Delineating the zone of topsoil disturbance around buried utilities on agricultural land

Installation of pipeline utilities (oil, natural gas, water) in central Canada prior to the 1970s often resulted in extensive mixing of topsoil with subsoil materials within the easements due to largely unregulated construction practices. The main objectives of this study were (1) to develop a simple field protocol for the rapid delineation of the zone of topsoil disturbance (or topsoil–subsoil mixing) around buried utilities on agricultural land in southern Ontario, and (2) to characterize the zone of topsoil disturbance in the vicinity of an existing pre-1970s pipeline in terms of agronomically important soil properties. The study was carried out at six farm sites chosen along a pipeline easement (30+ years old) in southern Ontario. Soil organic carbon content, CaCO₃ content and pH were found to be useful in delineating the zone of topsoil disturbance around the buried utility. Standardized laboratory techniques for determination of these three soil attributes were used to analyse surface soil samples (Ap horizons) taken at 1·5 m intervals along 45·7 m long transects oriented perpendicular to the easement. In addition, rapid field tests for these same three variables were adopted/developed and tested, and two portable instruments were evaluated for their usefulness for in situ soil property measurements. In particular, a Minolta^™ CR-310 Chroma Meter was successfully used to relate moist soil colour to the organic carbon content of the surface soil. The chromaticity coordinate a* (CIE L*a*b* colour space notation) was shown to provide good estimates of organic carbon content for soils of medium to fine texture in this region of Ontario. The zone of topsoil disturbance was most often characterized by an appreciable increase in per cent CaCO₃ equivalent and pH, and a decrease in organic carbon content (dilution), over the pipeline trench when compared to off-easement areas. The zone of topsoil disturbance was usually a minimum of 15 m wide (i.e. the approximate width of the original trench and workspace areas during construction), and frequently much wider due most likely to wet soil conditions at the time of construction, agricultural tillage translocation of topsoil over time, and other factors. It is recommended that rapid on-site determinations of the zone of topsoil disturbance should be based primarily on field estimates of CaCO₃ content (10 per cent HCl) and organic carbon content (a* chromaticity coordinate using a portable colorimeter). Copyright © 1999 John Wiley & Sons, Ltd.     

Row Distance and Tree Heights in Apple Trees

Abstract

The apple cultivars ‘Discovery’, ‘Jonagold’ and ‘Mutsu’ were planted in 1980 at row distances of 3 and 4.5 m. Tree heights of 1.5, 2 and 2.5 m were established at 3 m row distance, and 2.25, 2.75 and 3.25 m at 4.5 m row distance. The tree heights were effective from 1985–86; yield and fruit development were followed during 1982–90. Yield per tree, tree size and fruitfulness were larger at the wider row distance, especially for ‘Mutsu’. Thus, in ‘Mutsu’, yield per hectare at 4.5 m equalled that at 3 m, contrary to ‘Discovery’ and ‘Jonagold’, where yield per hectare was higher at 3 m. Also, dry matter contents and colour development (‘Jonagold’) were improved by 4.5 m row distance in several cases. Reduced tree heights decreased yields and colour development (‘Jonagold’), but with minor reductions at tree heights of 2.0–2.5 m during the first 7–8 years. A tree height of 1.5 m, at 3 m row distance, responded negatively, especially for ‘Discovery’ and ‘Jonagold’.     

Chemical Composition of Ten Blackcurrant (Ribes nigrum L.) Cultivars

Abstract

Ten blackcurrant cultivars were evaluated for some quality components. On average, the sugar content was 9.0%, of which fructose made up 45%, glucose 40% and sucrose 15%. Soluble solids were 15.4% as an average for the ten cultivars in three years. The acid content was 5.1% of fresh weight, 88% was citric acid and 12% malic acid. The ascorbic acid content varied from 67 mg per 100 g fresh fruit in Hedda, to 204 mg per 100 g in Blackdown. Except for Hedda and Øjebyn, which both had low values of ascorbic acid and colour properties, the quality components of the cultivars were found to be within an acceptable range.     

一种棉铃虫成虫体色突变体的遗传分析

在棉铃虫常规饲养种群中发现一种成虫体色突变体,该突变体腹、翅颜色与野生型显著不同,用杂交试验对该突变体进行了研究。研究发现,突变体与野生型正反交F1代成虫体色均显示野生型色;F2代成虫野生型和突变体的分离比为3.23∶1;回交BC1代中野生型和突变体分离比为1.13∶1;F2代中的突变体自交,后代全部表现为突变。遗传分析结果表明,该成虫体色突变体属常染色体上单基因控制的隐性遗传性状。     

热烫条件对速冻黄花菜颜色和脆度的影响

为了保证速冻黄花菜良好的颜色和质地，该试验采用5因素4水平正交试验设计，对速冻黄花菜热烫处理条件如热烫液的组成、热烫温度、热烫时间、固液比和氯化钙的浓度进行了探讨。结果表明，以0.05%的柠檬酸加上0.05%氯化钙溶液作为热烫液，取1∶7的固液比，在90℃的温度下热烫40 s，是速冻鲜黄花菜加工时热烫处理的最优条件。     

脱水菠菜贮藏过程中颜色变化动力学

为了探讨脱水菠菜在贮藏过程中叶绿素变化及其与颜色损失的关系,鲜菠菜经过热烫处理后冷冻干燥,包装后在25、35、45和55℃下贮藏,测定贮藏过程中叶绿素和颜色变化,以确定脱水菠菜叶绿素和颜色变化动力学。结果表明：无论是否经过热烫前处理,经过冻干技术得到的脱水菠菜,在贮藏过程中其叶绿素的降解与颜色损失都遵循一级反应动力学方程,且叶绿素的减少与颜色损失密切相关（R2＞0.95,p＜0.05）。在未经热烫和经热烫处理后冻干的菠菜其叶绿素降解的活化能分别为39.99 kJ/mol和41.44 kJ/mol。而用色度计测定的红绿值a*和色彩角值h中,经过热烫前处理的脱水菠菜其活化能分别是18.93 kJ/mol和48.08 kJ/mol,而未经烫漂的分别为18.20 kJ/mol和44.04 kJ/mol。与热烫处理的样品相比,未热烫的脱水菠菜更容易失去叶绿素,热烫处理有利于延长脱水菠菜的货架期。相同前处理的脱水菠菜,在设定的贮藏温度下,叶绿素降解、红绿值a*和色彩角值h的速率常数随贮藏温度的升高均逐渐增大,低温贮藏有利于延长脱水菠菜的货架期。在常温下（20℃）脱水菠菜的货架期为168 d（未热烫）或465 d（热烫）。     

Bodengefüge gegen Verdichtungen schützen – Lösungsansätze für den Schutz landwirtschaftlich genutzter Böden

Protecting soil structure against compaction—proposed solutions to safeguard agricultural soils To safeguard the ecological soil functions and the functions linked to human activities, measures against harmful changes to the soil are required, in line with the precautionary principle. The German Federal Soil Protection Act sets obligations for precaution in agricultural land use and, if harmful changes to the soil are foreseeable, measures for averting a danger. The results of a research project of the Federal Environmental Agency show that it is possible to describe an impairment of the soil structure, using methods of soil analysis. But this as a sole information would not qualify for the identification of harmful changes to the soil in the context of the Soil Protection Act, which requires an assessment of the severity of disruption of soil functions and the respective subject of protection. This would make additional soil investigations on site mandatory. Approaches in agricultural engineering and soil physics have introduced procedures to preserve the soil structure, in accordance with the precautionary principle. But these procedures have different goals and different ranges of application and hence offer partial solutions to safeguard against soil compaction. The assessment model of “trafficability by measuring the rut depth” provides information about the compaction status of the soil under applied conditions for farming gear, without providing detailed information about affected soil layers. The soil‐physical model of classifying soils into “risk classes for harmful soil compaction” focuses on the relationship between topsoil compaction and crop yields. The soil‐physical models “precompression stress” and “loading ratio” provide information for the assessment of subsoil compaction and a prognosis of a possible impairment of the soil structure at the water content of field capacity. It is necessary to validate the individual models with additional regional data about soil structure before a final assessment of the prognoses is made.     

Soil Erodibility and Physicochemical Properties of Collapsing Gully Alluvial Fans in Southern China

In southern China, collapsing gully erosion produces massive deposits of sediment on the plough layer of alluvial fan farmland, leading to reduced nutrients, increased erodibility, and even desertification. The aim of this study was to investigate soil erodibility (the factor K in the universal Soil Loss Equation, USLE) and physicochemical properties of the alluvial fans of the most severe collapsing gully erosion areas (Hubei, Jiangxi, Fujian, and Guangdong provinces) in southern China. The soils of the collapsing gully alluvial fans had a higher bulk density, but a lower total porosity, saturated water content, and silt and clay fractions than the control (CK) soils from the farmland without desertification. Soil quality gradually decreased from fan edge to fanhead. Significant decreases were found in soil pH, organic matter, cation exchange capacity, and total potassium, nitrogen, and phosphorus, as well as available nitrogen, phosphorus, and potassium, resulting in a gradual decrease in soil nutrients from the fanedge to the fanhead. Soil erodibility was greatest in the fanhead, and soil erodibility K values of the alluvial fans were 53.71%, 66.28%, 67.53%, and 71.68 % greater than that in those of the CK soils of Hubei, Jiangxi, Fujian, and Guangdong, respectively, indicating a significant correlation between the soil erodibility K values and physicochemical properties, particularly sand fraction and organic matter content. The results provide new insights into the relationship between soil physicochemical properties and erodibility of alluvial fans, and suggest that improving soil structure might increase soil fertility in the collapsing gully alluvial fan farmland.     

Soil health – What should the doctor order?

The concept of soil health has been extensively reviewed in the scientific literature, but there is only patchy and inconsistent information available to farmers and growers who are concerned about the declining condition of their soils and are looking for appropriate test methods and management interventions to help reverse it. Although there are well‐established laboratory methods for soil chemical analysis, and a range of laboratory and field methods for measuring soil physical properties, only now are methods starting to emerge for soil biological analysis. This study provides an overview of the methods that are currently available commercially (or are close to commercialization) for farmers and growers in the UK. We examine the science underpinning the methods, the value of the information provided and how farmers and advisors can use results from such assessments for informed decision‐making in relation to soil management.     

Comparison of black,purple, and yellow barleys

Many barley landraces are purple-or black-seeded, but the chemical composition of these purple-and black- seeded barley is rarely examined. Therefore, studies were conducted to determine if the chemical composition of purple and black barleys differs from that of yellow barleys. Four sets of genetic materials were used for these studies: 96 doubled-haploid (DH) lines, 10 near-isogenic lines, 40 landraces, and four F3 bulks. The results showed that purple DH lines contained a similar amount of lignin as yellow DH lines and that anthocyanin-containing isogenic lines did not differ from anthocyanin-free lines in lignin content. Therefore, these results suggest that anthocyanin biosynthesis is independent of lignin biosynthesis in barley. The results also showed that black barley contained more protein and more lignin than yellow barley in two crosses and that among the 40 landraces studied, the three with the highest concentration of lignin happened to be black seeded. Lignin content was not associated with seed weight except in defective endosperm lines. The presence of pigments and a relatively high concentration of lignin might help reduce the level of kernel blight severity in black barley. More studies are needed to determine the chemical composition and pest resistance associated with purple and black barleys.     

土壤孔隙结构与土壤微环境和有机碳周转关系的研究进展

土壤结构是土壤功能的基础,不仅影响土壤养分的供应、水分的保持及渗透、气体的交换等过程,还为土壤微生物提供了物理生境,并调控土壤有机碳的周转这一关键过程。土壤的孔隙特征能够直接、真实地反映土壤结构的好坏;用土壤的孔隙特征作为试验指标能更好地反映土壤结构对这些过程的调节作用。在此基础上,将高度异质性的土壤孔隙结构同土壤微环境的变化和土壤有机碳的周转过程进行定量分析,对深入了解土壤结构在土壤生态系统中的功能至关重要。因此,着重从土壤孔隙结构对土壤微环境的影响及其与有机碳的关系两方面展开,剖析土壤孔隙结构调控作用下的土壤微环境响应过程,阐述土壤孔隙结构对土壤有机碳周转产生的直接、间接影响,强调土壤孔隙结构在调节土壤有机碳周转进程中的重要作用,并对土壤孔隙结构在调节土壤有机碳周转、植物残体分解及其与微生物协调作用机制等方面研究提出展望。     

土壤因子研究综述

介绍了国内外土壤因子的研究方法及研究成果,指出我国目前土壤因子研究中存在的问题,并结合我国土壤因子研究现状,认为继续土壤水蚀机理的研究是今后土壤因子研究的内容之一,同时,随着GIS和RS技术发展,应用GIS和RS技术研究区域土壤因子也将成为潮流。     

土壤润湿性受土壤特性及土地使用的影响

Depth distribution of soil wettability and its correlations with vegetation type, soil texture, and pH were investigated under various land use (cropland, grassland, and forestland) and soil management systems. Wettability was evaluated by contact angle with the Wilhelmy plate method. Water repellency was likely to be present under permanently vegetated land, but less common on tilled agricultural land. It was mostly prevalent in the topsoil, especially in coarse-textured soils, and decreased in the subsoil. However, the depth dependency of wettability could not be derived from the investigated wide range of soils. The correlation and multiple regression analysis revealed that the wettability in repellent soils was affected more by soil organic carbon (SOC) than by soil texture and pH, whereas in wettable soils, soil texture and pH were more effective than SOC. Furthermore, the quality of SOC seemed to be more important in determining wettability than its quantity, as proofed by stronger hydrophobicity under coniferous than under deciduous forestland. Soil management had a minor effect on wettability if conventional and conservation tillage or different grazing intensities were considered.     

设施栽培下原状土与扰动土水分特性的试验研究

以四川省双流县设施栽培土壤为研究对象,对其原状土与扰动土的土壤水分特征曲线、水分物理性质和比水容量等项目进行了研究。结果表明,扰动土水分特征曲线总体变化趋势与原状土较为一致。在低吸力阶段,相同吸力条件下扰动土含水量高于原状土,在高吸力阶段两者差异较小。扰动土毛管孔隙度、总孔度和凋萎含水量在剖面上的总体变化趋势与原状土较为一致。扰动土不同土层田间持水量和有效水含量差异较小,原状土的田间持水量和有效水含量均随土层加深而减少。在低吸力阶段,相同吸力条件下扰动土比水容量远高于原状土,但随土壤水吸力增加,扰动土比水容量变化趋势逐渐与原状土一致。     

植物苗期根系抗侵蚀特性试验研究——以构树和顶坛花椒为例

植物的固土抗蚀作用大小与其根系密切相关,而根系特征决定了根的固土抗蚀作用的发挥,本文以相同基质下构树和顶坛花椒不同特征的根系为研究对象.通过研究根系特征与土壤抗冲性、抗蚀性、抗拉性、紧实度的关系,结果表明,苗期根系能强化土壤抗冲性,构树苗、顶坛花椒苗根系强化值大小分别为78.01>77.71;根系可提高土壤抗蚀性,其抗蚀性强弱为.构树苗>顶坛花椒苗>对照,构树、顶坛花椒、对照试验的土壤水稳性指数分别为4.36,3.16,1.67;不同树种根系对土壤的固结能力不同,构树苗生长下的土壤抗拉能力为214.92 N,明显大于顶坛花椒苗生长下的土壤154.87 N;土壤紧实度大小为构树苗>顶坛花椒苗.并采用加权综合指数法综合评价了苗期不同特征植物根系的固土能力强弱,得出构树苗综合指数为1.058.而顶坛花椒苗为0.902.即构树苗的固土能力强于顶坛花椒,以期为今后的水土保持工作提供一定的理论依据.     

长期化肥有机替代对黑土颜色及腐殖物质的影响

基于30年长期定位试验,通过测定黑土光谱反射率和不同腐殖质组分含量,探究了不同施肥对黑土土壤腐殖质含量、土壤颜色及二者之间的关系。试验设置5个处理:(1)休耕(Fallow);(2)不施肥处理(CK);(3)单施化肥(NPK);(4)有机肥部分替代化肥(NPKM);(5)秸秆部分替代化肥处理(NPKS)。结果表明:与NPK处理相比,Fallow、NPKS、NPKM分别显著提高49.7%,74.3%,27.0%的土壤有机碳含量(p<0.05)。NPKM处理中胡敏酸(HA)含量最高为3.9 g/kg,随后依次为CK、NPKS、NPK、Fallow。NPKM、NPKS和Fallow处理中土壤富里酸(FA)含量为2.2~2.3 g/kg,显著高于NPK和CK。NPKM处理中胡敏素(HM)含量为18.6 g/kg,显著高于其他处理(p<0.05)。不同处理间土壤光谱反射率由高到低依次为NPK>Fallow、CK>NPKS>NPKM,与CK处理相比,NPK土壤光谱反射率在平均提高6.5%,NPKS和NPKM则分别降低11.1%和15.1%。根据线性相关分析结果,黑土土壤光谱反射率与土壤HAHM均呈显著负相关关系(p<0.01),相关系数(r)分别为-0.858,-0.681。综合上述结果,长期有机物料投入可以显著提高黑土腐殖物质含量,降低黑土光谱反射率,使黑土颜色加深,而长期化肥施入则使黑土光谱反射率提高,出现"褪色"现象,有机粪肥在黑土中对土壤有机质和腐殖质含量的提升效果优于秸秆。     

金沙江干热峡谷中退化的土壤生态系统生物学特征初探

Distribution characteristics of soil animals,microorganisms and enzymatic activity were studied in the dry red soil and Vertisol ecosystems with different degradation degrees in the Yuanmou dry hot valley of the Jinsha River,China.Results showed that Hymenoptera,Araneae and Collembola were the dominant groups of soil animals in the polts studied.The numbers of groups and individuals and density of soil animals in the dry red soil series were higher than those in the Vertisol series,and the numbers of individuals and density of soil animals decreased with the degree of soil degradation.Bacteria dominated microbiococnosis not only in the dry red soils but also in the Vertisols.Microbial numbers of the dry red soil series were higher than those of Vertisol series,and decreased with the degree of soil degradation.The activities of catalase,invertase,urease and alkaline phosphatase declined with the degradation degree and showed a significant decline with depth in the profiles of both the dry red soils and the Vertisols,but activities of polyphenol oxidase and acid and neutral phosphatase showed the same tendencies only in the Vertisols.It was concluded that the characteristics of soil animals,microorganisms and enzymatic activity could be used as the bio-indicators to show the degradation degree of the dry red soils and Vertisols.Correlation among these soil bio-indicators was highly significant.     

Relationship between greenhouse gas emissions and changes in soil gas diffusivity in a field experiment with biochar and lime

Reducing greenhouse gas emissions from arable soil while maintaining productivity is a major challenge for agriculture. Biochar is known to reduce N₂O emissions from soil, but the underlying mechanisms are unclear. This study examined the impact of green waste biochar (20 Mg ha^?1) and lime (CaCO₃; 2 Mg ha^?1) application on soil gas transport properties and related changes in these to soil N₂O and CO₂ emissions measured using automated chambers in a field experiment cropped with maize. In situ soil water content monitoring was combined with laboratory measurements of relative soil gas diffusion coefficient (D_p/D₀) at different matric potentials, to determine changes in D_p/D₀ over time. Cumulative N₂O emissions were similar in the control and lime treatment, but much lower in the biochar treatment. Cumulative CO₂ emissions decreased in the order: lime treatment > biochar treatment > control soil. When N₂O emissions were not driven by excess N supply shortly after fertilisation, they were associated with D_p/D₀ changes, whereby decreases in D_p/D₀ corresponded to N₂O emissions peaks. No distinct pattern was observed between CO₂ emissions and D_p/D₀. Cumulative N₂O emissions were positively related to number of days with D_p/D₀ < 0.02, a critical limit for soil aeration. These results indicate that improved soil gas diffusivity, and hence improved soil aeration, may explain the effect of biochar in reducing N₂O emissions. They also suggest that knowledge of D_p/D₀ changes may be key to explaining N₂O emissions.     

Into the Pedocene—Pedology of a changing world

Pedology, or the study of soil, is often viewed focusing on soil formation, morphology, mapping and classification. But the study of soil has largely expanded beyond these four areas and now includes quantitative studies using soil legacy data combined with technological advances in data collection, soil sampling and computation. We have global availability of soil information and can retrieve pedological information for any location including some indication of its accuracy. Scientific and technological developments in pedology have been led by the rise of several subdisciplines including pedometrics, digital soil mapping, spectral pedology, digital soil morphometrics, hydropedology, microbial pedology, astropedology and the development of pedotransfer functions. With the expansion of pedology and its relevance for understanding the earth system and tackling global change, it is postulated that soil science has now entered the ‘Pedocene’—a soil epoch equivalent to the Anthropocene. The Pedocene is characterized by the quantitative understanding and evaluation of the global soil system, and the effects of human-induced changes brought to soil.