Effect of land use on soil nutrients in the loess hilly area of the Loess Plateau,China

Understanding the effects of land use change on soil properties is important for soil quality improvement and sustainable land use. In this study, six land use types including wasteland (WLD), cropland (CLD), abandoned land (ABD), artificial grassland (AGD), shrubland (SLD) and woodland (WOD) were selected to analyse the effects of land use types on soil nutrient in the Anjiapo catchment in the western part of the Loess Plateau in China. Significant differences were found in soil organic matter (SOM), total nitrogen (TN) and nitrate nitrogen (NON) (P < 0.01) between the six land use types. Our study also showed that land use types have different effects on soil nutrient storage, and vegetation restoration may improve soil nutrients and soil quality. While crop plantation can significantly decrease soil fertility, the trend can be reversed by cropland abandonment and afforestation. It is recommended that more C input, alternative cultivation practices, vegetation restoration and education and techniques training of local farmers could be used to improve soil conditions and to advance the sustainable land use and local development in the loess hilly area in the Loess Plateau of China. Copyright © 2005 John Wiley & Sons, Ltd.     

施肥和地膜覆盖对黄土旱塬土壤理化性质和冬小麦产量的影响

【目的】研究黄土高原旱作农业区施肥等措施对耕层土壤理化性质和作物农艺性状的影响,为保持土壤适度生产力,选择适合黄土塬区可持续发展的新型增产措施提供理论基础。【方法】通过设在渭北旱塬的多年田间定位试验,选取不施肥空白对照、施氮磷肥、施氮磷钾肥、氮磷肥加生物炭、氮磷肥加生育期地膜半覆盖和氮磷肥加夏闲期地膜半覆盖共6个处理,所有处理均在冬小麦收获后和播种前进行翻耕。分析了不同处理耕层土壤理化性质、冬小麦产量及农艺指标。【结果】与对照相比,施氮磷肥显著提高了耕层土壤饱和导水率,降低耕层土壤紧实度,显著增加冬小麦生育期耗水量,提高水分利用效率和降雨利用效率,显著提高了耕层土壤中有机质、全氮、硝态氮、铵态氮、全磷、有效磷等养分的含量,连续三年提高冬小麦的产量均在一倍左右。与氮磷肥处理相比,增施钾肥处理增加了冬小麦拔节期耕层土壤紧实度,却显著降低了收获期土壤容重、增加了总孔隙度,并显著提高了水分利用效率,在一定程度上增加了耕层土壤全氮、有机质含量,使冬小麦的叶面积指数显著增加,连续三年冬小麦平均产量达4500 kg/hm2;增施生物炭处理耕层土壤容重降至最低为1.16 g/cm3,增加了土壤总孔隙度,导致饱和导水率最大为0.049 cm/min,提高了水分利用效率;耕层土壤中的有机质、全氮、全磷、有效磷的含量有一定增加,冬小麦的产量有所提升;施氮磷肥基础上的生育期地膜半覆盖与夏闲期地膜半覆盖,均显著降低了耕层土壤饱和导水率,增加了土壤紧实度,提高了冬小麦水分利用效率,耕层土壤中有机质、铵态氮、速效钾的含量有所增加,全磷含量降低,土壤pH下降,除去受灾年份,冬小麦平均产量在4700～4800 kg/hm2之间。【结论】与对照相比,长期施用氮磷化肥显著提高冬小麦的产量,却导致土壤pH下降。在施氮磷肥的基础上增施生物炭,可以显著改善土壤物理化学性质,增加冬小麦产量,但其经济投入过高。在施氮磷肥的基础上,增施钾肥与生育期地膜半覆盖,改善了耕层土壤养分状况,有一定的经济效益,是适宜黄土塬区的冬小麦增产措施。     

Effect of soil compaction on hydraulic properties of two loess soils in China

Soil compaction affects hydraulic properties, and thus can lead to soil degradation and other adverse effects on environmental quality. This study evaluates the effects of three levels of compaction on the hydraulic properties of two silty loam soils from the Loess Plateau, China. Undisturbed soil cores were collected from the surface (0–5 cm) and subsurface (10–15 cm) layers at sites in Mizhi and Heyang in Shaanxi Province. The three levels of soil compaction were set by increasing soil bulk density by 0% (C0), 10% (C1) and 20% (C2) through compression and hammering in the laboratory. Soil water retention curves were then determined, and both saturated hydraulic conductivity (K_s) and unsaturated hydraulic conductivity were estimated for all of the samples using standard suction apparatus, a constant head method and the hot-air method, respectively. The high level of compaction (C2) significantly changed the water retention curves of both the surface and subsurface layers of the Heyang soil, and both levels of compaction (C1 and C2) changed the curves of the two layers from the Mizhi site. However, the effects of compaction on the two soils were only pronounced below water tensions of 100 kPa. Saturated hydraulic conductivities (K_s) were significantly reduced by the highest compaction level for both sampled layers of the Heyang soil, but no difference was observed in this respect between the C0 and C1 treatments. K_s values decreased with increasing soil compaction for both layers of the Mizhi soil. Unsaturated hydraulic conductivities were not affected by soil compaction levels in the measured water volume ratio range, and the values obtained were two to five orders of magnitude higher for the Mizhi soil than for the Heyang soil. The results indicate that soil compaction could strongly influence, in different ways, the hydraulic properties of the two soils.     

Effects of land use on soil erosion and nitrogen loss in the hilly area of the Loess Plateau,China

This study examines the effects of land use and slope angle on runoff, soil loss and nitrogen loss from hillslopes of the Loess Plateau in China. Farmland, wasteland and four forest treatments (sea buckthorn+poplar, immature sea buckthorn, mature sea buckthorn, and immature Chinese pine) were the types of land use that were compared. The results showed that July was the critical period for runoff, soil loss and nitrogen loss from farmland. Farmland was the most susceptible land use. Sea buckthorn+poplar, immature sea buckthorn, and mature sea buckthorn limited the runoff, soil loss and nitrogen loss. Farmland on slopes over 15 degrees should be abandoned because of the high erosion rate and nitrogen loss. Copyright © 2003 John Wiley & Sons, Ltd.     

黄土高原坡地表层土壤饱和导水率和水分含量空间变异特征

表层土壤水分含量和饱和导水率对深层土壤水分的动态的变化具有重要的决定作用。在黄土高原坡地（50m×360 m）范围内进行网格（10 m×10 m）取样,用地统计学方法研究表层（0～30 cm）土壤饱和导水率和水分含量的空间变异特征。结果表明：1）坡地表层土壤密度变化规律为坡下位大于坡上位,土壤饱和导水率变异系数为0.37,属于中等变异强度;2）饱和导水率和自然对数化的饱和导水率在360 m尺度内均不具备空间结构特征,是纯随机变量,线性有基台模型适用于描述表层土壤水分的分布特征,水分分布存在明显的块金效应,并且随滞后距离的增加半方差变大;3）饱和导水率和水分含量从坡上位到坡下位均呈现波浪式变化,饱和导水率大的采样点土壤水分含量低,反之则高。     

黄土高原小流域不同坡地利用方式的水土流失特征

坡地是黄土高原水土流失的主要来源,坡地利用方式与水土流失的关系研究是黄土高原水土流失综合治理与植被恢复中的重要基础科学问题。在陕北神木县六道沟小流域内,选择谷子地、黑豆地、退耕撂荒地、荒草地和柠条地等5种利用方式修建标准径流小区,观测了产流产沙状况,分析比较其水土流失特征。结果表明：观测期内谷子、黑豆、退耕撂荒、荒草和柠条等5个小区的产流量分别为2.1、2.2 、1.5、1.2和0.9 m3,径流系数分别为4.1%、4.6%、2.9%、2.4%和1.9%,产流量大小顺序为黑豆＞谷子＞退耕撂荒＞荒草＞柠条,最大产流量为最小值的2.4倍。谷子、黑豆、退耕撂荒、荒草和柠条等5个小区的侵蚀产沙量分别为196.6、228.6、27.2、23.3和10.4 kg,其大小顺序为黑豆＞谷子＞退耕荒草＞天然荒草＞柠条,最大土壤流失量为最小值的22.0倍,表明草灌木等植被类型在保持水土的作用方面要明显高于坡耕地,为评价流域植被恢复的水土环境效应和水土流失治理模式选择提供了基础数据参考。     

黄土高原生态工程区土壤容重及饱和导水率的分布特征

土壤水力性质是影响水分运动、溶质运移以及流域水文模型模拟的重要参数。近年来,黄土高原实施的退耕还林（草）工程、治沟造地工程等重大生态工程,影响了该区域的地形地貌、土壤水力性质等。深入研究流域尺度土壤容重（Bulk Density,BD）与饱和导水率（Ks）的动态变化特征,对于理解重大生态工程影响下的水文过程演变规律具有重要意义。本研究以黄土高原重大生态工程影响的典型小流域为对象,采用80 m×80 m的网格布点（89个样点）,分别于2016年9月（夏末）、11月（初冬）和2017年3月（初春）采集土壤表层（0～5 cm）环刀样品,分析BD和Ks的动态分布特征及其影响因素。结果表明：BD在0.93～1.61 g/cm3之间变动,Ks介于0.01～7.30 cm/min;BD呈弱变异性,变异系数（Coefficient of Variation,CV）为10%,而Ks呈强变异性（CV=166%）。坡面BD显著小于沟底（P<0.05）,而Ks则显著大于沟底（P<0.05）。坡面林地和草地BD表现出显著的季节性差异（P<0.05）,而Ks在林地、灌木和草地之间均表现出显著的季节性差异（P<0.05）。地形对流域内的土壤水力参数分布有显著影响,外界环境（温度）变化是决定BD和Ks呈季节性动态变化的重要因素。多因素方差分析表明土地利用类型对BD与Ks均有显著影响;采样时间对Ks有显著影响,对BD无显著影响。相关结果可为揭示重大生态工程区小流域土壤水力参数的动态变化规律及其主控因素提供数据支撑和理论参考,有助于小流域水文过程的模型模拟研究与精细调控。     

Simplified equations for the determination of the hydraulic properties of horticultural substrates by one‐step outflow experiments

Simplified algebraic equations are derived to calculate directly the Brooks and Corey model parameters using data obtained from one‐step outflow experiments and saturated hydraulic conductivity. The suggested method has been demonstrated only for horticultural substrates and is verified experimentally for four substrates with satisfactory agreement of the results.     

黄土高塬沟壑区典型小流域土地利用变化及其对水土流失的影响

 基于水土保持学基本理论并结合RS、GIS技术,以黄土高塬沟壑区典型小流域一杨家沟小流域为主要研究对象,并与未治理的小流域——董庄沟小流域进行对比,以1954—2008年的降水、径流、泥沙以及土地利用变化为基础数据,以水利部颁布的《土壤侵蚀分类分级标准》为标准,研究杨家沟小流域50多年来的土地利用变化及其对水土流失的影响。结果表明：1)杨家沟小流域自50年代初开始采取水土保持治理措施以来,土地利用发生了较大的变化,林地面积大幅增加;2)杨家沟小流域水土流失状况得到了明显改善,年产流降雨量、年径流量、年输沙量、土壤密度都明显减小,侵蚀强度分级中强烈、极强烈、剧烈侵蚀面积不断减少;3)杨家沟小流域水土流失状况虽然得到了有效控制,但还可以加大治理力度,调整土地利用类型和土地利用结构,部分坡度较大的耕地应严格退耕还林,进一步植树造林,提高未利用地利用率,更加有效地控制水土流失。     

Multi‐factorial causes of land‐use change: land‐use dynamics in the agropastoral village of Im Mial,northwestern Syria

Land‐use dynamics in drylands are complex processes. In the context of a typical agropastoral village in northwestern Syria Im Mial, the effects of demographic and social changes, reduced soil productivity, changes in agricultural technologies and historical events on land use and land productivity are examined. Decreasing yields, mainly the result of reduced fallow periods and low investments in the land, and the deterioration of the grazing resources are the two main signs of the loss of land productivity in the area. The growing population forces the villagers to practise continuous rainfed barley cultivation with no or only occasional fallow, and without any application of plant nutrients. Also, technological changes, from the use of donkey ploughs and hand harvesting to less labour‐intensive and time‐consuming cultivation practices with tractors and combine harvesters, and the increased importance of stubble in the livestock diet have contributed to the reduction of the fallow periods. The villagers attribute the yield decreases mainly to the low rainfall in the area. The high rainfall variability discourages the fallowing of fields because continuous cultivation maximizes the chances for good harvests in years with high rainfall. There is also an expansion of cultivation into the less fertile and sloping traditional grazing areas. Population growth, increased numbers of livestock and the expansion of cultivated land into grazing areas has also put pressure on the grazing resources of the village. The possession of livestock is seen as a sign of wealth and the villagers aim to have large flocks of animals. For them, livestock is also an important means for investment of cash earned from off‐farm work, which is the main source of income for most of the households in the village. There is a recent trend of increasing levels of crop‐livestock integration with less free grazing that produces higher return to the land users. This may also have a positive effect on the restoration and conservation of the degraded natural traditional grazing grounds. The stabilization and productive use of the land resources in this dry environment requires the combined and interdisciplinary effort from both the land‐users and the policy‐makers. Copyright © 2001 John Wiley & Sons, Ltd.     

黄土高原南部土地利用/覆被变化的土壤侵蚀效应

基于3S技术对黄土高原南部地区土地利用/覆被变化及空间分布格局进行了综合测评,同时应用通用土壤流失方程(USLE)定量研究了不同土地利用方式下的土壤侵蚀效应.研究表明,研究区1980-2005年共有1 123.80 km2耕地被用为城镇建设用地,建设用地面积净增了1 238.29 km2,林地、草地面积总量变化小,但局部地区流转特征显著;与此同时,该区土壤侵蚀模数从11.54 t/(hm2·a)增至13.81t/(hm2·a),1980和2005年黄土沟壑区侵蚀模数的峰值分别为1 708.52和1 584.69 t/(hm2·a).该区域土壤侵蚀效应与土地利用空间格局耦合性较强,林地、草地由于分布区域海拔高,坡度陡,侵蚀强烈,而地势低洼、平坦地区(建设用地、耕地、未利用地)的土壤侵蚀强度小.林地、草地的土壤侵蚀效应由于受到地形因素的影响,对降雨侵蚀因子增强的响应尤其明显.2005年该区林地和草地的平均侵蚀模数分别增加了2.34和7.32 t/(hm2·a),并且微度以上侵蚀等级的面积有所增加.     

基于GIS的黄土高原生态系统服务价值对土地利用变化的响应及生态补偿

以黄土高原为研究对象,基于GIS技术,采用土地利用转移矩阵、土地利用动态度方法,研究1985-2005年黄土高原地区土地利用变化对生态系统服务价值的影响以及相应的生态补偿标准。结果表明：1）1985-2005年,黄土高原地区土地利用类型主要为草地和农地,占土地利用方式的75％以上,但农地面积总体在减少,林地面积在不断增加;2）聚落为最活跃的土地利用类型,聚落和湿地＋水体呈扩张的发展趋势;3）土地利用变化引起区域生态环境效应,20年间黄土高原地区生态系统服务总价值上涨约0．01％,其中森林增加最多,约为0．09％,农地的生态服务价值下降最多,约为-0．02％,而生态服务功能中,除了与农地和荒漠相关的废物处理和食物生产服务功能下降外,其他生态服务功能均表现为增加;4）根据黄土高原生态系统服务价值,确定该地区的生态补偿标准约为4亿2732万元。     

Simplifying the evaporation method for quantifying soil hydraulic properties

Since about 25 years, we have measured the unsaturated hydraulic conductivity function and water retention curve with the evaporation method of more than 1500 mineral and organic soils samples. From this data base, 104 representative samples of varying texture and dry bulk density were selected and the temporal dynamics of the basic measured values (mass or water loss, respectively, and tension change over time) was analyzed. With the exception of sand, water loss per time interval was constant in all other mineral and organic soils during the measuring time in the tension range between 0 and about 60 kPa. In sands, the nonlinear water loss over time by evaporation can be described by a quadratic function with high accuracy (r² > 0.99). For all other soils, a linear function is sufficient (r² > 0.99). The use of evaporation functions enables extending weighing intervals. This reduces costs for the measuring equipment and increases the effectiveness of the method while maintaining the same quality of unsaturated hydraulic conductivity and water retention functions. It was confirmed that measuring with two tensiometers is sufficient for accurate hydraulic conductivity and water retention function. Reducing evaporation by screening the sample surface helps to decrease hydraulic gradients and keeps tension distributions approximately linear with depth. This is recommended in particular for clayey soils.     

黄土区小流域土壤容重和饱和导水率的时空动态特征

土壤水力性质是评估降水入渗、径流发生以及土体可蚀性的重要参数。研究小流域尺度土壤水力性质的时空动态特征,对于以小流域为基本单元的黄土高原综合治理具有直接意义,有助于加深对相关生态水文过程的理解。以陕西省神木县六道沟老叶满渠小流域为对象,进行50 m×50 m网格布点(共73个样点),2014年8-10月期间每月测定1次表层土壤容重和饱和导水率,结合经典统计学与地质统计学的方法研究容重和饱和导水率的时空变化规律。结果表明:1)小流域尺度容重的月际变化趋势较为一致,整体呈正态分布规律,饱和导水率的月际变化强烈,呈偏态分布;容重较饱和导水率变化范围较小,变异程度较低;2)小流域尺度容重和饱和导水率在8-10月的半方差可用指数模型进行最优拟合,两者均表现出中等程度的空间依赖性;Kriging插值图表明小流域容重总体差异性较小,而饱和导水率差异显著;8-10月,西坡局部区域、坡顶的容重呈逐月增大趋势,而饱和导水率呈减小趋势;3)Pearson相关性分析表明,8-10月单次测定的容重和饱和导水率之间的相关性不明显;在同一土壤类型下(干润砂质新成土)表现出极显著的负相关关系(P0.01)。     

黄土高原上黄试区土地利用适宜性评价

针对黄土高原上黄试区自身特点,结合专家评议,建立了该区土地利用适宜性评价指标体系.采用专家打分法对各指标进行量化分级与权重确定.运用ArcView 3.2软件将该流域划分为185个地块,并建立各地块的空间和属性数据库.利用软件的空间叠加分析功能与综合指数法研究了各地块土地利用的适宜程度.结果表明:上黄试区宜牧地面积最大,约为419.04 hm2 (52.31％);宜农地次之,约为195.35hm2(24.39％);宜林地面积最小,仅为46.8 hm2 (5.84％);宜林牧土地面积约为139.86 hm2 (17.46％).评价结果可为上黄试区最佳土地利用方案的确定提供数据基础.     

25年长期定位不同施肥措施对关中塿土水力学性质的影响

土壤水力学性质和功能的变化是评价长期施肥是否维持土壤可持续健康发展的重要方面。该研究通过采取"国家黄土肥力与肥料效益监测基地"的表层原状土壤,分析测定了撂荒(LH)、休闲(XX)、不施肥(CK)、单施氮肥(N)、氮磷钾肥(NPK)和有机肥与氮磷钾肥配施(MNPK)6个处理的土壤水分特征曲线、饱和导水率和紧实度等指标,评价了长期定位施肥对土壤基本物理性质和水力学性质的影响。结果表明:1)与CK、N和NPK处理相比,MNPK处理显著提高了土壤有机碳、饱和导水率和孔隙度,而降低了土壤容重和紧实度(P0.05)。2)不同施肥处理之间的土壤水分特征曲线表现出一定的差异,其土壤持水能力强弱为:XXN≈NPKCKMNPKLH;MNPK处理较CK、N和NPK处理持水能力分别提高2.57%、3.33%和7.34%;V-G模型拟合结果表明残余含水量(θ_r)、饱和含水量(θ_s)和进气值倒数(a)都存在一定程度的差异,θ_r在MNPK处理最大,XX最小;θ_s在N处理最大,MNPK次之,CK最小。进气值(1/a)在XX处理最大,LH最小。3)当量孔隙的分布主要在9μm大孔隙范围内,其次是0.2μm小孔隙范围,0.2～9μm之间的中孔隙分布较少。综上,MNPK有助于改善土壤结构,提高土壤持水性,降低土壤容重和紧实度,有助于作物生长和高产,是关中地区较为适宜的施肥措施。     

Grazing‐induced alterations of soil hydraulic properties and functions in Inner Mongolia,PR China

Increasing grazing intensities of sheep and goats can lead to an increasing degradation of grasslands. We investigated four plots of different grazing intensities (heavily grazed, winter‐grazed, ungrazed since 1999, and ungrazed since 1979) in Inner Mongolia, PR China, in order to study the effects of trampling‐induced mechanical stresses on soil hydraulic properties. Soil water transport and effective evapotranspiration under “heavily grazed” and “ungrazed since 1979” were modeled using the HYDRUS‐1D model. Model calibration was conducted using data collected from field studies. The field data indicate that grazing decreases soil C content and hydrophobicity. Pore volume is reduced, and water‐retention characteristics are modified, the saturated hydraulic conductivity decreases, and its anisotropy (vertical vs. horizontal conductivity) is influenced. Modeling results revealed higher evapotranspiration on the ungrazed site (ungrazed since 1979) compared to the grazed site (heavily grazed) due to wetter soil conditions, more dense vegetation, litter cover, and decreased runoff and drainage, respectively. Grazing modified the partitioning of evapotranspiration with lower transpiration and higher evaporation at the grazed site owing to reduced root water uptake due to reduced evaporation and a patchy soil cover.     

Temporal and spatial changes of soil erosion under land use and land cover change based on Chinese soil loss equation in the typical watershed on the Loess Plateau

Land use and land cover change (LULCC) directly affect the temporal and spatial change of soil erosion. As a typical governance watershed in the hilly and gully area of the Loess Plateau, the Jiuyuangou watershed has experienced significant LULCC in the past 10 years due to conversion of farmland to forests, economic construction, and cropland abandonment. However, the evolution process of soil erosion change and LULCC in the watershed is unclear, as is the relationship between the two. This study used satellite images to extract information on LULCC in the watershed and the Chinese soil loss equation (CSLE) model to evaluate the temporal and spatial evolution of soil erosion in the watershed from 2010 to 2020. The main results showed that (1) the continuous vegetation restoration project in the watershed reduced soil erosion from 2010 to 2015; however, the increased frequency of extreme rainfall events after 2015 reduced its impact. The annual average soil erosion modulus decreased from 10.85 t ha⁻¹ year⁻¹ in 2010 to 8.03 t ha⁻¹ year⁻¹ in 2015 but then increased to 10.57 t ha⁻¹ year⁻¹ in 2020; (2) the main land use and land cover (LULC) type in the Jiuyuangou watershed is grassland, accounting for 62% of the total area, followed by forestland, cropland, buildings, and water. Cropland has the largest multi-year average soil erosion modulus, followed by grassland and buildings, with forestland having the smallest; (3) significant spatial correlations occurred between soil erosion change and LULCC for common ‘no change’ and common ‘gain’ in the settlements, roads, and areas near the human influences with good soil and water conservation, but not other regions due to the influence of climatic factors (heavy rain events). Thus, we should repair terraces, control dams in the watershed, and actively conserve water and soil. This study provides a scientific reference for planning and managing water and soil conservation and ecological environment construction in the watershed.     

Long‐term‐fertilization effects on soil organic carbon,physical properties,and wheat yield of a loess soil

The large dryland area of the Loess Plateau (China) is subject of developing strategies for a sustainable crop production, e.g., by modifications of nutrient management affecting soil quality and crop productivity. A 19 y long‐term experiment was employed to evaluate the effects of fertilization regimes on soil organic C (SOC) dynamics, soil physical properties, and wheat yield. The SOC content in the top 20 cm soil layer remained unchanged over time under the unfertilized plot (CK), whereas it significantly increased under both inorganic N, P, and K fertilizers (NPK) and combined manure (M) with NPK (MNPK) treatments. After 18 y, the SOC in the MNPK and NPK treatments remained significantly higher than in the control in the top 20 cm and top 10 cm soil layers, respectively. The MNPK‐treated soil retained significant more water than CK at tension ranges from 0 to 0.25 kPa and from 8 to 33 kPa for the 0–5 cm layer. The MNPK‐treated soil also retained markedly more water than the NPK‐treated and CK soils at tensions from 0 to 0.75 kPa and more water than CK from 100 to 300 kPa for the 10–15 cm layer. There were no significant differences of saturated hydraulic conductivity between three treatments both at 0–5 and 10–15 cm depths. In contrast, the unsaturated hydraulic conductivity in the MNPK plot was lower than in the CK plot at depths of 0–5 cm and 10–15 cm. On average, wheat yields were similar under MNPK and NPK treatments and significantly higher than under the CK treatment. Thus, considering soil‐quality conservation and sustainable crop productivity, reasonably combined application of NPK and organic manure is a better nutrient‐management option in this rainfed wheat–fallow cropping system.     

Soil Quality Indicators in Relation to Land Use and Topography in a Small Catchment on the Loess Plateau of China

Better understanding of how the loess soils respond to topography and land use under catchment‐scale vegetation restoration is needed to enable science‐based land management interventions for the policy‐driven “Grain‐for‐Green” eco‐restoration program in the Loess Plateau of China. The objective of this study was to characterize the relationships of four selected soil quality indicators to land use under vegetation restoration and topography for a small catchment (0·58 km²) in the Loess Plateau. The major land uses established in the catchment are cropland, fallow (i.e., natural revegetation), grassland, and jujube orchard. The four soil quality indicators were soil organic carbon (SOC), soil total nitrogen (STN), soil total phosphorus (STP), and mean root zone soil water content during the wet season (MRZSWwet). SOC, STN, and MRZSWwet were significantly different (p < 0·05) for different land uses. Grassland showed the highest values for these three properties, whereas cropland had relatively low values for SOC and STN. Land use had no effect on STP, although the lowest value was observed in grassland. Spatial analysis showed that various relations between soil quality indicators and topography (slope and elevation) were observed. These relations were generally weak for most of them, and they varied with land uses. Further analyses indicated that land uses, slope, and elevation had significant effects on the relations between different soil quality indicators. The results here should provide useful information for the further development of “Grain‐for‐Green” program. Copyright © 2012 John Wiley & Sons, Ltd.