predict the observed proportion by mass of total phosphorus (TP) in runoff with a coefficient of efficiency of 0.96. Direct soil sampling of the road surface could also be used to predict the proportion by mass of TP in runoff. Concentrations of total nitrogen in forest road materials were found to be at the lower detection limit of the laboratory instruments.     

Soil structural degradation in SW England and its impact on surface‐water runoff generation

Field investigations between 2002 and 2011 identified soil structural degradation to be widespread in SW England with 38% of the 3243 surveyed sites having sufficiently degraded soil structure to produce observable features of enhanced surface‐water runoff within the landscape. Soil under arable crops often had high or severe levels of structural degradation. Late‐harvested crops such as maize had the most damaged soil where 75% of sites were found to have degraded structure generating enhanced surface‐water runoff. Soil erosion in these crops was found at over one in five sites. A tendency for the establishment of winter cereals in late autumn in the South West also often resulted in damaged soil where degraded structure and enhanced surface‐water runoff were found in three of every five cereal fields. Remedial actions to improve soil structure are either not being undertaken or are being unsuccessfully used. Brown Sands, Brown Earths and loamy Stagnogley Soils were the most frequently damaged soils. The intensive use of well‐drained, high quality sandy and coarse loamy soils has led to soil structural damage resulting in enhanced surface‐water runoff from fields that should naturally absorb winter rain. Surface water pollution, localized flooding and reduced winter recharge rates to aquifers result from this damage. Chalk and limestone landscapes on the other hand show little evidence of serious soil structural degradation and <20% of fields in these landscapes generate enhanced runoff.     

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.     

A comparison of the texture of grassland and eroded sandy soils from Shropshire, UK

In previous studies, periodic sampling of topsoils on runoff plots on sandy soils at the Hilton experimental site, Shropshire, UK, suggested erosion decreased the topsoil clay content and increased the coarse fraction. However, a comparison of soil and sediment properties suggested erosion selectively removed sand. Therefore, to cross-check the effects of erosion on soil properties, topsoil samples were collected from bare, eroded runoff plots and compared with samples from adjacent non-eroded grassland. Bare, eroded soil was stonier and particularly deficient in sand compared with grassed soil. Textural differences were very marked in the medium and coarse sands, especially the 0.5–1.0 mm fraction. On the basis of mean properties, the grassed soil was a very slightly stony loamy sand and the bare soil a slightly stony sandy loam. Soil organic matter was significantly less in the bare soils than the grassed soils and thus may have contributed to the higher erodibility of sands in bare soils.     

冻融条件下土壤可蚀性对坡面氮磷流失的影响

冻融作用与水力侵蚀的复合作用更容易使土壤发生侵蚀,进而加剧土壤养分的流失,为了揭示冻融作用下土壤可蚀性对坡面养分流失的影响,该文采用室内模拟降雨试验,研究了不同土壤含水率(SWC)下坡面的降雨产流产沙及养分流失特征,并分析了土壤可蚀性对坡面全氮(TN)和全磷(TP)流失的影响。结果表明:产流率与产沙率之间呈现正线性相关关系,相关方程斜率的绝对值可作为土壤可蚀性指标。径流中氮磷的流失主要受径流率控制,受土壤可蚀性影响较小(P0.05);而土壤可蚀性显著影响着泥沙中氮磷和总的氮磷流失(P0.01)。土壤可蚀性对黄土坡面氮素流失的影响与冻融作用有关,而土壤可蚀性对坡面磷素流失的影响与冻融作用无关,磷素的流失随着土壤可蚀性增加而增加。因此,在黄土地区,应当采取一系列的生态建设措施来控制水土流失,降低土壤可蚀性,从而减少坡面养分的流失。该研究结果为冻融条件下黄土坡面水-土和氮磷等养分流失机制提供了有效指导。     

Zum Einfluß organischer Bodenbedeckung auf den lateralen Transport von Isoproturon auf der Bodenoberfläche

On the Effect of Organic Surface Cover on Lateral Transport of Isoproturon on Soil Surface The losses of the herbicide isoproturon with the surface runoff and the sediment loss have been measured by means of rainfall simulations on microplots (0.5 × 1 m²) with different mulch materials and increasing soil cover percentages (wheat straw vs. rape leafs). Soil cover by straw showed no significant effect on the runoff discharge, but the total loss of isoproturon increased between 22 and 37%. Soil cover by rape leafs diminished the runoff by between 13 and 61%, the reduction of isoproturon loss was in the same range. It was shown, that the different influences of different mulch materials on runoff and soil loss can lead to different pesticide losses. Therefore, the only giving of “mulch” without specification does not describe such experiments sufficiently.     

Modeling Interrill Erosion on Unpaved Roads in the Loess Plateau of China

Unpaved roads play an important role in soil loss in small watersheds. In order to assess the impact of these unpaved roads in the Loess Plateau of China, runoff and sediment yields from road‐related sources must be quantified. Field rainfall simulation experiments were conducted under three slope gradients and five rainfall intensities on unpaved loess roads in a small watershed. Results showed that the runoff generation was very fast in loess road surface (time to runoff < 1 min) and produced a high runoff coefficient (mean value > 0·8). Soil loss rates were decreased as surface loose materials were washed away during a rainstorm. Rainfall intensity, initial soil moisture, and slope gradient are key factors to model surface runoff and sediment yield. Soil loss on loess road surface could be estimated by a linear function of stream power (R² = 0·907). Four commonly interrill erosion models were evaluated and compared, and the interrill erodibility adopted in the Water Erosion Prediction Project model was determined as 1·34 × 10⁶ (kg s m⁻⁴). A new equation taking into account different parameters like rainfall intensity, surface flow discharge, and slope gradient was established. Copyright © 2013 John Wiley & Sons, Ltd.     

Umsetzung von Cyanamid,Harnstoff und Ammonsulfat in Abhängigkeit von Temperatur und Bodenfeuchtigkeit

Transformation of cyanamide, urea and ammonium sulfate as influenced by temperature and moisture of soil The conversion of cyanamide, urea and ammonium sulfate solutions to nitrate was investigated in a sandy silt loam (pH 6.2) in relation to temperature and soil moisture conditions. 1. Cyanamide was transformed to urea within 1–5 days. Increasing temperature (2°–100°C) accelerated the breakdown, whereas high moisture conditions (120 % of total water capacity) decreased transformation. 2. The hydrolysis of urea to ammonia took place within 5–10 days even at 2°C regardless of whether cyanamide or urea was added. Low soil moisture (40 % of total water capacity) and high temperature (up to 50°) accelerated the breakdown. 3. Following urea application (20 mg N) there was a transient formation of up to five times more nitrite (0.5 mg NO₂-N) as compared with cyanamide or ammonium sulfate treatments. 4. Clear differences were observed in the rates of nitrification. The rate was greater for urea than for cyanamide and ammonium sulfate. The formation of nitrate began at 2°C, with an optimum between 20° and 30°C. Under flooded conditions (120 % of total water capacity) and low temperature the rate of nitrification was slow. At higher temperatures rapid denitrification took place.     

聚丙烯酰胺对扰动红壤可蚀性及临界剪切力的影响

为了利用化学措施防治工程水土流失,研究了聚丙烯酰胺（PAM）对扰动红壤土壤可蚀性及临界剪切力的影响。采用室内人工模拟降雨试验,探讨了5o、10o、15o、20o、25o 5种坡度,0.8、1.1、1.4 mm/min 3种雨强下不同土壤处理后坡面水动力学参数、径流输沙率与流量、土壤可蚀性及临界剪切力的变化关系。试验结果表明,在相同的径流流量下,对照的输沙率是施加PAM后的300倍;施加PAM后,红壤扰动土的可蚀性由13.223 g/(min·N)降低到0.2693 g/(min·N),径流的临界剪切力大小由0.77 N/(m2·min)增加到1.47 N/(m2·min)。施加PAM可显著降低土壤可蚀性,增加径流临界剪切力。研究成果为PAM应用于工程水土流失防治提供了一定的理论依据。     

滇池流域农田径流磷素流失的土壤影响因子

试验采用田间原位模拟降雨并结合多元线性回归（逐步）的统计分析方法,分别在滇池流域的6个点位研究旱季和雨季农田土壤的理化性质与径流中磷素流失的关系。结果表明：在旱季和雨季进行的田间原位模拟降雨的平均产流起始时间、产流历时、产流量和平均出水速度均无显著的差异。旱季径流的产流强度曲线比雨季波动大;2次试验中,质地为砂质粘壤土的大渔乡元宝村（C-2）点的初始产流强度和平均产流强度均最大。土壤孔隙度与降雨平均入渗率呈显著正相关关系（R=0.332^＊,n=12）;0-5 cm的土壤速效磷（Olsen-P）含量与地表径流中总磷（TP）、水溶性的总磷（DTP）和水溶性正磷酸盐（DRP）及颗粒态磷（PP）的流失量呈极显著的正相关,是影响磷素流失的最重要因子,且0-5 cm土壤有机质含量与径流中TP、DTP和DRP的流失量呈负相关;0-5 cm,5-20 cm的土壤含水量皆与TP、DTP、DRP和PP流失量呈负相关;土壤pH与DTP流失量呈正相关,与颗粒态磷（PP）流失量呈负相关。