Soil organic carbon in density fractions of tropical soils under forest – pasture – secondary forest land use changes

Our knowledge of effects of land use changes and soil types on the storage and stability of different soil organic carbon (SOC) fractions in the tropics is limited. We analysed the effect of land use (natural forest, pasture, secondary forest) on SOC storage (depth 0–0.1 m) in density fractions of soils developed on marine Tertiary sediments and on volcanic ashes in the humid tropics of northwest Ecuador. The origin of organic carbon stored in free light (< 1.6 g cm^?3) fractions, and in two light fractions (LF) occluded within aggregates of different stability, was determined by means of δ¹³C natural abundance. Light occluded organic matter was isolated in a first step after aggregate disruption by shaking aggregates with glass pearls (occluded I LF) and in a subsequent step by manual destruction of the most stable microaggregates that survived the first step (occluded II LF). SOC storage in LFs was greater in volcanic ash soils (7.6 ± 0.6 Mg C ha^?1) than in sedimentary soils (4.3 ± 0.3 Mg C ha^?1). The contribution of the LFs to SOC storage was greater in natural forest (19.2 ± 1.2%) and secondary forest (16.6 ± 1.0%) than in pasture soils (12.8 ± 1.0%), independent of soil parent material. The amount of SOC stored in the occluded I LF material increased with increasing silt + clay content (sedimentary soils, r = 0.73; volcanic ash soils, r = 0.58) and aggregation (sedimentary soils, r = 0.52; volcanic ash soils, r = 0.45). SOC associated with occluded I LF, had the smallest proportion of new, pasture‐derived carbon, indicating the stabilizing effect of aggregation. Fast turnover of the occluded II LF material, which was separated from highly stable microaggregates, strongly suggested that this fraction is important in the initial process of aggregate formation. No pasture‐derived carbon could be detected in any density fractions of volcanic ash soils under secondary forest, indicating fast turnover of these fractions in tropical volcanic ash soils.     

The phosphorus composition of contrasting soils in pastoral,native and forest management in Otago,New Zealand: Sequential extraction and 31P NMR

The distribution and form of P in soil is central to the sustainability of agricultural practice. This study used sequential fractionation and ³¹P nuclear magnetic resonance spectroscopy (³¹P NMR) of NaOH–EDTA extracts to examine the influence of pastoral, native (undisturbed) and forest land use on soil P forms in 5 contrasting soils ranging from a Regosol to a Rendzina in Otago, New Zealand. Climatic factors likely to influence soil P distribution were negated by careful site selection. Together with a decrease in soil organic C (31%), total P decreased in forested soils (mean=674 mg kg⁻¹) compared to native soils (mean=784 mg kg⁻¹). In contrast, the ratio of inorganic to organic P increased (10%) probably due to mineralization of organic P in forest soils, while for pasture soils, accumulation of P in inorganic forms due to P inputs via fertilisers and animal dung was to blame. Investigation of the organic P forms in NaOH–EDTA extracts of each land use by ³¹P NMR indicated that diesters were greatest in the native soil (4–12% of total P in spectra), and declined as a proportion of total P in pasture soils and more so in forest soils. This was reflected in a decline of the diester to monoester ratio. However, the ratio was generally greater in forest than pasture soils and attributed to the labile nature of diesters, mineralization of monoesters in forest soils, and an increase in monoesters in pasture soils from inositol phosphates in plant debris. This effect was pronounced in the Regosol due to sandy texture and the preferential accumulation of plant debris in coarse particle size fractions. Due to the depletion of soil P reserves, forest soils in the area should be followed by pasture and well managed fertiliser additions before replanting.     

Aluminum Forms in Solid Phase of Soils Developed over Schists as a Function of Land Use

ABSTRACT

Land use may modify certain soil properties while soil physicochemical characteristics can influence metal partitioning in soils. Therefore, the total content and various forms of aluminum (Al) in solid phase of schist-developed topsoils (0–20 cm) in NW Spain under different land uses (i.e., forest, pasture, and cultivation) were evaluated to identify the Al-bearing phases. Aluminum fractionation was performed, using a six-step sequential extraction procedure with ammonium acetate, hydroxylamine hydrochloride, ammonium oxalate in darkness, hydrogen peroxide, ammonium oxalate under ultraviolet radiation, and acid digestion. Mean concentrations of total Al were similar in the soils under three land uses. Mean percentage of the various Al forms in all soils were in the following order: residual fraction > amorphous compounds > crystalline compounds > water-soluble/exchangeable/specifically adsorbed > bound to oxidizable organic matter > manganese oxides. The forest soils contained considerably higher contribution of amorphous compounds (16.3%) to total Al concentration compared with the soils under other two uses (mean about 9%). Maximum mean concentration of exchangeable Al was also observed in forest soils (mean 8.8% of total Al vs. about 4% in pasture soils and cultivated soils); this is attributed to lower pH and higher organic matter content of the forest soils. Thus, this study revealed the impact of land use on the Al-bearing phases and, hence, in its bioavailability to plants.     

Patterns of Organic Matter Accumulation in Soils of the Semiarid Argentinian Pampas

A-horizons of 48 Haplic Phaeozems and Kastanozems in plain sites of the Semiarid Argentinian Pampas under three contrasting management systems (virgin bushland, permanent pasture and continuous agriculture) were studied. Morphological characteristics, organic carbon and total nitrogen levels and E4:E6 ratios were determined on the assumption that both quantity and quality of organic matter should be related to soil texture of parent materials in this region since other soil forming factors are uniform. The more intensive land use produced an averaged decrease of 7 cm in A-horizon thickness and degradation of soil structure, but little changes in color and properties of boundaries to AC horizons. In virgin soils organic carbon and nitrogen contents correlate with silt + clay fractions (r = 0,92 and 0,99, respectively), while E4:E6-ratios are related to clay contents (r = ?0.69*) confirming the strong influence of soil texture. Agricultural-management and pasture use of soils lead to dispersion of these correlations probably because of differential influence of varying intensities of land use within each management system. Soils under continuous agriculture show lower organic carbon contents than virgin soils only at clay + silt > 40%. Eragrostis curvula-pastures seems to be more effective in restoring organic matter and nitrogen levels in sandy but not in loamy soils with respect to virgin soils. This may be due to a better efficiency of E. curvula-roots in coarse than in fine textured soils to produce humificable residues than the autochthonous grass species.     

Carbon,nitrogen, phosphorus and enzymatic activity under different land uses in a tropical,dry ecosystem

We compared total C, N and P, available forms of N and P and dehydrogenase, urease and acid phosphatase activities in soils from primary forests, 26‐year‐old pastures and 26‐year‐old secondary forests in the tropical dry forest region of Chamela, Jalisco, Mexico. We hypothesized that, because of their natural regeneration and greater plant diversity, secondary forest soils would have higher fertility and enzyme activities than pasture soils and would be more similar to primary forest soils. We predicted also that enzymes would be better indicators of land‐use effects on soil fertility than nutrients. Only one nutrient, available phosphorus, and one enzyme, acid phosphatase, were significantly and consistently affected by land use. As expected, these parameters were greater in primary and secondary forests than in pastures. Principal components analysis using all variables placed secondary forests intermediate between primary forests and pastures, as predicted, and total C, N and P, available P, ammonium, phosphatase, urease and the C:P ratio were the variables associated with this spatial arrangement of land uses. We conclude that secondary forest soils showed improved fertility and were overall closer to primary forests than to pastures in most variables measured.     

Effect of Land-Use History on Soil Carbon and Nitrogen in a Mediterranean Catchment

The impact of land use on soil organic matter was investigated. Five land cover types (pine forest, olive groves, wheat, wheat/maize cultivation systems, and a shrub pasture) belonging to three land-use categories from the same catchment in the island of Lesvos, Greece, were used. The soils developed under similar pedogenetic processes and accepted similar agricultural practices for at least 30 years. The results showed that the land-use and cover types ranged according to their total soil carbon (C) content as follows: forest > double cultivation > wheat > olive > pasture. Crop plantations contained 31 to 40% less C at their upper 0- to 45-cm layer than forest. Pasture had shallow soils with a small C accumulation but high C concentration, whereas olive groves had the lowest concentrations of both soil C and nitrogen (N). Olive grove soils were the most prone to degradation but possessed the greatest potential for C sequestration.     

Soil Property Changes After Conversion from FOrest to Pasture in Mount Sacinka,Artvin, Turkey

Turkey's forests have been continuously facing conversion into both agriculture and pasturelands, causing not only degradation and fragmentation of forested lands but also negative changes in soil properties that have not been thoroughly investigated. In order to determine possible changes in some physical and hydrophysical soil parameters along with the dispersion ratio between natural coppice forests and the neighbouring forest‐to‐grassland converted areas, a foothill of Mount Sacinka in Artvin was chosen as a research area. Besides land use, possible effects of elevation change on soil properties due to the mountainous and moderately steep landscape of the region were also taken into consideration. The soil samples were analysed for soil texture, permeability, field capacity, bulk density, organic matter, pH and dispersion ratio. The results indicated that whereas permeability (43·05 mm h⁻¹ in forest and 18·82 mm h⁻¹ in pasture), field capacity (43·45% in forest and 38·08% in pasture) and organic matter (6·36% in forest and 5·34% in pasture) values turned out to be higher in forest soils, bulk density (0·91 g cm⁻³ in forest and 1·06 g cm⁻³ in pasture) and pH (5·89 in forest and 6·55 in pasture) values were low in grassland soils, meaning that conversion has negative effects on soil properties. Additionally, the mean dispersion ratios of 27·55% and 33·58% for forest and pastureland soils, respectively, indicated soil erosion problems in both land uses. In addition, as for elevation effect, forest soils especially showed better characteristics at higher elevations with high permeability, field capacity and organic matter and low pH and dispersion ratio. Copyright © 2015 John Wiley & Sons, Ltd.     

Land-use effects on organic matter and physical properties of soil in a southern Mediterranean highland of Turkey

Forest and grassland soils in highlands of southern Mediterranean Turkey are being seriously degraded and destructed due to extensive agricultural activities. This study investigated the effects of changes in land-use type on some soil properties in a Mediterranean plateau. Three adjacent land-use types included the cultivated lands, which have been converted from pastures for 12 years, fragmented forests, and unaltered pastures lands. Disturbed and undisturbed soil samples were collected from four sites at each of the three different land-use types from depths of 0–10 cm and 10–20 cm in Typic Haploxeroll soils with an elevation of about 1400 m. When the pasture was converted into cultivation, soil organic matter (SOM) pool of cultivated lands for a depth of 0–20 cm were significantly reduced by, on average 49% relative to SOM content of the pasture lands. There was no significant difference in SOM between the depths in each land-use type, and SOM values of the forest and pasture lands were almost similar. There was also a significant change in soil bulk density (BD) among cultivation (1.33 Mg m⁻³), pasture (1.19 Mg m⁻³), and forest (1.25 Mg m⁻³) soils at depth of 0–20 cm. Only for the pasture, BD of the depth of 0–10 cm was significantly different from that of 10–20 cm. Depending upon the increases in BD and disruption of pores by cultivation, total porosity decreased accordingly. Cultivation of the unaltered pasture obviously increased the soil erodibility measured by USLE-K factor for each soil depth, and USLE-K factor was approximately two times greater in the cultivated land than in the pasture indicating the vulnerability of the cultivated land to water erosion. The mean weight diameter (MWD) and water-stable aggregation (WSA) were greater in the pasture and forest soils compared to the cultivated soils, and didn’t change with the depth for each land-use type. Aggregates of >4.0 mm size were dominant in the pasture and forest soils, whereas the cultivated soils comprised aggregates of the size ≤0.5 mm. I found that samples collected from cultivated land gave the lowest saturated hydraulic conductivity values regardless of soil depths, whereas the highest values were measured on samples from forest soils. In conclusion, the results showed that the cultivation of the pastures degraded the soil physical properties, leaving soils more susceptible to the erosion. This suggests that land disturbances should be strictly avoided in the pastures with the limited soil depth in the southern Mediterranean highlands.     

土地利用方式对红枫湖入湖流域土壤团聚体磷含量及其形态的影响

以贵州省安顺市红枫湖入湖口4种典型土地利用方式（玉米地、菜园、林地及撂荒地）为研究对象,分别探讨了土地利用方式对0—15em和15～30cm两个层次土壤团聚体总磷含量及其形态的影响。结果表明,不同土地利用方式下,原状土壤及各粒级团聚体总磷含量均表现为玉米地〉菜园〉撂荒地〉林地。土壤各粒级团聚体磷形态含量以ResidualP、NaOH—P、NaHCO3-P为主,其中ResidualP在各土地利用方式中的含量均最高,变幅分别为玉米地28．3％～45．4％、林地61．1％-72．7％、菜园45．9％～53．0％、撂荒地52．1％-72．4％;玉米地和菜园土壤均表现为有机磷含量约为无机态含量的2倍;随团聚体粒径的减小,土壤对总磷含量的贡献率呈减少趋势,土壤团聚体对总磷含量贡献主要集中在5～2mm和2~0．5mm两个粒级中,贡献率均达77％以上,其中耕作土壤（玉米地、菜园）中5-2mm和2-0．5mm两个粒级团聚体中的磷是湖泊面源污染中磷素的主要贡献载体,也是造成湖泊富营养化的关键因素。     

Land use effects on soil carbon fractions in the southeastern United States. II. changes in soil carbon fractions along a forest to pasture chronosequence

Since land use change can have significant impacts on regional biogeochemistry, we investigated how conversion of forest and cultivation to pasture impact soil C and N cycling. In addition to examining total soil C, we isolated soil physiochemical C fractions in order to understand the mechanisms by which soil C is sequestered or lost. Total soil C did not change significantly over time following conversion from forest, though coarse (250–2,000 m) particulate organic matter C increased by a factor of 6 immediately after conversion. Aggregate mean weight diameter was reduced by about 50% after conversion, but values were like those under forest after 8 years under pasture. Samples collected from a long-term pasture that was converted from annual cultivation more than 50 years ago revealed that some soil physical properties negatively impacted by cultivation were very slow to recover. Finally, our results indicate that soil macroaggregates turn over more rapidly under pasture than under forest and are less efficient at stabilizing soil C, whereas microaggregates from pasture soils stabilize a larger concentration of C than forest microaggregates. Since conversion from forest to pasture has a minimal impact on total soil C content in the Piedmont region of Virginia, United States, a simple C stock accounting system could use the same base soil C stock value for either type of land use. However, since the effects of forest to pasture conversion are a function of grassland management following conversion, assessments of C sequestration rates require activity data on the extent of various grassland management practices.     

Consequences of forest conversion to pasture and fallow on soil microbial biomass and activity in the eastern Amazon

The main change in soil use in Amazonia is, after slash and burn deforestation followed by annual crops, the establishment of pastures. This conversion of forest to pasture induces changes in the carbon cycle, modifies soil organic matter content and quality and affects biological activity responsible for numerous biochemical and biological processes essential to ecosystem functioning. The aim of this study was to assess changes in microbial biomass and activity in fallow and pasture soils after forest clearing. The study was performed in smallholder settlements of eastern Brazilian Amazonia. Soil samples from depths of 0–2, 2–5 and 5–10 cm were gathered in native forest, fallow land 8–10 yr old and pastures with ages of 1–2, 5–7 and 10–12 yr. Once fallow began, soil microbial biomass and its activity showed little change. In contrast, conversion to pasture modified soil microbial functioning significantly. Microbial biomass and its basal respiration decreased markedly after pasture establishment and continued to decrease with pasture age. The increase in metabolic quotient in the first years of pasture indicated a disturbance in soil functioning. Our study confirms that microbial biomass is a sensitive indicator of soil disturbance caused by land‐use change.     

宁南山区不同生态恢复措施对土壤环境效应影响的研究

通过对宁南山区采取不同恢复措施的土壤水分、理化性质及酶活性的研究结果表明：土壤平均含水量最高的是农田18．61％，其次为林地16．73％、人工草地9．95％，最小的为天然草地9．20％；土壤总孔隙度、土壤碱解氮排列顺序为林地〉农田〉人工草地〉天然草地；土壤毛管孔隙度、土壤速效磷平均含量排列顺序为人工草地〉林地〉农田〉天然草地；土壤有机质平均含量为灌木林地〉农田〉天然草地〉人工草地；土壤速效钾的平均含量为天然草地〉农田〉人工草地〉灌木林地。土壤尿酶含量为人工草地〉天然草地=农田〉林地；土壤蔗糖酶、多酚氧化酶的含量为人工草地〉天然草地〉林地；过氧化氢氧化酶的含量为人工草地〉天然草地=农田〉林地。     

基于沙化状况和适宜性的土地利用结构调整

根据科尔沁沙地2000年的土地利用数据、从相同时期的TM影像上提取的土地沙漠化数据和土地适宜性数据，运用ARC/INFO、ARCVIEW软件和Access统计软件，分析了研究区土地利用、土地沙漠化和适宜性之间的对应关系，基于土地利用现状和适宜性进行了土地利用结构的调整，确定调整土地的面积及其空间分布。主要结论如下：草地、耕地和林地是主要土地利用类型，沙漠化原因存在差异，耕地沙化的主要原因是不宜耕作的林地、草地的开垦，而林地和草地的沙化则是由于土地质量差、利用强度大而造成的。土地利用结构调整后，耕地面积减少，草地和林地面积增加。科尔沁沙地的治理应将土地利用结构调整与农业、畜牧业经营方式的改变、土壤改良结合起来。     

A concept of compaction

Bulk density data of about 150 soil profiles from America, Europe and Asia were used to obtain the regression curve of void ratio ? as a function of vertical stress σ_z. For virgin soils straight lines were obtained if a linear scale was used for ? and a logarithmic scale for σ_z. The slope of these lines was steepest for forest zone soils, less steep in soils of high-grass zones and flattest in short-grass soils. This difference is attributed to varying amounts of loosening by bio- and cryoturbation. Thus the compaction state of virgin soils is that of normal compaction caused by pedogenic processes which are superimposed on previous strong overconsolidation due to desiccation. Against this background agricultural land use creates overconsolidation in the upper soil layers, which is particularly pronounced when the previous bioturbate action has been strong. Young soil deposits cannot develop normal compaction, because of the lack of previous drying of the whole profile.     

Water-stable aggregates, glomalin-related soil protein, and carbohydrates in a chronosequence of sandy hydromorphic soils

The conversion of pasture to cropland leads to a decline of aggregation in topsoils and to a decrease of aggregate-binding agents such as carbohydrates and glomalin-related soil protein (GRSP). Till now, studies on soil aggregation focused either on carbohydrates or on GRSP as a binding agent in aggregates. In this study we analyse the development of the relationship between carbohydrates, GRSP, TOC and aggregate-stability following land-use change. Furthermore, we discuss the contents of carbohydrates, GRSP and TOC in each of the aggregate fractions. For these purposes, a chronosequence of sites, which were converted from pasture to cropland at different periods in history, was established. To get further insight into the impact of different types of land-use, also soils under forest, either afforested or permanent, were studied. The mean-weight diameter (MWD) of water-stable aggregates, the carbohydrate, and the GRSP content were determined in 49 soils. It was found that the MWD of the water-stable aggregates decreased monoexponentially (R² = 0.66) by 66% during the first 46 years after conversion of the soils from pasture to cropland. During the same period, the carbohydrate content decreased very rapidly after the land use change by 64% and the GRSP content decreased more slowly by 57%. The MWD of the forest soils were in the same range as those of the permanent pasture soils although they exhibit significantly higher TOC contents, which indicate that other stabilization mechanisms are dominant in forest soils, less important in the chronosequence soils. TOC, carbohydrates and the GRSP contents were sigmoidally correlated with the MWD. Among the four water-stable aggregate fractions TOC and carbohydrates exhibited high contents in the macroaggregates and were less present in the microaggregates. GRSP, in contrast, was more equally distributed among the four water-stable aggregate fractions.     

Modelling soil organic carbon stocks and their changes in the northeast of Spain

Currently, there is little information about soil organic carbon (SOC) stocks and changes in Mediterranean areas at a regional scale. We modelled an area of 95 269 km² in northeast Spain using the Global Environmental Facility Soil Organic Carbon (GEFSOC) system to predict SOC stocks and changes in pasture, forest and agricultural soils. The spatial distribution of the different land‐use categories and their change over time was obtained by using the Corine database and official Spanish statistics on land use from 1926 to 2007. The model predicted the largest current SOC stock in forest soils at 578 Tg C. Agricultural soils were the second largest SOC reservoir, containing 244 Tg C. During the last 30 years, the model predicted a total SOC gain in the 0–30‐cm soil layer of 34 Tg C. Forest and grassland‐pasture soils had a decline in their stored SOC of 5 and 3 Tg C, respectively, because of the reduction in the soil surface occupied by both classes. The greatest SOC gain was predicted in agricultural soils with 42 Tg C caused by changes in management, which led to increases in C inputs. Although model uncertainty was not quantified, some hypothetical assumptions about the initialization and parameterization of the model could be potential sources of uncertainty. Our simulations predicted that in northeast Spain soil management has contributed to the sequestration of substantial amounts of atmospheric CO₂ during the last 30 years. More research is needed in order to study the potential role of soils as atmospheric CO₂ sinks under different managements and climatic conditions.     

Effects of Land Use on Concentrations and Chemical Forms of Phosphorus in Different-Size Aggregates

Land use has been recognized as an important driver of environmental change on all spatial and temporal scales. This study was conducted to determine the effects of land uses on phosphorus concentration in bulk soil and in water-stable aggregates in different soils. The study was conducted on three soil types (Ferrosols, Cambosols, and Primosols), which were collected from three different locations from southeast China and under three land uses (Uncultivated, Vegetable and forest land) the region is characterized as a hill and plain area. Accordingly, a total of 24 soil samples were collected. The results showed that average contents of total P were 0.55–1.55 g/kg, 0.28–1.03 g/kg and 0.14–0.8 g/kg for the soils: Cambosols, Ferrosols and Primosols respectively. Vegetable and forest land led to higher total phosphorus contents in these soils than in the uncultivated land. An aggregate fraction of >2 mm under forest land made up the largest percentage (30 up to 70%), whereas the size fraction <0.106 mm made the least contribution (5 up to 20%) in all soil types. Vegetable land increased the total phosphorus, organic phosphorus and Olsen P and phosphorus forms in the soils. It implies that the conversion of natural ecosystem to vegetable land increased the phosphorus proportion in the soils, which could have negative impact on the environmental quality.     

Land‐Use Effects on Soil Nutrient Cycling and Microbial Community Dynamics in the Everglades Agricultural Area,Florida

Soil subsidence has become a critical problem since the onset of drainage of the organic soils in the Everglades Agricultural Area (EAA), which may impair current land uses in the future. The objectives of this study were to characterize soil microbial community‐level physiology profiles, extracellular enzymatic activities, microbial biomass, and nutrient pools for four land uses: sugarcane, turfgrass, pasture, and forest. Long‐term cultivation and management significantly altered the distribution and cycling of nutrients and microbial community composition and activity in the EAA, especially for sugarcane and turf fields. The least‐managed fields under pasture had the lowest microbial biomass and phosphorus (P) levels. Turf and forest had more microbial metabolic diversity than pasture or the most intensively managed sugarcane fields. Land‐use changes from sugarcane cropping to turf increased microbial activity and organic‐matter decomposition rates, indicating that changes from agricultural to urban land uses may further contribute to soil subsidence.     

Effects of land use and clay content on soil structure as measured by Fracture Surface Analysis

Soil clods were collected from the A horizons of six soils (3 Aqualfs and 3 Uderts) in the vicinity of Bayreuth in northern Bavaria. The soils had a range of clay contents and came from arable, meadow (pasture) and forest areas. The soils ranged in workability from easily workable to difficult to work. The clods, still moist as collected, were fractured into two parts by tensile stress and one part of each clod was embedded in polyester resin. The embedded clod parts were then sectioned to show profiles of the fracture surfaces. The profiles were digitized by a television scanner. Statistical measures of the roughness of the fracture surfaces were computed. Fracture surface roughness was strongly influenced by land use and soil clay content. Soil workability was related to fracture surface roughness and hence also to land use and soil clay content. Ease of soil working was mainly associated with the presence of soil structural features larger than 10 mm.     

人为干预下喀斯特峡谷区不同土地利用类型对土壤理化性质的影响

[目的]探究人为干预下喀斯特峡谷区不同土地利用类型对土壤理化性质的影响,为岩溶山区的生态环境保护和可持续发展提供科学依据。[方法]以贵州省花江喀斯峡谷示范区生态系统土壤为研究区,选取典型喀斯特石漠化治理区域进行野外定点取样,通过室内分析的方法进行不同土地利用石漠化地区土壤理化性质比较研究。[结果](1)土壤含水量随着土层深度的增加递增,土壤含水量大小依次为:封山育林径流场坡改梯自然灌丛撂荒地,形成土壤水分的垂直变化;(2)经过改良后坡改梯通过种植花椒的田间持水量明显比草地含量高,相对于进行石漠化治理并合理耕作的坡改梯花椒地来说,荒草地的持水能力明显下降;(3)石漠化环境下土壤颗粒分散、土体结构破坏,土壤通透能力下降,孔隙的变化规律为:林地坡改梯灌草丛耕地撂荒地;(4)示范区土壤总钾偏高,与pH值呈正相关,总氮普遍低于全国农田氮含量,土壤养分不足。[结论]不同土地利用条件下土壤特征有显著差异,这种差异是基于不同石漠化等级下不同土地利用的治理措施造成的。花江示范区土壤持水效益低,土壤养分不足,不利于耕作,农业产量不高,建议花江示范区应减少耕地,多种植经济林和草地,保护天然林地。