澳大利亚、中国和泰国的热带地区的土壤化学退化的量化及修复

Soil and land degradation in the tropics can be identified and described in terms of physical,chemical,and biological changes from its pristine state brought about by natural and anthropogenic influences.A characteristic of these ecosystems is their capacity to recycle nutrients through soil organic matter(SOM). Following disturbance through changed land management.SOM is rapidly mineralized and there is a cor responding decline in fertility and the variable charge component of the cation exchange capacity.As these ecosystems are strongly dependent on SOM for their functionality,changed land use can have irreversible impacts on the productivity of these systems.The paper focuses on quantifying chemical degradation throughbenchmaking using data from paried sites in tropical China and Thailand using surface charge finger printing.Using values taken from the fingerprint of an undistubed soil,an index of chemical degradation from ideality was calculated.Various management stratgeies that attempt to reverse degradative trends or improve poor quality soils in their natural condition are discussed.such as the ddition of natural clays and silicated materials.Results are present to whow the effect of each of the aforementional strategies on surface charge characteristics and associated increases in plant productivity.     

丘陵区土地整理对土壤理化性状的影响

该文以莱芜市里辛土地整理项目为例,采用野外采样和室内分析相结合的方法,研究了丘陵区土地整理对土壤理化性状的影响。研究结果表明,土地整理对土壤物理性状影响极显著或显著;对土壤化学性状影响不显著;各土壤理化性状的变异系数,除土壤体积质量增加、土壤黏粒稍有增加外,其他均下降,整理后土壤理化性状更均匀。土壤理化性状变化原因主要是整理中注重物理措施、忽视土壤培肥,施工不规范及国家有关标准不具体等造成。今后应重视土壤培肥,规范施工,完善有关土地整理标准、明确各项土壤理化性状指标等,以确保土壤质量提高。     

沙地整治下榆林土地利用及土壤有机质时空分异特征

毛乌素沙地是典型的生态脆弱区,近年来针对其在榆林境内的沙地整治利用取得显著成效,也对土壤环境产生了深刻影响。为了探究沙地不同整治利用方式对土壤有机质的影响,该研究选取榆林市显性沙地,利用多光谱遥感影像及相关光谱指数,结合沙地土地利用变化特征,通过XGBoost机器学习方法,反演1990-2020年土壤有机质含量;分析不同土地类型下土壤有机质含量变化,通过半变异函数揭示了其空间变异性,厘清人为因素和自然环境的影响程度。结果表明,30 a间榆林5 460 km2沙地中超过半数得到整治和利用,沙地-草地是最主要的地类转变方式,建设用地面积增长最迅速;沙区土壤有机质含量上升,但整体呈现先增加后降低的趋势,有机质均值由0.34%增长至0.79%,近10年降低至0.51%;榆林沙区土壤有机质具有较强的空间自相关性。起初,人为利用对其有积极作用,但随着沙地的利用强度增大,对土壤有机质产生负向作用,进而致使其含量下降,面临土地退化危机。建议加强退化林草的修复改良,放缓建设用地开发力度,研究以期为沙地整治提供理论和实践借鉴意义,保护榆林沙地土壤环境安全。     

Traditional soil and land appraisal on fadama lands in northeast Nigeria

Abstract. As part of a study of recession farming on the 'fadama' lands on a segment of the Komadugu-Yobe floodplain, a survey was carried out to investigate the local farmers' perception of soil types and management practices. The farmers are clearly aware of the differences in soil type on the fadama and they possess unique skills in managing their farm lands. The farmers classify fadama soils for recession farming by assessing soil texture and soil drainage conditions by feel and observation. Integrating such local knowledge into soil surveys will lead to better practical definition of mapping units and give soil names that have more meaning for the farmers.     

土地退化/恢复中土壤可蚀性动态变化

利用EPIC公式计算了不同开垦和退耕年限的土壤可蚀性K值,对黄土高原典型自然恢复区子午岭林区土地退化/恢复过程中土壤可蚀性的动态变化进行了系统的研究。结果表明：土地开垦后,土壤颗粒向粗骨化方向发展,有机碳含量降低,土壤可蚀性逐渐增强;土地退耕过程中,土壤有机碳含量逐渐增加,肥力水平提高,可蚀性逐渐减小;土壤中有机碳含量、全氮含量、水稳性团聚体含量以及团聚度与土壤可蚀性K值相关最为密切;土壤可蚀性的强弱本质上取决于土壤有机碳含量,恢复植被以提高土壤有机质含量,促进土壤团聚体的形成,增强土壤团聚度,是降低土壤可蚀性能的重要途径。     

中国东南部丘陵红壤地区的土地可持续利用

In the present work,an integrated analysis of natural and socio-economic conditions in the hilly red soil region of southeastern China is made by means of a Geographic Information System.Particular emphasis lies on soil degradation and other adverse ecological and environmental effects of the prevalent and irrational land-use systems of mono-and valley-agriculture in the region.Moreover,taking into account the simultaneous existence of enormous potentials and serious constraints and the high diversity and complexity of the biophysical and socio-economic environments,a set of strategies and countermeasures are also proposed for appropriate management of environmental resources,in terms of maintaining harmony between utilization and coservation of the natural environment,including 1) adjustment of the agricultural structure and optimization of ecological patterns of stereo-agriculture;2) improvement and integrated exploitation of the low-yield lands and wastelands;3) ehabilitation and conservation of soil and water resources;and 4) establishment of production bases of tropical and subtropical cash crops and fruits.     

有机物质阴阳离子对调节土壤pH的作用

The process of organic materials increasing soil pH has not yet been fully understood. This study examined the role of cations and organic anions in regulating soil pH using organic compounds. Calcareous soil, acid soil, and paddy soil were incubated with different simple organic compounds, pH was determined periodically and CO2 emission was also measured. Mixing organic acids with the soil caused an instant decrease of soil pH. The magnitude of pH decrease depended on the initial soil acidity and dissociation degree of the acids. Decomposition of organic acids could only recover the soil pH to about its original level. Mixing organic salts with soil caused an instant increase of soil pH. Decomposition of organic salts of sodium resulted in a steady increase of soil pH, with final soil pH being about 2.7-3.2 pH units over the control. Organic salts with the same anions （citrate） but different cations led to different magnitudes of pH increase, while those having the same cations but different anions led to very similar pH increases. Organic salts of sodium and sodium carbonate caused very similar pH increases of soil when they were added to the acid soil at equimolar concentrations of Na^＋. The results suggested that cations played a central role in regulating soil pH. Decarboxylation might only consume a limited number of protons. Conversion of organic salts into inorganic salts （carbonate） was possibly responsible for pH increase during their decomposition, suggesting that only those plant residues containing high excess base cations could actually increase soil pH.     

Long‐term effects of lime and gypsum additions on no‐till corn and soybean yield and soil chemical properties in southern Brazil

A long‐term experiment on a clayey, kaolinitic, thermic Rhodic Hapludox where dolomitic lime was applied to the surface (either at 4.5 t/ha or at 1.5 t/ha per yr for 3 yr), or incorporated into the topsoil (4.5 t/ha), and gypsum applied to the surface (3, 6, and 9 t/ha), was carried out to evaluate their effects on soil profile chemical properties and yields of corn (Zea mays L.) and soybean (Glycine max L. Merrill). Lime applied to the soil surface at either full or split rates, or incorporated and surface‐applied gypsum had long‐lasting effects on soil acidity or calcium and sulphur availability respectively, as measured 8 yr after application. Grain yields of corn and soybean were not influenced by liming. Gypsum at 9 t/ha significantly increased corn grain yields by 7 and 8% respectively 7–10 yr after application, but did not affect soybean grain yields. The differences in response of the corn and soybean crops to gypsum might be related to the Ca²⁺ uptake by plants because of cation exchange properties of roots, being smaller for corn than for soybean. The use of gypsum in no‐till systems becomes more viable when corn is grown with a greater frequency in crop rotation.     

Assessing land degradation in the Monduli District,northern Tanzania

One of the many contentious issues facing the appropriate and accurate assessment of land degradation is the varying emphasis placed on vegetation degradation and soil degradation processes. This has led to the compartmentalization of land degradation assessment methods, depending on the particular perspective adopted. The land degradation assessment method presented here attempts to take into account both vegetation and soil degradation. This methodology is applied to the southern part of the Monduli District of northeast Tanzania, an area typifying the so‐called ‘affected drylands’ of Africa. Three sets of land cover maps synchronized against long‐term rainfall data (1960s, 1991 and 1999) were used to assess land degradation in the area. Utilizing these three sets of land cover maps as a basis for change detection, it is possible to distinguish areas that experienced changes in vegetation due to rainfall variability from those areas that were subject to changes consequent upon anthropological factors. All areas that displayed overall depletion of natural and semi‐natural vegetation due to human factors were deemed to have undergone land degradation, whereas areas that experienced inter‐annual land cover changes due to rainfall variability were classified as experiencing cover change due to ecosystem dynamics. This method provides a complete and appropriate assessment of land degradation in the study area and can be used to improve degradation assessment in other semiarid areas. Copyright © 2006 John Wiley & Sons, Ltd.     

红壤坡地不同土地利用方式土壤蒸发和植被蒸腾规律研究

为明确红壤坡地土壤水分耗散特征,通过田间定位观测,分析了农作区、茶园和桠柑园土壤水分蒸发和蒸腾过程。结果表明：蒸发、蒸腾与土壤表层含水率和植被叶面积指数关系密切,不同利用方式日蒸发量大小顺序为遮荫茶园〈对照茶园〈桠柑园〈农作区。茶树和桠柑蒸腾速率日变化曲线均呈现单峰型,桠柑日蒸腾速率比对照茶树弱,这两种土地利用方式下6—10月均以蒸腾耗水为主。遮荫可有效削弱茶园土壤蒸发及植被蒸腾。茶园蒸发受微地形条件影响较大,梯地蒸发比梯坎蒸发弱,而农作区和桠柑园土壤蒸发更多受水分条件的影响。合理的土地利用方式和适度遮荫可以有效降低红壤坡地土壤水分散失,提高水分利用效率和防治季节性干旱。     

Quantification and Remediation of Soil Chemical Degradation in Tropical Australia,China and Thailand

Soil and land degradation in the tropics can be identified and described in terms of physical, chemical,and biological changes from its pristine state brought about by natural and anthropogenic influences. Acharacteristic of these ecosystems is their capacity to recycle nutrients through soil organic matter (SOM).Following disturbance through changed land management, SOM is rapidly mineralized and there is a cor-responding decline in fertility and the variable charge component of the cation exchange capacity. As theseecosystems are strongly dependent on SOM for their functionality, changed land use can have irreversible im-pacts on the productivity of these systems. The paper focuses on quantifying chemical degradation throughprinting. Using values taken from the fingerprint of an undisturbed soil, an index of chemical degradationimprove poor quality soils in their natural condition are discussed, such as the addition of natural clays andsilicated materials. Results are present to show the effect of each of the aforementioned strategies on surfacecharge characteristics and associated increases in plant productivity.     

Implications of soil substrate and land use for properties of fen soils in North-East Germany Part I: Basic soil conditions,chemical and biological properties of topsoils

Abstract

The objective of the paper was to analyse the implications of the origin of peat (muck) soil substrate, the current type of land use and the state of anthropogenic soil development for the topsoil properties of fens. Chemical and biological properties of peat soils of the Rhin-Havelluch lowland and the Uckermark rural landscape were analyzed. The unit water content according to Ohde and the ash content were utilized to characterize the anthropogenic development status of peat topsoils. Several chemical properties were significantly influenced by soil substrate, in particular by the proportion and kind of the mineral component. The substrate was associated with the hydrological type of mire and the soil development state. TOC/N ratio and microbial activity were increased in cases of high lime spring mires and moorshified low ash peat. The proportion of easily soluble organic carbon increased, whereas the sulphur content decreased with the soil development state. The nitrogen content and the proportions of oxalate soluble iron and aluminium reached maxima in the moorshified state. The type of land use (grassland, forest) significantly influenced the topsoil pH and the proportion of oxalate soluble phosphorus. Soils under forest were clearly determined by topsoil acidification.     

Impact of indigenous‐based interventions on land conservation: a case study of a soil conservation and agroforestry project,Arumeru District,Tanzania

Land degradation has been identified as a serious problem in Tanzania since the 1920s. Among the factors normally cited as contributing to land degradation are deforestation, overgrazing and inappropriate farming practices. Several attempts by the government to arrest the problem have been based on top‐down approaches. Indigenous‐based interventions are among the alternative practices adopted by the Soil Conservation and Agroforestry Project in Arumeru District, Tanzania. The main objective of this study was to assess the impact of the indigenous‐based interventions on land conservation. More specifically the study intended to assess farmers' perception of land degradation, the adoption rate of indigenous‐based interventions, the impact of those interventions, and lastly the sustainability of those interventions. Data for the study were collected through Participatory Rural Appraisal (PRA) techniques and a questionnaire survey. The Statistical Package for Social Sciences (SPSS®) was used to analyse quantitative data and Content and Structural‐Functional Analyses were used for qualitative data. The study found that the rate of land degradation was perceived by respondents to be rather severe. The study also revealed that indigenous‐based interventions, which require minimal labour and capital, have been highly adopted by many farmers while labour/capital intensive ones have been taken up by fewer farmers. In general, indigenous‐based interventions appear to have eased farm operations and contributed towards increased crop yield, improved soil fertility and increased income. Success in some of the indigenous interventions warrants their wider promotion beyond the project area. Copyright © 2005 John Wiley & Sons, Ltd.     

Regeneration of sylvopastoral lands in the Sahel zone under village management conditions

This article reports the results of a study aimed to develop an approach for the rehabilitation of sylvopastoral lands that would be applicable and sustainable under local village-management conditions. Stabilization measures involved protection against exploitation activities during a period of five years, with accompanying low-cost restoration measures (all locally known) including (i) alignments of dead wood along the contour, (ii) spreading (mulching) of dead wood, and (iii) alignments of small stones along the contour. Monitoring demonstrated remarkable and continuing regeneration of the vegetation, with restoration measures clearly accelerating such regeneration. Low-intensity grazing did not appear to be harmful. The study also demonstrated the synergy between the herbaceous and woody plant layers. However, village management of the area was increasingly neglected, and after the five-year period exploitation levels reverted back to normal, so that the results will not be sustained. This was due to neglect of socio–economic issues, including insufficient insight into the norms and values attributed by the villagers to such low potential sylvopastoral lands. Future research should focus on the socio–economic aspects of land rehabilitation, as technical means are widely known, including appropriate low-cost measures based on local practices. Recommendations focus on principles and steps to be undertaken for successful and sustainable land rehabilitation. © 1998 John Wiley & Sons, Ltd.     

Evaluating land degradation for assessment of land vulnerability to desert conditions in the Sokoto area,Nigeria

There are no standard indicators to evaluate or predict desertification. This paper describes an attempt to assess vulnerability to desert conditions in part of the Sokoto district in northwestern Nigeria, using remote sensing coupled with other ancillary data (erosion, sealing, crusting, compaction, cover change, organic matter monitoring, salinity and aridification) within a geographic information system environment.     

长期施用化肥对黄土丘陵区坡地土壤物理性质的影响

研究了17年长期定位施用化肥对黄土丘陵区坡耕地土壤物理性质的影响。结果表明: 长期施用化肥,表层（015 cm）土壤物理性状没有明显退化,中层（1530 cm）和下层（3045 cm）土壤物理性质有不同程度的改善; 长期施用化肥对水稳性团聚体影响大于土壤容重和孔隙度; 团聚体含量和稳定性在表层、中层和下层土壤中均得到不同程度地提高; 容重和孔隙度在表层和下层土壤中略有恶化,在中层土壤上得到改善。长期不同水平化肥单施对土壤物理性状无显著影响,而氮磷配施交互作用明显高于单施处理,且施肥效果为氮磷配施氮肥处理磷肥处理。处理N2P1最有利于改善研究区土壤物理性状,提高土壤的稳定性。     

不同土地利用方式对黄河三角洲盐碱地土壤理化性质的影响

采用野外调查取样和室内分析相结合的方法,分析3种不同土地利用方式对黄河三角洲河口区盐碱地土壤理化性质的影响。结果表明:1)刺槐林地土壤表层0～10 cm有机质和全氮质量分数均最高,分别为17.30和1.04g/kg,0～20 cm平均土壤密度(1.33 g/cm3)和0～100 cm平均土壤电导率(290.25μs/cm)均小于柽柳林地和棉花地,0～20 cm平均土壤孔隙度(51.91%)和黏粒质量含量(3.99%)均大于柽柳林地和棉花地;2)柽柳林地0～100cm平均土壤pH值为6.77,极显著低于刺槐林地和棉花地(P<0.01),平均土壤速效钾质量分数最高(104.47 mg/kg),极显著高于棉花地(P<0.01),而与刺槐林地差异不显著,0～100 cm平均土壤速效磷质量分数为棉花地>柽柳林地>刺槐林地;3)人工栽植的刺槐林地土壤理化性状优于天然更新的柽柳林地和人工耕作的棉花地。研究结果可为黄河三角洲河口区盐碱地土地合理利用和改良提供参考。     

旱地土壤硝态氮与氮素平衡、氮肥利用的关系

利用长期肥料试验资料研究了土壤氮素平衡、氮肥利用率和土壤硝态氮之间的相互关系。结果表明,小麦不同施肥处理的氮肥利用率（NUE）为30.9%~65.8%,平均53.6%;土壤硝态氮累积率2.3%~44.1%,平均13.2%;氮素表观损失率25.0%~42.7%,平均33.2%。一般情况下,氮素盈余值与氮肥用量呈正相关,与磷肥用量呈负相关;土壤中硝态氮的数量与氮素盈余值呈正比,与氮肥利用率呈反比。黄土旱塬地区,小麦在经济合理施氮条件下,氮素盈余值为13.79 kg/hm2,硝态氮累积量为23.00 kg/hm2,说明过量施用一定数量的氮肥对保持作物生产力和土壤氮素营养是必要的。     

Biological tools for the assessment of contaminated land: applied soil ecotoxicology

Abstract. Chemical analysis alone is inadequate for comprehensively assessing the impact of soil pollution on biota. The term bioavailability can only be applied in a context specific to a target biological receptor or a proven chemical surrogate. Integration of biological and chemical data can often yield significant advances in hazard assessment and act as a suitable baseline for making site-specific risk assessments. Here, the value of biological techniques is discussed and their application described. The relative merit of test selection is considered and the new direction being developed in sublethal assessments. Currently, however, one of the major limitations is the seeming lack of flexibility of many assays in that they are either applicable to agricultural systems or industrial scenarios, but rarely to both. As a consequence, few assays have internationally adopted protocols. The introduction of new methods and the continued improvement and refinement of assays make this area of soil science dynamic and responsive.     

Influence of former lynchets on soil cover structure and soil organic carbon storage in agricultural land,Central Czechia

Lynchets represent a traditional landscape element in agricultural landscapes having multiple functions in soil material redistribution, water retention, biodiversity and landscape character. They act as a barrier to translocated soil matter, and they can store a significant amount of soil material and soil organic carbon. Lynchets developed in many regions during formation of agriculture landscape as field boundaries or path networks. Further management led to unleveling of the fields and development of lynchets. During the 20th century, a large number of lynchets disappeared in Central and Western Europe due to land consolidation, intensification and industrialization of agriculture. This study was performed at a large agricultural study plot with dissected relief (Central Czechia) with the aim of assessing the influence of former but now completely levelled lynchets on actual soil stratigraphy, depth, soil organic carbon stocks and structure of soil units. The soil profiles in 20‐m‐long transects perpendicular to former lynchets were analysed, and statistical relationships between the positions above, in and below the former lynchets were assessed. The results showed high variability of studied soil characteristics in the areas of former lynchets. Statistically significant greater A horizon thickness (50–100 cm) and SOC stock (12.7 kg/m²) were observed in the location of a former lynchet, where colluvial soils were identified. Other areas of accumulation were identified below a lynchet, at the former break‐in‐slope. The strip above a lynchet was identified as a sediment delivery area, having a partly truncated soil profile. SOC concentration and SOC stock in A horizon did not differ significantly in the positions in, above or below a lynchet.