基于多元回归估算残留P

The remaining phosphorus （Prem）, P concentration that remains in solution after shaking soil with 0.01 mol L-1 CaCl2 containing 60μg mL-1 P, is a very useful index for studies related to the chemistry of variable charge soils. Although the Prem determination is a simple procedure, the possibility of estimating accurate values of this index from easily and/or routinely determined soil properties can be very useful for practical purposes. The present research evaluated the Prem estimation through multiple regression analysis in which routinely determined soil chemical data, soil clay content and soil pH measured in 1 mol L-1 NaF （pHNaF） figured as Prem predictor variables. The Prem can be estimated with acceptable accuracy using the above-mentioned approach, and pHNaF not only substitutes for clay content as a predictor variable but also confers more accuracy to the Prem estimates.     

Digital soil mapping in Germany—a review

Digital soil mapping as a tool to generate spatial soil information provides solutions for the growing demand for high‐resolution soil maps worldwide. Even in highly developed countries like Germany, digital soil mapping becomes essential due to the decreasing, time‐consuming, and expensive field surveys which are no longer affordable by the soil surveys of the individual federal states. This article summarizes the present state of soil survey in Germany in terms of digitally available soil data, applied digital soil mapping, and research in the broader field of pedometrics and discusses future perspectives. Based on the geomorphologic conditions in Germany, relief is a major driving force in soil genesis. This is expressed by the digital–soil mapping research which highlights the great importance of digital terrain attributes in combination with information on parent material in soil prediction. An example of digital soil mapping using classification trees in Thuringia is given as an introduction in digital soil‐class mapping based on correlations to environmental covariates within the scope of the German classification system.     

松嫩平原北部粮食主产区克山县三生空间识别

精准识别并掌握粮食主产区生产、生活、生态空间对保障国家粮食安全促进国土空间健康可持续发展具有重要意义，该研究以克山县为研究区，基于克山县2015年土地利用变更调查矢量数据库，采用耦合协调度与反距离权重插值的方法，通过探析三生功能之间的耦合协调性，对研究区三生空间进行细粒度网格下的精准识别。研究结果表明：1）研究区以生产功能为主且空间分布较为均衡；生活功能主要体现在农村居民点与建制镇并与生产功能呈现出空间一致性；生态功能具有一定的空间分异特征与生产功能、生活功能表现出明显的空间互补性。2）研究区以三生功能磨合区与协调区为主基调，符合粮食主产区功能定位。3）研究区可识别出6种空间，整体上呈现出以生产-生活-生态空间与生产-生态空间为主体并零星伴有其他功能的国土空间格局。研究结果可为粮食主产区"三区三线"的划定提供科学依据。     

Estimating the water retention curve from soil properties: comparison of linear, nonlinear and concomitant variable methods

The unsaturated soil hydraulic functions involving the soil–water retention curve (SWRC) and the hydraulic conductivity provide useful integrated indices of soil quality. Existing and newly devised methods were used to formulate pedotransfer functions (PTFs) that predict the SWRC from readily available soil data. The PTFs were calibrated using a large soils database from Hungary. The database contains measured soil–water retention data, the dry bulk density, sand, silt and clay percentages, and the organic matter content of 305 soil layers from some 80 soil profiles. A three-parameter van Genuchten type function was fitted to the measured retention data to obtain SWRC parameters for each soil sample in the database. Using a quasi-random procedure, the database was divided into “evaluation” (EVAL) and “test” (TEST) parts containing 225 and 80 soil samples, respectively. Linear PTFs for the SWRC parameters were calculated for the EVAL database. The PTFs used for this purpose particle-size percentages, dry bulk density, organic matter content, and the sand/silt ratio, as well as simple transforms (such as logarithms and products) of these independent variables. Of the various independent variables, the eight most significant were used to calculate the different PTFs. A nonlinear (NL) predictive method was obtained by substituting the linear PTFs directly into the SWRC equation, and subsequently adjusting the PTF parameters to all retention data of the EVAL database. The estimation error (SSQ) and efficiency (EE) were used to compare the effectiveness of the linear and nonlinearly adjusted PTFs. We found that EE of the EVAL and the TEST databases increased by 4 and 7%, respectively, using the second nonlinear optimization approach. To further increase EE, one measured retention data point was used as an additional (concomitant) variable in the PTFs. Using the 20 kPa water retention data point in the linear PTFs improved the EE by about 25% for the TEST data set. Nonlinear adjustment of the concomitant variable PTF using the 20 kPa retention data point as concomitant variable produced the best PTF. This PTF produced EE values of 93 and 88% for the EVAL and TEST soil data sets, respectively.     

西南喀斯特典型区国土空间地域功能优化分区

国土空间优化是促进喀斯特地区可持续发展的重要抓手,也是解决喀斯特地区生态和贫困问题的有效途径。为实现喀斯特地区国土空间的协调发展,研究以西南喀斯特典型区广南县为例,基于城镇-农业-生态功能协调方法和国土空间"双评价"方法的探索,以及冲突空间修正规则的制定,提出了一种国土空间地域功能综合优化分区方法,并结合地理空间建模和统计分析工具,构建了喀斯特地区国土空间地域功能综合优化分区格局。结果表明:1)最适宜级和适宜级占比之和最多的是生态保护适宜性,为61.21%,主要分布于北部和东部,城镇开发适宜性最少,为27.81%,主要分布于中部和南部,农业开发适宜性为49.80%,主要分布于东北部和东部;资源环境承载力以VI级和V级为主,在东北部和东南部承载力等级最高,在南部、西南部和西北部最低;2)在国土空间地域功能优化分区中,与生态功能相关的国土空间类型占据喀斯特地区发展的主导地位,占79.54%,与城镇功能相关的国土空间类型最少,占2.35%;以城镇功能为主导的区域主要分布于中部和东南部,以农业功能为主导的区域主要分布于北部、西部和东部,以生态功能为主导的区域主要分布于北部和南部。3)双评价方法和城镇-农业-生态功能协调方法的结合能够更精准化和更合理的构建喀斯特地区国土空间格局。不同国土空间地域功能类型的合理布局将为喀斯特地区生态环境质量的提升、石漠化状况的治理以及国土空间的协调发展提供借鉴和参考。     

基于模糊顺序形态学的植物叶片脉络边缘提取

植物叶片是作物分类和识别的简单有效方法,叶片的脉络和边缘特征提取是识别叶片的基础步骤。植物叶片图像通常受噪声影响,提取清晰的脉络和边缘比较困难,该文提出了基于模糊顺序形态学的植物叶片脉络边缘特征提取方法。首先,根据像素邻域特性,利用植物叶片脉络边缘及内部区域的差异性,构造了隶属度函数;然后,依据Sugeno模糊模型,定义了能够增大叶片脉络边缘和内部区域差异的模糊规则,进行模糊推理;该文采用了抑制噪声特别有效的顺序形态学边缘检测算子,对图像进行脉络边缘提取,最终得到植物叶片脉络和边缘信息图像。试验结果表明,该文方法克服了自然环境中噪声的影响,提取的植物叶片脉络和边缘更加清晰、定位更加准确。     

Pedotransfer functions for the pool size of slowly mineralizable organic N in sandy arable soils

The major aim of this study was to evaluate how the pool size of slowly mineralizable, ‘old’ soil organic N can be derived from more easily accessible soil and site information via pedotransfer functions (PTF). Besides modeling, this pool size might be of great importance for the identification of soils with high mineralization potential in drinking‐water catchments. From long‐term laboratory incubations (ca. 200 days) at 35 °C, the pool sizes of easily mineralizable organic N (N_fast), mainly in fresh residues, and slowly mineralizable, ‘old’ soil organic N (N_slow) as well as their first‐order rate coefficients were obtained. 90 sandy arable soils from NW Germany served to derive PTFs for N_slow that were evaluated using another 20 soils from the same region. Information on former land‐use and soil type was obtained from topographical, historical, and soil maps (partly from 1780). Pool size N_slow very strongly depends on soil type and former land‐use. Mean pool sizes of N_slow were much lower in old arable lowland (105 mg N kg^–1) than upland soils (175 mg N kg^–1) possibly due to lower clay contents. Within lowlands, mean pool sizes in former grassland soils (245 mg N kg^–1) were 2 to 3 times larger than in old arable soils due to accumulation of mineralizable N. In contrast, mean pool sizes of N_slow were lowest in recently cleared, former heath‐ and woodland (31 mg N kg^–1) as a result of the input of hardly decomposable organic matter. Neither N nor C in the light fraction (density < 1.8 g cm^–3) was adequate to derive pool size N_slow in the studied soils (r² < 0.03). Instead, N_slow can be accurately (r² = 0.55 – 0.83) derived from one or two basic soil characteristics (e.g. organic C, total N, C : N, mineral fraction < 20 μm), provided that sites were grouped by former land‐use. Field mineralization from N_slow during winter (independent data set) can be predicted as well on the basis of N_slow‐values calculated from PTFs that were derived after grouping the soils by former land‐use (r² = 0.51***). In contrast, using the PTF without soil grouping strongly reduced the reliability (r² = 0.16).     

Changes in Agricultural Land Use Affecting Future Soil Redistribution Patterns: A Case Study in Southern Tuscany (Italy)

Land‐use changes (LUCs) can be defined as the result of the direct action of the stakeholders in a particular area and natural or human driving forces. LUCs can influence various processes within the landscape and can have an impact on landscape functions. An analysis of the impact of LUCs on landscape processes can help to focus future rural policies. LUCs in Mediterranean areas particularly affect landscape functions because of their agro‐pedoclimatical characteristics. The aims of this work are as follows: (i) to characterise LUCs in the last 11 years in a typical Mediterranean area, the Trasubbie river basin (southern Tuscany, Italy); (ii) to extrapolate these changes and create spatially explicit LUC scenarios for the near future; and (iii) to simulate how and where the predicted LUCs may affect soil redistribution. We carried out an analysis of LUCs within the study area and used the trends to propose alternative scenarios for 2013. For these years, we spatially allocated land use (using the Conversions of Land Use and its Effects model) and used a landscape process model (landscape process modelling at multi‐dimensions and scales) to assess soil redistribution patterns. Land use in the study area changed almost linearly between 1996 and 2007, with cereals and annual fodder crops decreasing, and vineyards, perennial pastures and land abandonment increasing. Our LUC scenario extrapolates these dynamics to make predictions for 2013. A comparison of LAPSUS results between LUC and baseline scenarios for 2013 showed an increase in terms of net soil loss and total erosion, and a decrease in terms of sediment delivery ratio. Copyright © 2013 John Wiley & Sons, Ltd.     

根系对土壤机械压力影响的模拟试验

为了研究根系对土壤机械压力的大小、分布和影响因素以及各个因素与其相互关系,该研究采用自制的压力测量装置,测定并分析了不同模拟根系对不同体积质量土壤产生的机械压力及其影响因素。试验结果表明：模拟根系对土壤机械压力与根系直径呈极显著（p＜0.01）幂函数关系,随着直径增加,根系对土壤的机械压力增加;随着土壤体积质量增加和土层深度增加,根系对土壤机械压力增加;当植株受到风力作用时,随着风力变大,根系对土壤机械压力呈递增变化。模拟研究表明,根系生长可以对土壤产生机械压力,地表风力等扰动力量也可以传递到根系并引起这种机械压力的变化,这种压力可能会对土壤结构和物理行为产生影响,需要进一步深入研究。尽管该文是通过模拟根系进行模拟生长试验,仍然对研究根系生物力学有指导意义。