Validation of topsoil texture derived from agricultural soil maps by current dense soil sampling

Agricultural soil maps were created to facilitate the management of fields. Such maps, at very large scale (1:5000), cover almost the entire agricultural land in Poland. These maps can be very useful for precision field management. However, they were prepared about 40–50 years ago using old mapping techniques with mainly field (organoleptic) examination of soil. For this reason it is necessary to verify agreement between such maps with the current soil status. In the case of detection of disagreements it is important to identify the causes and propose methods for improving soil maps. Only few studies were made in this aspect. The soil texture (ST) of the upper layer, as presented on the agricultural soil maps from the 1960s and 1970s, was compared with the actual ST of the same four fields in northern and central Poland. For laboratory ST determination, soil samples were collected in a dense sampling network. On average, the agreement of the ST presented on the agricultural soil maps and determined in this study was classified as medium for three fields and good for one field. However, the presence of field areas with poor agreement between the ST determined in this study and that shown on the agricultural maps was detected in all investigated fields. Identified causes for this comprised imprecision of ST determination using the organoleptic method, the generalization of the soil quality maps, and erosion processes during the years between soil mapping and this investigation. The improvement of ST presentation on the large scale soil maps might be achieved by quite denser soil sampling for ST analysis supported by ECa, yield and NDVI maps.     

黄土高原塿土覆盖层与黏化层的土壤水文效应

黄土高原(土娄)土在《中国土壤系统分类(修订方案)》中属土垫旱耕人为土类的相应亚类,其土壤水分状况是诊断表层所属人为表层类堆垫表层(覆盖层)和诊断表下层(黏化层)的重要诊断特征。以土壤持水性能、蒸发性能和水分移动性能为切入点,对(土娄)土覆盖层和黏化层的土壤水文效应进行研究论证,以期对土垫旱耕人为土类及其亚类的诊断层与诊断特征获取更深层的认识。     

The effect of soil texture and soil drainage on emissions of nitric oxide and nitrous oxide

Abstract. Agricultural soils are important sources of the tropospheric ozone precursor NO and the greenhouse gas N₂O. Emissions are controlled primarily by parameters that vary the soil mineral N supply, temperature and soil aeration. In this field experiment, the importance of soil physical properties on emissions of NO and N₂O are identified. Fluxes were measured from 13 soils which belonged to 11 different soil series, ranging from poorly drained silty clay loams to freely drained sandy loams. All soils were under the same soil management regime and crop type (winter barley) and in the same maritime climate zone. Despite this, emissions of NO and N₂O ranged over two orders of magnitude on all three measurement occasions, in spring before and after fertilizer application, and in autumn after harvest. NO emissions ranged from 0.3 to 215 μg NO-N m^–2 h^–1, with maximum emissions always from the most sandy, freely drained soil. Nitrous oxide emissions ranged from 0 to 193 μg N₂O-N m^–2 h^–1. Seasonal shifts in soil aeration caused maximum N₂O emissions to switch from freely drained sandy soils in spring to imperfectly drained soils with high clay contents in autumn. Although effects of soil type on emissions were not consistent, N₂O emission was best related to a combination of bulk density and clay content and the NO/N₂O ratio decreased logarithmically with increasing water filled pore space.     

东北典型黑土耕层颗粒组成与腐殖质层厚度的关系

土壤颗粒组成是影响土壤肥力的主要物理性质之一.为了了解东北黑土腐殖质层厚度与土壤颗粒组成的关系,通过在东北典型黑土区选择典型坡面,调查不同地貌部位土壤腐殖质层厚度,测定耕层土壤的颗粒组成,分析腐殖质层厚度和耕层土壤颗粒组成随地貌部位的变化趋势,以及土壤颗粒组成与腐殖质层厚度的关系.结果表明:土壤腐殖质层厚度由上坡至坡脚...     

Minirhizotron quantification of soybean root growth as affected by reduced A horizon in soil

Shallow soil A horizon (topsoil) caused by soil erosion and soil movement from cultivation is known to reduce soil and crop productivity. The reduction may be related to limitation of root growth. A field study was conducted to investigate the effects of topsoil thickness on distributions of root density and growth. Soybeans [Glycine max (L.) Merr.] were grown on plots of Mexico silt loam (fine, montmorillonitic, mesic Mollic Endoaqualfs) with topsoil thicknesses of 0, 12.5, 25.0, and 37.5 cm above the Bt horizons. Root density was measured 60 and 90 days after planting using a minirhizotron video‐camera system. Root density was significantly reduced as topsoil thickness decreased from 37.5 to 0 cm. Mean density and net change of the density across profile between 30 and 60 days of growth had a linear function of topsoil thickness. The reduction and lower activity induced by shallow topsoil were attributed to detrimental properties in the Bt horizons. Root distribution pattern and rooting depth were not significantly affected by topsoil thickness. The roots appeared to be accumulated on the upper layers of the Bt horizons. Roots growing in thicker topsoil were more active than roots growing without topsoil. High soil moisture content during the growing season may mitigate the detrimental effects of shallow topsoil, inhibit root penetration, and enhance root activity.     

Associations between soil texture,soil water characteristics and earthworm populations in grassland

Abstract

The aim of the present study was to investigate the relationships between soil physical characteristics and earthworms in a regional-scale field study in Denmark. The earthworm populations along within-field gradients in soil texture were quantified at five field sites, representing dominant soil types of Denmark. Eleven earthworm species were found, but populations were mainly dominated by Aporrectodea tuberculata and A. longa. Despite considerable variation in soil parameters across the five study sites the results suggest that the biomass of anecic worms (or A. longa as a species) was not causally associated with the soil parameters studied. This indicates that there must be other causal factors associated with the abundance (and composition) of anecic worms that are not among the soil texture and structure parameters studied. On the other hand, soil texture (Coarse sand) was associated with the abundance of the dominant endogeic species, A. tuberculata, but not endogeic worms in general. It was hypothesized that anecic and endogeic earthworms might respond to local soil water characteristics rather than soil texture, but this hypothesis could not be confirmed with the present data.     

烟田土壤质地的空间变异性研究

为了解烟田土壤质地的空间变异情况进而为烟草精准施肥提供依据,本研究在地统计学和GIS的支持下,以半方差函数为基本工具,分析了平顶山地区典型烟区耕层土壤质地的空间变异特征,并运用普通克里格(Kriging)进行最优无偏线性插值,制作了黏粒、砂粒和粉粒的空间分布图。结果表明,研究区域内不同土壤颗粒在较大范围内存在空间自相关性,黏粒、砂粒和粉粒的空间自相关距离分别为609m、657m和429m;黏粒和砂粒由结构性因素引起的空间变异达80%。各向异性分析都表明,黏粒和砂粒存在较强烈的各向异性,粉粒各向异性则较小。对试验土壤来说,土壤质地具有较强的空间自相关性和变异性,这可能是影响土壤养分空间变异性的主要原因,因此在设计施肥方案时应考虑土壤质地空间变异性的影响。     

稻壳掺播对土壤质地及烟叶生产的影响

皖南烟区土壤主要为水稻土,质地偏黏,不利于烟叶生长,为此,在宣城烟区耕作层土壤中掺播一定体积比例的稻壳,探讨其对土壤质地和烟叶生产的影响。结果表明:①随着掺播稻壳比例的增加,0.02～2mm的土壤颗粒和土壤有机质含量增加,土壤体积质量(容重)、含水量和pH降低,但这种趋势随着时间推移而逐渐减缓。②烟田耕作层土壤掺播稻壳总体上有利于烤烟生长,能够提高烟叶产量和品质,经济效益也明显提高。其中以掺播20%～30%的稻壳(稻壳体积/土壤体积)时烤烟的农艺性状、经济性状及工艺评价结果最佳。     

Micromorphology of a clayey Bs horizon in an ash-derived podzolic soil from shimokita peninsula in northeastern Japan

It is well known that most developed Podzols or Spodosols occur on coarse- textured materials with a low content of weatherable minerals (Duchaufour 1977; McKeague et al 1983). In the Podzols derived from such parent material*. the th and/or Bhs horizons show definite evidence of illuviation characterized by continuous cementation, presence of cracked coatings on sand grains, and/or distinct dark pellets, These features were, therefore, adopted as the morphological criteria for spodic horizons in the Soil Taxonomy (Soil Survey Stalt 1975). The problem is to determine whether such criteria can be applied to Podzolic soils derived from volcanic ash which consists of fine, weatherable minerals.     

Soil compaction and soil management – a review

Soil compaction is an important component of the land degradation syndrome which is an issue for soil management throughout the world. It is a long standing phenomenon not only associated with agriculture but also with forest harvesting, amenity land use, pipeline installation, land restoration and wildlife trampling. This review concentrates on the impact of soil compaction on practical soil management issues, an area not previously reviewed. It discusses in the context of the current situation, the causes, identification, effects and alleviation of compaction. The principal causes are when compressive forces derived from wheels, tillage machinery and from the trampling of animals, act on compressible soil. Compact soils can also be found under natural conditions without human or animal involvement. Compaction alters many soil properties and adverse effects are mostly linked to a reduction in permeability to air, water and roots. Many methods can be used to measure the changes. In practical situations, the use of visual and tactile methods directly in the field is recommended. The worst problems tend to occur when root crops and vegetables are harvested from soils at or wetter than field capacity. As discussed by a farmer, the effects on crop uniformity and quality (as well as a reduction in yield) can be marked. By contrast, rendzinas and other calcareous soils growing mainly cereals are comparatively free of compaction problems. The effect of a given level of compaction is related to both weather and climate; where soil moisture deficits are large, a restriction in root depth may have severe effects but the same level of compaction may have a negligible effect where moisture deficits are small. Topsoil compaction in sloping landscapes enhances runoff and may induce erosion particularly along wheeltracks, with consequent off‐farm environmental impacts. Indirect effects of compaction include denitrification which is likely to lead to nitrogen deficiency in crops. The effects of heavy tractors and harvesters can to some extent be compensated for by a reduction in tyre pressures although there is concern that deep‐seated compaction may occur. Techniques for loosening compaction up to depths of 45 cm are well established but to correct deeper problems presents difficulties. Several authors recommend that monitoring of soil physical conditions, including compaction, should be part of routine soil management.     

沙质草地生境中植物群落对土壤质地演进的响应

利用空间代替时间,选取6个沙地生境类型(硬质灰钙土H_1,沙质灰钙土H_2,固定沙地H_3,半固定沙地H_4,半流动沙地H_5和流动沙地H_6),通过对其土壤颗粒组成、草地植物群落结构及数量特征的分析,研究沙质草地植物群落演替对土壤沙化过程的响应。结果表明:(1)从硬质灰钙土到流动沙地,物种丰富度分别为9,12,9,9,9,5种;演替初期(H_1-H_2)多年生草本植物种占绝对优势,演替中期(H_3-H_4)一年生植物优势度明显,演替后期(H_5-H_6)则以半灌木占主导地位;各演替阶段禾本科植物均有很高的优势度,在半流动沙地阶段成为最大优势物种,在沙质灰钙土后藜科植物优势度保持相对稳定,菊科和豆科植物分别在固定沙地和半固定沙地阶段逐渐消失。(2)物种多样性在沙质灰钙土最高,到固定沙地持续递减,而到流动沙地时又增大,生态优势度与物种多样性变化趋势正好相反,均匀度表现出先减小后增大的趋势,相邻的两个群落间具有较高的相似度。(3)从硬质灰钙土到流动沙地,0—10cm土层土壤黏粉粒含量极显著减少(p0.01),而粗砂粒极显著增加(p0.01),土壤颗粒分形维数由2.52下降到1.73。(4)一年生草本植物优势度与土壤黏粉粒含量、土壤颗粒分形维数呈显著负相关(p0.05);豆科植物优势度与土壤粉粒组分、土壤颗粒分形维数间呈显著正相关(p0.05);物种多样性与粉粒组分含量呈极显著正相关(p0.01),与细砂粒组分含量、土壤颗粒分形维数间呈显著正相关(p0.05)。     

气候和土壤质地对土壤有机碳影响的区域差异研究

The agricultural soil carbon pool plays an important role in mitigating greenhouse gas emission ana unaerstanamg the son orgamc carbon-climate-soil texture relationship is of great significance for estimating cropland soil carbon pool responses to climate change. Using data from 900 soil profiles, obtained from the Second National Soil Survey of China, we investigated the soil organic carbon （SOC） depth distribution in relation to climate and soil texture under various climate regimes of the cold northeast region （NER） and the warmer Huang-Huai-Hai region （HHHR） of China. The results demonstrated that the SOC content was higher in NER than in HHHR. For both regions, the SOC content at all soil depths had significant negative relationships with mean annual temperature （MAT）, but was related to mean annual precipitation （MAP） just at the surface 0-20 cm. The climate effect on SOC content was more pronounced in NER than in HHHR. Regional differences in the effect of soil texture on SOC content were not found. However, the dominant texture factors were different. The effect of sand content on SOC was more pronounced than that of clay content in NER. Conversely, the effect of clay on SOC was more pronounced than sand in HHHR. Climate and soil texture jointly explained the greatest SOC variability of 49.0% （0-20 cm） and 33.5% （20-30 cm） in NER and HHHR, respectively. Moreover, regional differences occurred in the importance of climate vs. soil texture in explaining SOC variability. In NER, the SOC content of the shallow layers （0-30 cm） was mainly determined by climate factor, specifically MAT, but the SOC content of the deeper soil layers （30-100 cm） was more affected by texture factor, specifically sand content. In HHHR, all the SOC variability in all soil layers was predominantly best explained by clay content. Therefore, when temperature was colder, the climate effect became stronger and this trend was restricted by soil depth. The regional differences and soil depth influence underscored the importance of explicitly considering them in modeling long-term soil responses to climate change and predicting potential soil carbon sequestration.     

Variability in topsoil texture and carbon content within soil map units and its implications in predicting soil water content for optimum workability

The ability to predict the timing of optimum soil workability depends on knowledge of the extent and structure of variability in main physical characteristics of the soil. Our objectives were to quantify the variability in texture and carbon content within soil map units in a small agriculture-dominated catchment in South-east Norway and to assess implications of variability in texture and carbon content on land management operations, using the predicted maximum water content for optimum workability as an example. Information from three different sources were used: a soil map (1:5000), a large sample grid (100 m spacing, 270 ha extent), and a small sample grid (10 m spacing, 2.25 ha extent). Readily available information on texture and organic matter content from the soil map was found to be of limited use for soil management due to broad textural classes together with deviations from the mapped main textural classes. There were significant differences in clay, silt and sand content between the different soil textural classes on the soil map. Statistical distributions within soil map units were generally either positively or negatively skewed and the coefficient of variation was intermediate, 15–50%. Most of the variation in both grids was spatially correlated. The large grid was dominated by a patchy structure, whilst the small grid showed a systematic trend with a gradual transition indicating fuzzy boundaries between map units in this catchment. The effective range for texture was 16 times larger in the large grid. Implications of variability in texture and carbon content on land management operations were assessed for the maximum water content for optimum workability (Wopt), predicted using pedotransfer functions. Wopt was usually in the same range as the water content at–100 kPa matric potential, indicating that considerable evaporation in addition to drainage is required for obtaining workable conditions in the field. The time required for obtaining the water content was estimated to about 5 days, which is longer than an average length of periods without precipitation in the area, median 3.7 days. Wopt predicted from the soil map deviated strongly from Wopt predicted from the sample grids. Comparing estimates of Wopt from the large grid with measurements in the small grid showed differences corresponding to ±2–3 days of evaporation.     

Combining ground penetrating radar methodologies enables large-scale mapping of soil horizon thickness and bulk density in boreal forests

Forest soil properties must be observed with the appropriate resolution by depth and landscape area to understand biogeomorphological controls on soil carbon (C). These observations, particularly in boreal forests, have been limited because of the poor resolution and unavailability of physical soil sampling results, especially for soil bulk density measurements. Ground penetrating radar (GPR) has been demonstrated to non-destructively and continuously estimate forest soil properties required in Cstock estimates, such as soil horizon thickness and soil bulk density, across small spatial scales and shallow depths. Yet, successful small-scale forest GPR approaches represent a potential opportunity to obtain soil property estimates at relevant resolution and depth across forest landscapes, enabling improvement to much needed soil mapping and stock estimates. This review discusses the existing soil property studies that utilize ground penetrating radar (GPR) and explores how the adaptation of GPR methodology can contribute to investigating soils in forest landscapes. We have identified common GPR surveying practices, data processing steps and interpretation methods employed in multiple studies. These approaches have proven effective in obtaining higher-resolution estimates of important soil properties, such as bulk density and horizon thickness, within small-scale forest plots. By applying relevant findings in this review to our own boreal forest investigation across an 80 m hillslope transect, we provide recommendations on how to tailor GPR methodology for landscape-scale estimates of soil horizon thickness and bulk density to examine forest soil property distribution. These findings should enable the future collection of soil datasets informing the distribution of soil C stocks and their relationship to landscape features, and thus their controls and responses to climate and environmental change.     

Hierarchical Bayesian models for soil CO2 flux using soil texture: a case study in central Hokkaido,Japan

Hierarchical Bayesian (HB) methods are useful tools for modeling multifaceted, nonlinear phenomena such as those encountered in ecology, and have been increasingly applied in environmental sciences, e.g., to estimate soil gas flux from different soil textures or sites. We have developed a model of soil carbon dioxide (CO₂) flux based on soil temperature (T, 5 cm depth) and water-filled pore space (WFPS, 5 cm depth) using HB theory. The HB model was calibrated using a dataset of CO₂ flux measured from bare soils belonging to four texture classes in 14 upland field sites in a watershed in central Hokkaido, Japan, in the nonsnow-cover season from 2003 to 2011. The numerical software HYDRUS-1D was used to simulate daily WFPS, and the estimated values were significantly correlated with the measured WFPS (R² = 0.68, P < 0.001). Compared to a nonhierarchical Bayesian model (Bayesian pooled model), the CO₂ predictions with the HB model more accurately represented texture-specific observations. The simulation–observation fit of the CO₂ flux model was R² = 0.64 (P < 0.001). More than 90% of the observed daily data were within the 95% confidence interval. The HB model exhibited high uncertainty for high CO₂ flux values. The HB model calibration revealed differing sensitivity of CO₂ flux to T and WFPS in different soil texture classes. CO₂ flux increased with an increase in T, and it increased to a lesser degree with a finer texture, possibly because the clay and silt facilitated soil aggregation, thus reducing temperature fluctuations. WFPS values between 0.48 and 0.64 resulted in optimal conditions for CO₂ flux. The minimum WFPS value increased with an increase in clay content (P < 0.05). Although only a small number of soil types were studied in only one season in this study, the HB model may provide a method for predicting how the effects of soil temperature and moisture on CO₂ flux change with texture, and soil texture could be regarded as an upscaling factor in future research on regional extrapolation.     

不同质地潮土夏玉米推荐施肥方法研究

为推动夏玉米科学施肥,在河南省砂壤、中壤和黏壤质潮土上采用田间试验研究了Nutrient Expert(NE)和Agro Services International Inc(ASI)法推荐施肥对夏玉米产量和经济效益的影响及基于NE推荐施肥的氮磷钾肥利用效率。结果表明,各推荐施肥处理夏玉米产量、纯收益和蛋白质产量均表现为黏壤>中壤>砂壤,NE推荐施肥处理的产投比最高,其次是ASI推荐施肥处理,推荐施肥可显著增加夏玉米植株养分积累量,促进籽粒产量和蛋白质产量的提高。在砂壤、中壤和黏壤上的NE推荐施肥处理比农民习惯施肥处理分别增产7.22%、3.84%和11.32%,ASI推荐施肥分别增产13.44%、10.60%和11.20%。NE推荐施肥处理中施氮对夏玉米的增产效应最大,氮肥农学效率和氮磷钾肥利用率均表现为黏壤>中壤>砂壤,磷、钾肥农学效率均表现为砂壤>黏壤>中壤,3种质地潮土的肥料农学效率均表现为磷肥>钾肥>氮肥。由此得出,NE推荐施肥适宜在黏壤质潮土推行,而ASI法推荐施肥适宜于砂壤和中壤质潮土。     

土壤质地和灌水器材料对负压灌溉出水流量及土壤水运移的影响

负压灌溉法是一种新近提出的节水灌溉技术,灌溉时供水水头为“负值”,即灌溉水源高程低于灌水器高程。不同材料灌水器和土壤质地是影响灌溉系统出水流量及土壤水运移的重要因素。该文研究了在高程差H为-0.5 m情况下两种灌水器及两种质地土壤对两者的影响。结果表明：灌水器相同时,累计入渗量、水平和垂直最大湿润距离随时间呈幂函数关系变化;在历时相同时黏壤土较砂壤土大;湿润体近似为六分之一的竖直椭球体,但黏壤土水平与垂直最大湿润距离之比大于砂壤土。土壤质地相同时,纤维灌水器较陶土灌水器出水流量高。试验结果进一步证明了负压灌溉的可行性,并为确定负压灌溉系统应用范围及规划设计过程中灌水器选择提供了依据。     

Assessment of soil texture class on agricultural fields using ECa,Amber NDVI,and topographic properties

Soil texture (ST) is relatively stable over time, although it may change due to erosion, clay eluviation, and other processes. Soil texture affects soil quality, productivity and management. Therefore, indirect, accurate methods for assessing of soil texture classes (STCs) are needed in agricultural practice. A study was performed on four production fields in northern and central Poland to compare the fitting performance of STC models based on apparent electrical conductivity (ECa), topographic properties (elevation, slope gradient and wetness index) and Amber NDVI measurements. One common and accurate indicator of STCs was not found for all study fields. On average, ECa was most accurate in indicating areas of different STCs within the fields, but it tended to overestimate the size of sandy areas on loamy fields and vice versa. The accuracy of STC assessment using ECa measurements may be biased due to imperfect soil drainage, high elevations, which increase evaporation and STC variation with depth. STC assessment using Amber NDVI measurements may be useful, particularly on flat and sandy fields, but the results are affected by the same factors as ECa, and additionally by crop growth stages and by the weather conditions in the period preceding the measurements. Despite the good quantitative results of the STC assessment by elevation (one field) and by the topographic wetness index (another field), both terrain attributes failed to accurately indicate the distribution of some STC areas within each field. Therefore, in landscapes developed from deposits of the last glaciation relevant ST differences might not sufficiently be detected by the analysis of terrain attributes alone. The selection of STC predictors and evaluation of the assessment quality must consider both the quantitative indicators such as correlation and determination coefficients describing relationships between ST and ECa, NDVI and topography and percentage of a field area with accurately indicated STC and the distribution of areas with different STCs within a field. The use of ECa, NDVI values, and topographic properties for STC assessment may be useful in reducing costs of soil sampling and analysis, but cannot replace it.     

耕层厚度对华北高产灌溉农田土壤有机碳储量的影响

针对华北平原长期少免耕可能导致的耕层变浅、变紧的问题,通过人为设置不同耕层厚度试验,采用等质量土壤有机碳库储量和层化比的研究方法,研究了4种耕层厚度（10、20、30、40 cm）水平下0～50 cm土壤有机碳的变化。2 a的田间试验结果表明,不同耕层厚度对土壤有机碳含量有显著差异,与2007年试验开始时相比,土壤有机碳质量分数都不同程度下降,下降幅度为22%～48%。利用等质量计算方法表明20 cm耕层厚度的处理土壤有机碳储量最高。通过层化比的研究表明,随着时间的推移,20 cm的耕层厚度层化比最高,其