机械压实过程中复垦土壤紧实度影响因素的模拟分析

机械碾压造成的土壤压实是土地复垦中面临的主要问题之一,影响土壤压实程度的因素很多,除土壤自身的因素以外,还包括压实机械、压实次数以及土层厚度等。该文基于统计学的理论,采用2×5×4的混合试验设计并建立模拟实验区,使用重锤模拟分析了2种压实机械、不同压实次数(1、3、5、7、9次)和不同土层厚度(0~10cm、10~20cm、20~30cm、30~40 cm)上土壤紧实度的变化情况,并在SPSS中进行变量的方差分析和多重比较,试图找到机械压实过程中影响土壤紧实度的因素及其变化水平。结果表明:增加压实机械的承重轮面积能够有效降低对土壤的压实作用;压实机械、土层厚度和压实次数都是影响土壤紧实度的显著性因素且各因素的贡献率(97%)远高于随机误差;自卸汽车在第5次压实之后就已经使上层土壤紧实度达到最大值,而履带式推土机需要压实7次,土地复垦中应尽量选择履带型机械,碾压次数控制在5~7之内;机械压实的过程中,各土层厚度之间土壤紧实度的大小关系并不是一成不变的,中间层次(10~30 cm)的土壤由于同时受到来自上下2个方向的作用力,紧实度相对较高;不同次数的压实对土壤紧实度的影响深度和程度不同,在一定范围内,随着压实次数的增加,单次压实对土壤紧实度的影响逐渐减小。     

前期含水量对机械压实土壤结构特征的影响

使用美国MT865履带式拖拉机对东北典型黑土区耕地土壤进行1,3,8,13次的积累压实试验,通过对土壤硬度、广义土壤结构指数的测定及计算·并结合土壤三相的二维三系图对比分析了不同前期含水量条件下土壤机械压实特征.结果表明:由于表层0-10 cm含水量的不同.相对高含水量的土壤剖面受机械压实的影响范围 较低含水量时深10 cm,且各个层次的土壤硬度增量的变化趋势也相对低含水量时滞后10 cm,从初次碾压开始就体现了积累压实作用,在其压实影响范围内硬度与对照相比提高了22.58%～753.85%;而低含水量的土壤则具有相对较强的抗机械压实的能力,同时发现,在土壤承受能力范围内,适当的压实可以有效调节土壤三相,改善土壤结构;秸秆还田不仅具有传统的蓄水保墒、培肥改土的效用,还可以缓解作业机械对土壤的压实.     

冻融条件下藻结皮覆盖对土壤结构的影响

[目的]为研究生物结皮覆盖和冻融作用对土壤结构的影响。[方法]以黄土高原北部风沙土为研究对象,采用室内模拟冻融的方法,利用田口方法分析不同冻融次数、冻融前土壤初始含水量和生物结皮(藻结皮)盖度对土壤结构特征的影响。[结果](1)通过正交试验获取的土壤结构指数(I_GSS)为75.57～96.57,信噪比(S/N)为37.55～39.70 dB,通过田口方法确定的最佳因子组合为15次冻融循环、15%初始含水量、80%藻结皮覆盖度,其预测结果为I_GSS=98.09,S/N=39.89 dB。(2)I_GSS与冻融次数、初始含水量、藻结皮盖度均呈正相关关系,各因子对土壤结构指数的主效应表现为初始含水量>冻融次数>藻结皮覆盖度;各因子对土壤结构指数变化的贡献率为初始含水量(52.17%)>冻融次数(31.95%)>藻结皮覆盖度(2.12%)。(3)土壤结构指数的变化来自于冻融过程中土壤水分的散失和孔隙扩张,藻结皮覆盖可以减缓冻融过程中水分的散失,从而减缓I_GSS变化。[结论]研究使用正交...     

基于稀土氧化物示踪法探究冻融循环对黑土团聚体周转的影响

为区分土壤团聚体形成和破碎过程,阐明冻融循环对黑土土壤结构的影响,本文利用稀土氧化物（REOs）示踪技术,通过室内模拟实验,探究不同初始含水量（50 %田间持水量（T50） vs. 100 %田间持水量（T100））和冻融循环次数（0次、3次、6次、12次和20次）对团聚体粒径分布、平均质量直径（MWD）以及团聚体周转过程的影响。研究结果表明：同一初始含水量下,随着冻融循环次数的增加,MWD、>0.25 mm和<0.053 mm团聚体含量显著降低,0.25～0.053 mm团聚体含量显著增加（P < 0.05）。6次冻融循环后,T50处理下的MWD显著高于T100处理（P < 0.05）,5～2 mm和<0.25 mm团聚体含量无显著差异。除5～2 mm团聚体外,相邻粒级团聚体之间周转更为激烈;在同一冻融循环次数下,5～2 mm团聚体向0.25～0.053 mm团聚体的破碎量在T100处理下显著高于T50处理（P < 0.05）。冻融循环促进了>0.25 mm团聚体的破碎和＜0.053mm的团聚,表现为0.25-0.053mm团聚体的累积,该变化与土壤初始含水量无关。冻融循环过程中,MWD与各粒径团聚体相对形成量呈显著正相关,与其相对破碎量呈显著负相关（P < 0.05）。随着冻融循环次数的增加,各粒径团聚体周转时间显著增加（P < 0.05）。同一冻融循环次数下,>0.25 mm团聚体的周转时间高于<0.25 mm团聚体,T100处理下的团聚体周转时间显著高于T50处理（P < 0.05）。综上所述,冻融循环次数和土壤初始含水量通过影响团聚体形成和破碎过程改变土壤结构的稳定性。本研究结果可为进一步探究冻融循环下黑土土壤结构变化提供理论依据。     

冻融对沼泽湿地土壤水稳性大团聚体的影响

水稳性大团聚体(>0.25 mm)是土壤侵蚀和质量的重要表征指标.通过室内培养,在不同含水量、冻融次数和压实处理条件下,研究冻融过程对三江平原沼泽湿地土壤水稳性大团聚体的影响.结果表明,冻融过程影响土壤水稳性大团聚体含量,但压实和土壤起始含水量对湿地土壤的水稳性大团聚体影响较小,而冻融次数影响显著.4次冻融前,随着冻融次数的增加,不同处理的土壤水稳性大团聚体含量呈增加趋势;4次冻融后,高含水量处理的土壤水稳性大团聚体变化不明显,而低含水量处理的土壤水稳性大团聚含量有微弱增加.     

不同磷水平对紫花苜蓿产量和品质的影响

不同磷水平对苜蓿产量和品质的影响研究表明 ,在苜蓿充分供应氮、钾等其它营养的情况下 ,施用磷肥能显著增加植株生长高度和侧枝数 ,增加植株生长高度 8 2～ 10 1cm ,增加植株侧枝数 0 9～ 1 8个/株 ;能大幅度提高苜蓿鲜草产量 ,增产 30 8%～ 70 2 % ;对反映苜蓿品质的各营养成分含量影响不明显 ,但能增加单位面积牧草营养成分总产量 ;增施磷肥不仅可以显著增加苜蓿对磷的吸收 ,而且能不同程度地促进苜蓿对钾和钙的吸收 ;本试验条件下的经济最佳施磷 (P2 O5)量为 10 2 4kg/hm2 。     

不同施工机械对煤矿区复垦土壤颗粒组成的影响

以建筑垃圾、粉煤灰、煤矸石作为填充材料,研究自卸汽车和履带式推土机2种不同复垦机械在不同压实次数下,土壤颗粒组成的变化。结果表明:(1)复垦中通过1,3,5,7,9次机械碾压,土壤颗粒中砂粒含量减少,粉粒含量增多,在颗粒组成上有细化现象。(2)自卸汽车复垦,随着压实次数的增加,土壤颗粒均匀指数呈现"W"形变化;履带式推土机压实复垦下,土壤颗粒均匀指数呈现倒"V"形变化。(3)用粉砂质壤土作为覆土复垦时,自卸汽车碾压3次,履带式推土机碾压5次与自然耕地颗粒组成相似度最大,即自卸汽车碾压3次、履带式推土机碾压5次为土地复垦的临界碾压次数。(4)粒径5.86μm是土壤粒径中处于"物理性粘粒"部分含量的最高值。自卸汽车碾压对土壤"物理性粘粒"的影响主要集中在4.83~7.11μm范围内,履带式推土机碾压对土壤"物理性粘粒"的影响主要集中在3.98~8.64μm范围内。     

采用Gompertz函数的水稻土压缩特性研究

土壤压实模型是预测压实破坏的常用方法,但土壤压实模型的应用常因输入参数（土壤压缩特性及其与不同土壤物理性质之间的关系）的缺乏而受到限制。为定量地评价土壤水力学性质和土壤结构对土壤压缩特性的影响,该文利用土壤固结仪对25种不同含水率和容重的重塑土样进行单轴压缩试验,并采用Gompertz函数对试验数据进行拟合以获取土样的回弹指数、压缩指数和先期固结压力。试验结果表明,Gompertz函数对水稻土试验数据的拟合效果较优,决定系数为0.991～0.999。水稻土回弹指数为0.003～0.138,与容重呈负相关,与含水率呈正相关。水稻土压缩指数为0.115～0.839,与容重呈负相关,与含水率呈二次多项式关系。水稻土先期固结压力为33～127 kPa,与容重呈正相关,与含水率呈负相关。该研究建立的土壤压缩特性与含水率和容重之间的传递函数,可用于大尺度范围内水稻土压缩特性的预测;同时这些传递函数可作为土壤压实模型的输入参数,用于农业机械作业引起的压实破坏的量化和土壤压实风险的评估。     

雨滴直径对表土结构和入渗特征的影响

为探究雨滴击溅对表层土壤结构和入渗特征的影响,揭示土壤微结构与入渗间的深层关联,以黄土高原土为对象,采用模拟降雨、同步辐射CT扫描和入渗试验,系统地分析了不同雨滴击溅作用下土壤结构变化与入渗速率间的关系。结果表明:(1)击溅土壤结构发生变化,团聚体数量和三维分形维数显著增加,孔隙体积和大孔隙率显著减小。雨滴直径越大,击溅后的团聚体破碎程度越强,孔隙堵塞率最高达46.40%。(2)雨滴击溅下,破碎的团聚体堵塞孔隙,在土壤表层形成致密低渗的结皮层,结皮强度随雨滴直径和击溅次数的增加逐渐增加。(3)土壤入渗速率随雨滴直径和击溅次数的增加逐渐减小,经过3次雨滴击溅后减渗效应最高可达91.81%。(4)土壤稳渗速率与雨滴直径和土壤结构特征参数呈显著指数关系变化。研究表明,雨滴直径显著影响表层土壤结构和入渗特征,雨滴直径越大,土壤结构越分散,土壤入渗能力越低。     

拖拉机田间行走对土壤特性及冬小麦生长的影响

农业机械的过度使用、密集轮作以及不适当管理等都会造成土壤压实。试验研究了拖拉机行走对土壤特性和小麦生长的影响。试验所使用的耕作机械包括轮式、履带式和手扶式三种拖拉机,分析了土壤压实对小麦生长以及土壤结构不连续性的影响。试验数据表明,土壤密度、土壤阻力以及土壤水分一般会随拖拉机行走次数增加而增大。同时,文中给出了小麦根系与秸秆间蕴涵的机理关系。试验数据还表明,小麦发芽率在显著性水平P≤0.05时,不同处理组之间无明显差异。但是,2、4、6、8、10、12、18周以及收割时的小麦秸秆高度在显著性水平P≤0.01时,各处理组之间却存在显著差异,其中轮式和手扶式拖拉机处理组高于履带式拖拉机处理组。当显著性水平分别为P≤0.05和 P≤0.01时,不同处理组的小麦根长度和密度间也存在显著差异,其中轮式和手扶式拖拉机处理组同样表现出更好的结果。总之,拖拉机行走会显著影响干物质、谷物产量等小麦生长参数。然而,作物产量不仅受土壤压实的影响,同时很大程度上也取决于天气以及土壤初始压实等因素。     

Soil compaction effects on soil bulk density and penetration resistance and growth of spring barley (Hordeum vulgare L.)

Abstract

The weight of the tractor is not the only factor affecting soil compaction. Soil-management practices, such as the use of fertilizers and pesticides, also affect soil properties through an increased number of overriding. The aim of the current study was to investigate compaction effects on soil physical properties, such as dry bulk density and penetration resistance, and the growth of spring barley (Hordeum vulgare L.) as a monoculture. The five-year experiment was conducted on the Estonian University of Life Sciences’ research field at Eerika, near Tartu in 2001–2005. The soil of the experimental site is sandy loam Stagnic Luvisol. The treatments included were no compaction, one pass, three passes, and six passes. All passes were track-by-track. Measurements of soil and plant were made in the earing phase of barley and measurements of yield in the maturity phase of barley. The compaction treatment was conducted using an MTZ-82 tractor (total weight 4.84 Mg). Neither fertilizers nor herbicides were used. 5 years after compaction distinguishable subsoil and topsoil compaction was detected. Soil deformation increases with the number of passes; in the case of six passes soil bulk density increased by 0.15 Mg m^?3 and penetration resistance by 3 MPa. However, there were no significant differences in the soil bulk density and penetration resistance between treatments compacted with one and three passes. The effect of compaction on soil bulk density was higher when the soil was compacted under wet conditions. Compaction decreased the quantity of barley shoots, their phytomass, and grain yield by more than 80%. In the second year of the experiment the dry weight of above ground biomass decreased by almost three times and shoots’ density by 1.5 times, compared with the first year results. In the third year of the experiment the biomass, plant density, and grain yield of barley were stabilized and no further decreases were detected in the following two experimental years. The results from the experiment revealed that even a low weight tractor can induce subsoil compaction and a high decrease of plant productivity by repeated passes over time.     

Combined effects of soil texture and machine operating trail gradient on changes in forest soil physical properties during ground-based skidding

Wood extraction by heavy machinery has always been associated with soil disturbance in mountain forests,and the degree of soil degradation is influenced by several factors,including site and soil characteristics,soil moisture,type of equipment used,and number of machine passes.The effects of ground-based skidding operations on the physical properties of soils with different texture were evaluated at different levels of traffic frequency and trail gradient at two sites in an Iranian temperate forest.The treatments included combinations of three different traffic frequencies(3,8,and 14 passes of a rubber-tired cable skidder),three levels of trail gradient(10%,10%–20%,and20%) and two soil texture classes,clay loam(Site 1) and sandy loam(Site 2).The average gravimetric soil moisture at the time of skidding was 23%(Site 1) and 20%(Site 2).The average dry bulk density and total porosity of the undisturbed soil(control) were0.71 g cm~(-3) and 73.3% at Site 1(clay loam) and 0.86 g cm~(-3)and 59.1% at Site 2(sandy loam),respectively.At site 1(fine-textured soil),rutting began after three passes of the skidder,whereas at site 2(coarse-textured soil),rutting occurred only after eight passes.Independent of the traffic frequency and trail gradient,machine impact on the fine-textured soil caused greater increases in bulk density and rut depth compared to that on the coarse-textured soil.After three skidder passes and independent from trail gradients,dry bulk density at Site 1 increased by 54.8% compared to that of the undisturbed control,and the increase was 45.5% at Site 2.Therefore,medium to fine-textured soils are more susceptible to compaction than coarse-textured soils.Such soils,especially when moist,should be protected using brush mats created from harvesting residues during the forest processing phase.     

PA—Precision Agiculture: Wheel Traffic Influence on Poplar Regeneration and Grass Yield

All transport in forest stands occurs on the ground that at the same time is used as a growth substrate, not only for timber production but for grass as well in several Argentine production systems. Heavy traffic will damage the ground vegetation, affect tree roots and compact the soil to a degree where the tree roots have difficulty in regenerating in the damaged zone. The main objective of this research was to evaluate changes in soil compaction, introduced by traffic, during harvesting operations in a timber forest where grass production is also used for cattle feeding. Four experimental variables were measured: changes in bulk density in the profile, changes in penetration resistance, grassland yield and forest plantation regeneration after harvesting traffic. The work was performed in the south of the Rolling Pampa region, Argentina. The soil was a fine clayey, illitic, thermic Typic Argiudoll. Treatments consisted of four different traffic intensities, due to different passes of a tractor pulling a trailer on the inter-row area of the plantation, during harvesting operations. Increasing the number of traffic passes, increased the depth at which differences in cone penetration resistance values began to be significantly higher.The increments in bulk density values after traffic were not so evident as those in penetration resistance values, but the same tendencies were shown. The least traffic intensity, corresponding to only one pass, resulted in a reduction of grass yield (40·3%) in comparison with the control (no traffic) treatment, although there was no effect on tree regeneration. Traffic within the plantation impacted principally on tree shoot mortality, with a maximum of 51·5%, measured 1 year after traffic, recorded in the ten pass treatment. Grassland production within the plantation, after harvesting operations, was directly associated with forest regrowth.     

Comparison of soil preparation methods for rice production in the Middle Nile Delta,Egypt

Field experiments were conducted during the summer seasons of 2011 and 2012 in the Middle Delta of Egypt to compare alterations in saving water and grain yield of transplanted rice in clay loam soil after compaction, wet tillage (puddling) and dry tillage (non-puddling). The results indicate that compacted soil gave higher grain yield, higher irrigation water productivity, higher net income, higher benefit–cost ratio, and less water consumption than wet and dry tillage. The results suggest that soil compaction by four passes of steel plank (2 m long and 600 kg weight) before planting rice is beneficial in terms of saving water and net return. In addition, it can be used instead of the non-puddling method under the conditions of the studied area. Therefore, soil compaction can be considered as a pioneering method of pre-planting soil preparation to increase rice yield and to save irrigation water. It is highly recommended to be used by farmers.     

Regression analysis of some factors influencing soil compaction

Experiments were conducted in a laboratory soil bin, at the Regional Research Center of Asian Institute of Technology, to develop compaction models for a silty clay loam soil. The development of the models made use of dimensional analysis techniques. Three independent parameters were investigated: (1) tire variables (section width, diameter, inflation pressure), (2) soil variables (moisture content, initial cone index), and (3) external variables (travel speed, axle load, number of passes). Bulk density and cone index were considered as dependent variables. Results showed that axle load and number of tire passes were the most prominent factors which greatly influence soil compaction. Furthermore, soil moisture content, aspect ratio, and tire inflation pressure also revealed significant effects. The greatest soil compaction occurred during the first three passes of the tire. Soil compaction models were established and were found to provide good predictions. The trend established by the models signifies that general relationships can be established to predict soil compaction related to soil types. Furthermore, the models provided predictions at different soil and machine working conditions. Using the models, assessment of soil compaction can be made to develop a decision support system to establish useful recommendations for appropriate soil management practices and solutions to site-specific soil compaction problems.     

Soil compaction caused by harvesting,skidding and wood processing in eucalyptus forests on coarse‐textured tropical soils

Eucalyptus forests play a major role in the world economy, providing raw materials for different purposes. In planted forests, harvest operations performed by heavy machinery may cause severe soil compaction. This study aimed to evaluate the impact of a full‐tree harvesting system in planted eucalyptus forests from Northeastern Brazil. Different soils were evaluated (two Hapludults and one Haplorthod) in two horizons (BA and Bt). We tested different equipment, namely feller buncher, skidder (with traffic intensities of 3, 6, 12 and 16 passes), flail (at different ground‐contact points), grapple saw and loader. The soil physical attributes reflected not only the impact of equipment traffic but also the intrinsic differences between the soils. Bulk density (ranging from 1.36 to 1.80 t m^?3 after trafficking) related well to soil class and horizon. Precompression stress (ranging from 203 to 430 kPa) and degree of compaction (76%–94%) following trafficking were well correlated, while increase in bulk density (reaching a maximum of 20%) related more strongly to soil moisture. A contingency table was constructed with the number of compacted samples and further examined by correspondence analysis. Compaction varied according to soil, horizon and equipment, indicating that machine–soil interactions are very specific and demand detailed research under different conditions. The Haplorthod experienced the greatest amount of compaction, whereas the Hapludult‐2 was more resistant (60% and 25% of compacted samples, respectively). The grapple saw and the skidder at higher traffic intensities (12 and 16 passes) exerted the highest mechanical impacts (81% and 67% of compacted samples, respectively).     

Effect of induced compaction by wheel traffic on soil physical properties and yield of maize in Romania

Results of field experiments with soil compaction induced by wheel traffic applied uniformly to cover the entire surface of the experimental plots are reported. Compaction was done immediately before sowing, and each year, in each location, the same treatments were repeated on the same plots. The number of tractor passes varied between 0 and 30. The experiments were conducted during the 1978–1981 period in four locations with different soil and climatic conditions.Changes in soil physical properties, as well as in the yield of maize grain, were shown to be related to the number of tractor passes according to regression formulae of the type: Y = aX^b. Most of the changes were recorded between 0 and 8–10 passes, while with more than 15–20 passes changes became negligible. The average maximum increase in bulk density was 20–25% as compared with the non-compacted control plot, and the average maximum decrease in yield was 46%. Moisture content in the compacted control plot, and the was 2–3% (w/w) lower than in the control plot, except for the soils with poor drainage where the lower part of the compacted topsoil showed an increase in moisture content. Air content in the compacted plots often dropped below 10, and occasionally to nearly 0% (v/v). For three of the four locations, grain yield of maize linearly decreased by 13 kg ha^?1 (or 0.18% of the control plot yield) for each 1 kg m^?3 increase in bulk density.     

优化灌溉制度提高苜蓿种植当年产量及品质

为探讨灌溉定额及分配对滴灌苜蓿种植当年生产性能及水分利用效率的影响,该研究设3种滴灌灌溉定额,分别为3 750(W1)、4 500(W2)、5 250 m3/hm2(W3),且在W2处理下,设3种灌溉定额分配模式(Q1:刈割前灌溉本茬次总灌水量的35%+刈割后灌溉本茬次总灌水量的65%;Q2:刈割前灌溉本茬次总灌水量的50%+刈割后灌溉本茬次总灌水量的50%;Q3:刈割前灌溉本茬次总灌水量的65%+刈割后灌溉本茬次总灌水量的35%)。结果表明,滴灌苜蓿种植当年,不同灌溉量条件下,苜蓿的株高、叶茎比、茎粗、生长速度、干草产量、粗蛋白(crude protein,CP)含量均为W3W1处理,中性洗涤纤维(neutral detergent fiber,NDF)、酸性洗涤纤维(acid detergent fiber,ADF)含量为W3W2处理,水分利用效率(water use efficiency,WUE)为W1W3处理;不同灌溉定额分配条件下,苜蓿的株高、叶茎比、茎粗、生长速度、干草产量、CP、WUE均为Q1Q3处理,且Q1处理的干草产量最高达到9 916~10 172 kg/hm2,WUE为3.31~3.39 kg/(mm·hm2),NDF、ADF含量为Q1Q3处理。适宜的灌水量(4 500 m3/hm2)有利于苜蓿种植当年干草产量的提高,并保持较高的粗蛋白含量和相对较低的纤维含量;刈割前灌溉本茬次总灌水量的35%,并在刈割后灌溉本茬次总灌水量的65%,有利于苜蓿种植当年干草产量的提高及营养品质的改善。     

Long-term effects of a single compaction by heavy field traffic on yield and nitrogen uptake of annual crops

The long-term effects of soil compaction by heavy traffic on crop growth were examined in field experiments on a heavy clay (Vertic Cambisol) and an organic soil (Mollic Gleysol). There were three treatments: one pass and four repeated passes with a tandem axle load of 16 Mg, with wheel tracks completely covering the plot area, and a control without experimental traffic. Both loadings compacted the soils to a depth of 0.4–0.5 m. For 9 years after the loading, spring cereals (oats, wheat and barley) were the main crops grown. Yield, moisture content at harvest, thousand-kernel and bulk weight and nitrogen uptake of crops were determined each year. Although lodging of crops in the control and sometimes also in the treatment with one pass complicated the interpretation of results, especially for the organic soil, compaction clearly did affect crop production. For several years after the loading, it decreased yields and nitrogen uptake of crops and lowered seed moisture contents at harvest. Effects of the compaction were especially marked on the clay soil in the first 3 years and the rainy sixth year. Taken as a mean of the first 8 years, compaction of the clay soil with four passes reduced the yields by 4% and nitrogen uptake of annual crops by 9%. Compaction of the organic soil with four passes decreased the yield by 1% and nitrogen yield by 4%, as a mean of the first 5 and the last 3 years. The bulk weight or the thousand-kernel weight of yields was not notably affected by the compaction.     

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.