Abstract: While having been successfully used for soil compaction for many years, intelligent compaction (IC) technology is still relatively new for asphalt pavement construction. The correlation between Compaction Meter Value (CMV) from the IC compactor and the compaction degree of the asphalt layers is hard to identify, mainly due to: (1) multi-layer structure of the road, (2) non-linear behaviour of asphalt materials, and the measuring depth of the IC roller. In this study, the possibility of utilising CMV to evaluate the density of different asphalt pavement layers was examined. The displacements of the newly placed surface layer and the underlying layers under a vibratory roller were analysed using the original Witczak model and the multi-layer pavement analysis software BISAR. A method was proposed to filter the effects of the underlying layers on CMV. Data from two asphalt pavement IC compaction projects in Tennessee were employed to verify the proposed filtering method. Further laboratory methods to simulat...

Abstract: Full-scale tests were conducted to study the influence of the operating frequency of a vibratory roller on the compaction of crushed gravel in a controlled environment. Tests were performed at both ...

Abstract: Intelligent compaction (IC) technologies yield a large number of data useful for quality control and quality assurance (QC/QA) in the construction of soil subgrade and embankments. A main c...

Abstract: The progressive increase in the size and weight of farm machinery causes concerns due to the increased risk of soil compaction that arises from non-organized vehicle traffic. Controlled traffic farming (CTF) offers an effective means to manage compaction by confining all load-bearing wheels to the least possible area of permanent traffic lanes. Although CTF is relatively well-established in Australia and in some countries in Northern Europe, its benefits and suitability for Central European conditions have not been demonstrated. A long-term experimental site was established in 2010 in Nitra, Slovakia, using a 6 m 'OutTrac-CTF' system with shallow non-inversion tillage practices. The 16 ha experimental field of loam soil is representative of land used for arable cropping in Central Europe. Four traffic intensities (non-trafficked, one traffic event per year with a single pass, multiple passes with permanent traffic lanes, and random traffic) were evaluated using two traffic systems: controlled (CTF) and non-controlled traffic farming (referred to as random traffic farming or RTF). This article reports the findings derived from the first four years of the project and focuses on the effects of traffic systems on yields observed in cereal crops (winter wheat, spring barley, and maize) grown at the site in a rotation cycle. Significant differences (p < 0.1) in yield are reported due to the heterogeneity of the field and the seasonal effect of weather. The results of this investigation suggest that CTF systems have potential to increase production sustainably in arable farming systems in Central Europe. Well-designed CTF systems using commercially available machinery allow for reductions in the area affected by traffic of up to 50% compared with random, non-organized traffic systems. Results also show that in years when soil moisture was not limiting, the yield penalty from a single (annual) machine pass was relatively small (~5%). However, in dry years, compaction caused by multiple machinery passes may lead to yield losses of up to 33%. When considering the ratio of non-trafficked to trafficked area within the different CTF systems evaluated in this study, yield improvements of up to 0.5 t ha-1 for cereals are possible when converting from RTF to CTF. Given the assumptions made in the analyses, such yield increases translate into increased revenues of up to 117 USD ha-1 (1 Euro= 1.1 USD). For Central European farming systems, the main benefit of CTF appears to be improved efficiency and enhanced agronomic stability, especially in dry seasons, where the significant yield penalty from machinery passes is likely.

Abstract: Chiselling has been used to alleviate soil compaction but cover crops with deep, vigorous roots can improve root growth and activity of the cash crop for a longer time. The determination of root activity in addition to root mass or length may improve the understanding of plant response to compaction. The objective of this experiment was to evaluate root growth and activity as affected by the alleviation of soil compaction using mechanical and biological methods. The experiment was conducted in Botucatu, Sao Paulo, Brazil, from 2009 to 2011, on a clay, Typic Rhodudalf soil. Crop rotations including pear millet (Pennisetum glaucum), soybean (Glycine max), grain sorghum (Sorghum bicolor), maize (Zea mays), ruzi grass (Brachiaria ruziziensis) and castor bean (Ricinus communis) in plots, either chiselled or not. Root growth was assessed by core sampling and root activity was determined indirectly using rubidium injected at several depths as a marker. Root activity was instrumental in interpreting the effects of tillage and crop rotations on soil amelioration. Compared with the initial compacted condition, chiselling increased root growth and activity just for the first 18 months of the experiment, but crop rotations, mainly including ruzi grass and castor bean, increased root growth and activity in the soil profile from the second year on. Generally, root mass was poorly correlated with root activity, except in the case of ruzi grass. Introduction of ruzi grass plus castor bean into the cropping system improves not only root growth and activity in the soil profile but also soybean yield.

Abstract: Soil compaction is a critical issue in agriculture having a significant influence on crop growth. Sugar beet ( Beta vulgaris L.) is accounted as a crop susceptible to compaction. Reduction of leaf area, final yield, and root quality parameters are reported in compacted soils. The most obvious visual indicator of topsoil compaction is root depth affected by agricultural tractor and machinery traffic up on the soil. Such indicators are mainly correlated to initial soil condition, tyre features, and number of passages. Monitoring and controlling frequency and position of machine traffic across the field, in such a way that passages are completed on specific, well-defined tracks, can assist with minimization of compaction effects on soil. The objective of the present work was to analyze the subsoil compaction during the growing period of sugar beet with different farming approaches including controlled traffic passages and random traffic. To this end, tests were carried out following each agro technical operation using penetrometer readings in order to monitor the state of cone-index after each step. In addition, at the harvesting time, root quality parameters were analyzed with particular attention to length and regularity of the taproot, total length, circumference, mass, and above-ground biomass. Such parameters were usefully implemented in order to evaluate the effects of controlled traffic passages compared to the random traffic in a cultivation of sugar beet. Results highlight how an increase in crop yield, derived from samples monitored, higher than 10% can be expected with implementation of a careful traffic management.

Abstract: Eucalyptus forest plantations are normally devoid of understory vegetation that is often assumed to be associated with Eucalyptus allelopathic effects. The objective of this study was to determine the influence of high soil compaction and low soil moisture content on inhibition of the germination of understory seeds in Eucalyptus forests and thus would result in the scarcity of understory vegetation. The soil water content above the depth of 1 m of six major understory vegetation types was analyzed to determine if there was a correlation between soil water content and understory vegetation. The effects of soil treatment (soil-loosening vs. no soil-loosening) and water supply amount (2500, 2000, 1500, 1000, 500, 250, or 0 ml of water per day) on the seed germination rate of Stylosanthes sp. were explored using an artificial climate chamber experiment. Influence of soil source (five Eucalyptus forest soils vs. two non-Eucalyptus forest soils) and water supply (0, 50, 150, 200, or 400 ml of water every day) on the germination rate of five types of seed were assessed using a three-factor analysis of variance (ANOVA). Soil-loosening and water supply significantly (P < 0.05) increased seed germination rate with the contribution rates of 26.14 and 42.93 %, respectively. Analysis of variance for three-factor experiments revealed a significant (P < 0.05) effect of water supply and vegetation seed type on the germination rate of plant seeds. No significant effect of soil type was observed on germination rate, indicating that germination rate was not affected by soils in Eucalyptus forest. The conservation of soil characteristics, such as water content and compaction, during the development of a Eucalyptus forest plantation may be an effective strategy for encouraging the growth of understory vegetation. This study highlights the importance that in dry areas or areas prone to long-term drought, it would be preferable to retain native vegetation.

Abstract: Subsoil compaction is a serious long-term threat to soil functions. Only a few studies have quantified the mechanical stresses reaching deep subsoil layers for modern high wheel load machinery. In the present study we measured the vertical stresses in the tyre–soil contact area and at 0.3, 0.6 and 0.9 m depths of a sandy loam soil at field capacity water content. The soil was ploughed annually to a depth of 0.25 m and was tested in the spring following autumn ploughing but before secondary tillage. The machinery tested was a tractor–trailer system for slurry application with a total weight of 52 Mg. Wheel loads ranged from approximately 20 to 70 kN. The tyres were all radial ply with volumes ranging from 0.63 to 1.23 m3. The tyre inflation pressures were generally above those recommended by the manufacturer and ranged from 170 to 280 kPa. The stress distributions in the contact area were highly skewed. Across tyres, the maximum stress in the contact area correlated linearly with, but was much higher than, the mean ground pressure. For each of the three soil depths, the maximum stresses under the tyres were significantly correlated with the wheel load, but not with other loading characteristics. The data predict a 6.6-kPa increase in vertical stress at 0.9 m depth for each 1-Mg addition to the wheel load. The soil stress observations support a simple rule of thumb combining wheel load and inflation pressure in calculation of subsoil vertical stress. We measured vertical stresses up to 300, 100 and 45 kPa at soil depths of 0.3, 0.6 and 0.9 m respectively. Comparing these with the data in the literature regarding soil strength and measured compaction effects on the soil studied, we conclude that the traffic event investigated is likely to induce serious effects on soil properties and functions to a depth of at least 0.7 m.

Abstract: Agricultural machinery traffic is one of the main causes of soil compaction in modern agriculture. Soils with weak inherent soil structural stability already have low bearing capacity and, when subjected to intensive tillage with a high frequency of traffic, are susceptible to severe soil compaction. In this study, repeated wheeling experiments were carried out on an Iranian clay soil prepared at two water contents (corresponding to 0.9 and 1.35 × water content at the lower plastic limit), two wheel loads (light and heavy rear wheel loads of a two-wheel-drive tractor) and two vehicle travel speeds (0.5 and 1 m s–1). The experiments tested whether the stress variations due to repeated wheeling are mainly due to variations in rut depth with repeated tyre passes and whether traffic at a higher travel speed has a smaller compaction effect. Mean normal stress was measured at three depths (0.15, 0.25 and 0.35 m) beneath the centre of tyres using cylindrical Bolling probes. Rut depth and cone index were measured after each pass. The results showed a linear increase in rut depth with consecutive tractor passes, with a greater increase on wet soil. However, bulk density increased more in dry soil than in wet soil at 0.15 and 0.25 m depth, most likely due to soil water content being close to the optimum Proctor water content. At 0.35 m depth, the bulk density increase was larger for wet soil, with obvious impacts of wheel load and travel speed (greater increase for slower speed and heavier wheel). Cone index generally increased with repeated tractor passes, with the greatest increase at 0.35 m depth in wet soil under heavy rear wheel traffic. Stress generally increased with increasing rut depth due to repeated wheeling. Reduced distance between the soil–tyre interface and the Bolling probes with increasing rut depth was investigated as a potential reason using analytical stress simulations, but could not fully explain the increase in stress with rut depth. Therefore, additional factors (e.g. soil strength) must have contributed to the stress increase with increasing number of tractor passes.

Abstract: Soil compaction of arable land, caused by heavy machinery constitutes a major threat to agricultural soils in industrialized countries. The degradation of soil structure due to compaction leads to decreased (macro-) porosity resulting in increased mechanical impedance, which adversely affects root growth and crop productivity. New crop cultivars, with root systems that are adapted to conditions of increased soil strength, are needed to overcome the limiting effects of soil compaction on plant growth. This study aimed (i) to quantify the genetic diversity of early root system development in wheat and to relate this to shoot development under different soil bulk densities and (ii) to test whether root numbers are suitable traits to assess the genotypic tolerance to soil compaction. Fourteen wheat genotypes were grown for 3 weeks in a growth chamber under low (1.3 g cm−3), moderate (1.45 g cm−3), and high soil bulk density (1.6 g cm−3). Using X-ray computed tomography root system development was quantified in weekly intervals, which was complemented by weekly measurements of plant height. The development of the root system, quantified via the number of axial and lateral roots was strongly correlated (0.78 < r < 0.88, p < 0.01) to the development of plant height. Furthermore, significant effects (p < 0.01) of the genotype on root system development and plant vigor traits were observed. Under moderate soil strength final axial and lateral root numbers were significantly correlated (0.57 < r < 0.84, p < 0.05) to shoot dry weight. Furthermore, broad-sense heritability of axial and lateral root number was higher than 50% and comparable to values calculated for shoot traits. Our results showed that there is genetic diversity in wheat with respect to root system responses to increased soil strength and that root numbers are suitable indicators to explain the responses and the tolerance to such conditions. Since root numbers are heritable and can be assessed at high throughput rates under laboratory and field conditions, root number is considered a promising trait for screening toward compaction tolerant varieties.

Abstract: Studies have shown that black plastic used as a mulch at' planting time under conditions of limited or no irrigation, greatly increased the growth of the vines Although the exposed plastic film deteriorated within two years, the favourable effect persisted to the fifth year after planting, bringing the mulched vines to production a year earlier than the unmulched vines The advantages of plastic mulch are conservation of soil moisture, more uniform soil temperatures, weed control and less soil compaction These factors increase root and shoot growth, and improve both survival of the young vines and production The durability of the plastic film was extended by covering it with a layer of soil, and thus a longer period of weed control was obtained

Abstract: Agrochronosequences of chernozems with different periods of their use in rainfed farming with application of traditional technologies have been studied in a typical forest-steppe area in Belgorod oblast Certain stages in the development of these soils during more than two centuries of their agricultural use have been identified These stages are related to changes in the intensity and direction of soil forming processes, such as soil compaction, soil aggregation, dehumification of the upper horizons, calcification of the soil profiles, argillization, etc A significant impact on the soil changes during the agrogenic evolution of chernozems is exerted by the digging activity of burrowers, which is especially pronounced in the old-arable chernozems

Abstract: Many farmers periodically use deep tillage operations to alleviate compaction in the soil profile caused by natural factors or machinery traffic. In 2012 and 2013, a study was initiated in the Pannonian region of Croatia to study the effects of No-Tillage (NT), Conventional Tillage (CT), and Deep Tillage (DT) on soil compaction, measured by Bulk Density (BD), Soil Water Content (SWC), Penetration Resistance (PR) and Total Soil Porosity (TSP). The experiment was conducted on Pseudogley (Stagnosol). The results showed that DT was superior to CT and NT treatments. DT caused least soil physical degradation, with BD being in the following order: DT< NT< CT. Soil water depletion under NT treatment was confined more to the upper soil layers than under DT and CT. Under the CT treatment, the PR values indicate the occurrence of impermeable layers at depths greater than 25 cm in wet conditions (2012) and at depths greater than 10 cm in dry conditions (2013). NT did not differ significantly from tilled treatments in soil compaction measured by BD, providing an interesting alternative for soil management. Perennial ploughing should be avoided as the only long term soil management strategy, while additional strategies which include controlled traffic and soil loosening every 1-2 years should be implemented on Pseudogley in Pannonian Croatia.

Abstract: In laboratory experiments, we investigated how media with varying ratio of peat:sand and two levels of compaction influence dispersal success of entomopathogenic nematode (EPN) species with different foraging strategies: Steinernema carpocapsae (ambusher), Heterorhabditis downesi (cruiser) and Steinernema feltiae (intermediate). Success was measured by the numbers of nematodes moving through a 4 cm column and invading a wax moth larva. We found that both compaction and increasing peat content generally decreased EPN infective juvenile (IJ) success for all three species. Of the three species, H. downesi was the least affected by peat content, and S. carpocapsae was the most adversely influenced by compaction. In addition, sex ratios of the invading IJs of the two Steinernema species were differentially influenced by peat content, and in the case of S. feltiae, sex ratio was also affected by compaction. This indicates that dispersal of male and female IJs is differentially affected by soil parameters and that this differentiation is species-specific. In conclusion, our study shows that organic matter: sand ratio and soil compaction have a marked influence on EPN foraging behaviour with implications for harnessing them as biological pest control agents.

Abstract: Wintering cows on forage crops leads to urine being excreted onto wet, compacted soils, which can result in significant emissions of nitrous oxide (N2O). A field trial was conducted to determine the N2O emission factor (EF3; proportion of urine-N lost as N2O-N) for dairy cows wintered on a kale forage crop on a poorly drained soil. Urine was collected from non-lactating dairy cows on a forage kale diet and applied at 550 kg N ha−1 to artificially compacted soil to simulate trampling and non-compacted soil in a kale field. Cumulative N2O losses over four months were 7.38 and 2.64 kg N2O-N ha−1 from urine applied to, respectively, compacted and non-compacted soil. The corresponding EF3 values 0.75% and 0.30%, respectively, differed (P = .003) due to compaction. Combining our results with previous studies, where brassica-fed livestock urine was applied to soils supporting a forage brassica crop, suggested a significant relationship between soil water-filled pore space (WFPS) and brassica-derived urin...

Abstract: The restitution coefficient is an important elementary physical parameter related to the research and development of agricultural machinery. The kinematic model of maize seed in the falling and impacting processes was developed to measure the restitution coefficient between maize seed and soil. A test bench for measuring the restitution coefficient was designed and built referred to the theory of mirror reflection. The velocities for impacting maize seed were measured and analyzed in a three-dimensional space via high-speed photography, and then restitution coefficients of in different impact conditions were obtained. On this basis, this study took flat dent seed and round seed as samples. Single factor tests were conducted to analyze the influences of these factors on the restitution coefficient. The impact angle, falling height, soil compaction, soil moisture, maize moisture content and different parts of seed were selected as test factors. The corresponding regression equations were obtained by analysis. The results showed that, as the impact angle was bigger than 25°, the restitution coefficient increased with the increase of impact angle. The restitution coefficient had a linear decreasing trend with the increase of falling height. As the soil compaction strength was 200-350 kPa, the restitution coefficient increased with the increase of soil compaction. As the soil compaction strength was larger than 350 kPa, the changing trend of the restitution coefficient was relatively stable. As the soil moisture content was 13.5%-18%, the restitution coefficient decreased with the increase of soil moisture. As the soil moisture content was 18%, the restitution coefficient was the minimum. As the maize moisture content was 11%-16%, the restitution coefficient decreased with the increase of maize moisture content. The rotational motion always occurred in falling process of flat dent seed and round seed. The probabilities of crown part and lateral part of maize seed impacting with soil were the highest, and the restitution coefficient between crown part and soil was higher than that of other parts in the same condition. Keywords: maize seed, soil, restitution coefficient, mirror reflection, high-speed photography, measurement DOI: 10.3965/j.ijabe.20171003.2173 Citation: Wang J W, Tang H, Wang J F, Jiang D X, Li X. Measurement and analysis of restitution coefficient between maize seed and soil based on high-speed photography. Int J Agric & Biol Eng, 2017; 10(3): 102–114.

Abstract: Differences between two maize and two triticale genotypes grown in low soil compaction (LSC), moderate soil compaction (MSC) and severe soil compaction (SSC) and with a limited (D) or excess (W) soil water content were observed as a decrease in shoot (S) and root (R) biomass, leaf greening (SPAD) and increase in membrane injury (LI), root and leaf water potential (ψ), photosynthesis (Pn), transpiration (E) and stomata conductance (gS). Close correlations between ψL and ψR, and between differences ψL and ψR (Δψ) were found. Drought or waterlogging with LSC conditions in both maize genotypes resulted in higher WUE than in control plants (LSC C), but under the SSC WUE declined. However, for triticale differences in WUE, between treatments were small and insignificant. In general, changes in markers were greater for genotypes sensitive to the soil compaction (Ankora, CHD-12) than in resistant ones (Tina, CHD-247) and were higher in seedlings grown under SSC conditions.Abbreviations: ψR, ψL: root and l...

Abstract: Experiments on small (about 10 m in length) runoff plots on slopes of 1°–3° subjected to sprinkler irrigation in the southern Cis-Ural forest-steppe region showed that the formation of surface runoff is controlled by the intensity and character (intermittence) of sprinkler irrigation, its duration, and the state of the soil surface. On the clay-illuvial moderately leached agrochernozem, the surface runoff is developed after 14‒20 h of irrigation imitating heavy rain (180–210 mm rainfall), after 15 min (24 mm) under shower, and after 10 min (23 mm) under heavy shower. Runoff appeared on the plowed plots unprotected by plants after 100–140 mm of heavy rainfall 6 h earlier than on the fallow plot; in the case of shower and heavy shower on the unprotected plot, it appeared virtually immediately. Turbidity of runoff flows gradually increased after the beginning of runoff under heavy rain and sharply increased under heavy shower. After reaching its maximum, it decreased. The contents of fine fractions, humus, and nutrients in the solid runoff (drift) were higher under lower rain intensity (heavy rain) than under showers and heavy showers; they were higher in all the drifts than in the soil on the adjacent slope. Long (about 24 h) continuous artificial heavy rain (0.17–0.22 mm/min) caused slight soil compaction and some improvement of the structure of the surface soil layer both on the fallow plots and on the plowed plots.

Abstract: Soil compaction, a process that decreases the free space among soil particles and hinders the underground movement of soil organisms, is one of the increasing impacts of mankind on the world’s ecosystems. We investigated the responses of subterranean ants to soil compaction by testing the following predictions: (i) soil from a trail is more compressed, leading to (ii) a decrease in species richness and a selective shift in ant assemblage composition, which is made up by (iii) species with a smaller body size that can apply a greater relative strength to move through soil particles. We carried out this study in and outside of a recreational ecology trail in a forest fragment in Vicosa, MG, Southeastern Brazil. The compaction was higher in the soil from the trail than outside of it. No change was observed in species richness, but soil compaction promoted a shift in ant assemblage composition, with ant size decreasing with an increase in soil compaction. However, ants did not appear to apply a greater strength to soil particles for moving in habitats with a high soil compaction. Overall, organisms at superficial soil layers appeared to be sensitive to even moderate human impacts that promote a filtering of the ant assemblage species composition, with small body size being a required trait.

Abstract: Planted forests occupy more than 6.5 million ha in Brazil, where harvest and logging operations are performed with increasingly heavier machinery, increasing the risk of soil compaction. Soil compaction can be avoided if soil load bearing capacity is not exceeded, what makes it important to assess both the soil strength and the impact of different operations. The aim of this study was to evaluate the load bearing capacity of some coarse textured soils (two Hapludult and one Haplorthod) in two soil horizons (BA and B), from northeastern Brazil; and to assess the impact of harvest and logging operations performed with harvester and forwarder. Although the Haplorthod presented higher load bearing capacity in both the BA horizon (for the whole moisture range) and the B horizon (for higher water contents), it suffered the greatest soil compaction. Traffic with the harvester resulted in soil compaction in both the BA and the B horizons, but the increase in bulk density was higher on the later, reaching 18.7% in the Haplorthod. The forwarder traffic intensity and the presence of plant residue cover significantly affected the occurrence of soil compaction. In the BA horizon, the increase in soil bulk density for different forwarder traffic intensities was 3 passes ~ 6 passes < 12 passes ~ 16 passes. The increase in bulk density was higher in the Haplorthod, reaching 32% after 16 forwarder passes over bare soil. Significant linear regressions were obtained from the number of forwarder passes and the increase in bulk density.

Abstract: Drought is the major constraint to rainfed rice productivity in South Asia, but few reports provide detailed characterization of the soil properties related to drought stress severity in the region. The aim of the study was to provide a compilation of drought breeding network sites and their respective levels of drought stress, and to relate soil parameters with yield reduction by drought. This study characterized levels of drought stress and soil nutrient and physical properties at 18 geographically distributed research station sites involved in rice varietal screening in Bangladesh, India, and Nepal, as well as at farmers’ fields located near the research stations. Based on soil resistance to penetration profiles, a hardpan was surprisingly absent at about half of the sites characterized. Significant relationships of depth of compaction and yield reduction by drought indicated the effects of soil puddling on susceptibility to cracking, rather than water retention by hardpans, on plant water availability in this region. The main difference between research stations and nearby farmers’ fields was in terms of soil compaction. These results present an initiative for understanding the range of severities of reproductive-stage drought stress in drought-prone rainfed lowland rice-growing areas in South Asia.