The effect of sodium and calcium on physical properties and micromorphology of two red-brown earth soils

The effect of treatment with either gypsum or sodium chloride on the saturated hydraulic conductivity ( K _s) of repacked soil columns and modulus of rupture (MOR) was studied on surface samples of two red-brown earth soils from SE wheat belt in Australia.
When the exchangeable sodium percentage (ESP) of the two soils was increased to >80, K _S was substantially reduced and MOR increased relative to the untreated soil; the values of the parameters were nearly equal for these pairs of high ESP soils. However, after treatment with gypsum the Raywood soil had a K _s twice, and a MOR less than half, the corresponding values for the Glenloth soil.
Micromorphological and scanning electron microscope (SEM) observations suggest that the increase in K _s following gypsum treatment is associated with an increase in visible macropores and reduced clay dispersion; Na treatment increased dispersion at the soil surface, with the clay particles forming an impermeable surface seal and illuviation argillans.     

Amelioration on some physical properties and nutrient availability of an exposed B horizon of red-brown earth

Abstract. Following removal of the upper 40 cm of soil, the physical properties of the exposed B horizon of a red-brown earth (Goulburn clay loam) were ameliorated using a combination of gypsum (5.4 ha⁻¹) and rye grass. Phosphorus (P), nitrogen (N) and potassium (K) fertilizers were added to improve nutrient availability. The ameliorated properties of the exposed B horizon were compared with those of equivalent depths from an adjacent intact profile of Goulburn clay loam.
Initially, during the establishment phase of the rye grass, the gypsum increased the electrolyte concentration in the 0–10 cm layer, and stabilized the soil surface against mechanical dispersion. After 18 months all the gypsum in the 0–10 cm layer had dissolved. However, in the presence of rye grass, the soil surface was no longer susceptible to dispersion by the mechanical impact of water. The rye grass improved soil physical properties mainly in the upper 20 cm of the exposed B horizon. Water-stable aggregation > 2000 μm and macroporosity increased, and bulk density and penetrometer resistance of the soil decreased.
Continuous applications of P, N and K fertilizers resulted in a gradual improvement in the nutritional properties of the exposed B horizon. However, because of the large phosphorus adsorption by the exposed clay, 300 kg P ha⁻¹ was required to provide sufficient available phosphorus in the 0–10 cm layer.     

Strip-tillage effect on seedbed soil temperature and other soil physical properties

The no-tillage system is perceived as having lower soil temperatures, wetter soil conditions, and greater surface penetration resistance compared with conventional and other conservation tillage systems. Concerns associated with the effect of the no-tillage system on certain soil physical properties (i.e. soil temperature, moisture, and compaction) prompted this study to evaluate the effect of an alternative tillage system, strip-tillage, on these physical properties, compared with chisel plow and no-tillage systems. The study was conducted on two Iowa State University research and demonstration farms in 2001 and 2002. One site was at the Marsden Farm near Ames, where the soils were Nicollet loam (Aquic Hapludolls) and Webster silty clay loam (Typic Haplaquolls). The second site was at the Northeast Research and Demonstration Farm near Nashua, where the soils were Kenyon loam (Typic Hapludolls) and Floyd loam (Aquic Hapludolls).Soil temperature increased in the top 5 cm under strip-tillage (1.2–1.4 °C) over no-tillage and it remained close to the chisel plow soil temperature. This increase in soil temperature contributed to an improvement in plant emergence rate index (ERI) under strip-tillage compared with no-tillage. The results show no significant differences in soil moisture status between the three tillage systems, although the strip-tillage soil profile has slightly greater moisture content than chisel plow. Moisture content through the soil profile particularly at the lower depths under all tillage treatments was greater than the plant available water (PAW). However, the changes in soil moisture storage were much greater with strip-tillage and chisel plow than no-tillage from post-emergence to preharvest at 0–30 and 0–120 cm. It was observed also that most change in soil moisture storage occurred between post-emergence and tasseling. Penetration resistance was similar for both strip-tillage and no-tillage, but commonly greater than chisel plow. In general, the findings show that strip-tillage can contribute effectively to improve plant emergence, similar to chisel plowing and conserve soil moisture effectively compared with no-tillage.     

The effect of preplanting soil preparation and soil management on soil physical parameters in an apple orchard

Abstract. Effects on soil physical properties in a trial which compared establishing an apple orchard on grassed and cultivated soil and of maintaining soil with or without a vegetative cover post-planting are discussed. On a fine sandy loam soil (Fyfield series) prone to erosion, bulk density, water filled porosity and soil erosion, measured at intervals after the establishment year, were all unaffected by the use of grass. Infiltration rate was much higher on grassed than on herbicide treated soil as was the apparent ability to accept heavy rainfall.     

耕深对土壤物理性质及小麦-玉米产量的影响

为了解不同犁底层破除程度对黄淮海平原农田土壤蓄水保墒、穿透阻力动态变化及作物产量的影响,在山东德州试验基地以冬小麦-夏玉米轮作农田为研究对象,设置4个犁底层厚度处理,分别为犁底层不破除(RT15)、犁底层破除1/3(DL20)、犁底层破除2/3(DL25)和犁底层完全破除(DL40)。结果表明:1)完全或者部分破除犁底层均能够显著降低10~30 cm土层容重和穿透阻力,各处理降低幅度具体表现为DL40DL25DL20RT15。2)DL20、DL25和DL40处理有利于增加降水或灌溉后水分入渗,冬小麦苗期20~70 cm土壤平均含水率分别较RT15处理提高5.3%、15.9%和23.6%,且冬小麦季耗水量分别较RT15处理提高4.9%、10.2%和11.6%;DL20、DL25和DL40处理夏玉米苗期20~70 cm土壤平均含水率分别较RT15处理提高7.7%、14.2%和15.8%,但夏玉米季耗水量分别较RT15处理降低5.8%、7.6%和10.5%。3)冬小麦季0~15和15~30 cm土层穿透阻力均表现为双峰型,且2土层受冻融作用影响各处理在越冬期达到穿透阻力峰值1 489.2~2 128.1和1 925.4~4 423.7 kPa;30~45 cm土层各处理穿透阻力变化规律在两季作物生长后期差异较大,冬小麦生长后期表现为DL40DL25DL20RT155,而夏玉米后期表现为DL40DL25DL20RT15。4)相对完全打破犁底层,部分打破犁底层更有利于提高水分利用效率,显著增加作物产量,DL25处理冬小麦和夏玉米产量分别较DL40处理增加4.2%和2.4%。综合考虑,DL25是目前相对较好的犁底层改良方式,此时犁底层厚度适当,既可节省农机能耗,又可兼有透水、增产效能。     

Effect of repeated tractor wheeling on stress/strain properties and consequences on physical properties in structured arable soils

The discussion about the effect of repeated short time wheeling on long-term changes in soil structure and pore functioning reveals a great uncertainty. On the one hand it is told that soil structure elements are rigid and do not undergo intense changes in pore functions as a consequence of the short loading interval during each single wheeling. On the other hand, the complete deterioration of the structure elements and pore functions is assumed to occur, which also results in changes of the shrinkage pattern, soil strength including even strength regain. Consequently, the effect of wheeling on soil deformation and stress/strain distribution was investigated in a soil bin which contained Hiwassee clay at the NSDL, Auburn. If the soil is very strong due to aggregation, plow pan formation or dryness, soil stress applied by repeated wheeling results in an increased primarily vertical soil particle displacement in the Hiwassee clay soil while during repeated wheeling (up to 10×) a more pronounced displacement linked with a more intense movement of particles can be proofed. With increasing number of wheeling events, new platy or again coherent structure elements are formed, which create a very different pore system. The more intense is soil wheeling, the smaller is the saturated hydraulic conductivity and the higher is the unsaturated one at a given pore water pressure value. Such changes are the more pronounced the more completed is the rearrangement of the still existing aggregates into new units like plates. Due to shear because of the three-dimensional soil displacement even under dry conditions such aggregates can be redisturbed and a coherent but very compacted soil horizon can be formed. Under those conditions the values of bulk density are even higher than the Proctor density.     

Effect of the number of tractor passes on soil rut depth and compaction in two tillage regimes

The initially high level of soil compaction in some direct sowing systems might suggest that the impact of subsequent traffic would be minimal, but data have not been consistent. In the other hand on freshly tilled soils, traffic causes significant increments in soil compaction. The aim of this paper was to quantify the interaction of the soil cone index and rut depth induced by traffic of two different weight tractors in two tillage regimes: (a) soil with 10 years under direct sowing system and (b) soil historically worked in conventional tillage system. Treatments included five different traffic frequencies (0, 1, 3, 5 and 10 passes repeatedly on the same track). The work was performed in the South of the Rolling Pampa region, Buenos Aires State, Argentina at 34°55′S, 57°57′W. Variables measured were (1) cone index in the 0–600 mm depth profile and (2) rut depth. Tyre sizes and rut depth/tyre width ratio are particularly important respect to compaction produced in the soil for different number of passes. Until five passes of tractor (2WD), ground pressure is responsible of the topsoil compaction. Until five passes the tyre with low rut depth/tyre width ratio reduced topsoil compaction. Finally, the farmer should pay attention to the axle load, the tyre size and the soil water content at the traffic moment.     

耕翻和秸秆还田深度对东北黑土物理性质的影响

为了明确耕翻和秸秆还田深度对土壤物理性质的影响,在东北黑土区中部进行了6 a的耕翻和秸秆还田定位试验,设置了免耕（D0）、浅耕翻（0～20 cm）（D20）、浅耕翻+秸秆（D20S）、深耕翻（0～35 cm）（D35）、深耕翻+秸秆（D35S）、超深耕翻（0～50 cm）（D50）和超深耕翻+秸秆（D50S）7个处理开展研究,秸秆还田处理将10 000 kg/hm2秸秆均匀地还入相应的耕翻土层。结果表明,耕翻和秸秆还田深度是影响土壤物理性质的重要农艺措施。与初始土壤相比,免耕显著增加了0～20 cm土层土壤容重,减少了孔隙度、持水量、饱和导水率和>0.25 mm水稳性团聚体的含量（WAS>0.25）（P<0.05）,而对20～50 cm土层没有显著影响（P>0.05）。在0～20 cm土层,除了D50处理显著降低了WAS>0.25含量以外,D20,D35和D50处理对各项土壤物理指标均没有显著影响;而D20S和D35S处理则显著改善了该层各项土壤物理指标。在>20～35 cm土层,D35、D35S、D50和D50S处理显著改善了该土层各项土壤物理指标（除了2014年的容重）。在>35～50 cm土层,D50和D50S处理对各项土壤物理指标改善效果显著,特别是相应土层通气孔隙度和饱和导水率显著增加。研究结果表明耕翻配合秸秆对土壤物理指标的改善效果优于仅耕翻处理。综合评分结果也表明D35S和D50S处理分别对>20～35 cm和>35～50 cm土层土壤物理性质的改善效果最好,说明在质地黏重的黑土上深翻耕或者超深翻耕配合秸秆还田通过土层翻转秸秆全层混合施用能够显著改善全耕作层土壤的物理性质,增加耕层厚度,扩充土壤的水分库容,提高黑土的水分调节能力。     

The effect of urban refuse compost and different tractors tyres on soil physical properties, soil erosion and maize yield

Application of urban refuse compost to agricultural soil could help to solve municipalities' problems related to the increasing production of waste only if soil property improvement and environmental conservation can be demonstrated. The use of low-pressure tractor tyres is another proposal in modern agriculture for reducing soil compaction. This study thus aimed to detect the effects of both compost and low-pressure tractor tyres on soil loss, runoff, aggregate stability, bulk density, penetrometer resistance and maize (Zea mays L.) yield. A 3-year field experiment was carried out on a hilly (15% slope) clay loam soil in central Italy. Twelve plots (200 m² each) were monitored with tipping-pot devices for runoff and soil erosion measurement. Treatments were: compost addition (64 Mg ha⁻¹), mineral fertilisation, use of low-pressure tyres, use of traditional tyres, with three replicates, in a fully randomised block design. Compost was applied once at the beginning of the experiment. Runoff reduction due to compost ranged between 7 and 399 m³ ha⁻¹ during seasons, while soil erosion was reduced between 0.2 and 2.4 Mg ha⁻¹. Mean weight diameter (MWD) of stable aggregates, measured on wheel tracks, increased by 2.19 mm, then progressively decreased. Compost significantly increased bulk density by 0.08 Mg m⁻³ due to its inert fraction content. This effect was less evident in the second and third year, probably due to harrowing. Maize yields were slightly, but significantly, reduced in composted plots by 1.72 Mg ha⁻¹ in the third year. Low-pressure tyres significantly reduced soil loss in the third year by 1 Mg ha⁻¹. Furthermore, they did not significantly influence runoff volumes and soil structural stability. Low-pressure tyres or compost addition were singly able to prevent an increase in penetrometer resistance due to agricultural machinery traffic. Low-pressure tyres increased the maize yield during the 3 years and the difference (0.4 Mg ha⁻¹) became significant in the third year. In conclusion, results show the positive lasting effect of compost in ameliorating soil physical properties and reducing runoff and soil erosion. Low-pressure tyres appear justifiable both for the observed increase of grain production and reduction of soil compaction. This latter effect is, nevertheless, masked by compost addition which is also able to reduce penetrometer resistance. Further research is required to explain the causes of the slight inhibition of grain yield observed when compost was compared with mineral fertilisation.     

Effect of tillage depth on physical properties of a tropical soil and on yield of maize, sorghum and cotton

Field experiments were carried out to study the effect of three tillage depths (5, 15 and 30 cm) on soil physical properties and on yield of maize (Zea mays), sorghum (Sorghum bicolor) and cotton (Gossypium hirsutum) on a ferruginous tropical soil. The increase in porosity due to deep tillage was only temporary and differences in water storage and movement were only noticeable during the early part of the rainy season. Deep tillage increased the yield of maize and cotton by about 10% but sorghum yield was not affected.     

The effect of surface growth of blue-green algae and bryophytes on some microbiological,biochemical, and physical soil properties

Summary The influence of surface growth of inoculated cyanobacteria (blue-green algae) on subsurface properties of a brown earth, silt loam soil was studied in reconstituted flooded soil columns. One blue-green algae species, Nostoc muscorum, become dominant within the first 7 days of inoculation. In light control columns (not inoculated) a bryophyte, Barbula recurvirostra, was dominant although significant growth of indigenous blue-green algae occurred. The blue-green algae counts were in the range of 1×10⁶ g^-1 dry soil in the surface layer (0–0.7 cm) in both columns. Any effect of surface phototrophic growth on soil properties was restricted to the surface layer. In inoculated columns there was a twofold increase in microbial biomass and an eightfold increase in bacterial numbers by week 13. However, bacterial numbers declined so that there was only a 2.8-fold increase by week 21. Dehydrogenase (x2.1), urease (x2.8) and phosphatase (x3.1) activities and polysaccharides (+69%) increased by week 21 as a result of the blue-green algae inoculation along with a significant improvement in soil aggregation. However, similar increases occurred in the light control columns, indicating that given appropriate conditions of light and moisture indigenous species may be ultimately as effective as introduced species in bringing about biochemical and microbiological changes to soil.     

Effects of tillage method on soil physical properties, infiltration and yield in an olive orchard

The long-term effects of two different tillage systems, conventional (CT) and no tillage (NT), were studied in an olive orchard in Santaella (Southern Spain) for 15 years. In both tillage systems, two distinct zones developed in the orchard in relation to soil physical properties; one underneath the tree canopy, and the other in the rows between trees. Surface soil organic matter content, bulk density, cone index, macroscopic capillary length and hydraulic conductivity showed significant differences between tillage systems and positions. After 15 years, the NT treatment achieved greater bulk density and cone index values than CT. This compaction reduced the infiltration rate of NT soil with respect to CT, particularly in the rows between trees. Despite that reduction, the NT soil retained a moderate infiltration potential. That may be explained by the high infiltration rates and macroporosity of the zone beneath the tree, the temporary effects of tillage on infiltration and probably by the self-repair of soil structure in the Vertisol studied. Yield was not affected by tillage except in one year with very low precipitation, where NT significantly yielded more than CT. The reduction in infiltration in NT must have been compensated by unknown factors that improve the tree water supply in drought years.     

The effect of different post-restoration cropping regimes on some physical properties of a restored soil

Abstract. The aggregate stabilities of a soil restored after opencast mining and an undisturbed soil were measured over a complete cropping year from the time of ploughing a grass ley in autumn. This was to examine the effects of various post-restoration cropping regimes on soil aggregate stability and soil porosity. A wet sieving technique and a mild dispersion method were used to determine indices of soil macro- and micro-aggregate stability, respectively. Air filled porosity at field capacity and crumb porosity were also determined. Removal, storage and restoration decreased macro- and micro-aggregate stability. After restoration, the different grass managements i.e. cutting for silage and grazing, had similar effects on soil aggregate stability and maintained greater aggregate stability than the arable regimes. The pattern of fluctuation in soil macro-aggregate stability over the year was similar under all crops at both sites, but at the restored site there was a decline in stability, and differences in the air filled porosity at field capacity developed between cropping regimes. Micro-aggregate stability was less at the restored than at the undisturbed site and showed no seasonal variation or difference between cropping regimes. However, a difference in crumb porosity between cropping regimes did develop.     

The effect of soil pH manipulation on chemical properties of an agricultural soil from northern Idaho

Abstract

Selected chemical properties of an artificially acidified agricultural soil from northern Idaho were evaluated in a laboratory study. Elemental S and Ca(OH)₂were used to manipulate the soil pH of a Latahco silt loam (fine‐silty, mixed, frigid Argiaquic Xeric Argialboll), which had an initial pH of 5.7. A 100 day incubation period resulted in a soil pH manipulation range of 3.3 to 7.0. Chemical properties evaluated included: N mineralization rate, extractable P, AI, Mn, Ca, Mg and K and CEC. N mineralization rate (assessed by anaerobic incubation) decreased with decreasing soil pH. Nitrification rate also decreased as NH₄ ⁺‐N accumulated under acid soil conditions. Sodium acetate extractable P was positively linearly correlated (R²= 0.87) with soil pH over the entire pH range evaluated. Potassium chloride extractable Al was less than 1.3 mg kg^‐1of soil at pH values higher than 4.4. Consequently, potential Al toxicity problems in these soils are minimal. Extractable Mn increased with decreasing soil pH. Soil CEC, extractable Mg, and extractable K all decreased with increasing soil pH from 3.3 to 7.0. Extractable Ca levels were largely unaffected by changing soil pH. It is likely that the availability of N and P would be the most adversely affected parameters by soil acidification     

土壤压实对土壤物理性质及小麦氮磷钾吸收的影响

为了研究土壤压实对土壤物理性质以及小麦养分吸收情况的影响,在2006和2007年进行了两轮田间试验.试验中,先用旋耕机对田块进行旋耕,耕深10cm,然后使用手扶式、轮式、履带式拖拉机在旋耕后的田块中通过1次(T1)、2次(T2)、4次(T3)以对土壤进行压实处理,对照组(T4)不作任何压实处理.压实处理后再次对土壤表层进行浅旋耕,耕深5 cm,耕后用播种机进行小麦播种,小麦品种为南京-601.试验结果发现,次表层土壤的压实处理显著影响次表层土壤的容重,孔隙度,小麦蛋白质含量以及植物中N、P、K的含量.除次表层的土壤容重在T3组中最大,T4组中最小外,其他参数值在T4组中最大,T3组中最小.并且,随着次表层土壤压实程度的增加,几乎所有的参数(土壤容重除外)都有所减少.不过,与第一年相比,参数值在第二年略有增加.总之,土壤压实严重破坏土壤结构,不利于小麦对养分的吸收.     

Effect of soil characteristics, seeding depth, operating speed, and opener design on draft force during direct seeding

Direct seeding practices that promote soil and water conservation and reduce input costs have become an increasingly accepted alternative to conventional tillage systems in western Canada. The objective of the present study was to determine the relative importance of soil characteristics, seeding depth, operating speed, and opener design on draft forces during direct seeding in central Saskatchewan. Draft was measured for nine different openers operated at 1–5 cm seeding depths and three ground speeds in four untilled Chernozemic soils that differed in soil moisture and/or texture. The average increase in opener draft for all fields was 4% for each km h⁻¹ increase in speed. Although the range in soil consistency was small, there was a 24% increase in draft in heavy clay compared to sandy loam soil. Draft force of the average opener increased by nearly 20% for each centimeter increase in seeding depth. However, highly significant interactions among most of the variables investigated indicated that the relative performance of openers was not consistent for the range of conditions evaluated. Large differences among the draft forces of different openers operated at different depths in soils with different consistencies were particulary noteworthy. For example, a 4.5-fold increase in the draft of a low versus a high draft opener operated at 1.25 versus 5.0 cm seeding depth at 7.5 km h⁻¹ in moist, heavy clay soil emphasized the large influence that opener design and seeding depth have on tractor power requirements and direct seeding input costs.     

Effects of pre-sowing compaction on soil physical properties, soil atmosphere and growth of oats on a clay soil

The effects on a number of soil physical and aeration parameters of compaction during spring pre-sowing operations were measured on a clay soil (49% clay). A soil-tyre contact stress of 200 kPa was applied by tractor tyres.
Yield of an oat crop was reduced by 30% as a result of compaction. Total porosity of the soil was reduced by 6% v/v owing to loss of pores > 60 μm, and water retention was increased. The resultant decrease in air-filled porosity greatly reduced gas diffusion and air permeability coefficients of the soil, and, for a time, O₂ content of the soil atmosphere was significantly lowered in the compacted treatment. Penetrometer resistance after sowing was 3.5 MPa in the control and 4.5 MPa in the compacted treatment; in the latter, root growth was inhibited until the soil dried and cracked. By the end of June, canopy temperature measurements indicated water stress in the oat crop on compacted soil but not in that on the control.
The results obtained indicated that air permeability, measured in the field, of 1 mm s⁻¹ provides a satisfactory single value below which crop growth is likely to be reduced.     

土壤容重对土壤物理性状和小麦生长的影响

以黑土和白浆土为试材 ,进行筒栽试验 .结果表明 ,适宜小麦生长的容重范围分别为 1 .1 5～1 .3 0 g/cm3和 0 .9～ 1 .0 5g/cm3.     

Effects of soil compaction on the relationships between nematodes,grass production and soil physical properties

As farm machinery has become heavier, concern has grown about its direct effects on soil physical conditions and its indirect effects on crop yields and soil biota. To study the relationships between these parameters, non-grazed temporary grassland plots on a loamy sand soil were subjected to full-width load traffic with widely different loads (0, 4.5, 8.5 and 14.5 t) one to four times per year for a period of 5 years. Soil bulk density was monitored as an indicator of soil compaction. Grass yield was measured throughout the experimental period. Root distribution over the soil profile and nematodes populations were assessed during the final year of the experiment. Results indicate that a moderate degree of compaction (∼4.5 t load) gave the highest crop yield and that at higher degrees of compaction roots failed to penetrate into the deeper soil layers (>20 cm depth). Total numbers of nematodes were not affected by compaction, but their distribution over the various feeding types shifted towards a population with increased numbers of herbivores and decreased numbers of bacterivores and omnivores/predators. This change in the structure of the nematode assemblage is associated with poorer conditions for crop growth.