藏东南区梯田和复合坡耕地土壤侵蚀对有机碳和全氮空间分布格局的影响

[目的] 查明青藏高原东南部地区坡耕地土壤侵蚀空间分布格局及其对土壤有机碳(SOC)和全氮(TN)顺坡迁移过程的影响,为该区土地资源利用及土壤资源保护提供科学依据。[方法] 利用¹³⁷Cs核素示踪技术,结合现场调查,研究藏东南地区梯田系列和复合坡耕地土壤侵蚀空间分布格局差异;采用相关分析,探明坡面土壤¹³⁷Cs面积浓度与同样深度(30 cm) SOC、TN面积浓度之间的相关性。[结果] ①在整个梯田系列内,土壤¹³⁷Cs面积浓度从坡顶到坡脚呈离散分布格局,上部梯田下坡部位土壤¹³⁷Cs面积浓度明显高于紧邻的下部梯田上坡土壤,且上坡梯田表现为土壤侵蚀,而下坡和坡脚梯田则表现为土壤沉积;在单个梯田景观内,土壤侵蚀速率主要呈上部坡位高,下部坡位低的趋势; ②复合坡坡耕地土壤侵蚀速率表现为先波动减少,然后逐渐增加的趋势,即坡顶部位土壤侵蚀速率相对较高,顺坡向下逐渐变小,在坡中部和下部表现为沉积,在坡脚部位土壤侵蚀速率又逐渐增加; ③梯田系列和坡耕地土壤¹³⁷Cs面积浓度与SOC,TN面积浓度之间均具有显著的相关关系(p＜0.05)。[结论] 在藏东南地区,梯田有效地改变了该区的土壤侵蚀空间分布格局,土壤¹³⁷Cs示踪技术可以较好地示踪该区坡耕地土壤、SOC和TN顺坡迁移和空间再分布状况,防控耕作侵蚀的危害也应当得到与水蚀同样的重视。     

宁南黄土高原阳洼流域137Cs分布及侵蚀特征研究

利用137Cs示踪方法,对宁南黄土高原阳洼流域土壤137Cs分布及土壤侵蚀进行了初步研究。结果表明:流域137Cs基准值为(1 966.99±112.06)Bq/m2。流域内林草地土壤剖面137Cs呈指数型分布,坡耕地137Cs在耕层内呈均一分布。受坡位影响,坡耕地上坡137Cs质量活度为中、下坡的25.14%~27%。流域内坡耕地土壤侵蚀最高,平均为3 889.95 t/km2,自然荒坡最小,仅为坡耕地的17.83%,坡耕地是流域泥沙的主要侵蚀溯源区。阳洼流域土壤侵蚀存在明显的空间格局,不同土地类型下土壤137Cs面积活度、土壤侵蚀模数呈斑块状镶嵌分布,以靠近流域西南边界、中部及东南部区域土壤侵蚀模数最大,平均侵蚀速率在3 405.59~7 080.73 t/(km2.a),沉积与侵蚀明显区域间有过渡区域。坡度是影响该流域土壤侵蚀空间变化的主导因子,但土壤侵蚀速率并不简单随坡度增加而增大,它还受土地利用方式、坡位、降雨等因素影响。     

紫色土坡耕地土壤物理性质空间变异对土壤侵蚀的响应

为了研究不同坡度和坡长的耕地上土壤侵蚀对土壤物理性质空间变异的影响,通过地形测量、137 Cs示踪、土壤物理性质分析等方法对川中丘陵紫色土区土壤物理性质对土壤侵蚀的响应进行了研究,结果表明：在中等坡度（16.60%～25.10%）的梯坡地上,耕作侵蚀处于主导地位,是导致耕层土壤物理性黏粒含量和容重在梯坡地上总体差异不大（CV＜6.3%）,且与137Cs含量不相关的主要原因;在已退耕还林的陡梯坡地上（35.60%）,水蚀占据主导地位,导致耕层土壤物理性黏粒含量和容重均与137Cs的含量显著相关。在长坡耕地上(10.10%),具有分选搬运能力的水力侵蚀占据主导地位,致使耕层土壤物理性黏粒含量与137Cs的含量具有显著的相关关系,而容重却与137Cs含量没有显著的相关关系。川中丘陵区坡耕地上,耕作侵蚀和水蚀共同作用于土层深度,使土层深度在坡顶、上坡最浅,在坡脚最深,顺坡向下逐渐增加。因此,在川中丘陵区不同坡长的坡耕地上,占主导地位的土壤侵蚀类型导致坡耕地上土壤物理性质出现相应的变化。     

川北山区坡耕地土壤活性有机碳对土壤侵蚀的响应

为探明侵蚀对坡耕地土壤活性有机碳的影响,利用137 Cs示踪技术,并结合土壤理化分析,研究了川北山区坡耕地土壤侵蚀所引起的土壤再分配对土壤有机碳与活性有机碳空间变异性的影响。结果表明,川北山区坡耕地土壤侵蚀是水蚀和耕作侵蚀共同作用的结果,强烈的耕作导致坡上部发生严重的土壤侵蚀;侵蚀对坡耕地土壤有机碳与活性有机碳分布影响较大,土壤有机碳与活性有机碳含量与137 Cs含量呈显著正相关,坡上部土壤有机碳与活性有机碳含量贫瘠,而在坡下部相对富集。因此,山区坡耕地土壤肥力的空间分布特征在今后的土地施肥管理中应引起关注。     

紫色丘陵区土壤侵蚀对土壤生物学肥力的影响

为更好地理解侵蚀土壤质量变化,该文利用137Cs技术探讨了川中丘陵区紫色土陡坡耕地土壤侵蚀对土壤生物学肥力的影响。结果表明,与无侵蚀的坡地相比,陡坡耕地土壤微生物量碳含量及碱性磷酸酶、蔗糖酶活性分别显著降低41%、44%、17%,土壤生物学肥力退化指数MFDI达-35%。陡坡耕地土壤蔗糖酶活性与137Cs浓度显著正相关（r=0.643,p=0.024）,表明蔗糖酶活性随土壤侵蚀强度增大而降低。耕作侵蚀造成的陡坡耕地上坡土壤损失导致土壤微生物量碳含量、碱性磷酸酶、脲酶及蔗糖酶活性最低,而耕作侵蚀造成的陡坡耕地坡底土壤堆积导致这4个微生物特性最高,结果陡坡耕地这些微生物特性的空间变异分别增大2.8、0.8、1.4、4.5倍。紫色土陡坡耕地土壤生物学肥力退化与空间变异性增大在今后的土地管理中应引起关注。     

川中丘陵区坡耕地侵蚀空间分布的WEPP模型和137Cs法研究

当前核素示踪技术和侵蚀产沙模型联合应用于侵蚀空间分异规律研究甚少且主要集中在流域尺度上。本研究利用WEPP模型和137Cs核素示踪技术估算了川中丘陵区简阳县贾家村附近两块坡耕地的侵蚀速率,进而对两种方法估算的侵蚀速率在坡面上的空间分布规律进行了分析。研究表明用137Cs核素示踪法测算的两块坡耕地的侵蚀速率随坡长增加而呈波动变化特征,用WEPP模型估算的坡耕地和坡耕地的土壤侵蚀速率随坡长增加而增大。坡耕地I顶部极高的137Cs计算的侵蚀速率和极低的WEPP模型计算的侵蚀速率表明人工刨地耕作逐渐把该坡耕地顶部的耕作土迁移至下部并将坡顶变成该坡耕地内最贫瘠的部分。用WEPP模型模拟的侵蚀速率与用137Cs计算的侵蚀速率在量上和空间分布上都有较大的不同,这说明在川中丘陵区用WEPP模型来估算传统耕作方式下坡耕地的侵蚀速率存在一定的局限性。     

三峡库区紫色土坡耕地土壤侵蚀的137Cs示踪研究

坡耕地是三峡库区的重点水土流失区和河流泥沙的主要来源地.采用~(137)Cs示踪技术对三峡库区紫色土坡耕地的土壤侵蚀速率进行了定量研究.结果表明,新政小流域的~(137)Cs本底值为1 420.9 Bq/m~2;平均坡度为11.4°的缓坡耕地的~(137)Cs面积活度介于398.5～1 649.6 Bq/m~2之间,坡长加权平均值为816.0Bq/m~2;采用改进的简化质量平衡模型计算了坡耕地的土壤侵蚀速率,结果得出该坡地的土壤侵蚀模数介于-3 358.8～4 937.4 t/(km~2·a),其加权平均值为1 294.6 t/(km~2·a).受犁耕作用的影响,坡耕地两个坡段的土壤侵蚀速率随坡长增加大致都呈下降趋势,并在坡段下方出现了堆积.坡耕地土壤侵蚀速率不高的原因,一方面是由于所研究坡耕地属于缓坡,坡度较小,另一方面则是由于当地农民总结出了一套有效防止水土流失的耕作方式,使得土壤侵蚀强度大大降低.     

~(137)Cs技术研究岩溶高原湿地小流域土壤侵蚀特征

运用137Cs技术研究了威宁草海沙河小流域不同土地利用方式和地貌部位的土壤侵蚀特征。结果表明:研究区137Cs的背景值为879Bq·m2;农耕地土壤剖面中137Cs中呈均匀分布,非农耕地土壤剖面中呈指数递减分布;不同土地利用方式下,137Cs的面积活度值从大到小为灌丛地人工草地农耕地,土壤侵蚀模数值为农耕地草地灌丛地;不同地貌部位土壤中,137Cs面积活度值从大到小为下坡中坡上坡,侵蚀模数值变化为上坡中坡下坡。小流域年均侵蚀模数为:1254.9t·(km2·a)-1,灌丛地侵蚀模数为462.6t·(km2·a)-1,人工草地为630.4t·(km2·a)-1,农耕地为3311.8t·(km2·a)-1。因此,在小流域水土流失综合治理过程中,农耕地是治理的重点。     

红砂岩母质红壤侵蚀作用的137Cs法初步研究

不合理的开发和利用所导致植被覆盖的破坏严重，致使红砂岩母质地区长期以来遭受到强烈的土壤侵蚀，采用136s技术，研究红砂岩发育的红壤典型小流域的土壤侵蚀作用，结果表明，该流域的137Cs基准值为2014Bqm^-2，对于非耕作土壤而言，137Cs在土壤剖面中呈峰值型分布，最大分布深度约为15cm，对于耕作土壤而言，则在耕作层内呈均一分布，耕作层以下则急剧下降，典型断面研究表明，上坡部坡耕地的侵蚀作用强于下坡部，且山顶面积较小的耕地的侵蚀作用比面积较大的坡顶耕地要大，总体而言，坡耕地的流失是相当严重的。     

~(137)Cs示踪采煤沉陷坡土壤侵蚀及其对土壤养分的影响

为更好地理解矿区土壤退化机理,该文利用137Cs技术研究了焦作矿区具有15a沉陷历史的采煤沉陷坡土壤侵蚀特征及其对土壤养分的影响。沉陷坡137Cs含量从坡顶到下坡逐渐降低,及至坡脚急剧增大且表现出最高的值。基于137Cs本底(1 645 Bq/m2),沉陷坡坡顶至下坡表现为土壤侵蚀,而坡脚为土壤沉积。沉陷坡土壤侵蚀高达3.75 kg/(m2·a),属于中度侵蚀。沉陷坡土壤黏粒含量沿下坡方向增加,表明水蚀的分选性搬运。与对照区相比,沉陷坡侵蚀区土壤总有机碳(total organic carbon,TOC)、水溶性有机碳(water-soluble organic carbon,WSOC)、全氮、碱解氮、全磷、有效磷含量均出现了显著降低(P0.05);沉积区除WSOC显著降低(P0.05)外,其他养分含量变化不明显(P0.05)。在沉陷坡的侵蚀区,TOC与WSOC含量沿下坡方向逐渐减小,表现出与137Cs一致的分布格局;其他养分含量的坡面变化与137Cs分布不一致。相较于对照区,WSOC/TOC与碳氮比、碳磷比在沉陷坡侵蚀强烈的坡位分别出现了显著增大与降低(P0.05)。研究结果表明:1)焦作矿区自采煤沉陷坡形成以来发生了较严重的水蚀;2)侵蚀引起的土壤再分配影响沉陷坡土壤碳、氮、磷动态,其中,土壤再分配对土壤碳动态的影响最强;3)在土壤侵蚀作用下,采煤沉陷坡侵蚀强烈的坡位土壤有效态碳、氮、磷养分潜在的侵蚀风险大。采煤沉陷坡土壤侵蚀及其对土壤养分的不利影响应引起矿粮复合区土地整治的关注。     

137Cs tracing of the spatial patterns in soil redistribution,organic carbon and total nitrogen in the southeastern Tibetan Plateau

The southeastern Tibetan Plateau, which profoundly affects East Asia by helping to maintain the stability of climate systems, biological diversity and clean water, is one of the regions most vulnerable to water erosion, wind erosion, tillage erosion, freeze–thaw erosion and overgrazing under global climate changes and intensive human activities. Spatial variations in soil erosion in terraced farmland (TL), sloping farmland (SL) and grassland (GL) were determined by the ¹³⁷Cs tracing method and compared with spatial variations in soil organic carbon (SOC) and total nitrogen (total N). The ¹³⁷Cs concentration in the GL was higher in the 0–0.03 m soil layer than in the other soil layers due to weak migration and diffusion under low precipitation and temperature conditions, while the ¹³⁷Cs concentration in the soil layer of the SL was generally uniform in the 0–0.18 m soil layer due to tillage-induced mixing. Low ¹³⁷Cs inventories appeared at the summit and toe slope positions in the SL due to soil loss by tillage erosion and water erosion, respectively, while the highest ¹³⁷Cs inventories appeared at the middle slope positions due to soil accumulation under relatively flat landform conditions. In the GL, the ¹³⁷Cs data showed that higher soil erosion rates appeared at the summit due to freeze–thaw erosion and steep slope gradients and at the toe slope position due to wind erosion, gully erosion, freeze–thaw erosion and overgrazing. The ¹³⁷Cs inventory generally increased from upper to lower slope positions within each terrace (except the lowest terrace). The ¹³⁷Cs data along the terrace toposequence showed abrupt changes in soil erosion rates between the lower part of the upper terrace and the upper part of the immediate terrace over a short distance and net deposition on the lower and toe terraces. Hence, tillage erosion played an important role in the soil loss at the summit slope positions of each terrace, while water erosion dominantly transported soil from the upper terrace to the lower terrace and resulted in net soil deposition on the flat lower terrace. The SOC inventories showed similar spatial patterns to the ¹³⁷Cs inventories in the SL, TL and GL, and significant correlations were found between the SOC and ¹³⁷Cs inventories in these slope landscapes. The total N inventories showed similar spatial patterns to the inventories of ¹³⁷Cs and SOC, and significant correlations were also found between the total N and ¹³⁷Cs inventories in the SL, TL and GL. Therefore, ¹³⁷Cs can successfully be used for tracing soil, SOC and total N dynamics within slope landscapes in the southeastern Tibetan Plateau.     

Variation of chemical properties as affected by soil erosion on hillslopes and terraces

The variation in soil nutrients is crucial to the understanding of productivity of soil undergoing erosion overall, as the latter can result in a decline in soil quality and crop production in the whole landscape. Two toposequences (a long slope and terraced field series) were selected from hilly areas of the Sichuan Basin, China, to determine the effects of soil redistribution rates and topographic changes on P, K and CaCO₃ contents, and examine the contribution of water and tillage erosion to the variation and distribution pattern in these chemical properties within different landscapes. For the long slope, soil loss occurred at upper slope positions and soil accumulation was present at lower slope positions. However, terrace banks create a line of zero downslope transport of soil, and lead to abrupt changes in ¹³⁷Cs inventories over very short distances between the upper (or lower) part of the terrace and the lower (or upper) part of the neighbouring terrace. Extractable K concentrations are significantly related to ¹³⁷Cs inventories on both the long slope and terraced fields, which suggests that the distribution of extractable K is closely linked to soil redistribution. However, it is noticeable that no close relationship between extractable P concentrations and ¹³⁷Cs inventories was found on the terraced fields, while there was a highly significant correlation between the two variables on the long slope. The variation in extractable P by soil redistribution was enhanced on the long slope, but was concealed on the terraced fields due to the presence of CaCO₃. It is suggested that the variation in extractable P not only depends on soil redistribution in relation to fine soil particles, but is also influenced by other factors such as P‐fixation onto CaCO₃, the concentration of which itself is linked to soil erosion and redistribution. Therefore, extractable P dynamics with reference to soil erosion are relatively complex on carbonate‐rich soil and parent materials in areas such as those represented by the Sichuan Basin. Tillage erosion, the dominant soil redistribution process on terraced fields, was found to be a major contributor to the variation in soil chemical properties in the terraced field landscape, while water erosion plays an important role in the variation in soil chemical properties in the long slope landscape. In the case of carbonate‐rich soils or parent materials, however, tillage erosion did not create accumulations of extractable P in depressions, whereas water erosion results in extractable P losses at upper slope positions and accumulation at lower slope positions.     

Dual roles of tillage erosion in lateral SOC movement in the landscape

The facts that the global carbon budget cannot be currently balanced and current estimates of agricultural sources and sinks may be inaccurate, may be linked to unaccounted‐for erosion‐induced changes in soil organic carbon (SOC). A closed landscape with field banks and an open landscape without field banks were selected from two sites located in Jianyang County, Sichuan Province, and Zhongxian County, Chongqing Municipality, respectively. In these landscapes, the role of tillage and water erosion was examined using measurements of soil redistribution in relation to ¹³⁷Cs radionuclide depth‐stratigraphy, to elucidate the mechanism of SOC depth distribution in the soil profile and resultant stocks in agricultural landscapes of terraced field systems. Changes in the ¹³⁷Cs inventory at different landscape positions depend on both ¹³⁷Cs concentrations of individual subsample layers (5‐cm depth) and the vertical extent of ¹³⁷Cs depth distribution in the terrace system with field banks, while the changes are only associated with the vertical extent of ¹³⁷Cs depth distribution in the terrace system without field banks because of similar ¹³⁷Cs concentrations of individual subsample layers. The profile shape of SOC depth distribution exhibits notable differences between the upper and lower parts of the terrace in systems with field banks, but no apparent differences were found in the systems without field banks and the SOC profile shape is similar to that of the upper part of the terrace in systems with field banks. It is suggested that SOC depth distribution in these two types of terraced field systems is controlled by different soil erosion patterns. Tillage erosion playing a dominant role in the process of soil erosion within a landscape can increase SOC stocks. However, SOC depletion takes place in situations where the two processes of tillage and water erosion are both important and tillage erosion acts as a delivery mechanism for water erosion. We conclude that tillage erosion plays a dual role: enhancing carbon storage at depositional positions, and accelerating carbon depletion when combined with water erosion within the same landscape.     

川中丘陵区人工刨地耕作方式下紫色土坡耕地侵蚀速率的137Cs和210Pbex双核素示踪法研究

Purple soils are widely distributed in the Sichuan Hilly Basin and are highly susceptible to erosion, especially on the cultivated slopes. Quantitative assessment of the erosion rates is, however, difficult due to small size of the plots of the manually-tilled land, the complex land use, and steep hillslopes. 137Cs and 210Pbex (excess 210Pb) tracing techniques were used to investigate the spatial pattern of soil erosion rates associated with slope-land under hoe tillage in Neijiang of the Sichuan Hilly Basin. The 137Cs and 210Pbex inventories at the top of the cultivated slope were extremely low, and the highest inventories were found at the bottom of the cultivated slope. By combining the erosion rates estimates provided by both 137Cs and 210Pbex measurements, the weighted mean net soil loss from the study slope was estimated to be 3100 t km-2 year-1, which was significantly less than 6930 t km-2 year-1 reported for runoff plots on a 10°cultivated slope at the Suining Station of soil Erosion. The spatial pattern of soil erosion rates on the steep agricultural land showed that hoe tillage played an important role in soil redistribution along the slope. Also, traditional farming practices had a significant role in reducing soil loss, leading to a lower net erosion rate for the field.     

Assessment of soil losses on cultivated land by using the Cs technique in the Upper Yangtze River Basin of China

This paper presents the results of using the ¹³⁷Cs technique to assess soil erosion rates of both sloping cultivated land and flat terraces in the Upper Yangtze River Basin, China. The study was carried out on eighteen sloping cultivated fields and four flat terrace fields in eight counties and cities over the eastern part of the basin. The ¹³⁷Cs-reference inventory ranged from 620.5 to 2573.2 Bq/m². For the 18 sloping cultivated fields, the average ¹³⁷Cs inventory over a field ranged from 204.9 to 1847.7 Bq/m², which accounts for 15–77% of the local ¹³⁷Cs reference inventory, and the average water erosion rate ranged from 758 to 9854 t/km² per year, with erosion rates of <1000 t/km² per year in two fields; 1000–5000 t/km² per year in eight fields; and >5000 t/km² per year in eight fields. It is apparent that most of the sloping cultivated fields suffer severe or very severe soil erosion. For the four terrace fields under this study, the average ¹³⁷Cs inventory over a field ranged between 915.8 and 2675.4 Bq/m², which accounts for 97–104% of the local ¹³⁷Cs reference inventory. However, water erosion is very slight on the terrace fields and little soil is lost from the terraces. The study also indicated that the severity of soil erosion is strongly related to soil texture and slope gradient.     

Distribution of soil organic carbon and phosphorus on an eroded hillslope of the rangeland in the northern Tibet Plateau, China

Some studies on the relationship between soil erosion and subsequent redeposition of eroded soils in the same field and soil quality have been conducted in croplands, yet few studies have revealed this relationship in rangelands. We selected a toposequence with a slope of 30% and a horizontal length of 342 m from the rangeland in the northern Tibet Autonomous Region, China (31°16′N, 92°09′E) to determine the relationship between soil erosion, soil organic carbon (SOC) content and available P patterns within a hillslope landscape. Soil samples for the determination of ¹³⁷Cs as well as SOC, available P and particle‐size fractions were collected at 20 m intervals along a transect of this hillslope. Soil redistribution was caused primarily by wind erosion at toe‐slope positions, but primarily by water erosion at the hillslope positions above the toe‐slope. In upper‐ and mid‐slope portions (0 m to 244 m horizontal length), SOC content is closely correlated to ¹³⁷Cs concentration (r = 0.74, P < 0.01, n= 15), suggesting that SOC distribution along the slope was similar to ¹³⁷Cs distribution, which itself was dependent on topographic changes. However, SOC contents in toe‐slope portions are less than those above the toe‐slope (i.e. upper‐ and mid‐slope portions), and the correlation between ¹³⁷Cs and SOC in the toe‐slope portion is weaker than that above the toe‐slope. A highly significant correlation (r = 0.72, P < 0.001, n= 20) between ¹³⁷Cs concentration and available P was found within the whole hillslope landscape, implying the distribution pattern of available P was somewhat different from that of SOC. We suggest that the distribution of SOC within the hillslope landscape is also affected by factors such as assimilation rates due to difference in grassland productivity at different points and different biological oxidation rates of carbon related to patterns of moisture distribution.     

凌源市推广“金字塔”模式开发治理成效显著

凌源市推广“金字塔”模式开发治理成效显著刘海潮，张凤山，祁放（辽宁省凌源市水利局，１２２５００）凌源市水土保持小流域综合治理，经过多年的不断完善、总结、提高，形成了一林戴帽，二林围顶，果牧拦腰，两回穿靴，一龙坐底的产金字塔＂综合治理模式ＪＩ９８８年经...     

耕作侵蚀及其对土壤肥力和作物产量的影响研究进展

在坡耕地景观内，由于农耕工具和重力作用而引起的耕作位移使土壤发生向下坡运动或向上坡运动(依赖于耕作方向)，导致净余土壤量向下坡传输、堆积，重新分配，从而形成耕作侵蚀。试验研究表明耕作侵蚀是坡耕地的主要侵蚀形式之一，耕作侵蚀发生最严重的区域是坡度较大、坡体短的坡耕地。该文就耕作侵蚀的概念、发生机理、典型的耕作侵蚀模型的发展，以及耕作侵蚀对土壤肥力和作物产量影响的研究现状作了简要论述，特别总结了针对中国的地貌和耕作工具特征而进行的耕作侵蚀的研究成果。指出在一定的景观范围内，耕作侵蚀是十分严重的，甚至其严重程度已经超过了水蚀。但是相对于水蚀而言，耕作侵蚀研究还很少，因此加强耕作侵蚀的研究是十分必要的。只有这样才能正确评价农耕地侵蚀状况，准确制定土壤保持措施和采用减少耕作侵蚀力的耕作工具，从而有效地控制土壤侵蚀。     

土壤侵蚀对坡耕地耕层质量退化作用及其评价趋势展望

土壤侵蚀是导致坡耕地耕层质量退化和土壤生产力不稳定的关键驱动因素。该文从水蚀区坡耕地侵蚀控制和生产功能角度,在解析地块尺度土壤侵蚀、水土保持、农业活动对坡耕地耕层生态过程作用特征的基础上,系统分析了土壤侵蚀对坡耕地耕层质量退化作用、影响效应及作用途径。认为:1)坡耕地耕层质量变化由降雨侵蚀、耕作活动交互作用的生态过程决定,2种作用的时间、空间尺度不同;耕层土壤参数在坡耕地农业生产中作用分为保水、保土、保肥和增产潜力,由地块尺度农作物-耕层耦合效应决定土壤生产能力、坡耕地水土流失特征及耕层侵蚀性退化方向及程度。2)土壤侵蚀对坡耕地耕层质量退化作用表现为土壤性质恶化、土壤质量劣化、土地生产力衰退3个方面,耕层土壤物理性质变异程度大于化学性质变异,径流作用导致的土地生产力衰退大于土壤流失作用。3)坡耕地耕层质量评价指标体系应兼顾侵蚀下降、产量提升2个目标,地块尺度诊断指标有效土层厚度、耕层厚度、土壤容重、土壤抗剪强度、土壤有机质、土壤渗透性可作为合理耕层评价最小数据集;坡耕地合理耕层适宜性分为5级,其诊断指标分级标准宜与土壤侵蚀分级和耕地地力分级衔接。4)坡耕地合理耕层评价未来应密切关注耕层质量诊断指标最小数据集、坡耕地合理耕层阈值/适宜值分级标准、坡耕地水土流失阻控标准拟定3个主要方向。研究可为深入认识坡耕地侵蚀性退化机制,辨识坡耕地合理耕层调控途径以及坡耕地合理耕层构建技术参数提供依据。