Effect of tillage treatments upon soil tests for soil acidity,soil phosphorus and soil potassium at three soil depths

Abstract

Soil samples were obtained at 0–3, 3–6, 6–9 and 0–9 inch depths from experimental plots receiving five tillage treatments. Each of two samplers composited approximately six one‐inch cores from each plot. Soil samples were analyzed for acidity, P and K using routine analysis procedures in the University of Illinois Soil Testing Laboratory.

Few significant differences were attributed to sampler and it was concluded that samplers using similar sampling techniques were obtaining soil samples from the same population.

No significant differences in soil acidity at different depths were observed. The different tillage methods did significantly affect soil P at the 0–3 inch depth, but had no significant effect on soil P at deeper depths. Different tillage methods also significantly affected soil K values at different depths.     

Usability of soil survey soil texture data for soil health indicator scoring

Soil textural information is an important component underlying other soil health indicators. Soil texture analysis is a common procedure, but it can be labor intensive and expensive. Soil texture data typically are available from the Soil Survey Geographic (SSURGO) database, which may be an option for determining soil health texture groups (SHTG). The SSURGO database provides soil texture information in the soil map unit (SMU) name, taxonomic class category (family), and detailed values (≤ 2 mm soil fraction) of percent sand, silt and clay by soil horizon. The objective of this study was to examine the possibility of using SSURGO data for SHTG at the 147-ha Cornell University Willsboro Research Farm in New York state as an alternative for soil texture data determined manually on collected soil core samples. Comparative results revealed that representative values for soil texture from the SSURGO database generally matched measured mean values for all SMUs.     

土壤含水率与土壤碱度对土壤抗剪强度的影响

土壤含水率和土壤碱度是表征土壤物理化学性质的两个重要参数。通过室内三轴不固结不排水试验，研究了土壤含水率和土壤碱度对土壤抗剪强度的影响。试验处理采用5种土壤碱度(土壤可交换钠百分比ESP=0、5、10、20、40)和4种土壤质量含水率(0.05、0.10、0.20以及饱和含水率0.34)水平。试验结果显示，土壤黏聚力随着土壤含水率的增加基本上呈先增大后减小之趋势；当土壤含水率在0.10附近时黏聚力达到其最大值。土壤内摩擦角随着土壤含水率的增加而线性减小。土壤碱度对土壤黏聚力的影响机理较为复杂，其影响效果随土壤含水率的增加而减小；但土壤碱度对土壤内摩擦角的影响较小。土壤碱度对土壤抗剪强度的影响程度明显地小于土壤含水率对其的影响程度。     

Relationships between soil respiration and soil moisture

The interaction of soil microbes with their physical environment affects their abilities to respire, grow and divide. One of these environmental factors is the amount of moisture in the soil. The work we published almost 25 years ago showed that microbial respiration was linearly related to soil-water content and log-linearly related to water potential. The paper arose out of collaboration between two young researchers from different areas of soil science, physics and microbiology. The project was driven by not only our curiosity but also the freedom to operate without the constraints common to the current system of science management. The citation history shows three peaks, 1989, 1999 and from 2002 to the present day. Interestingly, the annual citation rate is as high as it has ever been. The initial peak is due to the application of the work to studies on microbial processes. The second peak is associated with the rise of simulation modelling and the third with the relevance of the findings to climate change research. In this article, our paper is re-evaluated in the light of subsequent studies that allow the principle of separation of variables to be tested. This re-evaluation lends further credence to the linear relationship proposed between soil respiration and water content. A scaled relationship for respiration and water content is presented. Lastly, further research is suggested and more recent work on the physics of gas transport discussed briefly.     

A soil core for routine soil sampling

Abstract

The design, materials and dimensions for constructing a coring device for sampling soil fauna and flora at different depths is described.     

Relationship between soil respiration and soil moisture

Microbial activity is affected by changes in the availability of soil moisture. We examined the relationship between microbial activity and water potential in a silt loam soil during four successive drying and rewetting cycles. Microbial activity was inferred from the rate of CO₂ accumulating in a sealed flask containing the soil sample and the CO₂ respired was measured using gas chromatography. Thermocouple hygrometry was used to monitor the water potential by burying a thermocouple in the soil sample in the flask. Initial treatment by drying on pressure plates brought samples of the test soil to six different water potentials in the range -0.005 to -1.5MPa. Water potential and soil respiration were simultaneously measured while these six soil samples slowly dried by evaporation and were remoistened four times. The results were consistent with a log-linear relationship between water potential and microbial activity as long as activity was not limited by substrate availability. This relationship appeared to hold for the range of water potentials from ?0.01 to ?8.5 MPa. Even at ?0.01 MPa (wet soil) a decrease in water potential from ?0.01 to ?0.02 MPa caused a 10% decrease in microbial activity. Rewetting the soil caused a large and rapid increase in the respiration rate. There was up to a 40-fold increase in microbial activity for a short period when the change in water potential following rewetting was greater than 5 MPa. Differences in microbial activity between the wetter and drier soil treatments following rewetting to the original water potentials are discussed in terms of the availability of energy substrate.     

Volumetric soil measures for routine soil testing

Abstract

The design, dimensiors and materials for constructing volumetric soil measures for routine soil testing use are presented. Scoop calibration techniques are also described. Reproducibility of results obtained under routine laboratory, conditions are shown. The measures include volumes of 1.0‐, 2.5‐, 5.0‐ and 10‐ cm³ respectively.     

Why soil erosion models over-predict small soil losses and under-predict large soil losses

Evaluation of various soil erosion models with large data sets have consistently shown that these models tend to over-predict soil erosion for small measured values, and under-predict soil erosion for larger measured values. This trend appears to be consistent regardless of whether the soil erosion value of interest is for individual storms, annual totals, or average annual soil losses, and regardless of whether the model is empirical or physically based. The hypothesis presented herein is that this phenomenon is not necessarily associated with bias in model predictions as a function of treatment, but rather with limitations in representing the random component of the measured data within treatments (i.e., between replicates) with a deterministic model. A simple example is presented, showing how even a `perfect' deterministic soil erosion model exhibits bias relative to small and large measured erosion rates. The concept is further tested and verified on a set of 3007 measured soil erosion data pairs from storms on natural rainfall and run-off plots using the best possible, unbiased, real-world model, i.e., the physical model represented by replicated plots. The results of this study indicate that the commonly observed bias, in erosion prediction models relative to over-prediction of small and under-prediction of large measured erosion rates on individual data points, is normal and expected if the model is accurately predicting erosion rates as a function of environmental conditions, i.e., treatments.     

自然侵蚀量和容许土壤流失量与水土流失治理标准

在总结分析国内有关自然侵蚀量、容许土壤流失量研究成果的基础上,探讨自然侵蚀量与容许土壤流失量的关系,讨论制订水土流失治理标准的思路。认为水土流失治理标准的确定有3个参考值：1）标准值,即一定条件下的容许土壤流失量,是水土流失治理至少要达到的目标,且随着对不同土地利用类型的功能需求与可实施的最佳水土保持措施、以及所在水土流失类型区的侵蚀危害与治理约束条件的不同而不同;2）理想值,即正常自然侵蚀状态下的土壤流失量;3）极端值,即土壤流失量为0,不发生水土流失。水土流失治理应是先控制到现时生态环境与社会经济条件下的容许土壤流失量范围内,逐步达到自然正常侵蚀量或制止水土流失的发生;还应引入环境伦理、环境美学及景观设计等理念,最终实现土地的可持续利用、区域生态系统的健康稳定及人与自然的和谐友好发展。     

节水灌溉对盐渍土盐分调控与土壤微生物区系的影响

河套灌区是我国大型自流灌区之一,盐渍化是该区土壤主要障碍因素之一。目前,河套灌区葵花田生育期灌溉量约为1 100～1 200 m3hm-2,灌溉用水量偏大和地下水位偏高已成为制约当地灌溉农业可持续发展的主要障碍:一方面,水资源浪费严重;另一方     

An equivalent soil mass procedure for monitoring soil organic carbon in multiple soil layers

Soil carbon stocks are commonly quantified at fixed depths as the product of soil bulk density, depth and organic carbon (OC) concentration. However, this method systematically overestimates OC stocks in treatments with greater bulk densities such as minimum tillage, exaggerating their benefits. Its use has compromised estimates of OC change where bulk densities differed between treatments or over time periods. We argue that its use should be discontinued and a considerable body of past research re‐evaluated. Accurate OC estimations must be based on quantification in equivalent soil masses (ESMs). The objective of this publication is to encourage accurate quantification of changes in OC stocks and other soil properties using ESM procedures by developing a simple procedure to quantify OC in multiple soil layers. We explain errors inherent in fixed depth procedures and show how these errors are eliminated using ESM methods. We describe a new ESM procedure for calculating OC stocks in multiple soil layers and show that it can be implemented without bulk density sampling, which reduces sampling time and facilitates evaluations at greater depths, where bulk density sampling is difficult. A spreadsheet has been developed to facilitate calculations. A sample adjustment procedure is described to facilitate OC quantification in a single equivalent soil mass layer from the surface, when multiple‐layer quantification is not necessary.     

Assessment the effect of homogenized soil on soil hydraulic properties and soil water transport

Soil hydraulic properties play a crucial role in simulating water flow and contaminant transport. Soil hydraulic properties are commonly measured using homogenized soil samples. However, soil structure has a significant effect on the soil ability to retain and to conduct water, particularly in aggregated soils. In order to determine the effect of soil homogenization on soil hydraulic properties and soil water transport, undisturbed soil samples were carefully collected. Five different soil structures were identified: Angular-blocky, Crumble, Angular-blocky (different soil texture), Granular, and subangular-blocky. The soil hydraulic properties were determined for undisturbed and homogenized soil samples for each soil structure. The soil hydraulic properties were used to model soil water transport using HYDRUS-1D.The homogenized soil samples showed a significant increase in wide pores (wCP) and a decrease in narrow pores (nCP). The wCP increased by 95.6, 141.2, 391.6, 3.9, 261.3%, and nCP decreased by 69.5, 10.5, 33.8, 72.7, and 39.3% for homogenized soil samples compared to undisturbed soil samples. The soil water retention curves exhibited a significant decrease in water holding capacity for homogenized soil samples compared with the undisturbed soil samples. The homogenized soil samples showed also a decrease in soil hydraulic conductivity. The simulated results showed that water movement and distribution were affected by soil homogenizing. Moreover, soil homogenizing affected soil hydraulic properties and soil water transport. However, field studies are being needed to find the effect of these differences on water, chemical, and pollutant transport under several scenarios.     

Ecological standardization of soil and soil quality control

Theoretical bases are offered for the ecological soil standardization presuming the scientific substantiating of the allowable ecological state (quality) of the soil and the allowable anthropogenic impact on it. The modern experience of these bases’ application in regulatory-methodological, nature-control, and managerial practices is presented. The criteria are found for determining the levels of the allowable ecological quality of soil and the anthropogenic impact on it. The sources of the anthropogenic impact on the soil are characterized. A unified system of indices of soil quality and anthropogenic impacts and a mechanism for determining the range of the allowable values of these parameters have been developed taking into account the natural conditions and types of land use. Scientific-methodological approaches are proposed that support a certain balance between the allowable ecological status of the soil and the effects on it in connection with the mechanisms of the soil quality control in particular land plots.     

土壤调节剂对土壤物理性质的改善

Effects of non-ionic polyacrylamide(PAM),anionic polyacrylamide(PHP),cationic polyacrylamide(PCAM),non-ionic polyvinylalcohol(PVA),anionic hydrolyzed polyacrylonitrile(HPAN)and polyethleneoxide(PEO)on the physical properties of three different soil stpes were studied.content of water-stable aggregates larger than 0.25mm increased to varying extents for different soils and soil conditioners,Among the six kinds of condiftioners,non-ionic polyacrylamide(PAM) was the most effective for red soil while polyethyleneoxide(PEO)the least effective for Chao soil,red soil and yellow-brown soil.Water-stable aggregates with the molecular weight of PEO within a certain range.Only evaporation rate of Chao soil decreased after aplication of PAM and HPAN to Chao soil and red soil.     

Predicting soil solution chemical attributes from more easily measured soil and soil solution parameters

Abstract

An understanding of how soil solution ionic strength (I_s) and major cation activities influence crop growth is often limited by the extensive measurements required to characterize ionic composition and subsequent speciation exercises. Easily measured solution and soil attributes need to be identified that can predict these important solution parameters. Soil and soil solution chemical properties of four Ultisols in the Coastal Plain and Piedmont of North Carolina were used to develop models to predict ionic strength and solution cation attributes. GEOCHEM‐PC‐predicted I_s was linearly related to electrical conductivity (EC) across soils (r²=0.92), confirming that I_s for soil solutions with complex composition can be estimated from their electrical conductivity. Models of the form lnM_s=a+blnEC+clnM_E, or modifications thereof, were developed for predicting solution aluminum (Al), calcium (Ca), magnesium (Mg), and postassium (K) levels (M_s) from a knowledge of EC and either soil exchangeable cation #OPM_E) or cation saturation (MSAT_E) attributes. For each cation, total and free solution concentration and activity in absolute and saturation terms were investigated. The best models explained, at most, 68% of the variability associated with total solution Al concentration (Al_s‐T) or 74% when Al_s ‐T was expressed as a percent of major solution cations. Greater than 85% of the variability associated with solution Ca and Mg could also be accounted for, but only 67% of the variability associated with solution K could be explained. Including soil pH and interaction terms (M_ExEC, M_ExpH, and ECxpH) in models improved the relationship for total Al concentration (R²=0.87) and solution Ca parameters (R² ≥0.93), but not for solution Mg and K indices. None of the models could account for >30% of the variability associated with free concentration and activity of Al³⁺, suggesting that the prediction of these parameters for a particular Al species could not be made from a knowledge of soil pH, solution EC, and M_E or MSAT_E data.     

黑土区土壤侵蚀厚度对土地生产力的影响及其评价

为了研究黑土区土壤侵蚀厚度对土地生产力的影响,采用盆栽试验,人为剥离黑土表层0、5、10、15、20、25和30 cm土壤以模拟侵蚀厚度不同的耕层土壤,分析土壤侵蚀厚度对土壤理化性质、大豆生物性状和水分利用效率等指标的影响。并对TOPSIS(technique for order preference by similarity to ideal solution)模型进行改进,用于评价侵蚀厚度不同的土壤的土地生产力。结果表明:土壤全N、碱解N、全P、速效P、有机质含量和土壤田间持水率均随侵蚀厚度的增加而递减,土壤容重随侵蚀厚度的增加而递增。土壤侵蚀厚度对大豆生长有显著影响,随着侵蚀厚度的增加,大豆减产率呈"S型"曲线递增,产量、耗水量呈"Z型"曲线递减,水分利用效率呈指数曲线关系递减。改进的TOPSIS模型对不同侵蚀厚度下土地生产力的评价结果较为理想,计算的土地生产力指数随土壤侵蚀厚度的变化呈"Z型"曲线,与大豆产量的变化趋势相同,且二者呈指数函数关系,决定系数达0.996,均方根误差为0.65。研究结果可为黑土区土壤侵蚀防治提供理论依据。     

Tillage effects on soil degradation, soil resilience, soil quality, and sustainability

Soil degradation, decrease in soil's actual and potential productivity owing to land misuse, is a major threat to agricultural sustainability and environmental quality. The problem is particularly severe in the tropics and sub-tropics as a result of high demographic pressure, shortage of prime agricultural land, harsh environments, and resource poor farmers who presumably cannot afford science based recommended inputs. Tillage methods and soil surface management affect sustainable use of soil resources through their influence on soil stability, soil resilience, and soil quality. Soil stability refers to the susceptibility of soil to change under natural or anthropogenic perturbations. In comparison, soil resilience refers to soil's ability to restore its life support processes after being stressed. The term soil quality refers to the soil's capacity to perform its three principal functions e.g. economic productivity, environment regulation, and aesthetic and cultural values. There is a need to develop precise objective and quantitative indices of assessing these attributes of the soil. These indices can only be developed from the data obtained from well designed and properly implemented long-term soil management experiments conducted on major soils in principal ecoregions.     

Factors of soil formation in soil classification systems

The development of soil classification systems in Russia has been accompanied by certain changes in the attitude toward the factors of soil formation as criteria for separating soil units at the high taxonomic levels. The works of N.N. Rozov supported the traditional priority of the bioclimatic approach to the separation of soil types and subtypes in the classification systems of 1967 and 1977. In the new classification of Russian soils, the factors of soil formation are taken into account in a “hidden” form, through the diagnostic horizons and features reflecting the facial and zonal changes in the character of the pedogenesis and through the separation of several high-level soil taxa developing under specific combinations of lithological and geomorphic conditions. Ecological matrices illustrating the position of the soil types distinguished on the basis of substantive criteria in the field of soil-forming factors are included in the latest version of the new Russian soil classification system. The idea of these matrices fully corresponds to the logic of the factor-genetic soil classification system developed in the works of N.N. Rozov.     

Effect of soil acidification on the soil microflora

The effects of short and long term acidification on a few Alberta soils were studied with respect to bacterial numbers and total soil respiration. Significant reductions in bacterial numbers were observed in both short and long term acidified soils. Total soil activity was severely affected in an acid soil (pH 3.0, longterm) adjacent to a S block. A soil (pH 6.8) 200 m away from this S block when artificially acidified to pH 2.9 significantly reduced soil activity but not as drastically as found in the long term pH 3.0 soil. A garden soil (pH 7.7) which was also acidified to pH 3.2 showed no significant reduction in total soil respiration rate as compared to its unacidified control soil. These acid soils when amended with organic substrates demonstrated that certain physiological groups of organisms were severely inhibited by this acid condition. The importance of examining more than one parameter when assessing the effect of a potential pollutant on soil activity is discussed.