Abstract: Compaction of soils is a major construction activity in civil engineering, and particularly in the transport industry This paper presents a brief historical account of soil compaction development with special emphasis on transport geotechnics Proctor’s curves and California Bearing Ratio (CBR) are reviewed and the associated state-of-the-art field specifications are discussed The properties of compacted soil and the typical behaviours of compacted fill under in-service conditions are discussed Intelligent compaction is being increasingly adopted with a view to increased uniformity in compaction, lack of which is a major cause of premature pavement failure However, it needs further advancement to make it more intelligent The current state of the ability to predict compacted soil behaviour is reviewed and the limitations are identified Of more recent developments, interpretation of compacted soil behaviour with a three-dimensional state boundary surface is highlighted, and simplified behaviour can be interpreted and used in routine practice Areas that need further advancements in theory and practice are highlighted

Abstract: As the size and weight of agricultural equipment have increased significantly in the past few decades, the severity and depth of compacted zone may have increased proportionately Past research indicates that soil compaction affects crop growth and grain yield Very few studies have been conducted in North Dakota (ND) to understand soil compaction under the current machinery, and its effect on crop growth and yield The research was conducted on a no-till crop field at Jamestown, ND, USA for 2013 (corn) and 2014 (soybean) growing season The objective of this study was to evaluate the effect of wheel traffic on soil strength indices and its impact on crop emergence, development and yield The study also evaluated the effect of winter freezing-thawing cycle on soil compaction in the study field The experiment consisted of five soil transects and two traffic conditions based on machinery traffic in the field for both years such as most trafficked (MT) rows and least trafficked (LT) rows, laid out in a randomized complete block design with three replicates in strip-plot with space for corn season in 2013, and for soybean season in 2014 Data collected included soil resistance or cone index (CI), soil bulk density, soil moisture content, plant emergence, plant height and grain yield The results showed that CI values followed a similar pattern for different soil transects up to 375 cm depth and then increased sharply An average CI of 119 MPa was noted over the whole profile at 0–45 cm depth for the study area and not significantly different between MT and LT rows for both years Moderate compaction resulted in early emergence of corn plants in MT rows by 175% compared to LT rows The plant height didn’t show any significant difference between MT and LT rows for both years The yield data showed significant difference between the soil transects, but no difference was observed between MT and LT rows in both 2013 and 2014 season The interactions between soil transects and traffic conditions were not significantly different for all soil and plant related dependent variables The freeze-thaw cycle occurred during winter from 2013 to 2014 and 2014 to 2015 alleviated soil resistance over the whole soil profile at 0–45 cm depth Results show that different crops grown in a no till field are not very much influenced by wheel traffic The study also suggests that moderate compaction occurred after harvest in a no till field could be alleviated by the effect of freeze thaw cycle

Abstract: In the typical conventional fill compaction, the dry density, ρd, and the water content, w, are controlled in relation to reference values, (ρd)max and wopt, determined by standard laboratory compaction tests using a representative sample at a certain compaction energy level, CEL. Although CEL and soil type affect significantly (ρd)max and wopt, they change inevitably, sometimes largely, in a given earthwork project while field CEL may not match the value used in the laboratory compaction tests. Compaction control based on only an index of strength/ stiffness of compacted soil has such a drawback that, for a fixed value of ρd, the index may increase significantly as the degree of saturation, Sr, of compacted soil becomes lower than the optimum degree of saturation (Sr)opt defined as Sr when (ρd)max is obtained for a given CEL. In comparison, the value of (Sr)opt and the unified compaction curve in terms of ρd/(ρd)max vs. Sr − (Sr)opt relation of compacted soil are rather insensitive to variations in CEL and soil type. Besides, CBR (unsoaked and soaked), the unconfined compression strength, the elastic shear modulus and the collapse upon submerging of compacted soil and the cyclic undrained shear strength and the coefficient of hydraulic conductivity of saturated soil are all controlled by ρd and “Sr at the end of compaction”. As a standard method, it is proposed to control the values of w and ρd in such that Sr becomes (Sr)opt while ρd becomes large enough to ensue soil properties required in design fully taking advantage of available CEL. It is argued that the compaction control keeping Sr larger than a certain value (or the air void ratio va lower than a certain value) without controlling ρd is relevant as a simplified method only if Sr is controlled to become (Sr)opt while always keeping CEL high enough to ensure the soil properties required in design.

Abstract: Subsoil compaction is persistent and affects the wide diversity of ecological services provided by agricultural soils. Efficient risk assessment tools are required to identify sustainable agricultural practices. Vehicles should not transmit stresses that exceed soil strength. Wheel load is the primary source of high stress in the subsoil. However, very low contact stress without reduction of wheel load would also help reduce stress in the subsoil. The aims of our study were to: (i) test experimentally the use of tracks instead of tires as a technical solution to increase contact area and reduce the magnitude of contact stresses, (ii) compare effects of traffic on soil physical properties using tires or tracks, and (iii) evaluate a state-of-the-art method for risk assessment of soil compaction beneath tracks or tires at the European level. We measured contact stress below a fully-loaded sugar beet harvester equipped with either a large tire or with a rubber track in a realistic harvest situation. Seventeen stress transducers were installed across the driving direction at 0.1 m depth and covered with loose soil. Dry bulk density and air permeability were measured at 0.35 m depth after traffic. The contact area was larger and the maximum and vertical stress smaller beneath the rubber track than beneath the tire. Nevertheless, stress distribution beneath the rubber track was far from uniform, presenting high peak stresses beneath the wheels and rollers. Dry bulk density was similar after traffic for the two undercarriage systems, but air permeability was lower after traffic using the rubber track. Measured stress distributions beneath the tire and the track were used as input to calculate the soil profile vertical stress for comparison with soil strength at 0.35 m depth. Wheel load carrying capacity was calculated for European soils for assessment of subsoil compaction risk when using the tire, the rubber track, and the rubber track assuming an even stress distribution. As expected from the contact area and stress measurements, the rubber track could carry higher loads than the tire. However, the air permeability results are interpreted as soil distortion due to high shear forces under the rubber track. This calls for a further development of the risk assessment method.

Abstract: 495 It is hardly possible to reach a maximum seed yield without successful seedling establishment. The period of germination and seedling emergence prior to establishment is the most vulnerable stage in a crop’s life. Poor seedling emergence results in yield reductions. This may be due to poor soil water content (Forbes and Watson 1992), seed-soil contact (Stewart et al. 1999), inaccurate seed placement, low and high soil temperatures (Forbes and Watson 1992), soil insects or soil-born disease, soil compaction or smearing (Nasr and Selles 1995), surface crusting after sowing and poor quality

Abstract: Compaction quality is directly related to the structure and seepage stability of a rockfill dam. To timely and accurately test the compaction quality of the rockfill material, four real-time test indexes were chosen to characterize the soil compaction degree based on the analysis of roller vibratory acceleration, including acceleration peak value (ap), acceleration root mean square value (arms), crest factor value (CF), and compaction meter value (CMV). To determine which of these indexes is the most appropriate, a two-part field compaction experiment was conducted using a vibratory roller in different filling zones of the dam body. Data on rolling parameters, real-time test indexes, and compaction quality indexes were collected to perform statistical regression analyses. Combined with the spectrum analysis of the acceleration signal, it was found that the CF index best characterizes the compaction degree of the rockfill material among the four indexes. Furthermore, the quantitative relations between the real-time index and compaction quality index were established to determine the control criterion of CF, which can instruct the site work of compaction quality control in the rockfill rolling process.

Abstract: Compaction and rutting on forest soils are consequences of harvesting operations. The traditional methods used to investigate these consequences are time consuming and unable to represent the entire longitudinal profile for a forest trail. New methods based on photogrammetry have been developed. The overall objective was to compare photogrammetry and traditional methods (e.g. cone penetrometer, manual rut depth measurements, bulk density and porosity) used for the evaluation of soil compaction and rutting (i.e. depth and rut volume) after multiple passes of a loaded forwarder using two different tyre pressure levels. The comparison of photogrammetric versus manually measured profiles resulted in R2 0.93. Both tyre inflation pressure and number of passes had effect on soil disturbance. The rut volumes on 100 m long trails after 60 passes were 8.48 and 5.74 m3 for tire pressures of 300 and 150 kPa, respectively. Increased rut volume correlated positively with increased soil compaction and decreased ...

Abstract: Quantitative assessment of soil compaction is of great importance to construction work, precision agriculture, and geotechnical research. Currently, measurement of soil compaction is mainly performed through field measurements, and the accuracy is highly influenced by personnel experience. In addition, most of the current methods for soil compaction measurement are capable of real-time monitoring. This paper presents an exploratory study of using a piezoceramic-based active sensing approach coupled with wavelet packet analysis to quantitatively monitor soil compaction in real time. In the active sensing approach, a pair of smart aggregates (SA) consisting of piezoceramic transducers embedded inside a host material are embedded into soil. In the pair, one SA acts as transmitter to transmit a modulated stress wave towards the other SA, which acts as receiver. The attenuation ratio of the stress wave propagating energy in soil is governed by the degree of soil compaction, so that the received wave properties of the smart aggregate sensor can be further characterized by using wavelet packet as an index to evaluate the soil compaction in real time. Integrated with remote sensing technologies, the proposed method has potential to be utilized as a real-time remote-sensing technology, which can offer a solution in the monitoring the degree of soil compaction.

Abstract: The use of a permanent vegetation cover or frequent tillage in vineyards may affect soil water budget, nutrient availability, soil compaction, soil erosion and soil microbe biodiversity, and through all these and other factors also yield and wine quality parameters. The abundance and diversity of arbuscular mycorrhizal fungi (AMF) might also be influenced, but so far effects on AMF by permanent vege-tation cover (= no-tillage systems) or repeated chiseling and rotary-tillaging have rarely been compared in vineyards. The objective of this on-farm study was to determine AMF species richness and diversity in two adjacent vineyards in Palatinate (SW Germany). In both vineyards, grown on fertile Luvisols, the var. “Pinot Gris” was grown for 39 years, but with different soil cultivation and different fertilization strategies. In one vineyard, soil was maintained periodically without vegetation by passing rotatory cultivator and chiseling between the grapevine rows (‘inter-rows’) several times per year, preferably during spring and summer and in dependency of rainfall and ‘weed’ growth, and fertilization was mainly by organic fertilizers in the last ten years before soil sampling. In the other vineyard, a permanent vegetation has been established since planting, dominated by Lolium perenne, and mineral fertilizers were exclusively applied. Despite of similar high nutrient availability in both soils, in particular of phosphorus, astonishing high AMF species richness and diversity were found in both vineyards. In the no-tillage inter-rows, 34 AMF species were found, with a species composition typically for Central European permanent grasslands (Shannon diversity index 2.45). In the tillage system 24 AMF species were found with a composition as known for extensively used, cultivated Central European croplands (diversity index 2.26). We conclude that above all soil cultivation has affected AMF diversity in these Central European vineyards, while the level and type of fertilization affected the AMF communities only on a minor level.

Abstract: Soil compaction caused by field traffic is one of the main threats to agricultural landscapes. Compacted soils have a reduced hydraulic conductivity, lower plant growth and increased surface runoff resulting in numerous environmental issues such as increased nutrient leaching and flood risk. Mitigating soil compaction, therefore, is a major goal for a sustainable agriculture and environmental protection. To prevent undesirable effects of field traffic, it is essential to know where and when soil compaction may occur. This study developed a model for soil compaction risk assessment of arable soils at regional scale. A combination of (i) soil, weather, crop type and machinery information; (ii) a soil moisture model and (iii) soil compaction models forms the SaSCiA-model (Spatially explicit Soil Compaction risk Assessment). The SaSCiA-model computes daily maps of soil compaction risk and associated area statistics for varying depths at actual field conditions and for entire regions. Applications with open access data in two different study areas in northern Germany demonstrated the model’s applicability. Soil compaction risks strongly varied in space and time throughout the year. SaSCiA allows a detailed spatio-temporal analysis of soil compaction risk at the regional scale, which exceed those of currently available models. Applying SaSCiA may support farmers, stakeholders and consultants in making decision for a more sustainable agriculture.

Abstract: It is well known, that soil particle surface properties like cation exchange capacity, surface area, and charge density affect ion-exchange reactions in the root zone. However, the exchange processes at the root surface itself also depend on these properties: cation exchange capacity, surface area, which will be determined in this paper for the roots of young wheat, barley, rye, triticale, and maize plants. Undisturbed samples from a Haplic Luvisol developed from loess were taken at 5–10 cm depth from an “normally compacted” core part of the crop field (Ref.) (bulk density 1.29 ± 0.06 Mg m −3 ) and from a “compacted” (C) (bulk density 1.61 ± 0.05 Mg m −3 ) part in the headland. Plants were grown in these soil cores for 11 days in a growth chamber. The negative surface charge of the roots and apparent surface dissociation constants were determined based on potentiometric titration in pH between 3 and 10. The surface charges at pH = 7 and pH = 10 were taken as the root cation exchange capacity (CEC) and total negative surface charge (Q tot ), respectively. The differences between the adsorption-desorption data were used to estimate the total apparent surface area (S). The Q tot and S were used to calculate the surface charge density (SCD). Root lengths were determined using WinRHIZO 2007 program. Irrespective of plant species, an increase in the compaction level resulted in an increase in weakly acidic groups and in the total apparent surface area (by 10–25%). On the other hand, strongly acidic groups decreased, as well as the CEC (by 28–45%). Additionally Q tot (by 19–32%), SCD (by 26–46%), root length (by 12–80%), and shoot mass (by 43–81%) all decreased. The increases in S and decreases in the number of strongly acidic groups, CEC, Q tot , and SCD in response to soil compaction were less pronounced in coarse-grained maize than in all remaining small-grained cereals. However, the decreases in root length and shoot mass were the highest in maize. The decline in negative surface charge due to soil compaction is attributed to the cell wall structure deformation and lower production and outflow of the acidic groups from the cell interior and lesser quantity of charged root hairs. These results imply the need to consider the root surface charge properties along with root growth traits while studying nutrient uptake from compacted soil.

Abstract: Compaction of the superficial soil layer can seriously jeopardise the sustainability of no-till systems. This study investigated how the compressive properties of two Oxisols under long-term no-till vary with initial bulk density (BD) and initial matric suction expressed as p F. Based on our experimental data, we then propose pedo-transfer functions for estimation of the compressive parameters N (intercept of the virgin compression line), λ (compression index) and κ (recompression index). Undisturbed samples were collected in the topsoil of two Oxisols with 220 (C 220 ) and 320 g kg −1 (C 320 ) of clay, and subjected to uniaxial compression tests at different initial p F. For both soils, N , λ and κ varied lineally with initial BD, whereas we found a quadratic relationship with initial p F, with a maximum N , λ and κ at intermediate matric suctions ( p F = 2.4-2.7). The elastic rebound upon stress release, measured by κ , was high for our soils, and this was attributed to the high organic matter concentration that is typical for the superficial layer in no-till systems. The relationships between the compressive parameters ( N , λ and κ ) and initial conditions (BD, p F) were used to assess soil susceptibility to compaction. Simulations indicated that the susceptibility to compaction decreases with increasing initial p F for the C 220 soil, but that the C 320 soil is most susceptible to compaction at an initial p F of about 2.5. The functions for estimation of N , λ and κ from initial bulk density and initial matric suction proposed in this paper could be used in soil compaction models for prediction of soil compaction risks.

Abstract: The intensive use of agricultural machinery is promoting the soil compaction. The use of agricultural robots or autonomous machinery can intensify this problem, due its capacity to replicate the same trajectories. One of the possible strategies to minimize the effects of soil compaction is to control agricultural traffic instead of common random traffic. Since geo-referencing systems are present in almost all field operations it is possible to optimize trajectories to avoid to damage the crop and intensify the soil compaction. The controlled agricultural traffic on farms will not only increase production capacity, the incomes as well as the quality of the soil. In this work a novel approach based on A-star algorithm is proposed to reduce soil compaction in steep slope vineyards.

Abstract: Climate change is projected to prolong Finland’s short growing season at both ends though warming autumns are not expected to benefit arable crops such as cereals, in contrast to warming springs. To test the veracity of this, ex-post and ex-ante approaches were applied to assess the past and future roles of autumns on cereal growth. Long-term multi-location data were used to assess the response of spring cereal cultivars on late harvests in the past. Future changes in temperature and precipitation, derived from the simulations performed with 28 global climate models under the RCP4.5 and RCP8.5 scenarios, compared with a baseline period, with mid-point year 1986, were averaged for three 30-year periods with mid-point years of 2025, 2055, and 2085. The phenological timing of growing seasons in a changing climate was simulated with the WOFOST. Warming autumns have insignificant potential for additional cereal yield gains. Even the latest maturing wheat cultivars would mature by the same time or earlier than currently when sown earlier. However, inter-annual variability in harvest times remains high, and hence many emerging risks may result from the elevated autumn precipitation in the future that will accompany delayed harvests. Means to benefit from warming autumns and mitigate their potential harmful impacts, like increasing nutrient leaching, erosion, and soil compaction, are needed. Post-harvest sowing of nutrient scavenging catch crops may provide the necessary soil cover, produce biomass, increase soil carbon, and protect soil from erosion and compaction. Hence, double cropping may be a viable alternative to safeguard sustainable high-latitude agriculture in a changing climate.

Abstract: Soil compaction heterogeneity and water content are supposed to be decisive factors influencing plant growth. Our experiment focused on simulation of two soil moisture levels (0.16 and 0.19 g/g) plus two levels of clod proportion (30 and 60% volume) and their effects on root and leaf variables of maize (Zea mays L.). We studied number of pri mary and lateral roots as well as primary root length at the particular soil depths. Statistical tests showed that the decrease rate of the number of roots versus depth was significantly affected by the two studied factors (P < 0.01). Soil moisture and clod occurrence, interactively, affected leaf biomass (P = 0.02). Presence of clods modified root morphological features. Particularly, the diameter of primary roots in the clods was significantly higher than of those grown in fine soil (P < 0.01). For primary roots, which penetrated clods, branching density decreased considerably for the root segments located just after the clods (P = 0.01). Regarding their avoidance to clods and tortuosity, large differences were found between primary roots grown in the contrasting soil environments.

Abstract: Calligonum mongolicum is a successful pioneer shrub to combat desertification, which is widely used for vegetation restoration in the desert regions of northwest China. In order to reveal the limitations to natural regeneration of C. mongolicum by asexual and sexual reproduction, following the process of sand dune stabilization, we assessed clonal shoots, seedling emergence, soil seed bank density, and soil physical characteristics in mobile and stabilized sand dunes. Controlled field and pot experiments were also conducted to assess germination and seedling emergence in different dune soil types and seed burial depths. The population density of mature C. mongolicum was significantly different after sand dune stabilization. Juvenile density of C. mongolicm was much lower in stabilized sand dunes than mobile sand dune. There was no significant difference in soil seed bank density at three soil depths between mobile and stabilized sand dunes, while the emergence of seedlings in stabilized dunes was much lower than emergence in mobile dunes. There was no clonal propagation found in stabilized dunes, and very few C. mongolicum seedlings were established on stabilized sand dunes. Soil clay and silt content, air-filled porosity, and soil surface compaction were significantly changed from mobile sand dune to stabilized dunes. Seedling emergence of C. mongolicm was highly dependent on soil physical condition. These results indicated that changes in soil physical condition limited clonal propagation and seedling emergence of C. mongolicum in stabilized sand dunes. Seed bank density was not a limiting factor; however, poor seedling establishment limited C. mongolicum's further natural regeneration in stabilized sand dunes. Therefore, clonal propagation may be the most important mode for population expansion in mobile sand dunes. As a pioneer species C. mongolicum is well adapted to propagate in mobile sand dune conditions, it appears unlikely to survive naturally in stabilized sand dune plantations.

Abstract: Traffic of farm machinery during harvest and logging operations has been identified as the main source of soil structure degradation in forestry activity. Soil susceptibility to compaction and the amount of compaction caused by each forest harvest operation differs according to a number of factors (such as soil strength, soil texture, kind of equipment, traffic intensity, among many others), what requires the adequate assessment of soil compaction under different traffic conditions. The objectives of this study were to determine the susceptibility to compaction of five soil classes with different textures under eucalyptus forests based on their load bearing capacity models; and to determine, from these models and the precompression stresses obtained after harvest operations, the effect of traffic intensity with different equipment in the occurrence of soil compaction. Undisturbed soil samples were collected before and after harvest operations, being then subjected to uniaxial compression tests to determine their precompression stress. The coarse-textured soils were less resistant and endured greater soil compaction. In the clayey LVd2, traffic intensity below four Forwarder passes limited compaction to a third of the samples, whereas in the sandy loam PVd all samples from the 0-3 cm layer were compacted regardless of traffic intensity. The Feller Buncher and the Clambunk presented a high potential to cause soil compaction even with only one or two passes. The use of soil load bearing capacity models and precompression stress determined after harvest and logging operations allowed insight into the soil compaction process in forestry soils.

Abstract: The paper discusses possibilities of using the portable falling weight deflectometer to measure the bearing capacity and compaction of forest soils. Within the study, measurements were made using manual penetrometer and Loadman II portable falling weight deflectometer. To eliminate the extreme values, Grubbs’s test was used. The results indicate that Loadman II deflectometer may be used to measure both the bearing capacity and compaction of forest soils under the canopy as well as in transport lines. A significant difference was found between deflection of waterunaffected sites and water-affected sites (12.08 and 2.31 mm, respectively). Measurements of bearing capacity after removal of forest litter give far more precise details; however, the authors do not refuse the measurements without litter removal, either. To determine the degrees of soil compaction, it is useful to measure the soil reaction time; to measure the bearing capacity it is vital to measure deflection.

Abstract: Trials were performed to test the germination ecology of buried weed seeds as a function of physical soil conditions such as of burial depth, texture, and compaction. Indeed, these ecological conditions, due to the adopted agronomic practices, play a crucial role in modulating the seed bank germination dynamics. Experiments were carried out in open fields in confined soils (polypropylene pipes), and in the laboratory in Petri dishes. Sowing depth strongly inhibited the seed germination of the three weed species selected. This inhibition was found to be inversely proportional to the size of the soil particles. Compaction strongly increased the depth-mediated inhibition, especially in soils that were rich in clay particles, and was inversely proportional to the seed size. The physiological nature of the dormancy imposed by burial was investigated. In addition, ungerminated seeds, re-exhumed after deep-sowing for six months, were found to be in deep dormancy, especially after burial in compacted clay soil. This dormancy induction was more pronounced in weed species characterized by small seeds. Critical issues are discussed regarding weed seed bank ecophysiology and their management in sustainable agricultural cropping systems.

Abstract: Background : Riparian vegetation is strongly influenced by the surrounding land use. While it is known that urbanization processes can affect plant species composition and the ecological condition of the riparian zone, the specific responses require a fuller understanding. Hypothesis: The quality of riparian zones is inversely related to the degree of urbanization of adjacent areas, and that land uses that provide forest cover ensure a less degraded condition and greater diversity of species. Study site and year of study: Sabinal River basin, Chiapas, Mexico, 2015. Methods: Measures of the Riparian Quality Index (RQI) and plant species composition were compared among three different land use conditions (secondary forest, grasslands and crops, and human settlements). Results: Riparian zones adjacent to secondary forest showed higher RQI than those next to grasslands and crops and human settlements. Riparian zones within secondary forest also had a higher woody species richness and better substrate condition, whereas reaches adjacent to human settlements appeared paved and eroded, exhibiting soil compaction. Species richness and diversity were positively correlated to the RQI and were greater in riparian zones adjacent to secondary forest than in those next to human settlements. Conclusions: While grazing and cultivation affect the riparian zone, expansion of urban areas has a greater impact by reducing woody species richness and diversity, altering species composition and favoring soil compaction and bank erosion, which results in reduced riparian quality.

Abstract: To investigate the effects of returning wheat straw to croplands on soil compaction and nutrient availability, this trial was designed: (1) planted crops without fertilization (NF); (2) natural land without human activities (CT); (3) applied mineral fertilizers in combination with 7500 kg/ha wheat straw (WS-NPK); (4) applied mineral fertilizers in combination with 3750 kg/ha wheat straw (1/2WS-NPK); and (5) applied mineral fertilizers alone (NPK). It is found that, compared with NPK, the soil bulk density in 1/2WS-NPK and WS-NPK both decreased by more than 10% in the 0 cm to 15 cm layer, and by 6.93% and 9.14% in the 15 cm to 20 cm, respectively. Furthermore, in contrast to NPK, the soil available nitrogen in the 0 cm to 25 cm layer in 1/2WS-NPK and WS-NPK were higher by 17.43% and 35.19%, and the soil available potassium were higher by 7.66% and 17.47%, respectively. For soil available phosphorus in the depth of 5 cm to 25 cm, it was higher by 18.51% in 1/2WS-NPK and by 56.97% in WS-NPK, respectively. Therefore, returning wheat straw to croplands effectively improves soil compaction and nutrients availability, and the improvement in soil nitrogen and phosphorus availability is closely related to the amount of wheat straw.