The impact of land use on soil properties in a karst agricultural region of Southwest China: a case study of Xiaojiang watershed, Yunnan

Supported by RS and GIS, the land use change from 1982 to 2003 were analyzed and the impacts of land use changes on pH value, organic matter, total N, total P, total K, available N, available P, and available K in soil of Xiaojiang watershed, a typical karst agricultural region of Yunnan Province, Southwest China were assessed. The following aspects are concluded. （1） The total land use converted during the past 20 years in Xiaojiang watershed covers an area of 610.12 km^2, of which 134.29 km^2 of forestland was converted into cultivated land, and 210 km^2 of.unused land was converted into cultivated land. （2） The rapid growth of population and the economic development were the main driving forces of land use change. （3） With the change in land use, the soil properties have been changed significantly. The pH, organic matter, total N, total P, total K, available N, available P and available K in soil in 1982 were 6.3, 38.02 g·kg^-1, 1.86 g·kg^-1, 1.63 g·kg^-1, 10.94 g·kg^-1, 114.42 g·kg^-1, 11.65 mg·kg^-1 and 64.69 mg·kg^-1g, respectively; and those in 2003 were 6.73, 25.26 g·kg^-1, 1.41 g·kg^-1, 0.99 g·kg^-1, 12.6 g·kg^-1, 113.43 mg·kg^-1, 11.11 mg·kg^-1 and 151.59 mg·kg^-1, respectively. Pared samples t-test of the tested indices of soil properties indicate that those indices have changed significantly during the last 20 years. But the soil properties changed differently, due to the differences in land use change. （4） Also, with the change in land use and management measures of soil, the modifications in soil properties which developed from carbonate rocks were more sensitive than those in the soil developed from sandstone.

Impacts of Changes in Structure of Rural Land Property Rights on Agricultural Performance

In the reform process of the rural land property rights system,the incentive mechanism of the rural land property rights system has a crucial impact on the production activities of rural economic entities.Due to the different rights structures of the property rights system in different social and economic development stages,the land rights and interests enjoyed by rural economic subjects are different,and the degree of incentives for farmers is also different.This difference in incentives affects farmers investment in agricultural production factors,which in turn affects agricultural performance.This paper analyzes the incentive impacts of the structure of rural land property rights on the changes of farmers land rights and agricultural performance since the founding of the People s Republic of China,in order to further deepen the reform of the land system,protect the rights and interests of farmers,promote the modernization of agriculture and rural areas,and explore the realization form and operation mechanism of the rural collective land system in the new era.

Reform Paths of Rural Land Property Rights System in the Context of Agricultural Modernization

The reform of rural land property rights system can promote large-scale and intensive agricultural production,improve the quality of laborers,improve agricultural production efficiency,increase farmers'income,and effectively promote the development of agricultural modernization.In the context of the reform of the"separation of three powers",the rural land property rights system still has problems in terms of ownership,use rights,disposal rights,and income rights,which affect the healthy development of agricultural modernization.In this situation,it is necessary to further clarify the subject of rural land ownership,thoroughly improve the right to use rural land,vigorously improve the right to dispose of rural land,effectively protect the right to benefit from rural land,and deeply promote the reform of the rural land property rights system in order to effectively promote the development of agricultural modernization.

Effect of Agricultural Land Use Changes on Soil Nutrient Use Efficiency in an Agricultural Area,Beijing,China

Agricultural land use and management practices may affect soil properties,which play a critical role in sustaining crop production.Since the late 1970s,several new agricultural land use types had been introduced in the rural areas of China.The purpose of this study is to evaluate the effect of these land use changes on the soil properties,nu-trient absorption rate,and nutrient use economic efficiency ratio in an agricultural area of Beijing.Specifically,the cropland,the orchard and the vegetable field were examined.Results of this study suggest that land use and farming management practices significantly affect the content of soil organic carbon (SOC),total nitrogen (TN),total phos-phorus (TP),and available phosphorus in the surface layer of 0-25 cm (p<0.05) in the Yanqing Basin,northwestern Beijing.Soil nutrients in each agricultural land use type decrease rapidly with the increasing soil depth.Orchard and vegetable field tend to have higher soil nutrients than the cropland does.However,the soil nutrient-absorption rate (NAR) of the orchard and vegetable field is lower than that of the cropland,even though orchard and vegetable field may provide much higher economic benefit.While increasing SOC,TN,and TP in the orchard and vegetable field by intensive farming may be a valuable option to improve soil quality,potential increase in the risk of nutrient loss,or agricultural non-point source pollution can be a tradeoff if the intensive practices are not managed appropriately.

Path Choice of Rural Land Transfer in China

Establishing rural land collective property right system with clear ownership,complete powers and functions,smooth transfer,and strict protection is the basic guarantee to the equal exchange of land elements. In this study,the reform of relevant legal systems to China's rural land transfer was introduced firstly,and then the guiding ideology of China's rural land transfer was proposed. Finally,the ways of practicing rural land transfer in China were discussed. Based on the premise of insisting on and improving the strictest land preservation system,farmers should have the right to occupy,use,and transfer their contracted land,and they can transfer their land contracting and management right in ways of exchange,subcontracting,renting,stock cooperation,and trust. Exploring the ways of equal exchange of land elements according to local conditions is an important political and economic issue concerning the livelihood and development of farmers in China,so it should be conducted under the guidance of the correct ideas to integrate scattered land in China's rural areas,develop moderate-scale management,shorten the income gap between urban and rural areas,and realize balancing development of urban and rural areas in China.

Soil Health and Sustainable Land Resource Management Practices at Municipal Level: A Case from Bheri Nagarpalika (Municipality), Jajorkot District, Nepal

The increasing challenges of pressure and ever-growing demands on limited resources in Nepal by diverse actors,land degradation,biodiversity loss and climate change require the rational use of land resources to sustain and enhance productivity and maintain resilient ecosystems for achieving the sustainable and efficient use of resources,taking into account biophysical and socioeconomic dimensions.Regarding this,Nepal Government has realized and taken initiation of scientific and sustainable land use zoning following the National Land Use Act 2019(2076 B.S.)to use land resources in practicable and sustainable manner.Using spatial information techniques such asZ-3 satellite image,remote sensing(RS),global positioning system(GPS)and geographic information system(GIS).Multicriteria decision making(MCDM)methods for acquiring spatial/temporal data,through expert judgment techniques based on field observation as well as laboratory analysis result,it was found that the soil nutrient status of,the municipality varied spatially and has pH with very high acidic to slightly alkaline but most of the soils are slightly acidic(39.58%).Majority of the soil are loam and sandy loam type with very low to high level of organic matter.Most of the municipal area is under medium range of organic matter.Nitrogen content ranges from very low to very high level as to same ranges of phosphorous(37.69%).Potassium level is also in very high to low as 37 percent land area has high level of potassium.Reclamation of acidic soil mainly in leachable soil is recommended with the proper management of Nitrogen with addition of organic matter is needed to manage for improving crop production.

Soil chemical properties under modern and traditional farming systems at Khagrachari,Chittagong Hill Tracts,Bangladesh

Land degradation in Chittagong hill tracts has been taking place due to shrinkage of forest cover, policy weakness, population explosion, and inappropriate hill farming system. Modem farming system in the Chittagong hill tracts like Sloping Agricultural Land Technology （SALT） is practiced to provide a new strategy for developing lands for economic productivity and bio-diversity conservation through establishment of ecological community rather than traditional shifting cultivation which is no longer sustainable according to the carrying capacity of ecosystem of Chittagong hill tracts. This study is to find out changing trends of soil chemical properties of sites under modem and traditional farming systems at Khagrachari district of Chittagong hill tracts. The result of the research shows that Sloping Agricultural Land Technology has significantly higher capacity of production due to the presence of the highest percentage of organic carbon, organic matter, compared with shifting cultivated site. The study recommends that shifting cultivation may be changed into a relatively stable semi-permanent farming system through developing participatory integrated farming systems to establish stable production environment in the Chittagong Hill Tracts.

Salinity status of the 2011 Tohoku-oki tsunami affected agricultural lands in northeast Japan

As Japan has abundant annual rainfall(1,000 to 2,500 mm),soil salinity of agricultural lands has rarely been a major problem.Following the 2011 earthquake in the Pacific,large stretches of land along the coast in northeast Japan were devastated by a powerful tsunami.Saltwater damage of agricultural lands was so severe that agricultural crops could not be grown on large parts of the tsunami-inundated farmlands even two years after the disaster.This paper summarizes the status of agricultural lands in northeast Japan’s Tohoku region that were affected by the tsunami.The paper presents the results of a field study of agricultural lands in Miyagi Prefecture,where the extent of the seawater damage was the most severe,representing 67%of the total tsunami-affected agricultural lands.Forty samples from surface and underlying(undisturbed)soil were collected from 30 different locations in coastal and tsunami-inundated farmlands and from inland sites located beyond the limit of the tsunami inundation.The analyses and measurements showed that the extent of soil salinity varied greatly across these sites,with the highest electrical conductivity(EC)value of 3.72 dS m^(-1) found in the surface soil of Minamisanriku cho.In addition,two study sites adjacent to each other,Watari cho and Yamamoto cho,had maximum and minimum EC values of 2.0 dS m^(-1) and 0.21 dS m^(-1),respectively,in their underlying soils.A comparison of the major soil properties revealed that the salinity status of the tsunami-inundated farmlands was dependent on particle size distribution and therefore on the infiltration rate of the soil,as well as the relative physical position(elevation)of the farmland.This study led us to carry out further investigations and experiments(still on-going)related to restoration and mitigation work in the tsunami-inundated agricultural lands,giving the highest priority to the major soil properties of different field sites in Miyagi Prefecture.

秸秆覆盖免耕对坡耕地土壤理化性质及水土流失的影响

为探究秸秆覆盖免耕对坡耕地土壤理化性质的影响及该措施下的水土保持效益。通过设立秸秆覆盖免耕和传统耕作田间试验区,探究土壤孔隙结构、土壤含水量、化学性质、产流产沙情况。结果表明:秸秆覆盖免耕处理后,土壤深度(h)为0<h≤10 cm处土壤密度增加了14.16%,总孔隙度及非毛管孔隙度分别降低了10.85%、27.11%。土壤深度为0<h≤20 cm处土壤有机质及全氮流失量减少,有效改善了土壤养分含量及分布。土壤深度为10、20、30、40 cm处土壤含水量分别提高6.30%、5.78%、7.57%、9.03%。在相同降雨条件下,土层越深土壤水分滞留时间越短。秸秆覆盖免耕处理减弱了降雨侵蚀力对产流产沙的影响,产流产沙次数及数量较传统耕作处理有明显降低,产流、产沙次数分别减少3、5次,产流、产沙量分别减少53.07%、71.87%。秸秆覆盖免耕能够有效降低降雨对产流产沙的驱动力,减少土壤有机质及氮流失,调节土壤结构。

实现我国农业适度规模经营的EBSP分析

农业适度规模经营是实现我国农业现代化的必由之路,从理论上构建实现农业适度规模经营的一般分析框架具有重大的现实意义。运用马克思主义政治经济学分析范式,构建由环境分析、行为分析、结构分析和绩效评价四个部分组成的实现农业适度规模经营的EBSP分析框架:环境分析包括自然环境、社会经济环境和制度环境分析;行为分析考察政府、农户以及新型农业经营主体的行为选择与演化;结构分析研究农业适度规模经营主体的培育以及农业生产经营的组织化程度和社会化服务水平,亦是这一分析框架的核心;绩效评价主要从农民、农业和农村三个角度来进行,以收入指标为主、效率指标为辅。还应深化制度改革,规范主体行为,优化内在结构,完善激励机制,以促进农业适度规模经营的实现。

土地确权对农业生产率的影响——基于中国家庭金融调查(CHFS)的双重差分研究

土地产权的明晰界定对于农业生产率增长具有重要意义,中国新一轮渐进式的土地确权改革为探究两者的关系提供了一个良好的外生自然实验。使用中国家庭金融调查(CHFS)2013年和2015年两轮追踪面板数据,利用村庄间的土地确权进度差异构造多时点双重差分(Staggered DID)模型,检验土地确权对农业生产率的影响及其作用机制。研究发现,土地确权显著提高了农户的农业生产率,在修正样本选择性偏差、处理内生性问题、替换生产率测度指标等一系列稳健性检验后,该结果依然显著成立。进一步分析发现,土地确权对农业生产率的影响在不同土地规模、不同地区和不同生产率水平的农户之间存在异质性,对于土地规模较大、东部地区,以及农业生产率较高的农户,由确权导致的生产率增长效应显著更大。机制检验表明,土地确权的生产率增长效应主要是通过促进农户间土地流转和增加农业生产性投资实现的,而通过提高信贷可获得性促进农业生产率的机制尚未发挥作用。

农业投资与土地流转价格--基于地租理论视角

在农村土地所有权、承包权、经营权分置的制度安排下,土地流转价格成为全新的地租范畴。本文基于地租理论,以粮食规模经营主体为例审视了农业投资与土地流转价格的关系,并利用2017年与2019年中国农村家庭追踪调查数据(CRHPS)进行实证检验。结果显示,粮食规模经营主体的农业投资提高了土地流转价格;相比于一般性投资,专用性投资的影响效果更为明显。机制分析发现,粮食规模经营主体通过农业投资增加了粮食收入,部分收入以级差地租的形式转化为土地流转价格。进一步地,本文还发现农业投资尤其是一般性投资提高了地租率,表明该投资带来的边际收益更多地被转出方获得。这种利益分配不利于粮食规模经营主体等转入方,可能影响其投资的积极性;相比而言,专用性投资具有长期改良土地、降低土地经营权转出风险的作用,从而使得地租率出现明显下降。本文对于在地租理论框架下调节土地流转价格,实现土地流转的帕累托改进具有重要的政策含义。

安宁河干旱河谷区不同类型农用地土壤抗冲性及与土壤性质关系

[目的]揭示安宁河干旱河谷区不同类型农用地土壤抗冲性变化特征,阐明影响安宁河干旱河谷区农用地土壤抗冲性的主要土壤因子,并进而为安宁河干旱河谷区农用地水土流失防治提供科学依据。[方法]以桉树经济林(EEF)、马铃薯耕地(PCL)、牧草地(GL)、撂荒地(AL)和青花椒园地(GPG)为研究对象,采用原状土水槽冲刷法进行土壤抗冲性试验,同时采集土壤样品测定土壤性质,对土壤抗冲系数与土壤性质进行Pearson相关性和逐步回归分析。[结果](1)在15 min冲刷过程中,径流含沙量随冲刷时间的延长,先急剧下降随后趋于平缓稳定;抗冲系数随冲刷时间的延长总体呈增长趋势,二者关系用对数、逆函数或线性函数拟合效果较好;选取的5种类型农用地土壤抗冲性表现为GL>EEF>GPG>AL>PCL。(2)农用地土壤性质主要受人类活动的影响,GL和EEF土壤性质优良,AL和PCL较差,GPG介于上述二者之间,团聚体稳定性表现为GPG>GL>EEF>AL>PCL。(3)相关性和逐步回归分析表明,土壤抗冲性主要受土壤机械组成和水稳性团聚体影响,最优回归方程为:土壤抗冲系数=84.016-1.135×<0.25 mm水稳性团聚体-7.413×黏粒。[结论]安宁河干旱河谷区耕地土壤资源受到耕作的严重危害,土壤质量严重下降,园地土壤抗冲性和土壤性质相对较差,应加强对耕地和园地资源的重视和保护。

农地流转如何影响农业机械化——基于1878个水稻种植户的实证分析

在农业农村现代化不断推进的背景下,利用1878份南方水稻种植户调查数据,运用规模经济、农业分工和交易成本理论,探讨农地流转对水稻种植户机械化水平及其模式的影响。研究发现,农地流转显著提升了农业机械化水平,并促使机械化模式发生转变。利用农户产权安全感知度作为农地流转的工具变量,克服模型内生性,结果仍然稳健。具体而言,农户转入土地面积每增加一个百分点,其水稻种植机械化作业面积将增加0.386个百分点。同时,农户转入土地后自置农机的概率上升,而雇佣机耕和机收服务的概率下降,致使农机社会化服务市场转型。异质性分析表明,土地细碎化程度越高则更可能降低农地流转对农业机械化的正向影响;同时,中青年农户相比老年农户的农业生产机械化程度更高。为进一步推动小农户向现代农业转型,加快我国农业农村现代化进程,还需要加强土地产权保护、促进农地流转。

农地产权稳定性与农业低碳发展——基于新一轮农地确权改革的考察

研究目的:探析增强农地产权稳定性对农业低碳发展的影响及其内在机制,为深化农村土地产权制度改革和促进农业低碳发展提供理论支撑和经验证据。研究方法:基于2012—2021年中国市级面板数据,以2013—2019年开展的新一轮农地确权改革为准自然实验,采用交错双重差分模型探讨农地产权制度改革对农业低碳发展的影响。研究结果:农地产权稳定性的增强显著降低了农业碳强度,提升了农业碳效率,对农业低碳发展产生积极影响。这一结果在考虑内生性问题、异质性处理效应并进行一系列稳健性检验后依然成立。进一步分析表明,增强农地产权稳定性通过“规模经营”和“长期投资”效应促进农业低碳发展,同时也因市场化程度和普惠金融发展水平的不同产生异质性。研究结论:农地产权稳定性的增强在农业低碳发展过程中发挥了重要作用,应深化农村土地产权制度改革,因地制宜优化内外部发展环境,优化配套政策,多措并举推进农业低碳发展。

The effect of environmental factors on spatial variability in land use change in the high-sediment region of China＇s Loess Plateau

In areas with topographic heterogeneity, land use change is spatially variable and influenced by climate, soil properties, and topography. To better understand this variability in the high-sediment region of the Loess Plateau in which soil loss is most severe and sediment diameter is larger than in other regions of the plateau, this study builds some indicators to identify the characteristics of land use change and then analyze the spatial variability as it is affected by climate, soil property, and topography. We build two indicators, a land use change intensity index and a vegetation change index, to characterize the intensity of land use change, and the degree of vegetation restoration, respectively. Based on a subsection mean method, the two indicators are then used to assess the spatial variability of land use change affected by climatic, edaphic, and topographic elements. The results indicate that： 1） Land use changed significantly in the period 1998-2010. The total area experiencing land use change was 42,302 km2, accounting for 22.57%of the study area. High-coverage grassland, other woodland, and forest increased significantly, while low-coverage grassland and farmland decreased in 2010 compared with 1998.2） Land use change occurred primarily west of the Yellow River, between 35 and 38 degrees north latitude. The four transformation types, including （a） low-coverage grassland to medium-coverage grassland, （b） medium-coverage grassland to high-coverage grassland, （c） farmland to other woodland, and （d） farmland to medium-coverage grassland, were the primary types of land use change, together constituting 60% of the area experiencing land use change. 3） The spatial variability of land use change was significantly affected by properties of dryness/wetness, soil conditions and slope gradient. In general, land use changed dramatically in semi-arid regions, remained relatively stable in arid regions, changed significantly in clay-rich soil, remained relatively stable in clay-poor soil, changed dramatically in steeper slopes, and remained relatively stable in tablelands and low-lying regions. The increase in vegetation coincided with increasing changes in land use for each physical element. These findings allow for an evaluation of the effect of the Grain to Green Program, and are applicable to the design of soil and water conservation projects on the Loess Plateau of China.

农户生计资本对农地流转意愿与行为的影响机制——基于山东曲阜359份农户调查问卷的实证

[目的]探究农户生计资本五个维度对农地流转意愿及行为的影响机制,为推动农地合理流转、提高农地利用效益、促进适度规模经营提供科学依据。[方法]基于山东省曲阜市3镇12村调查获取的359份农户问卷数据,采用二元Logistic回归进行了分析。[结果]物质资本、金融资本与流转意愿和转入意愿呈5%显著相关,自然资本与转出意愿呈5%显著相关,社会资本与转入行为呈10%显著相关,物质资本、社会资本与转出行为呈10%显著相关。[结论]调研区域流转意愿较为旺盛,农地流转比例相对较高,但二者还存在一定差距。不同维度的生计资本对于流转意愿和流转行为的影响并不完全相同。为推动农地合理流转,应进一步完善农地流转市场机制,加强政府宏观调控与中介职能,提高农户生计资本。

Land degradation and integrated watershed management in India

In view of the stagnating productivity levels of irrigated agriculture,the contribution from rainfed agriculture should be increased to meet the requirements from the ever growing human and animal population of India.Land degradation is a major threat to our food and environment security and the extent of degradation problems are more pronounced in rainfed regions.Large potential of rainfed agriculture is untapped largely due to lack of enabling policy support and investments.In drought-prone rainfed areas,watershed management has shown the potential of doubling the agricultural productivity,increase in water availability,restoration of ecological balance in the degraded rainfed ecosystems by greening these areas and diversification of cropping farming systems.Impact of various watershed programmes can be substantially enhanced by developing new approaches and enabling policies new paradigm based on learnings over last 30 years for people-centric holistic watershed management involving convergence,collective action,consortium approach,capacity development to address equity,efficiency,environment and economic concerns is urgently needed.However,this can be used as entry point activity for improving livelihood for rural community.It has been realized that for sustainable developments of degraded lands,involvement of people(land less and beneficiaries)is very much essential.For the last decade efforts have been made institutionalize the organizations of the community&beneficiaries and ensuring their involvement in planning project formulation,implementation and maintenance.Government of India has launched various centre-sector,state-sector and foreign aided schemes for prevention of land degradation,reclamation of special problem areas for ensuring productivity of the land,preservation of land resources and improvement of ecology and environment.These schemes are being implemented on watershed basis in rainfed areas.Soil conservation measures and reclamation of degraded lands are decided considering the land capability and land uses.The efforts made so far resulted in enhancement of agricultural production and productivity of lands,increase in employment generation,improving the environment of the areas and socio-economic upgradation of the people.Integrated watershed management approach has been adopted as a key national strategy for sustainable development of rural areas.This has been proved by conducting monitoring and impact evaluation studies of the integrated watershed projects by external agencies.

典型岩溶农业区土地利用变化对土壤性质的影响——以云南小江流域为例

以云南省泸西县小江典型岩溶农业流域为研究单元,分析了流域1982￣2003年土地利用的变化及定点对比分析不同土地利用变化下土壤性质的变化,结果表明:小江流域1982￣2003年610.12km2的土地利用发生了变化,变化类型主要是由未利用地向耕地、林地以及林地向耕地的转变,人口的增加、社会、经济的发展和理智的生态决策是流域土地利用变化的主要原因;林地、未利用地转变为耕地后,土壤有机质、全氮、全磷含量大幅度降低,土壤pH明显升高,全钾、速效钾含量增加;短时间的退耕还林,土壤性质变化不明显;耕地转变为园地后,土壤性质得到明显的改善;而耕地转变为石漠化土地后,土壤性质发生显著变化,土壤有机质、全氮、全磷、碱解氮、速效磷含量大幅度降低,土壤pH明显升高;同时,研究表明土地利用变化对碳酸盐岩地层中发育的土壤性质的影响强度明显大于砂页岩地层中发育的土壤,表明碳酸盐岩地层中发育的土壤十分脆弱。

农牧交错带土地沙化的本质及其形成研究

通过对陕北农牧交错带不同类型沙化土地土体构型、土壤质地、元素组成和理化性质的分析 ,研究了土地沙化的本质。结果表明 :受风沙作用影响 ,土壤中细粒物质逐渐减少 ,颗粒组成变粗 ;表层消失 ,最终被流沙所取代 ,原土壤剖面被覆盖在沙层之下 ;土壤有机质及养分含量减少 ,保水保肥性能降低 ,生产力不断下降 ;现代土壤形成过程以侵蚀和风沙沉积为主 ,物质淋溶和化学风化微弱。研究区土地沙化可划分为 :风沙侵蚀为主、风沙蚀积平衡、风沙沉积为主和土壤形成发育 4个阶段 ;沙化土地的类型有 :肥力衰退质地粗化、表层剥蚀、片沙覆盖、流动沙丘与固定沙丘等 5种。