近40年来陕西省耕层土壤pH的时空变化特征

以陕西省耕层土壤为研究对象,利用1980s第2次土壤普查数据和2017年的705个样点分析数据,基于地统计学和ArcGIS分析耕层土壤pH时空变化特征,并采用相关分析和方差分析方法探讨其影响因素,对于陕西农业可持续发展及生态环境保护具有极其重要的意义。结果表明,陕北、关中及陕南地区耕层土壤pH均值依次为8.25、7.91、6.25,分别为弱碱性、弱碱性和弱酸性;各行政区耕层土壤pH排列顺序为延安榆林铜川咸阳渭南西安宝鸡商洛安康汉中。时间上,与1980s相比,陕北和关中耕层土壤呈碱化趋势,陕南耕层土壤呈酸化趋势;各行政区除榆林、安康、汉中和商洛耕层土壤呈酸化趋势,其余各市耕层土壤均呈碱化趋势。空间上,陕北和陕南耕层土壤pH拟合的最优半方差函数模型为线性模型,关中耕层土壤pH拟合的最优半方差函数模型为高斯模型,均表现出较强的空间相关性。陕北耕层土壤pH空间分布呈零星斑状特征,关中和陕南耕层土壤pH空间分布呈东部高于西部特征。坡向、海拔与陕西省耕层土壤pH显著相关,坡度越小,海拔越高,pH越大,不同类型的土壤pH存在差异。建议陕北和关中地区防治土壤盐碱化问题,陕南地区防治土壤酸化问题,以促进农业可持续发展和保障区域粮食安全。     

The role of commission VI during the last 50 years

The work of Commission VI is primarily concerned with the principles of soil management on the farm itself. In the earlier years, interest was principally focussed on developing systems of farming that were better adapted to conserve soil and water than the existing systems, and on developing improved systems of field drainage. More recently, attention has shifted to developing improved systems of cultivation and of irrigation of land liable to salinity and alkalinity problems; and this has been accompanied by much greater attention being given to problems of root growth and functioning in the soil.Soil and water conservation was initially concerned with the reduction of s soil erosion, whether by water or by wind, and as a consequence improved methods for the control of water have been developed either by increasing the permeability of the surface soil or by allowing the safe shedding of surplus water off the soil surface. One of the central problems of soil cultivation research has been the development of methods that allow the optimum use to be made of the wide range of herbicides that are being introduced into farming practice. This work is closely linked to two other important problems, namely the reduction of soil compaction due to the passage of implements and tractors over the land, and the reduction of the number and cost of cultivations needed to prepare an adequate seedbed, to control weeds, and to maintain soil permeability.     

The influence of soil pH on sorghum grain yields

Abstract

Sorghum bicolor (L.) Moench is sensitive to acid soil stress environments. Acid soil stress tolerance is quite complex and involves additively inherited characteristics dealing with aluminum and manganese toxicities and calcium, magnesium, and phosphorus deficiencies. Genotype‐by‐environment interactions in unstressed environments are normally high for yield parameters and stress environments escalate the problem. Thirty parental lines and hybrids were compared in the field at mean H₂O/KCI pH values of 6.6/5.9, 5.7/5.0, 5.0/4.6, and 4.4/4.1 from 1982–1988 on a Suches clay loam (Fluventic Dystrochrept). All yield data were compared against IS7173C (SC283), an internationally tolerant check. Mean yields decreased 19% as pH dropped from 6.6/5.9 to 5.0/4.6. Yields were reduced 67% as pH dropped from 5.0/4.6 to 4.4/4.1 which reinforced previous research indicating that soil pH must be below pH 4.9 (H₂O) and have less than 5% organic matter for proper acid soil stress screening and evaluation of sorghum. Soil aluminum saturation values averaging 50% provide a maximum level of stress for sorghum. Hybrids and parental lines responded differently to stress, with the most stable producer across environments and highest‐yielding hybrid being ASC599×GP140. Percent relative yield of SC283 and tolerance indices (low yield + high yield) gave parallel results and were particularly indicative of previous genotypic field responses. Hybrid combinations involving specific parental lines governed relative tolerance of each genotype.     

Impact of biochar on red paddy soil physical and hydraulic properties and rice yield over 3 years

Journal of Soils and Sediments - Biochar is a promising soil amendment to improve soil quality. This study was conducted to understand the effect of biochar on soil physical and hydraulic...     

Effect of biogas slurry addition on soil properties,yields, and bacterial composition in the rice-rape rotation ecosystem over 3 years

Journal of Soils and Sediments - Organic treatments may improve soil nutrient availability and ecological functions. This study aimed to determine the effect of biogas slurry (BS) on soil...     

Soil extension needs to be a continuum of learning; soil workshop reflections 10 years on

Effective extension of soil research builds landholder capacity to manage soils productively and sustainably. Government‐funded extension programmes also aim to improve the state of the environment through efficient use of resources and mitigating or preventing further land degradation. To these ends, a soil extension programme aimed at farmers in south‐eastern Australia was conducted during 2005–2008. The programme was designed to equip landholders with the knowledge, skills and confidence to diagnose and address soil constraints, as well as compile spatial information on soil properties. The programme involved four workshops that covered agricultural productivity, soil management and potential off‐site impacts. Workshops were held on‐farm and involved discussion, theory supported with practical exercises, and field visits. More than 1,400 participants were provided with subsidized soil tests to encourage soil monitoring and underpin the workshop theory on land capability and soil constraints (e.g., soil acidity, sodicity, salinity, nutrient decline and toxicities). Prior to the course, most participants did not regularly soil test so training on monitoring protocols was provided. The soil data indicated considerable phosphorus deficiencies, low organic carbon levels, and acidity across both cropping and pasture systems. Participant knowledge and land management intentions were tracked throughout the workshop series using surveys. The surveys identified a positive shift in the knowledge, understanding and confidence of most participants. However, a follow‐up survey 10 years later indicated that these changes may not have been broadly sustained. Based on our study, we recommend continued engagement of landholders along a learning pathway to maximize investment in soil extension.     

Isolating the influence of pH on the amounts and forms of soil organic phosphorus

Soil pH influences the chemistry, dynamics and biological availability of phosphorus (P), but few studies have isolated the effect of pH from other soil properties. We studied phosphorus chemistry in soils along the Hoosfield acid strip (Rothamsted, UK), where a pH gradient from 3.7 to 7.8 occurs in a single soil with little variation in total phosphorus (mean ± standard deviation 399 ± 27 mg P kg^?1). Soil organic phosphorus represented a consistent proportion of the total soil phosphorus (36 ± 2%) irrespective of soil pH. However, organic phosphorus concentrations increased by about 20% in the most acidic soils (pH < 4.0), through an accumulation of inositol hexakisphosphate, DNA and phosphonates. The increase in organic phosphorus in the most acidic soils was not related to organic carbon, because organic carbon concentrations declined at pH < 4.0. Thus, the organic carbon to organic phosphorus ratio declined from about 70 in neutral soils to about 50 in strongly acidic soils. In contrast to organic phosphorus, inorganic phosphorus was affected strongly by soil pH, because readily‐exchangeable phosphate extracted with anion‐exchange membranes and a more stable inorganic phosphorus pool extracted in NaOH–EDTA both increased markedly as soil pH declined. Inorganic orthophosphate concentrations were correlated negatively with amorphous manganese and positively with amorphous aluminium oxides, suggesting that soil pH influences orthophosphate stabilization via metal oxides. We conclude that pH has a relatively minor influence on the amount of organic phosphorus in soil, although some forms of organic phosphorus accumulate preferentially under strongly acidic conditions.     

中国土壤学过去30年在一些关键领域的研究进展

Due to continuous decreases in arable land area and continuous population increases,Chinese soil scientists face great challenges in meeting food demands,mitigating adverse environmental impacts,and sustaining or enhancing soil productivity under intensive agriculture.With the aim of promoting the application of soil science knowledge,this paper reviews the achievements of Chinese scientists in soil resource use and management,soil fertility,global change mitigation and soil biology over the last 30 years.During this period,soil resource science has provided essential support for the use and exploitation of Chinese soil resources,and has itself developed through introduction of new theories such as Soil Taxonomy and new technologies such as remote sensing.Soil fertility science has contributed to the alleviation and elimination of impeding physical and chemical factors that constrain availability of essential nutrients and water in soils,the understanding of nutrient cycling in agroecosystems,and the increase in nutrient use efficiency for sustainable crop production.Chinese soil scientists have contributed to the understanding of the cropland’s role in global change,particularly to the understanding of methane and nitrous oxide emission from rice fields and the effect of elevated carbon dioxide and ozone on rice-wheat system.Soil biology research has progressed in biological N fixation,distribution of fauna in Chinese soils,and bioremediation of polluted soils.A new generation of soil scientists has arisen in the last three decades.The gaps between research and application in these soil science fields are also discussed.     

Evaluation of coal combustion byproducts as soil liming materials: their influence on soil pH and enzyme activities

There is considerable interest in the use of coal combustion byproducts as soil liming materials in agricultural production, but there is concern that such use may be detrimental to the quality of agricultural soils. To evaluate these byproducts as liming materials and address issues related to soil quality, we compared the influence of different amounts of four combustion byproducts [fly ash and bed ash from a fluidized bed combustion furnace, lime-injected multistage burner residue, and spray dryer residue] and CaCO₃ on soil pH and activities of urease, phosphatase, arylsulfatase, and dehydrogenase in an acidic soil. Studies comparing the influence of the combustion byproducts and CaCO₃ on soil pH showed that on a weight basis of application, substantial differences were observed in the ability of these materials to influence soil pH but that such differences decreased markedly after the data were transformed to a CaCO₃ equivalent basis of application. Analysis of covariance for these transformed data indicated that whereas the liming abilities of fly ash and CaCO₃ were not significantly different when compared on the CaCO₃ equivalent basis, those of bed ash, multistage burner residue, and spray dryer residue were less than that of CaCO₃. Studies comparing the influence of the byproducts and CaCO₃ on soil enzyme activities showed that the effect of these liming materials on the enzyme activities studied was largely due to their influence on soil pH. The relationships obtained between soil pH and enzyme activities in soil amended with the liming materials generally demonstrated the marked similarities in the influence of the combustion byproducts and CaCO₃ on these activities when observed within the domain of soil pH. These studies showed that the combustion byproducts tested functioned as soil liming materials in a manner similar to that of CaCO₃ and seemed to have little adverse effect on soil quality.     

The influence of pH,soil type and time on adsorbtion and uptake by plants of Cd added to the soil

Adsorption of Cd by two soils and its uptake by perennial ryegrass (Lolium perenne) and winter rape (Brassica napus) as a function of pH (pH 4 to 7) and the amount of Cd added to the soil (0 to 5 mg kg^?1 soil) were studied in a 2-yr pot experiment. In the soils, the more soluble fractions of Cd increased as the pH was lowered. Increasing the pH from 5 to 7 by adding CaO invariably reduced the Cd-content of ryegrass plants, but this decrease was less consistent where the pH had only been increased to 6. In some cases, acidifying the soil with S to reach a pH of 4 also led to a decrease in plant Cd-content. The Cd-content of rapeseed plants was markedly higher at pH 4 than at pH 5. Plant damage at low pH was observed in this crop. Water-leachable and CaCl₂-extractable soil Cd levels as well as plant uptake were higher in the sand soil than in the clay soil, whereas 1M NH₄AcO (buffered at pH 4.8 and 7) extracted roughly equal amounts from both soils. Adding more Cd to the soil did not change the relation between Cd levels in soil and those in plants; instead the amounts of Cd in both increased in direct proportion to the amounts added. Fixation of added Cd apparently did not occur continuously at any pH or Cd-level during the 2-yr period, but seasonal variations in solubility and uptake were observed.     

Effects of cattle-lagoon slurry on a soil microbial community can be observed until depths of 50 m

The large amount of effluent generated by concentrated animal feeding operations (CAFOs) has raised concerns about contamination of groundwater and pollution of streams by compounds that penetrate the vadose zone. However, the possibility that a microbial community in the vadose zone under cattle-slurry lagoons (CSLs) may also be affected has not been considered. In the present study, we investigated the influence of long-term (30 years) accumulation of cattle slurry on the vertical distribution of a soil microbial community (microbial biomass [MB], CO₂ evolution, substrate utilization ability), until a 50-m depth, compared to a control site. Total soluble nitrogen (TSN) was found to be elevated fourfold, and MB was found to be threefold higher under the CSL compared to a control site. In general, the increase in MB is associated with higher soil moisture and higher nitrogen content. Substrate utilization ability was found to be significantly higher in a CSL in comparison to the control site. At the CSL site, a higher utilization of aromatic carboxylic acids typical of cattle slurry was obtained in the deeper soil layers (7–30 m), indicating a degree of microbial adaptation even at these depths. The soil layers under the CSL were more dynamic as the microbial functional diversity was significantly different between the layers, while no such difference was seen at the reference site. Our results, therefore, suggest that the infiltration of cattle slurry can affect the microbial community throughout the vadose zone. We also suggest that activity of the microbial community, as characterized by its substrate utilization ability, can be a bioindicator for anthropogenic activities and environmental changes even at depths below the rhizosphere (30 cm).     

根际微生物对植物与土壤交互调控的研究进展

土壤中拥有非常丰富的微生物群落,这些微生物对植物与土壤之间的交互作用起到了非常重要的调节作用,尤其是根际微生物,其中一些重要的功能微生物作为主要的共生功能体参与到植物根系养分转化中。对根际与根际土壤微生物的形成及其与土壤环境、植物根系之间互作关系的最新研究进展进行了综述,这些研究成果均肯定了根际微生物群落和多样性是积极促进植物个体和维持生态系统功能的活跃因子,并展望了今后土壤微生物在多组学、植物功能性状和全球变化方面的研究前景。     

Effects of the herbicide Topogard on soil respiration, nitrification, and denitrification in potato-cultivated soils differing in pH

We investigated the effects of Topogard 50 WP (3 kg ha^–1) on soil respiration, mineral N content, and number of denitrifying and total bacteria in four coarse-textured volcanic soils for 91 days. Topogard application decreased CO₂ evolution in acid soils (Tepedibi and Karaçakl) whereas soil respiration was initially increased in neutral and alkaline soils (Kaba and Balar). The herbicide application significantly stimulated ammonification in Kaba and Balar soils, while Tepedibi and Karaçakl soils showed significantly lower NH₄⁺-N contents than the control. The treatment inhibited the activity of nitrifying microorganisms and, thus it decreased the NO₃^–-N content in Tepedibi, Karaçakl, and Kaba soils, whereas the NO₃^–-N content was increased in Balar soil. The NO₂^–-N content of soils was not affected by the treatment. The activity of denitrifying bacteria was stimulated by the addition of herbicide in all soils, whereas the total number of bacteria was not influenced. It may be concluded that the effects of Topogard on the microbiological characteristics of coarse-textured soils are likely to be dependent on soil pH.     

Analysing resilience in dryland agro‐ecosystems: a case study of the Makanya catchment in Tanzania over the past 50 years

Dryland agro‐ecosystems in sub‐Saharan Africa provide the resource base for some of the fasted growing populations today. However, rainfall variability and poor soils make these systems inherently vulnerable, and land degradation reduces their capacity to cope with disturbances. In this paper we propose a theoretical framework for interpreting dynamics and resilience in such systems, where two aggregate variables, the agricultural soil water index and the ecosystem insurance capacity, are particularly important. We apply the framework to the case of the Makanya catchment in Tanzania and conclude that the studied area has moved towards an increasingly degraded state, where ecosystem services other than food have been lost, over the past 50 years. Three main drivers behind this are identified; a) institutional changes affecting strategies for natural resource management, b) increased dry‐spell frequency, and c) high population growth. We suggest that the reason for the dramatic effects is that these changes occurred simultaneously, reducing the adaptive capacity of the local population. However, several trends in the area today indicate that there is a window of opportunity for positive change. Copyright © 2007 John Wiley & Sons, Ltd.     

Effects of 10 years of conservation tillage on soil properties and productivity in the farming–pastoral ecotone of Inner Mongolia, China

Soil degradation and subsequent yield decline are the main factors limiting further development of agriculture on the farming–pastoral transition zone of China. A 10-year field experiment was conducted in Inner Mongolia to compare the long-term effects of no-tillage with straw cover (NT), subsoiling with straw cover (ST), rototilling with straw cover (RT) and traditional tillage (TT) using ploughs on soil properties and productivity in a spring wheat–oat cropping system. Long-term conservation tillage increased soil organic matter in the top 20 cm by 21.4%, total N by 31.8% and Olsen's P by 34.5% in the 0–5 cm layer compared to traditional tillage. Mean percentage of macro-aggregates (>0.25 mm, +20%) and macroporosity (>60 μm, +52.1%) also improved significantly in the 0–30 cm soil layer ( P  <   0.05). The largest yield improvements coupled with greatest water use efficiency (WUE) were achieved by no-tillage with straw cover. Ten-year mean crop yields increased by 14.0% and WUE improved by 13.5% compared to traditional tillage due to greater soil moisture and improved soil physical and chemical status. These improvements in soil properties and productivity are of considerable importance for the seriously degraded soils in semiarid Inner Mongolia, as well as for food security, sustainable agriculture and carbon storage in the farming–pasture transition regions of China.     

The influence of soil properties on denitrifying bacterial communities and denitrification potential in no-till production farms under contrasting management in the Argentinean Pampas

The aim of this work was to investigate the response of the structure, abundance and potential activity of denitrifiers to contrasting agricultural management in no-till production fields, across a regional scale within the highly productive Argentine northern Pampas. Treatment categories were grouped according to the sustainability of the soil management, in terms of crop rotation, fertilization, agrochemicals use and pest control, as good no-till agricultural practices (GAP) and poor no-till agricultural practices (PAP). Non-cultivated soils in each geographic location were also evaluated as reference groups.Mixed models, with sites treated as random factors, indicated that the potential denitrification activity and the size of the nirS community differed significantly between non-cultivated and PAP soils. Soil properties were separated into dynamic and inherent according to their variance components. The former had the largest part of their variances explained by agricultural management, while the latter were more affected by edaphic–climatic differences between sites. Both inherent and dynamic properties could explain the changes in potential denitrification activity, whereas changes in the abundance of denitrifiers were only related to inherent soil properties. Results from principal components analysis suggested site-specific response of most dynamic soil properties. Among the latter, only aggregate stability indices were strongly associated with potential denitrification activity after removing the geographical effect.     

Mapping to inform conservation: A case study of changes in semi-natural habitats and their connectivity over 70 years

Intensification of human activities has caused drastic losses in semi-natural habitats, resulting as well in declining connectivity between remaining fragments. Successful future restoration should therefore increase both habitat area and connectivity. The first steps in a framework for doing so are addressed here, which involve the mapping of past habitat change. We present a method which is unique in: the large area covered (2500 km²), the high resolution of the data (25 × 25 m), the long period assessed (70 years), and a system for translation of land use maps into Broad Habitat Types using soil surveys.We digitised land use maps from the 1930s for the county of Dorset in southern England. The resulting map was compared to the UK Land Cover Map of 2000. For our example area, land use shifted dramatically to more intensive agriculture: 97% of all semi-natural grasslands were converted into agriculturally-improved grassland or arable land as were large proportions of the heathlands and rough grasslands (?57%). The other important driver of change was afforestation (+25%). The larger habitat areas became fragmented, with average fragment size of different habitats falling by 31–94%. Furthermore, the connectivity between fragments dropped drastically, by up to 98%.Analyses such as those presented here not only quantify the scale and pattern of habitat loss, but are important to inform land-use planning to restore biodiversity by both increasing the available habitat and facilitating dispersal among habitat fragments. We discuss the possible steps for such a framework.     

The influence of soil deformations on the permeability to air

Samples were reconstituted in the laboratory from a cracking grey clay soil. Some samples were created with a granular structure in which there was no preferred macropore orientation, others were created with a strongly preferred macropore orientation. The samples were compressed and their air permeability measured. They were then sheared and their air permeability measured again. In the samples with a granular structure the change in permeability was dominated by the change in the volume of the pore space. Volume increase led to permeability increase and volume decrease led to permeability decrease. At low shear strains and low volume increases there was some loss of pore continuity leading to small permeability decreases. In contrast, permeability change in the samples with a preferred macropore orientation was dominated by macropore continuity. Permeability decreased both when volume decreased and also over a wide range of volume increases. These results are interpreted in terms of critical-state soil mechanics and used to construct ‘critical state for permeability’ lines analogous to the usual critical-state lines. It is suggested that these forms of behaviour encompass the likely bounds of behaviour of soils in many circumstances.     

The influence of temperature,pH/molarity and extractant on the removal of arsenic,chromium and zinc from contaminated soil

Purpose  

Normal soil washing leave high residual pollutant content in soil. The remediation could be improved by targeting the extraction to coarser fractions. Further, a low/high extraction pH and higher temperature enhance the pollutant removal, but these measures are costly. In this study, the utility of NaOH, oxalate–citrate (OC) and dithionite–citrate–oxalate (DCO) solutions for extracting of arsenic, chromium and zinc from contaminated soil were assessed and compared. In addition the effects of NaOH concentration and temperature on NaOH extractions, and those of temperature and pH on OC and DCO extractions, were evaluated.     

The effect of cation–anion interactions on soil pH and solubility of organic carbon

Alkaline soil is widely distributed and cultivated throughout the agricultural regions of the world. Organic carbon (OC) concentrations in alkaline soil are often small, partly because of the limitations of a high pH on the productivity of crops and pastures together with the effects of high pH on the chemistry of soil OC. Soil pH is often hypothesized to be a major factor in regulating OC turnover in agricultural soil, but there are few detailed studies on the effects of high pH on carbon cycling in alkaline soil. Sodium, K⁺, Mg²⁺ and Ca²⁺ are the major cations in alkaline soil, whereas Cl^?, , and are the major anions. The effect of different combinations of these cations and anions on soil pH and OC is not well described in the literature. The objectives of this study were to evaluate the effect of cations and anions on soil pH and to quantify the dissolution of OC in relation to these changes in pH. The results showed that (Na⁺, K⁺ and Mg²⁺) salts and CaCO₃ dominate in the pH range 7.0–8.5, and salts of Na⁺ and K⁺ dominate above pH 8.5. The amount of dissolved OC (DOC) increased significantly as pH increased. Therefore, the presence of large concentrations of and not only increased pH but also promoted the dissolution of soil OC. The concentration of Ca²⁺ modified this effect; large concentrations of Ca²⁺ increased the adsorption and reduced the concentration of DOC.