Increased Soil Compaction Research Articles

Which Selective Logging Intensity is Most Suitable for the Maintenance of Soil Properties and the Promotion of Natural Regeneration in Highly Continental Scots Pine Forests?–Results 19 Years after Harvest Operations in Mongolia

Scots pine (Pinus sylvestris L.) forests are one of the main vegetation types in the Asian forest-steppe zone. However, over-harvesting currently threatens the natural regeneration and sustainability of these forests. In this study, we examine the long-term effects of different logging intensities on soil properties and natural regeneration in a natural Scots pine forest in the West Khentii Mountains (Mongolia), 19 years after selective logging. Our experimental design included five treatments: clear cut (CC), treatments with high (HI), medium (MI), low (LI) intensities, and a reference parcel with no logging impact at all (RE). We described and quantified the harvest events and applied ANOVA and LMM modeling to analyze and explain the long-term impacts of the logging intensities on soil properties and natural regeneration. We found that logging has a significant negative influence on the physical and chemical properties of the soil because it increases soil compaction and reduces soil nutrients. The most critical impacts of logging were on soil bulk density, total porosity, organic matter, and total nitrogen and phosphorus. The LMM modeling showed that organic matter (OgM), total nitrogen (TN), available K (AK) and pH values are especially impacted by logging. Our study revealed that the values for all of these variables show a linear decrease with increasing selective logging intensity and have a level of significance of p < 0.05. Another finding of this study is that selective logging with low and medium intensities can promote natural regeneration of Scots pine to numbers above those of the reference site (RE). High intensity logging and clear-cuts, however, limit the regeneration of Scots pine, reduce overall seedling numbers (p < 0.05), and create conditions that are suitable only for the regeneration of deciduous tree species. This underlines the risk of Scots pine forest degradation, either by replacement by broad-leaf trees or by conversion into non-forest ecosystems.

Improvement of Properties of the Argillaceous Soils when Using Additives "Chimston" in Combination with Inorganic Astringent

Paper observes research of the mechanical characteristics of the stabilized soil with different «Chimston» additives. Current work focuses on the application of the «Chimston-1» and «Chimston-2» produced by Zipo research and production company. Stabilized soil is based on local soils: argillaceous sand ground and sand clay. Chemical additives are mixed with water according to the manufacture’s recommendations. Amount of the «Chimston-1» is 0.07% of the soil. Amount of the «Chimston-2» is 0.01% of the cement. During the research plasticize effect is studied, based on maximum density and optimal humidity. Water saturation, mechanical strength under tension in bending and compression. It is established, application of the "Chimson" additives allow to increase key characteristics of the stabilized soil without increasing of the cement. «Chimston-1» additive has strongly pronounced plasticize effect which allow to increase soil compaction and decrease optimal humidity. Additive "Chimston-2" is a water repellent with a high degree of efficiency with soil stabilization.

EFFECT OF TRAFFIC INTENSITIES OF A DIRECTIONAL FELLER AND SKIDDER ON THE COMPACTION OF A BRUNO NITISOL

ABSTRACT This study evaluated the compaction of a Bruno Nitisol caused by traffic intensities by a directional feller and skidder used to wood harvesting in a Pinus taeda stand. Data were collected at a forest company located in Parana State, Brazil. Samples were performed using an installation of four blocks (30 × 15 m) with subdivided plots and the treatments included a combination of five traffic simulations of directional feller and skidder machines, with the simulations performed in the plots at four soil depths, referred to as subplots. Compaction was evaluated by soil density, total porosity, microporosity, and macroporosity. The data were submitted to analysis of variance and the means were compared with the Tukey test at a 5% level of significance. Linear regression equations were also adjusted to represent the relation between traffic intensity, depth, and the variable of interest. The results showed that machine traffic caused higher compaction of the superficial soil layers, resulting in a 14.6% increase in soil density compared to the soil subjected to no machine traffic. The increase in traffic intensity of the skidder tractor reduced macroporosity by 62.5% and 53.8% at depths of 0-10 and 10-20 cm, respectively. Dragging of the logs by the skidder tractor increased soil compaction due to the several trips by the machine in a single line.

Impact of crop-livestock-forest integration on soil quality

Integrated agricultural production systems with trees, grain crops and forage species are important for land use optimization. However, they can result in non-uniform changes in physical and chemical soil properties. The objective of this work was to evaluate chemical and physical soil properties in a eucalyptus-based agroforestry system. The experiment was conducted in a Red–Yellow Argisol in Southeast Brazil. Eucalyptus (Eucalyptus grandis × E. camoldulensis) seedlings were planted in rows 12.0 m apart, and 2.0 m between plants. For 4 years the inter-row space was cropped to soybeans (Glycine max L. Merrill), Sunn hemp (Crotalaria juncea) and maize (Zea mays L.) in association with palisade grass (Urochloa brizantha). After that, the forage was grazed by beef cattle. Five years after the implementation of the experiment, chemical and physical soil analyses were performed along the profile. Non-uniform changes were observed in fertility and soil physics in the transect between the eucalyptus planting lines, both at the soil surface layers and in depth. Integrated crop/livestock production systems, where eucalyptus is intercropped with annual crops and forage grasses for grazing, results in lower soil fertility near tree lines and up to 100 cm deep over time. Next to the tree line there is an increase in soil compaction and reduced aggregate stability in the uppermost soil layer, while microporosity and soil structuring are increased in the soil deeper layers. These effects are probably due to animal trampling under the trees.

Soil physical properties, nitrogen uptake and grain quality of maize (Zea mays L.) as affected by tillage systems and nitrogen application

Soil compaction is a global issue pertaining to agricultural lands. The frequent use of farm machinery and field operations at the same depth are the major causes of soil compaction. The gradual increase in soil compaction deteriorates maize grain quality due to reduced nitrogen (N) uptake. Quality food production by reducing soil compaction is the need of time, which can be achieved through deep tillage and N management. In this study, three tillage systems viz. conventional tillage (using cultivator), tillage with mould board plough +2-cultivations (MBP), and tillage with chisel plough +2-cultivations (CP); and three nitrogen levels viz. 100, 150 and 200 kg ha–1 were used to evaluate their effect on soil properties, N uptake and grain quality in maize. Lower bulk density (1.41 Mg m–3), higher total porosity (0.47 m3 m–3) and higher nitrogen uptake (96.01 kg ha–1) was recorded under chisel plough (CP) compared with other tillage systems. Different N levels had significant effect on grain and total N uptake and grain quality, while soil properties remains unaffected. Higher N uptake was recorded with 200 kg ha–1 N application than other treatments. Similarly, 8.51% and 8.57% more grain protein contents were recorded with 200 kg ha–1 N during first and second year respectively. Unlike grain protein, starch and oil contents were negatively affected by N application being higher starch (71.7%) and oil contents (3.41%) with less N supply (100 kg ha–1). However, interaction effect of tillage and nitrogen levels was found non-significant for all studied parameters except for oil contents. Higher oil contents were recorded with MBP along with 100 kg ha–1 N application. Overall study indicated that deep ploughing with CP is important for maize to explore more soil area for nutrient uptake and N is also important for improving grain quality especially protein contents an important food constituent.

Can Faba Bean Physiological Responses Stem from Contrasting Traffic Management Regimes?

Our study examined how faba beans (Vicia faba L.) grown in soil conditions that simulate common traffic management regimes and water availabilities displayed alterations to their physiological state. Physiological changes were tracked through plant and sensor-based measurements, such as evapotranspiration, water use efficiency, aboveground biomass, stomatal conductance, and normalized difference vegetation index. A greenhouse experiment comprised of faba beans were sown into pots of two different soil types that were separated by treatments of dry bulk density and volumetric water content. The compaction treatment with a bulk density of 1.2 g cm−3 coupled with a volumetric water content of 41% displayed more favorable changes to the physiological state of the faba beans than the contrasting treatment of 1.4 g cm−3 bulk density at 33% volumetric water content. Handheld sensor-based measurements, such as the normalized difference vegetation index, exhibited a strong correlation with faba bean biomass production. Furthermore, the stomatal conductance was able to reveal plant water stress and capture evapotranspiration responses. Conclusive observations showed that increasing soil compaction restricted plant productivity. However, the presence of high water content was shown to offset the negative effects of heavily applied compaction while relatively lower water contents exacerbated differences in plant responses across compaction treatments.

Using computed tomography images to characterize the effects of soil compaction resulting from large machinery on three-dimensional pore characteristics in an opencast coal mine dump

Purpose: The use of heavy machinery in mining areas increases during mining and dumping of waste soils, causing severe soil compaction and potentially affecting soil recovery. This study aimed to capture the features of complex compacted soil pore structure using computed tomography (CT) and to quantify soil pore distribution properties based on Minkowski theory. Materials and methods: A total of 45 cylindrical soil columns were extracted from different soil layer at 5 sampling sites that differed in compaction level in Pingshuo opencast coal mine in Shanxi Province of China. The penetration resistance at these sites ranged from 27.3 to 1023.1 kPa. Three-dimensional reconstruction software VGStudio was used to obtain the morphological characteristics (pore volume density, VD; surface density, SD; mean curvature density, MCD; and Euler number, EN) of soil pores after processing the X-ray scanned image. Results and discussion: Compaction generally reduced VD, SD, and MCD, which ranged from 0.10 to 0.20, 2.23 to 2.80 mm 2 mm −3 , and 10.75 to 15.64 mm mm −3 respectively in undisturbed site P0, whereas, they ranged from 0.02 to 0.07, 0.13 to 0.60 mm 2 mm −3 , and 1.61 to 4.27 mm mm −3 respectively in highly compacted site P4. The three index exhibited the similar trend, and decreased with the increase of compaction level. Soil compaction had positive effects on EN, which was low at the depth of 20- to 40-cm layers but showed an increasing trend with increasing soil compaction level. The value of EN varied from 28,878 to 129,861 in P0, whereas it varied from 1,169,967 to 2,281,998 in P4. Conclusions: All of macroporosity, mesoporosity, and microporosity were significantly affected by heavy machinery compaction, among which macroporosity exhibited the maximum decrease in P4 compared to that in P0 (P0 ranged from 14.2 to 26.4% and P4 ranged from 0.2 to 1.4%). The soil compaction in mining area significantly affected soil properties, thus artificial methods such as fertilizer application and deep tillage were needed.

Effect of long-term straw mulching and no-tillage on physical properties of meadow soil in cold region.

The effects of different straw returning technology and farming system on soil physical properties is not clear in Heilongjiang Province, which is located in middle temperature zone with large amount of straw. Here, the effects of straw mulching on soil physical properties in meadow soil under no tillage conditions were studied in field experiments for eight consecutive years (2010-2017). The no straw covering (0%), 30% coverage (30%), 60% coverage (60%) and 100% coverage (100%) were disposed in the experiment. The results showed that straw mulching under no tillage significantly increased soil bulk density by 0.10-0.20 g·cm-3, which increased with the increases of coverage amount. Straw mulching increased soil solid fraction by 2.5%-7.8%. Soil temperature decreased with the increases of coverage amount, and this trend was more apparent on the surface of soil. The temperature reduction in 0-5 cm soil layer was 1.87-2.90 ℃. Soil water content significantly increased with the increases of straw mulching, with an enhancement of 6.4%-10.2%. Straw mulch decreased the total porosity and diameter of >0.05 mm aeration pores, increased the effective pore size of 0.05-0.002 mm, with the magnitude of such effects being positively dependent on coverage amount. There was no significant effect of straw mulching on inactive porosity of soil. Long-term straw mulching increased soil compaction and soil moisture, reduced soil temperature and total soil porosity, and increased soil available porosity in 0-5 cm soil layer.

Natural regeneration of Pinus brutia Ten. in a recreational public forest in Zawita-Kurdistan region, Iraq

Zawita natural forest has recently has been subject to mass recreational activities during spring that have denuded large areas of the forest. It was thus essential to assess regeneration before designing optimizing strategies. To this end, we studied the overstory canopy and microhabitat conditions for recruitment of Pinus brutia Ten in 10 plots (20 × 25 m) on the southern aspects where the Zawita natural forest is still present. In total, 1540 regenerating P. brutia were recorded, 854 seedlings, 597 saplings, and 89 trees. Seedlings and saplings were more frequent beyond the canopy than under the canopy of the parent trees. Regeneration requirements differed between seedlings and saplings. The probability of the occurrence of seedlings was negatively correlated with increasing litter depth and increasing soil compaction. The density of saplings only showed a positive significant correlation with increasing slope. The nearest neighbor index showed a trend toward a positive spatial association between understory shrubs with their neighboring seedlings at a mean distance of 1.6 m. Overall, the study highlighted the requirements for seedling regeneration as a relatively open canopy cover, a light understory litter layer, and non-compacted soils. These results are a step towards designing effective management and restoration programs.

GAS EXCHANGE AND PHOTOCHEMICAL EFFICIENCY IN LIMA BEAN GENOTYPES GROWN IN COMPACTED SOILS

ABSTRACT The effects of soil compaction on crop growth and productivity have been well studied in recent years, however, studies on the physiological responses of crops to compaction are scarce. The objective of this study was to evaluate the effect of soil compaction on gas exchange, and photochemical efficiency of lima bean (Phaseolus lunatus L.) genotypes of different growth habits. The experimental design was a randomized block in a 3×4 factorial arrangement, with three lima bean genotypes (Branca-Pequena, Orelha-de-Vó and Roxinha) and four compaction levels (soil densities of 1.1, 1.3, 1.5 and 1.7 g cm-3), with four replications. The following variables were evaluated at 38 days after sowing: photosynthetic rate (A), leaf transpiration (E), stomatal conductance (gs), internal CO2 concentration (Ci), instantaneous water use efficiency (WUE), intrinsic water use efficiency (iWUE), instantaneous carboxylation efficiency (iCE) and photochemical efficiency (Fo, Fm, Fv and Fv/Fm). The data were subjected to analysis of variance at 5% probability by the F test. The genotypes showed a reduction in the photosynthetic rate with increasing soil compaction. The soil compaction affected the photochemical efficiency of the genotype Orelha-de-Vó, with the Fm and Fv fitting to the linear model, and the Fv/Fm fitting to the quadratic model. The genotype Orelha-de-Vó had the highest rate of E and gs at the soil densities of 1.24 and 1.29 g cm-3, respectively. Regarding the photosynthetic rate, the genotype Roxinha is more efficient than Branca-Pequena at the soil density of 1.7 g cm -3.

Soil Physical Properties and Grain Yield Influenced by Cover Crops and Crop Rotation

The crop yield is related to several factors, among these, soil tillage, soil compaction and crop rotation. This study aimed to evaluate the winter cover crops and crop rotation influence on soil physical properties and grain yield of dry beans, maize and soybean for two growing seasons. Three experiments were conducted, corresponding to dry beans, maize and soybean crops. It was used the randomized block design with three treatments and four replications consisted by 3 × 10 m plots. The treatments were: two cover crops systems and crop rotation in no-till, and the control, consisting of winter fallow and conventional tillage. The cover crop dry matter, soil physical properties and grain yield for dry beans, maize and soybean in the two growing seasons were evaluated. Crop rotation systems and cover crops showed a trend to increase maize and soybean yields. Crop rotation in no-till increases soil compaction in the superficial layer compared to conventional tillage, but does not reduce the dry beans, maize and soybean yields.

Effects of soil compaction on growth variables in Cappadocian maple (Acer cappadocicum) seedlings

This study investigates the effects of increasing soil penetration resistance (SPR) on seedling morphology and seedling architecture. When seedlings of deciduous Cappadocian maple (Acer cappadocicum Gled.) were grown in a greenhouse in a loamy soil under a wide range of soil compactions, all morphological variables studied changed significantly with increasing SPR. The relationships between increasing SPR and all morphological responses except lateral root length followed a negative quadratic curve. All biomass variables except lateral root biomass showed a bell-shaped response with respect to SPR, with a maximum biomass variable between 0.6 and 1.2 MPa, decreasing at higher soil compaction values. All allocation ratios were significantly affected by soil penetration resistance. Biomass allocation to roots was also affected by soil compaction. There was not a significant relationship between the specific stem length and increasing soil penetration resistance. The specific root length showed two trends to increasing SPR; it first decreased in response to the moderate compaction treatment (up to about 1.2 MPa), then increased significantly. We concluded that increasing soil compaction caused morphological changes to root and shoot sections of A. cappadocicum seedlings.

Sugarcane straw removal effects on Ultisols and Oxisols in south-central Brazil

The maintenance of sugarcane straw on the field has an important role in preserving the soil properties and organic carbon content. However, there is a growing interest in removing part of this residue to use in bioenergy production. The effect of straw removal on soil quality is still poorly studied. The aim of this study was to evaluate the impact of short-term (2years) straw removal from soil surface on soil quality. Two experiments were carried out in São Paulo state, Brazil: one in an Oxisol (sandy clay loam soil) and another in an Ultisol (sandy loam soil). We have tested five rates of straw removal (i.e., equivalent to 0, 25, 50, 75 and 100%). Soil samples were taken from 0 to 2.5, 2.5–5, 5–10, 10–20 and 20–30cm layers to analyze pH, total C and N, P, K, Ca, Mg, bulk density and soil penetration resistance. The effects of straw removal were limited to the soil surface layer and differed between the two types of soil. Under the Oxisol, the straw removal favored soil physical degradation (i.e., increased soil compaction and resistance to penetration) and depletion of soil C stocks. On the other hand, straw removal management only affected chemical properties in the Ultisol, reducing nutrient contents (e.g., Ca and Mg). Based on a multivariate analysis that involving all attributes, the sandy texture soil (Ultisol) showed more sensitivity to straw removal management, even over this short period (2years), in which the removal of any amount of straw caused a negative impact on soil quality. In contrast, in the sand-clay-loam soil (Oxisol) the removal rate of up to 50% of the straw (i.e., the maintenance of ~ 8.7Mgha−1 of straw on soil surface) proved to be sustainable. Therefore, sugarcane straw removal should be site-specific, taking into account intrinsic soil properties and climate conditions, which preventing soil degradation and negative impacts on the provision of multiple ecosystem services. This guarantees the sustainability of the Brazilian bioenergy production.

Belowground Attributes on Reclaimed Surface Mine Lands over a 40‐year Chronosequence

AbstractReclamation following mining activities often aims to restore stable soils that support productive and diverse native plant communities. The soil re‐spread process increases soil compaction, which may alter soil water, plant composition, rooting depths, and soil organic matter. This may have a direct impact on vegetation establishment and species recruitment. Seasonal wet/dry and freeze/thaw patterns are thought to alleviate soil compaction over time. However, this has not been formally evaluated on reclaimed landscapes at large scales. Our objectives were to (1) determine soil compaction alleviation, (2) rooting depth, and (3) spatial patterns of soil water content over a time‐since‐reclamation gradient. Soil resistance to penetration varied by depth, with shallow compaction remaining unchanged, but deeper compaction increased over time rather than being alleviated. Root biomass and depth did not increase with time and was consistently less than the values in the reference location. Plant communities initially had a strong native component, but quickly became dominated by invasive species following reclamation, and soil water content became increasingly homogeneous over the 40‐year chronosequence. Seasonal weather patterns and soil organic matter additions can reduce soil compaction if water infiltration is not limited. Shallow and strongly fibrous‐rooted grasses present in reclaimed sites added organic matter to shallow soil layers, but did not penetrate the compacted layers and allow water infiltration. Strong linkages between land management strategies, soil properties, and vegetation composition can advance reclamation efforts and promote heterogeneous landscapes. However, current post‐reclamation management strategies are incompletely utilizing natural seasonal weather patterns to reduce soil compaction. Copyright © 2017 John Wiley & Sons, Ltd.

Soil compaction under different management practices in a Croatian vineyard

The use of machinery in vineyards is increasing soil compaction and erosion. However, there is a lack of information about the impacts of different management practices on soil conditions of vineyards. Therefore, the aim of this study was to assess soil compaction in Croatian vineyards under four different management systems: no-tillage (NT) system, conventional tillage (CT), yearly inversed grass covered (INV-GC) and tillage managed (INV-T) treatments. Four key top-soil (0–20 cm) parameters were assessed in the different land uses: bulk density (BD), penetration resistance (PR), soil water content (SWC) and carbon dioxide (CO2) fluxes. Tractor traffic increased the BD and PR in all treatments, with exception of CT treatment, as consequence of tillage. SWC showed higher values in INV-GC treatment during the dry period; meanwhile, it was similar during the wet season in every management type. Lower CO2 fluxes were found in INV-GC and NT than in the CT and INV-T treatments.

Reduction of the frequency of herbaceous roots as an effect of soil compaction induced by heavy grazing in rangelands of SW Spain

Rangelands in SW Spain constitute the most extensive ranching system on the Iberian Peninsula. During the last few decades, a significant increase in livestock numbers, along with a progressive substitution of cattle for sheep, have led to land degradation processes such as the reduction of grass cover and increased soil compaction in heavily grazed areas. Nevertheless, a better understanding of how soil compaction affects grass production is still needed. In this study, some of the effects of soil compaction due to heavy grazing are analysed, mainly the reduction of the frequency of herbaceous roots and its relationships with bulk density and soil penetration resistance. The study was carried out in 22 fenced areas grazed under different intensities (animal stocking rates: 0.19–15.76AUha−1). Undisturbed soil core and bulk samples were collected at 3 depth intervals in order to determine select soil properties (texture, organic matter content, and bulk density). Additionally, soil penetration resistance was quantified at 890 random points at different depths and soil moisture contents. Frequency of herbaceous roots was estimated for each soil horizon in 47 soil profiles and categorized into 4 classes: none, few, common and many. Results showed negative relationships between bulk density (>10cm depth) and the content of soil organic matter from 0 to 5cm (r=−0.061, p<0.05) and 5–10m depth (r=−0.824, p<0.005). Furthermore, a tendency for decreasing mean values of soil penetration resistance as the frequency of herbaceous roots increased was also observed. The values observed confirm that soil compaction provoked by an excessive number of animals reduced the quantity of herbaceous roots. The value of 2MPa traditionally accepted as restrictive for root growth is discussed. Findings presented here could be of interest for policy makers and farm owners to guide decisions about optimum animal stocking rates.

English

This study aimed to evaluate the effects of seed-furrow openers and soil compaction on parameters such as sowing quality and root growth of soybean. The experiment was conducted using a randomized blocks experimental design with split plots, with the plots arranged by compaction level (1.16, 1.20, 1.22 and 1.26 Mg m-3) and the subplots by type of furrow opener (double disk and shank type). Root growth was assessed at three depths (0.00-0.10; 0.10-0.20 and 0.20-0.30 m) in the sowing line and interrow. The sowing quality data means were compared using the Tukey test (p&le;0.05), while the root growth data means were compared using the LSD test (p&le;0.05). Penetration resistance increased with increasing soil compaction to a depth of 0.20 m. The sowing depth and mobilized soil area were not affected by soil compaction levels. The type of furrow opening mechanism only influenced the sowing depth, with greater depth achieved using the double disc. Neither the seed-furrow openers nor the level of soil compaction significantly influenced soybean root growth when evaluated in the sowing line. The type of furrow opening mechanism did not influence any of the evaluated parameters. Soil compaction altered soybean root growth in the interrow, but did not impede rooting. Regardless of the assessment depth in the interrow, there was a reduction in root volume, length, surface area and diameter with increased soil density. &nbsp; Key words: No-tillage, seeder, soil density, sowing depth, penetrometer resistance.

Exploring the correspondence between precompression stress and soil load capacity in soil cores

The soil precompression stress (σp) has been used as an estimator of the soil load bearing capacity, but a few researches have evaluated the correspondence to each other. In this study, we first evaluated in prepared soil cores the time needed for σp to reach a quasi-stable state. Afterwards, we waited the same time for using another set of soil cores to evaluate the changes on σp after the soil core received loads equal to its σp. The two experiments were performed using two Rhodic Hapludox (RH1 and RH2) and one Typic Paleodult (TP). In both experiments the σp was denominated as σp2R, because it was calculated using the two-line intersect method proposed by Dias Junior and Pierce (1995). In the first one, σp2R increased asymptotically over time after sample preparation. When the increasing rate of σp2R decreased down to 0.05kPad−1, we assumed that the increase in soil structure strength over time was small and had little effect on σp2R, which took place at 21days for RH1, 26days for RH2, and less than 1day for TP. The second experiment was performed after these times of structure strengthening. Four times in each soil, the σp2R was measured (σp2Ri) and this value was applied as a new load on the soil. Thus, σp2Ri was assumed as the maximum load previously received by the soil core, which was related to the subsequently measured σp2R(σp2Ri+1). The results indicate that σp2R overestimated the maximum load previously received by the soil, because the σp2Ri+1 was generally greater than σp2Ri. Also there were evidences that applying on soil a load equal to σp2R can increase soil compaction. If this tendency is confirmed by further studies using more sensitive techniques to evaluate soil structure changes, as computed tomography, the load limit to be applied to the soil should be less than σp2R, because loads equal to such value may overcome the soil load bearing capacity and progressively increase in the degree-of-compactness.

Impacts of Cattle Grazing of Corn Residues on Soil Properties after 16 Years

Core Ideas: Spring cattle grazing of corn residues slightly increased the risk of soil compaction. Fall cattle grazing of corn residues had no negative effect on soil properties. Increased soil compaction caused by grazing was small and did not reduce crop yield. Corn (Zea mays L.) residue grazing can be an important component of crop–livestock systems, but its long‐term impacts on soil properties are not well understood. Some producers are concerned that residue grazing can induce soil compaction and reduce crop yields. We assessed the 16‐yr cumulative effect of cattle grazing of corn residues on soil compaction, structural quality, soil C, fertility, and microbial communities and studied their correlations with corn and soybean [Glycine max (L.) Merr.] yield in a sprinkler‐irrigated no‐till corn–soybean system on a Tomek silt loam in eastern Nebraska. Three treatments were studied: (i) fall grazing [4.4–6.2 animal unit‐months (AUM) ha–1], (ii) spring grazing (9.3–13.0 AUM ha–1), and (iii) control (no grazing). Cattle grazing did not affect bulk density, wet soil aggregate stability, particulate organic matter, soil organic C, and nutrients except Ca and S. Spring grazing increased the cone index (soil compaction parameter) by 1.3 to 3.4 times relative to the control, but fall grazing had no effect. The increase in soil compaction caused by spring grazing was below the threshold limit (≤2 MPa) and did not reduce corn and soybean yields. Although grazing had a positive effect on the biomass of most microbial groups, the results were not significant, except for actinomycetes, which increased with residue grazing (p = 0.06). Overall, long‐term corn residue grazing had little or no effect on soil properties and the small changes did not affect crop yields.

Impact of Load and Inflation Pressure on Traffic-Induced Soil Compaction for Two Types of Flotation Tires

Abstract. An Automatic Air Inflation-Deflation (AAID) control unit was evaluated on a manure tanker equipped with Alliance model 390 30.5LR32 steel belted radial-ply and Michelin 650/75R32 172A8/172B TL MEGAXBIB radial-ply flotation tires. The objective was to validate the effectiveness of the AAID control unit from an engineering perspective and its benefits for field agricultural operations. The contact patch was characterized in terms of rut depth and width, and tire contact length. Soil cone index was used as an indicator of soil compaction caused by the weight of the manure tanker. Cone index and rut depth at the centerline and edge of both the Alliance and the Michelin tires were affected by tire inflation pressure and load. As inflation pressure or load increased, the cone penetration resistance in the contact patch increased, indicating an increase in soil compaction. The adjusted tire inflation pressure for field operation using the AAID control unit reduced the rut depth at a lug imprint at the tire centerline, at a high load of 68 kN per tire, by 18.4% and 15.6% for the Michelin and Alliance tires, respectively, and by 19.1% and 12.0% at a low load of 44 kN per tire for the Michelin and Alliance tires respectively. Keywords: Automatic air inflation deflation, Cone index, Contact patch, Flotation tire, Manure tanker, Rut depth, Rut width, Soil compaction management.