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Multiple disturbed and undisturbed soil samples were collected to assess the soil structure health in support of water use and management in a subtropical watershed, which is composed of shallow Entisols, near to Canguçu, RS state—Brazil. Various physico‐hydraulic properties related to soil structure, such as bulk density, total, micro and macroporosity, saturated hydraulic conductivity, organic carbon, soil water retention curve (SWRC), and the ranges of plant available water (PAWC) and drainable porosity (DP) were measured to be analyzed. The hydraulic‐energy indices of soil aeration and water retention were determined by integrating the areas under SWRC. Combining these properties with the contents of sand and clay, a unique blanket soil physico‐hydraulic health index (BSPHI) was formulated and applied to investigate the impact of land use and management on the soils of the Ellert Creek Watershed (ECW), thereby supporting soil physical health analysis and, consequently, the analysis of water and human health. The favorable outcomes found in the ECW soils under annual crops indicated good root aeration in the surface layer due to the balance between DP and PAWC. The BSPHI results showed that only about 19% of the areas exhibited unhealthy physical health. The soil structure in pasture areas of ECW was not significantly impacted by the extensive cattle grazing, whereas lands under native forest served as a control for the natural soil quality status. The BSPHI successfully captured small changes in soil structure, regardless of land use and management, highlighting its potential as a promising tool for evaluating soil health by assessing the soil physical quality. [ABSTRACT FROM AUTHOR]

The saturated hydraulic conductivity (Ks) and water retention curve (SWRC) parameters are important properties for simulating soil hydrological processes and characterizing soil conservation around the world. Therefore, Ks and SWRC are related with the soil physical quality (SPQ) and several SPQ indices can be derived from SWRC, such as the pore size distribution, relative field capacity, plant available water, drainable porosity, and soil hydraulic-energy indices (SHEI). It is well known that the soil structure can be assessed by using SHEI, but a possible physical relationship between Ks and SHEI was not examined yet. Therefore, the objective of this study was to investigate the behavior of Ks as function of SHEI for several soil textural classes. If this relationship be proved, then SHEI might be applied to improve the Ks prediction by PTF models. In this work, a data set of 395 measured SWRC's were fitted to the vG equation to obtain the SHEI to verify whether they are statistically correlated and physically dependent on Ks. The resulting parametric and non-parametric correlation results were split up according to six textural classes. The significant influence of Ks on at least one of the absolute SHEI (Aa or WRa) was verified on the numerical scale when all textures were grouped and on numerical and pF scales for clayey and silty textures. Ks showed significant impact on Aa and WRa indices in four textural classes. Furthermore, Ks had influence on the sum Aa + WRa denoted in pF scale for five of the six textural classes, with a significant linear correlation in the clayey texture when log (Aa + WRa) was applied. The significant and high correlation of Ks on the ratios WRa/AWC and Aa/φD was also observed in four of the six classes, and therefore the use of these indices is recommended for the development of PTFs for Ks prediction.

IntroductionSoil pore size distribution curve and using the optimal ranges of the location and shape parameters of this curve can be used to evaluate the soil physical quality. This research was carried out in an area of about 220 hectares of Torogh Agricultural and Natural Resources Research and Education Station, to determine the optimal ranges for soil pore size distribution curve parameters using the soil physical quality index. Different soil textures and the diversity in soil properties are the distinct features of this research station. Materials and MethodsTorogh Agricultural and Natural Resources Research and Education Station of Khorasan-Razavi province, with a semiarid climate, is located in south-east of Mashhad city. For the field measurements and laboratory analysis to determine the soil physical properties and indices, 30 points with different soil textures and structures were selected. Intact soil cores (5 cm diameter by 5.3 cm length) and disturbed soil samples were collected from 0-30 cm depth of each point. After the laboratory analysis and field measurements, 35 soil physical properties were measured and calculated. Soil particle size distribution and five size classes of sand particles, soil bulk, and particle density, dry aggregates mean weight diameter (MWD) and stability index (SI), soil moisture release curve (SMRC) parameters, S-index, soil porosity (POR) and air capacity (AC), soil pore size distribution (SPSD) curves, relative field capacity (RFC), plant available water measured in matric pressure heads of 100 and 330 hPa for the field capacity (PAW100 and PAW330), least limiting water range measured in matric pressure heads of 100 and 330 hPa for the field capacity (LLWR100 and LLWR330), integral water capacity (IWC) and integral energy (EI) of different soil water ranges, were the soil physical properties and indices which were determined in this study. Three parameters of modal, median, and mean pore sizes of the SPSD curves were considered as the location (central tendency), and three parameters of standard deviation, skewness, and kurtosis of the SPSD curves were considered as the shape parameters. Selection of the most important soil physical characteristics using principal component analysis (PCA) method by JMP software (ver. 9.02), weighting and scoring of the selected characteristics using PCA and scoring functions, respectively, and the summation of multiplied characteristics weights by their scores for each soil sample, were the four steps of calculation of the 0-1 value of soil physical quality index (SPQI). Soil samples were classified into four soil physical quality classes by SPQI values. The soils of the first class with the highest SPQIs (> 0.78) were considered to determine the optimal ranges of SPSD curves location and shape parameters. Results and DiscussionThe texture of soil samples were loam (40 %), silt loam (23 %), silty clay loam (17 %), clay loam (13 %), and sandy loam (7 %). Soil organic carbon was between 0.26-1.05 (%), and the average soil bulk density was 1.45 (gr.cm-3). The MWD values of studied soil samples were between 0.94-2.88 (mm), an average of 1.93 (mm). The average modal, median, and mean pore sizes as the location parameters of the SPSD curves were 60.3 (μm), 12.4 (μm), and 6.5 (μm), respectively. The average of standard deviation, skewness, and kurtosis as the shape parameters of the SPSD curves were 71.56 (μm), -0.36 and 1.15, respectively. The average modal pore sizes showed that the pores with a size of 60 (μm) had the highest frequency in soil samples. The range of calculated standard deviation of SPSD curves, along with the difference between the minimum and maximum mean pore sizes (24.6 μm), implied the diversity of pore sizes in the studied soils. The results of PCA showed that the four soil physical properties of PAW330 (0.1-0.2 cm3.cm-3), PORt (0.40-0.51 cm3.cm-3), LLWR100 (0.12-0.22 cm3.cm-3) and SI (0.76-2.61 %) accounted for about 88% of the variance between soil samples and were selected to calculate the SPQIs. The PAW330, PORt, LLWR100, and SI were entered into the calculation of SPQIs with weights of 0.46, 0.31, 0.15, and 0.08, respectively. All the selected physical properties were scored using the scoring function of more is better. The maximum and minimum values of SPQIs for the studied soils were 0.84 and 0.14, respectively. Five soil samples with SPQIs greater than 0.78 were classified as class 1 with the highest physical quality. The ranges between the minimum and maximum values of the SPSD curves, location, and shape parameters of these five soils were proposed as the optimal ranges. In this regard, the ranges of 29-92 (μm), 5-16 (μm), and 2-7 (μm) were suggested for optimal ranges of modal, median, and mean pore sizes, respectively. The optimal ranges of standard deviation, skewness, and kurtosis of the SPSD curves were proposed as 22-81 (μm), (-0.38)-(-0.33), and 1.14-1.15, respectively. ConclusionThe optimal ranges of SPSD curves location and shape parameters suggested in the literature may probably not apply to a wide range of agricultural soils. They must be evaluated in a more extensive range of land uses, soil management, and soil textures. In this research, the soils with the relatively higher physical quality had larger mean pore size and less SPSD curves standard deviation (less diversity of pore size) than the optimal ranges suggested in the literature. The optimal ranges of SPSD curves location and shape parameters proposed in this research are appropriate for medium to coarse-textured soils of regions with the semiarid climate in Iran.

ABSTRACT Physical properties of the Technosols formed by the tailings deposition may constitute a physical barrier that limits water movement and plant development due to the properties received from those sediments. This study aimed to evaluate the physical quality of the Technosols formed by the deposition of sediments displaced by the Fundão Dam failure, Mariana, Minas Gerais State, Brazil, based on the evaluation of physical properties and Load Bearing Capacity Models (LBCM). For that, three areas under different vegetation types were selected: eucalyptus (Euc), forest with human-assisted revegetation (RF), and forest with native vegetation (NF). Three sampling subareas were demarcated in each area: non-impacted areas (Ni), and Technosols formed in directly impacted areas (Di), and partially impacted areas (Pi). Undisturbed samples were collected in two layers and subjected to the uniaxial compression test after equilibration at five matric potentials. Soil compression curves and LBCM were determined. Soil bulk density (BD), total porosity (TP), organic matter (OM), granulometry, and particle density (PD) were also determined. Clay content was less significant, and the silt and very fine sand content was significantly higher in the Technosols, generating an increase in BD and reduction in TP. Technosols generally exhibited greater load-bearing capacity due to higher pre-consolidation pressure values attained by these soils due to the lower clay and OM contents. High resistance of these soils is one limitation for revegetation of the areas evaluated, being necessary management practices to improve physical properties of the Technosols.

Introduction Soil pore size distribution curve and using the optimal ranges of the location and shape parameters of this curve can be used to evaluate the soil physical quality. This research was carried out in an area of about 220 hectares of Torogh Agricultural and Natural Resources Research and Education Station, to determine the optimal ranges for soil pore size distribution curve parameters using the soil physical quality index. Different soil textures and the diversity in soil properties are the distinct features of this research station. Materials and Methods Torogh Agricultural and Natural Resources Research and Education Station of Khorasan-Razavi province, with a semiarid climate, is located in south-east of Mashhad city. For the field measurements and laboratory analysis to determine the soil physical properties and indices, 30 points with different soil textures and structures were selected. Intact soil cores (5 cm diameter by 5.3 cm length) and disturbed soil samples were collected from 0-30 cm depth of each point. After the laboratory analysis and field measurements, 35 soil physical properties were measured and calculated. Soil particle size distribution and five size classes of sand particles, soil bulk, and particle density, dry aggregates mean weight diameter (MWD) and stability index (SI), soil moisture release curve (SMRC) parameters, S-index, soil porosity (POR) and air capacity (AC), soil pore size distribution (SPSD) curves, relative field capacity (RFC), plant available water measured in matric pressure heads of 100 and 330 hPa for the field capacity (PAW100 and PAW330), least limiting water range measured in matric pressure heads of 100 and 330 hPa for the field capacity (LLWR100 and LLWR330), integral water capacity (IWC) and integral energy (EI) of different soil water ranges, were the soil physical properties and indices which were determined in this study. Three parameters of modal, median, and mean pore sizes of the SPSD curves were considered as the location (central tendency), and three parameters of standard deviation, skewness, and kurtosis of the SPSD curves were considered as the shape parameters. Selection of the most important soil physical characteristics using principal component analysis (PCA) method by JMP software (ver. 9.02), weighting and scoring of the selected characteristics using PCA and scoring functions, respectively, and the summation of multiplied characteristics weights by their scores for each soil sample, were the four steps of calculation of the 0-1 value of soil physical quality index (SPQI). Soil samples were classified into four soil physical quality classes by SPQI values. The soils of the first class with the highest SPQIs (> 0.78) were considered to determine the optimal ranges of SPSD curves location and shape parameters. Results and Discussion The texture of soil samples were loam (40 %), silt loam (23 %), silty clay loam (17 %), clay loam (13 %), and sandy loam (7 %). Soil organic carbon was between 0.26-1.05 (%), and the average soil bulk density was 1.45 (gr.cm-3). The MWD values of studied soil samples were between 0.94-2.88 (mm), an average of 1.93 (mm). The average modal, median, and mean pore sizes as the location parameters of the SPSD curves were 60.3 (سلم), 12.4 سلم)), and سلم) 6.5), respectively. The average of standard deviation, skewness, and kurtosis as the shape parameters of the SPSD curves were 71.56 (سلم), - 0.36 and 1.15, respectively. The average modal pore sizes showed that the pores with a size of سلم) 60) had the highest frequency in soil samples. The range of calculated standard deviation of SPSD curves, along with the difference between the minimum and maximum mean pore sizes (سلم 24.6), implied the diversity of pore sizes in the studied soils. The results of PCA showed that the four soil physical properties of PAW330 (0.1-0.2 cm3.cm-3), PORt (0.40-0.51 cm3.cm-3), LLWR100 (0.12-0.22 cm3.cm-3) and SI (0.76-2.61 %) accounted for about 88% of the variance between soil samples and were selected to calculate the SPQIs. The PAW330, PORt, LLWR100, and SI were entered into the calculation of SPQIs with weights of 0.46, 0.31, 0.15, and 0.08, respectively. All the selected physical properties were scored using the scoring function of more is better. The maximum and minimum values of SPQIs for the studied soils were 0.84 and 0.14, respectively. Five soil samples with SPQIs greater than 0.78 were classified as class 1 with the highest physical quality. The ranges between the minimum and maximum values of the SPSD curves, location, and shape parameters of these five soils were proposed as the optimal ranges. In this regard, the ranges of 29-5,)سلم) 92 - سلم(16), and 2- (سلم) 7 were suggested for optimal ranges of modal, median, and mean pore sizes, respectively. The optimal ranges of standard deviation, skewness, and kurtosis of the SPSD curves were proposed as 22-81 (0.33-)-(سلم), (- 0.38), and 1.14-1.15, respectively. Conclusion The optimal ranges of SPSD curves location and shape parameters suggested in the literature may probably not apply to a wide range of agricultural soils. They must be evaluated in a more extensive range of land uses, soil management, and soil textures. In this research, the soils with the relatively higher physical quality had larger mean pore size and less SPSD curves standard deviation (less diversity of pore size) than the optimal ranges suggested in the literature. The optimal ranges of SPSD curves location and shape parameters proposed in this research are appropriate for medium to coarse-textured soils of regions with the semiarid climate in Iran. [ABSTRACT FROM AUTHOR]

This data article provides high spatial resolution (1 cm) datasets and related figures of the penetrometer resistance (PR) and soil bulk density (BD) data of nine agricultural 50 × 160 cm soil profiles exposed to three tillage treatments and including a wheel track. Soil treatments are moldboard plowing (MP), deep loosening (DL), and minimum tillage (MT). It also provides bulk density data, soil moisture content at various suctions and the parameters of van Genuchten's model for 27 soil cores, and saturated hydraulic conductivity (Ks) of 49 soil cores. Both sample sets were sampled to cover the profile heterogeneity in two agricultural plots subjected to moldboard plowing and minimum tillage. Examples of reuse potential include (i) the use of these spatially explicit data in studies seeking to understand better and integrate the effect of treatment and machine traffic-induced soil structure in soil hydraulic and soil physical quality, and (ii) the development of pedotransfer functions with data incorporating the soil structural heterogeneity. This Data in Brief article complements the companion paper by Alonso et al. (2021) “A hybrid method for characterizing tillage-induced soil physical quality at the profile scale with fine spatial detail” in Soil and Tillage Research [1].

An application of different mulch materials may lead to changes in soil properties. Our previous study, focused on the impact of various mulches during the 4-year period, showed that the change in some properties can be very rapid (e.g., soil pH), but in other cases such as hydraulic properties, the changes can be gradual. To find out, whether the extension of the mulching period will further affect the studied soil properties, the experiment continued for another 2 years. Differences between values of organic carbon content (Cox), soil physical quality (Sinf), gravitational water (GW) and readily available water (RAW) of soils not covered by any mulch and under various mulches (bark chips; wood chips; wheat straw; Agrotex EKO+ decomposable matting; polypropylene fabric covered bark chips; crushed stone) were much larger than those observed in our previous study. On the other hand, the opposite trend was observed for the water stable aggregates (WSA) index or soil pH. Differences between additionally measured hydraulic conductivities at the pressure head of −2 cm and repellency index (RI) were mostly insignificant. Results indicated that organic mulches can either positively (e.g., increase WSA index and Cox, and decrease GW) or negatively (e.g., decrease Sinf and RAW, and increase RI) affect soil properties.

ABSTRACT The effects of machinery traffic and cover crops on soil physical properties have been underexplored under no-till agricultural production in subtropical environments. The objective of this study was to quantify the soil water infiltration rate and related soil physical properties in response to tractor traffic levels (0, 2, 5, and 20 passes) and the presence or absence of cover crops in a Xanthic Hapludox soil over two growing seasons under no-till conditions. The experiment was carried out in a randomized block design arranged in a factorial scheme with four replications. The traffic factor was constituted by the number of passes with a 6 Mg weight tractor. The winter crop management practices factor consisted of the cover crops (i) black oat (Avena strigosa) in 2017 and turnip (Raphanus sativus var. oleiferus) in 2018 compared with (ii) fallow with spontaneous vegetation. The soil water infiltration rate increased with cover crops when compared to fallow. Regarding tractor traffic levels, shortly after soil compaction, there was a lower water infiltration rate at 20 passes, 45 mm h-1 lower than the absence of tractor traffic. The soil water infiltration rate was positively correlated with macroporosity and negatively correlated with soil bulk density. After 14 months of soil compaction caused by tractor traffic, an improvement in the soil physical properties and the water infiltration rate was found, which were enhanced by the inclusion of cover crops.

Crop growth is often uneven within an agricultural parcel, even if it has been managed evenly. Aerial images are often used to determine the presence of vegetation and its spatial variability in field parcels. However, the reasons for this uneven growth have been less studied, and they might be connected to variations in topography, as well as soil properties and quality. In this study, we evaluated the relationship between drone image data and field and soil quality indicators. In total, 27 multispectral and RGB drone image datasets were collected from four real farm fields in 2016–2020. We analyzed 13 basic soil quality indicators, including penetrometer resistance in top- and subsoil, soil texture (clay, silt, fine sand, and sand content), soil organic carbon (SOC) content, clay/SOC ratio, and soil quality assessment parameters (topsoil biological indicators, subsoil macroporosity, compacted layers in the soil profile, topsoil structure, and subsoil structure). Furthermore, a topography variable describing water flow was used as an indicator. Firstly, we evaluated single pixel-wise linear correlations between the drone datasets and soil/field-related parameters. Correlations varied between datasets and, in the best case, were 0.8. Next, we trained and tested multiparameter non-linear models (random forest algorithm) using all 14 soil-related parameters as features to explain the multispectral (NIR band) and RGB (green band) reflectance values of each drone dataset. The results showed that the soil/field indicators could effectively explain the spatial variability in the drone images in most cases (R2 > 0.5), especially for annual crops, and in the best case, the R2 value was 0.95. The most important field/soil features for explaining the variability in drone images varied between fields and imaging times. However, it was found that basic soil quality indicators and topography variables could explain the variability observed in the drone orthomosaics in certain conditions. This knowledge about soil quality indicators causing within-field variation could be utilized when planning cultivation operations or evaluating the value of a field parcel. [ABSTRACT FROM AUTHOR]

The effects of machinery traffic and cover crops on soil physical properties have been underexplored under no-till agricultural production in subtropical environments. The objective of this study was to quantify the soil water infiltration rate and related soil physical properties in response to tractor traffic levels (0, 2, 5, and 20 passes) and the presence or absence of cover crops in a Xanthic Hapludox soil over two growing seasons under no-till conditions. The experiment was carried out in a randomized block design arranged in a factorial scheme with four replications. The traffic factor was constituted by the number of passes with a 6 Mg weight tractor. The winter crop management practices factor consisted of the cover crops (i) black oat (Avena strigosa) in 2017 and turnip (Raphanus sativus var. oleiferus) in 2018 compared with (ii) fallow with spontaneous vegetation. The soil water infiltration rate increased with cover crops when compared to fallow. Regarding tractor traffic levels, shortly after soil compaction, there was a lower water infiltration rate at 20 passes, 45 mm h-1 lower than the absence of tractor traffic. The soil water infiltration rate was positively correlated with macroporosity and negatively correlated with soil bulk density. After 14 months of soil compaction caused by tractor traffic, an improvement in the soil physical properties and the water infiltration rate was found, which were enhanced by the inclusion of cover crops. [ABSTRACT FROM AUTHOR]

Water scarcity threatens global food security and agricultural systems are challenged to achieve high yields while optimizing water usage. Water deficit can be accentuated by soil physical degradation, which also triggers water losses through runoff and consequently soil erosion. Although soil health in cropping systems within the Brazilian Cerrado biome have been surveyed throughout the years, information about soil erosion impacts and its mitigation are still not well understood; especially concerning the role of cropping system diversification and its effects on crop yield. Thus, the aim of this study was to assess whether ecological intensification of cropping systems –inclusion of a consorted perennial grass and crop rotation– could promote soil coverage and consequently decrease water erosion and soil, water, and nutrient losses. This work studied the effects of crop rotation and consorted Brachiaria, along with different levels of investment in fertilization on soil physical quality and on soil, water, and nutrient losses, and crop yields. Results proved that soybean monoculture (SS) is a system of low sustainability even under no-till in the Brazilian Cerrado conditions. It exhibited high susceptibility to soil, water, and nutrient losses, causing low crop yields. Our results showed that water losses in SS cropping system were approximately 10% of the total annual rainfall, and total K losses would require an additional 35% of K application. Conversely, ecological intensification of cropping systems resulted in enhanced soil environmental and agronomic functions, increased grain yield, and promoted soil and water conservation: high soil cover rate, and low soil, water and nutrient losses. Ecological intensification proved to be an adequate practice to boost crop resilience to water deficit in the Brazilian Cerrado.

The intense and successive use of mechanization in modern cropping systems has increased soil compaction under no-till areas. In this study, we aimed to assess the performance of a fixed shank coupled with a seeder for the mitigation of soil compaction induced by machinery traffic as an efficient alternative to replacing the chiseling and subsoiling operations in no-till areas. We evaluated a long-term experiment conducted in clay loam (Rhodic Haplustox) soil in southern Brazil. The experiment was conducted under a randomized block design, whose treatments consisted of three wheel-traffic intensities: 0 wheel-traffic (0 WT), 14 wheel-traffic (14 WT), and 28 wheel-traffic (28 WT), combined with four soil tillage mechanical interventions under a no-till field: no-till (NT), no-till with a fixed shank (NT + FS), soil chiseling (SC), and soil subsoiling (SS). The soil physical attributes evaluated were the soil penetration resistance (SPR), macroporosity (MaP), microporosity (MiP), total porosity (TP), bulk density (BD), field-saturated hydraulic conductivity (Kfs), S index, and plant-available water capacity (PAWC). In addition, three critical soil physical functions were evaluated by using a soil physical quality index (SPQI). The results showed that SPR was sensitive to soil compaction and captured differences among the mechanical intervention methods. Machinery traffic caused soil compaction, increasing SPR and reducing PAWC. Soil chiseling and subsoiling promoted lower BD, a higher TP, MaP, Kfs, and higher S index at the 0.05–0.15 m soil layer. Based on the SPQI, no changes were detected in the soil physical functions between NT and NT + FS. On the other hand, SC and SS enhanced soil physical functioning by 10%. We concluded that a 15-cm deep fixed shank could not mitigate the soil compaction induced by machinery traffic at the seeder operation. Therefore, this method is less effective in improving the soil's physical environment than chiseling and subsoiling operations. Finally, we encourage monitoring the persistence of these benefits on the soil over the subsequent crop seasons and in years with an intense water deficit along with the crop cycle. [ABSTRACT FROM AUTHOR]

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Different soil management strategies may either promote or degrade soil structure. This study aimed to test the Visual Evaluation of Soil Structure (VESS) method in a smallholder agroforestry system in the eastern Amazon. Three plots (P1, papaya field; P2, banana intercropped with cassava; P3, banana, cassava, and açaí), as well as an adjoining area under native vegetation (NV), were evaluated using VESS. Quantitative assessments of soil physical quality were also performed, including soil water retention curve (SWRC), bulk density (Bd), particle density (Pd), microporosity (Mi), macroporosity (Ma), total porosity (Tp), available water capacity (AWC), field capacity (FC), and permanent wilting point (PWP). The VESS scores in P2 (2.6) and P3 (1.8) were similar to NV (1.4), while P1 (2.8) had a poorer structure. P1 differed from the other plots, with lower Ma (0.05 m3 m−3) and Tp (0.39 m3 m−3), and higher Bd (1.57 Mg m−3), AWC (0.32 m3 m−3), and water retention at FC (θFC: 0.33 m3 m−3). VESS scores were significantly correlated with most quantitative measurements. These results indicate that VESS is effective to assess soil structure, providing a convenient strategy for soil structural quality assessment in smallholders from Amazon. [ABSTRACT FROM AUTHOR]

Based on soil sampling, lab experiment and support resistance monitoring, the disturbance of soil physical quality indices between different underground mining stages of No 52303 working face was studied in semi-arid region of western China. Soil sampling was conducted in same locations before and after mining in 2014. This study proved that soil water content, soil cohesion and soil porosity were greatly decreased, while bulk density and dry density were increased by coal mining. In comparison, coal mining had slight effect on organic matter, internal fraction angle, and D1 and D2 percent. Underground pressure monitoring showed that P1 during stage 2 was significantly greater than that during stage 1, indicating the large difference of pressure characteristics in tail areas of working face between two stages. Both soil water content and soil cohesion were decreased during two stages in two sites. Soil cohesion was strongly correlated to soil water content, and D1 and D2 percent in 2013 and 2014. Coal mining subsidence increased the cumulative probability to reach the same value of soil water content and soil cohesion. The cover depth produced different elastic and plastic zone widths between sites by theoretical model calculation, consistent with the support resistances in tail areas of working face. Higher pressure might cause a more serious destructive rock-soil body and a larger groundwater level decrease. The dryer and more serious erosive soil column induced by coal mining is a non negligible matter for the semi-arid region. [ABSTRACT FROM AUTHOR]

Compost amendment is a widespread agronomic practice, but little information is available about the short- and medium-term effects on clay soils. In this investigation, we selected three soil compost rates (treatments, T), i.e., fertilizer (T2 = 1.5 kg m−2), amending (T3 = 15 kg m−2), and organic (T4 = 75 kg m−2), that were compared to a control (T1). Our research accounts for the effects reached on representative large boxes (about 0.75 m3), without crops and for about eighteen months. An overall assessment of the physical and hydraulic properties of the soil was made, including infiltration rate or saturated hydraulic conductivity (Ks), water content and water retention (θ) of the soil, bulk density and structure, and several physical quality indicators obtained from the water retention curve, accounting for the optimal balance between water/air into the soil, pore volume distribution function, and soil features in the inflection point of the soil water retention curve. Additionally, the temporal changes of Ks were evaluated. The main results showed that (i) after eighteen months, and regardless of T, θ significantly improved by a factor of 1.2–1.3, but these improvements (up to 1%) were detected only close to water saturation (i.e., until 6 cm of soil pressure head) when little (T2) or no compost (T1) addition was considered, while a larger range was detected (until 60 cm) when higher rates (T3–T4) were used; (ii) Ks determination allowed to establish that compost effects vanished after about eleven months, but it was not possible to verify that composting increased the permeability of the investigated clay soil within that time frame; (iii) some significant correlations between Ks and some soil physical indicators estimated from both the inflection point of the water retention curve or bulk density suggested possible improvements in soil permeability. Because some factors (water content of the soil above all) could have affected the comparison of Ks measurements, further research on this topic is needed. [ABSTRACT FROM AUTHOR]

Soil structure controls key soil functions in both natural and agro‐ecosystems. Thus, numerous attempts have been made to develop methods aiming at its characterization. Here we propose an index of soil structure that uses relative entropy to quantify differences in the porosity and pore(void)‐size distribution (VSD) between a structured soil derived from soil water retention data and the same soil without structure (a so‐called reference soil) estimated from its particle‐size distribution (PSD). The difference between these VSDs, which is the result of soil structure, is quantified using the Kullback–Leibler Divergence (KL divergence). We applied the method to soil data from two Swedish field experiments that investigate the long‐term effects of soil management (fallow vs. inorganic fertilizer vs. manure) and land use (afforested land vs. agricultural land dominated by grass/clover ley) on soil properties. The KL divergence was larger for the soil receiving regular addition of manure compared with the soils receiving no organic amendments. Furthermore, soils under afforested land showed significantly larger KL divergences compared to agricultural soils near the soil surface, but smaller KL divergences in deeper soil layers, which closely mirrored the distribution of organic matter in the soil profile. Indeed, a significant positive correlation (r = 0.374, p < 0.001) was found between soil organic carbon concentrations and KL divergences across all sites and treatments. Despite challenges related to modelling the VSD of the reference soil without structure, the proposed index proved useful for evaluating differences in soil structure in response to soil management and land‐use change and reflected the expected effects of soil organic matter on soil structure. We conclude that relative entropy shows great potential to serve as an easy‐to‐use index of soil structure, as it only requires widely available data on soil physical and hydraulic properties. Highlights: A new index of soil structure is proposed based on relative entropyA method is developed that separates the effects of soil texture and structure on the pore spaceThe index identified soil structural differences in response to land use and soil organic carbon concentrations (SOC)The index shows the potential to serve as an easy‐to‐use metric of soil structure [ABSTRACT FROM AUTHOR]

Background and Objectives: The purpose of incorporating organic modifiers such as biochar with soil is stabilizing carbon, improving fertility, absorbing pollutants, and consequently increasing crop production. Biochar is a biofuel and the resultant of organic matters thermocouples. Biochars are produced in high temperature ovens and are commonly alkaline and so suitable for the acidic soils. However, if the raw materials are heated at low temperatures, the resulting biochar can be acidic and useful for modifying calcareous soils. The aim of this study was to investigate the effect of two types of acidic biochars of rice husk and pine cone for modifying the physical properties of two calcareous soils of Isfahan province. Materials and Methods: Based on a preliminary experiment, rice husk biochar (pH=5.64) and pine cone biochar (pH=6.56) produced at 300 °C were selected for this study. The experiment was performed in a completely randomized factorial design with three replications. Treatments included two types of biochar (pine cone and rice husk) mixed with soil at one, three and six percent (g/g), two types of soil (a sandy loam, Tiran and a clay loam, Lavark), and two incubation periods of one and six months, with 4 controls and a total of 28 pots. The treated soils were kept in an incubator at 25 °C and 60% of field (pot) capacity. At the end of the incubation periods, the soil moisture contents at field capacity and the permanent wilting point were measured respectively using sand-kaolin box and pressure plate devices and then soil available water contents was calculated. Results: The results showed that the addition of biochars improved some physical properties of soils. The treatment of the soils with 3% and 6% of biochars caused significant increases in the available water (AW) in the sandy loam soils compared to the control. The physical quality index of Dexter (SDexter) fitted by van Genuchten–Mualem was significantly increased in the sandy loam soil amended with 6% of the biochars and in the clay loam soil amended with 3% and 6% of the biochars. The use of biochars also improved the physical quality of the soil, described by the Dexter index, from poor to very good. Conclusion: The results of this study showed that addition of 6% rice husk biochar to the clay loam soil and at the 30 days incubation period, could improve soil properties. Therefore, according to these findings, the biochars produced from pine cones and rice husk can be suggested as a suitable conditioner for improving physical properties of the regional calcareous soils. [ABSTRACT FROM AUTHOR]

ABSTRACT Sugarcane culture in Brazil has expanded the planting area to degraded pastures and sandy soils. Sugarcane field reform is carried out after five or more harvest cycles, with conventional tillage, followed by planting sugarcane, or growing soybeans or a cover crop. This study aimed to analyze the effects of these different managements in the conventional sugarcane reform on the physical properties and organic carbon in an Argissolo Vermelho distrófico arênico (sandy Ultisol), located at latitude 21° 13’ 40” south, longitude 50° 52’ 06” west, and altitude of 449 m. In each management study, areas of 10 ha were delimited in which 36 months after the renovation period, during the 3rd crop cycle, soil samples were collected in eight trenches measuring 1.0 × 1.0 × 0.5 m, 30 m apart between the crop rows and 0.25 m from the planting furrow, to analyze: the stability index of aggregates in the layers of 0.00-0.10 and 0.10-0.20 m and density and porosity (total, macro, and microporosity) of the soil in addition to organic carbon, in the layers of 0.00-0.10, 0.10-0.20, 0.20-0.30 and 0.30-0.40 m. The results allowed us to conclude that the tillage+sugarcane and tillage+soy managements negatively affected the physical properties compared to the tillage+cover crop management, whose use of Crotalaria spectabilis provided higher Pt, higher Ma, and Mi, higher AS. Furthermore, the increase in carbon contents was low, with small variations between treatments.

Archeological Dark Earths, known in the Brazilian Amazon as Terra Preta de Índio are fertile and structured soils considered as a potential model for sustainable agriculture. In order to recreate these soils a field experiment, named New Dark Earth, was set up in 2003 in the municipality of Tailândia, state of Pará, northern Brazil. The treatments consisted of the application of organic residues (wastes from local industries) in a loamy sand soil: cattle bones, wood charcoal, shredded wood blades, and the control. The objective of this study was to evaluate the effect of these residues on soil physico-hydrological properties. The results showed that the residues did not significantly increase the soil organic carbon content. Only the wood charcoal resulted in some improvements in soil physico-hydrological properties, such as lower soil bulk density and higher total and microporosity, which was mainly attributed to the high porosity of this material. Consequently, it also presented more available water. For now, it was concluded that despite the three residues are widely available in the region, the use of wood charcoal seems to be the best alternative to bring improvements to the soil physical properties, mainly soil water retention. However, more studies need to be carried out. [ABSTRACT FROM AUTHOR]

The soils of the Brazilian semi-arid are under a constant process of degradation and sustainable agricultural production strategies must be adopted in order to alleviate this problem. Therefore, the objective of this work was to evaluate the physical-water behavior of an Albaqualfs four years after the implantation of crop-livestock-forest integration systems in the Brazilian semiarid. The experiment was installed in the county of Alagoinha, PB, in an Albaqualfs with a sandy-loam texture. Five integration systems in randomized block design (DBC) with four replications were evaluated: i) Purple Ipe (Tabebuia impetiginosa) + Brachiaria decumbens (iPF1); ii) Gliricidia (Gliricidia sepium) + Urochloa decumbens (iPF2); iii) Sabiá (Mimosa caesalpiniifolia) + Urochloa decumbens (iPF3); iv) Maize (Zea mays) + Urochloa decumbens (iLP); v) Urochloa decumbens (pasture). The data submitted to analysis of variance and Tukey's test (p<0.05) demonstrated that the crop-livestock-forest integrated system, after the period of four years, has not yet promoted significant physical improvement of the attributes of the Albaqualfs under study, however, an attribute such as the S index, presented satisfactory values. Regarding the condition prior to the implantation of the systems, there is a positive change in the structure, reflecting in the reduction of the bulk density of the soil and an increase in the total porosity. [ABSTRACT FROM AUTHOR]

Understanding the spatial structure of soil properties at field scale and introducing this information into appropriate data analysis methods can help in detecting the effects of different soil management practices and in supporting precision agriculture applications. The objectives of this study were: (i) assessing the spatial structure of soil physical and hydraulic properties in a long-term field experiment; (ii) defining a set of spatial indicators for gaining an integrated view of the studied system. In seventy-two georeferenced locations, soil bulk density (BD), initial volumetric soil water content (θi) and cumulative infiltration curve as function of the time (I(t)) were measured. The soil water retention curve (θ(h)) and the hydraulic conductivity function (K(h)) were then estimated using the Beerkan Estimation of Soil Transfer parameters (BEST) methodology. The volumetric soil water contents at soil matrix (h = −10 cm), field capacity (h = −100 cm) and wilting point (h = −15,300 cm) were considered. In addition, a set of capacitive indicators—plant available water capacity (PAWCe), soil macroporosity (PMACe), air capacity (ACe) and relative field capacity (RFCe)—were computed. The data were first analyzed for overall spatial dependence and then processed through variography for structural analysis and subsequent spatial interpolation. Cross-correlation analysis allowed for assessing the spatial relationships between selected physical and hydraulic properties. On average, optimal soil physical quality conditions were recorded; only PMACe values were indicative of non-optimal conditions, whereas mean values of all the other indicators (BD, Ks, PAWCe, ACe, RFCe) fell within optimal ranges. The exponential model was found to be the best function to describe the spatial variability of all the considered variables, except ACe. A good spatial dependence was found for most of the investigated variables and only BD, ACe and Ks showed a moderate autocorrelation. Ks was confirmed to be characterized by a relatively high spatial variability, and thus, to require a more intensive spatial sampling. An inverse spatial cross-correlation was observed between BD and Ks up to a distance of 10 m; significant cross-correlations were also recorded between Ks and PMACe and ACe. This result seems to suggest the possibility to use these soil physical quality indicators as covariates in predictive multivariate approaches.

This research was carried out in an organic crop sequence of cauliflowers (Brassica oleracea L.) and tomatoes (Solanum lycopersicum L.) intercropped with different cover crop species (burr medic (Medicago polymorpha L) and crimson clover (Trifolium incarnatum L.)) grown as living mulches and cultivated on a ridge system on a site characterised by extreme weather events (floods) in the Mediterranean environment. The objectives of the research were to: (i) investigate the impact of the combination of agro-ecological techniques (cover crops and organic fertilisation) on cash crops yield, biomass production and selected physical properties of the soil; (ii) evaluate the sustainability of the systems by using both energy inputs/outputs analysis and assessment of greenhouse gas emissions (GHG). Six treatment combinations were compared: intercropping with burr medic throughout the crop rotation, with and without organic fertilisers; growing crimson clover as a living mulch in the winter crop within the crop rotation, with and without organic fertilisers; cropping system without cover crops, with and without organic fertilisers. The findings highlighted that the introduction of cover crops in the rotation should be recommended since it resulted in higher crop production levels without negative impacts on soil physical properties, as well as in the best energy use efficiency and carbon efficiency in the system. The results of the soil physical quality assessment indicated that the agro-ecological practices had no significant effects on the soil properties. Therefore, in the Mediterranean conditions, the proposed agro-ecological approaches can be crucial to achieving sustainable organic agro-ecosystems. [ABSTRACT FROM AUTHOR]

The effects of the concentration of total suspended solids from municipal wastewater on the water infiltration process in a clayey soil were investigated as well as the suitability of infiltration models with different numbers of parameters. The experiment consisted of columns of soil of 20 cm long in which supply water and synthetic municipal wastewater with different concentrations of solids were applied. The soil was characterized with respect to particle size, porosity, soil and particle density, clay water-dispersed clay, and infiltration capacity. The accuracy of the Kostiakov, Kostiakov-Lewis, Horton, Phillip, Green-Ampt, and Swartzendruber infiltration models was assessed by using the statistical criteria: mean error (MAE), mean squared error (RMSE), determination coefficient (R2), index of agreement (d), and Akaike information corrected criterion (AICc). The results indicate that the application of wastewater rich in suspended solids reduces the macroporosity of the soil, due to the clogging of the pores, causing a reduction in the hydraulic conductivity of the saturated soil and the cumulative infiltration. Based upon the AICc, the Kostiakov-Lewis models proved to be the most appropriate, except for the treatment with the highest concentration of solids, in which the Swartzendruber model presented the lowest AICc. In general, the other statistical criteria corroborate this conclusion. [ABSTRACT FROM AUTHOR]

Tillage intensity and successive harvesting before sugarcane replanting are practices that may result in the formation of compacted layers. Compaction alters soil structure and influence soil water retention, soil aeration and soil strength. Thus, this study was designed to assess the soil physical indicators associated with water, air and soil strength functions of a sugarcane field subjected to six successive mechanised harvests. The experiment was performed in 2018 in sugarcane fields from the Carpina sugarcane experimental station, Pernambuco, Brazil. In situ penetrometer measurements were made, and soil cores were sampled at depths of 0–0.20, 0.20–0.40, 0.40–0.60, 0.60–0.80 and 0.80–1.00 m for determination of soil penetration resistance, field capacity and soil bulk density. We calculated the degree of compaction, water capacity and air capacity of cultivated soil and compared the results with indicators of a native forest soil adjacent to the experimental area. The results showed that successive sugarcane cultivation declined the soil physical quality for plant development. Measurements showed that the deterioration of soil physical quality occurs mainly up to 0.40 m depth, which is a layer that undergoes tillage intervention and is susceptible to the formation of plough pan below the tillage depth. An increase in soil compaction, strength and loss of aeration capacity were the main sources of the decline in the soil physical quality. These soil physical factors are known to cause severe restrictions to root development and plant performance. The alleviation of soil compaction with subsequent monitoring of the impact of field traffic (e.g. through machinery and soil conduction controls) could help prevent the decline of soil physical quality in sugarcane areas. [ABSTRACT FROM AUTHOR]

Electrolytes have been verified as a vital internal factor controlling soil aggregate stability (SAS). Several reports have focused on whether potassium promotes or demotes SAS and have shown contradictory results in different soils and clay mineralogy. Only a few studies have investigated such an effect on a soil-plant system, even though this information is critical for soil management practices to maintain soil structural stability. This research studied the dynamics of SAS as influenced by potassium in a soil-plant system. Corn as a test plant was grown on Haplic Acrisols (Typic Paleustults) in a greenhouse. The potassium adsorption ratio (PAR), cation ratio of structural stability (CROSS), and SAS were recorded on the day before planting (day 0), the day of planting (day 1), days 10, 20, 30, and the day of harvesting (day 55) at the tasseling stage. The corn growth, biomass, and potassium uptake were also examined. The relationship between soil and plant parameters was statistically tested. The results showed the existence of SAS dynamics caused by soil potassium change, with agreement among the responses for PAR, CROSS, and plant uptake. Within 24 h of soil treatment with potassium, the SAS move rapidly from 74% to 96%. It remained steady at 96–97% when the corn was in the vegetative stage and then fell significantly (α = 0.05) to 88% when the corn was in the tasseling stage, where the potassium uptake was maximized. The results implied that SAS is a sensitive index of soil physical quality associated with potassium, especially for tropical kaolinitic soils. [ABSTRACT FROM AUTHOR]

• Soil physical properties were investigated in response to grazing. • Grazing caused a noticeable increase in the soil penetration resistance. • Soil physical quality was reduced due to compaction. • Decrease in physical quality can be noticed after two grazing periods. Soils in areas under grazing undergo physical changes, of greater or lower intensity, by the action of animal trampling. Thus, the objective of this study was to evaluate the spatial dependence of the physical attributes and associated soil functionalities under trampling by cattle on rotational grazing in the region of Pernambuco, Brazil. The research was conducted at the Experimental Farm of the Federal Rural University of Pernambuco, Agreste region of the State of Pernambuco, Brazil. In the field, a paddock of 0.25 ha was demarcated and four crossbred dairy cattle (Holstein-Zebu) with an average weight of 450 kg were used, managed in a rotational grazing system that included 7 days of occupation and 28 days for pasture rest. Undisturbed soil samples were collected before the first passage of the animals in the paddock and at the end of each pasture rest period, i.e., at 0, 35, 70 and 105 days of study, in a 6 × 14 m mesh, which totalled 32 sampling points. At each point, bulk density (BD), total porosity (TP), water content (W), soil penetration resistance (PR) at depths of 0.00–0.10 and 0.10–0.20 m and the soil saturated hydraulic conductivity (K 0) were determined. The data obtained were submitted to descriptive, geostatistical and multivariate statistical analysis (canonical discriminant analysis). After a period of 105 days of grazing, at both evaluated depths, an increase in the average values of PR and BD and a reduction in the values of TP, K 0 and W was observed. Normal distribution was observed in all variables studied. The physical attributes of the soil presented a coefficient of variation between low and medium and strong spatial dependence in both grazing periods. The canonical multivariate analysis indicated a reduction in the soil physical quality, especially after the animals' second passage in the paddock. [ABSTRACT FROM AUTHOR]

Use of the curve gradient of the Soil Water Retention Curves (SWRC) in the inflection point (S Index) is one of the main indices for assessing the soil quality for management objectives in agricultural and garden lands. In this study Anneling Simulated – artificial neural network (SA-ANN) hybrid algorithm was used to identify the most effective soil features on estimation of S Index in Jiroft plain. For this purpose, 350 disturbed and undisturbed soils samples were collected from the agricultural and garden lands and then some physical and chemical soil properties including Sand, Silt, Clay percent, Electrical Conductivity at saturation, Bulk Density, total porosity, Organic Mater, and percent of equal Calcium Carbonate were measured. Moreover, the soil moisture amount was determined within the suctions of 0, 10, 30, 50, 100, 300, 500, 1000, 1500 KP using pressure plate. Then, the determinant features influencing the modeling of S Index were derived using SA-ANN hybrid algorithm. The results indicated that modeling precision increased by reducing the input variables. According to the sensitivity analysis, the Bulk Density had the highest sensitivity coefficient (sensitivity coefficient=0.5) and was identified as the determinant feature for modeling the S Index. So, since increasing the number of features does not necessarily increase the accuracy of modeling, reducing input features is due to cost reduction and time-consuming research.

ABSTRACT Integration of forage grasses with grain crops, such as maize, allows maintaining soil cover. The objective of this study was to evaluate the tensile strength, friability, and stability of soil aggregates in the maize and forage grass intercropping under no-tillage system. The study used a completely randomized block design with seven treatments and three replications. Undisturbed soil samples were collected in two seasons (2015 and 2016) at 0–0.10 m and 0.10–0.20 m soil depth. The following properties of soil aggregates were measured: tensile strength (TS), friability (F), gravimetric moisture (GM), weighted mean diameter (WMD), geometric mean diameter (GMD), and aggregate stability index (ASI). The intercropping of maize with Urochloa ruziziensis presented higher WMD and GMD at 0.10–0.20 m soil depth. Moreover, TS at 0.10–0.20 m soil depth was lower in maize without intercropping. The effects of the intercropping system on soil aggregates were better detected by aggregate stability than by TS or F. The intercropping of maize and U. ruziziensis improved soil aggregation to a higher extent than those systems with other forage grasses.

Various efforts have been carried out by the Indonesian Government to increase rice production, especially the construction of new paddy fields and paddy intensification through increasing intensity or planting frequency in a year. Overcoming the problems of chemical and physical soil properties that have caused low soil productivity is an effort that can be made to increase rice production. This study was aimed to assess the quality of soil physical and chemical properties of the paddy fields in order to find out the cause of the low productivity of paddy soils. The study was conducted in 24 locations in Banten and West Java Provinces. In general, based on their soil quality indexes, the study found that the soil physical quality of paddy soil is good and better than soil chemical quality. There was no significantly different between soil physical quality of paddy soil in Banten and West Java Provinces. However, the soil chemical quality of paddy soils in West Java Province is significantly better than in Banten Province. There were no limiting factors for soil physical properties, while in some locations, some limiting factors of soil chemicals properties were found. Dominant limiting factors for plant growth were the low available P, organic matter and total organic N contents, low pH, and low exchangeable K, and high level of Fe.

In agricultural crops, the use of swine and poultry waste as organic fertilizers results in gains in the productivity and reduction of production costs, but it may also change the physical properties and mechanical behavior of the soil, either increasing or reducing its quality. This study aimed to investigate the influence of applying increasing doses of liquid swine manure (160 m³ ha-1 year-1, 320 m³ ha-1 year-1 and 480 m³ ha-1 year-1) and poultry litter (6 Mg ha-1 year-1, 12 Mg ha-1 year-1 and 18 Mg ha-1 year-1), along four years, on the physical-mechanical properties and organic carbon content of a very clayey Rhodic Eutrudox. The application of liquid swine manure and poultry litter increased the surface soil organic carbon contents. The soil density decreased, whereas the total porosity and macroporosity increased, with the addition of liquid swine manure and poultry litter. There were no significant changes in the soil susceptibility to compaction.

The soil quality is defined as the ability of soil to function as an essential part of the human habitat. In this study, the effects of land use change (conversion of forest lands into agricultural lands) on the soil physical quality were studied in the Gilan-e-Gharb region. For this study, soil samples were collected from surface and subsurface layers of both land uses, and the peak and shoulder slope positions, in Miandar and Vidjanan catchments. Soil physical properties such as soil texture and particle size distribution, soil hydraulic conductivity, bulk density, mean weight diameter of aggregates, water holding capacity, and the soil organic carbon content were measured. The results showed that land use change of the forest to agricultural lands resulted in a sharp decline in the soil organic matter (52%) and an increase in silt and sand percentage and soil bulk density. Also, deforestation decreased the mean weight diameter of aggregates (from 0.39 to 0.14 mm in Miandar) and clay percent. It caused a reduction in the total porosity followed by a decrease of soil water holding capacity, and a decrease in the saturated hydraulic conductivity (from 10.34 to 1.86 cm/h), as well. In general, the results proved that the land use change from forest to agriculture severely decreased soil physical quality and its productivity.

Abstract: The objective of this work was to evaluate the influence of ryegrass (Lolium multiflorum) managements on the physical properties of a Haplohumox, and on the yields of corn and of ryegrass cultivated in succession to corn. The experiment was carried out in a randomized complete block design, with three treatments and three replicates, in which treatments were the different managements of ryegrass under no-tillage for silage, soil cover, and grazing. After nine years of management, samples were collected at 0.00-0.05, 0.05-0.10, 0.10-0.20, and 0.20-0.30-m soil depths, to determine the following soil properties: texture, total organic carbon, soil bulk density, macroporosity, microporosity, total porosity, and resistance to root penetration. The index of structural stability was estimated from texture and total organic carbon data. Maximum soil bulk density and permanent wilting point were also estimated from pedotransfer functions. Corn and ryegrass dry matter yields were determined from plants harvested inside the plot area. Total organic carbon content increased as depth increased. The ryegrass managements in no-tillage system, in succession to corn, does not influence the soil physical properties of a Haplohumox, and maintains high corn and ryegrass yields.

Abstract: The objective of this work was to evaluate the tensile strength, friability, aggregation, and the physical fractions of soil organic matter of a Rhodic Hapludox cultivated with sugarcane (Saccharum officinarum). The treatments consisted of one, three, and five years of cultivation of sugarcane, in the state of Rio Grande do Sul, Brazil. As a reference, a native forest adjacent to the cultivation area, with soil and relief characteristics similar to those of the cultivation areas, was used. Deformed samples were collected at 0.00-0.05, 0.05-0.10, and 0.10-0.20-m soil depths, for the determination of the soil physical attributes and for the physical fractionation of particle-size and density of the organic matter. The physical attribute evaluations were able to detect changes in the structural quality of the Oxisol, which resulted from the sugarcane cultivation. In comparison with the native forest, the stability and tensile strength of the aggregates decreased with the time of sugarcane cultivation. Tensile strength increased with soil depth, proportionally to the reduction of total soil organic carbon content. Soil preparation and straw burning reduce the input of fresh organic matter into the soil and accelerate the decomposition of the labile organic matter compartment, with negative consequences to soil physical properties over time.

Few studies deal with the impacts of long-term fertilization on soil mechanical physical properties. A long-term fertilization experiment initiated in 1996 was performed in the paddy soil (Endoaqualf) of China. The treatments included: control (CK), chemical fertilizers (NPK), rice straw (RS), pig manure (PM), rice straw plus chemical fertilizers (RS+NPK) and pig manure plus chemical fertilizers (PM+NPK). The PM, PM+NPK, RS and RS+NPK treatments significantly (p< 0.05) increased the percentage of > 2 mm macroaggregate compared with the CK treatment, while application of chemical fertilizers alone had no significant effect on the formation of macroaggregate. Application of organic fertilizers significantly increased soil liquid limit (LL), plastic index (PI), and deformation relative to CK, while decreased soil plastic limit (PL), COLE, TS and cohesion. In contrast, the application of chemical fertilizers significantly increased the PL, COLE, TS, cohesion and internal friction angle, while decreased the LL and PI compared with the PM treatment. The application of different types of organic fertilizers could also affect the soil mechanical properties differently. The study suggested that soil management practices in paddy soil should preferably include integrated use of chemical fertilizer and manure or straw to maintain better physical environment of the soil. [ABSTRACT FROM AUTHOR]

Land use change (LUC) alters soil structure and, consequently, the functions and services provided by these soils. Conversion from extensive pasture to sugarcane is one of the largest land transitions in Brazil as a result of the growth of the domestic and global demands of bioenergy. However, the impacts of sugarcane expansion on the soil structure under extensive pasture remains unclear, especially when considering changes at the microscale. We investigated whether LUC for sugarcane cultivation impacted soil microstructure quality. Undisturbed soil samples were taken from two soil layers (0–10 and 10–20 cm) under three contrasting land uses (native vegetation—NV, pasture—PA and sugarcane—SC) in three different locations in the central‐southern Brazil. Oriented thin sections (30 μm) were used for micromorphological analysis. The total area of pores decreased following the LUC in the following order: NV > PA > SC in both soil layers. The area of large complex packing pores (>0.01 mm²) also decreased with the LUC sequence: NV>PA>SC. Qualitative and semi‐quantitative micromorphological analysis confirmed porosity reduction was driven by the decrease in complex packing pores and that biological features decreased in the same LUC sequence as the quantitative parameters. Therefore, LUC for sugarcane expansion reduced microscale soil porosity, irrespectively of soil type and site‐specific conditions, indicating that the adoption of more sustainable management practices is imperative to preserve soil structure and sustain soil functions in Brazilian sugarcane fields. [ABSTRACT FROM AUTHOR]

Historically, due to a lack of measured soil physical data, the quality of Irish soils was relatively unknown. Herein, we investigate the physical quality of the national representative profiles of Co. Waterford. To do this, the soil physical quality (SPQ) S-Index, as described by Dexter (2004a,b,c) using the S-theory (which seeks the inflection point of a soil water retention curve [SWRC]), is used. This can be determined using simple (S-Indirect) or complex (S-Direct) soil physical data streams. Both are achievable using existing data for the County Waterford profiles, but until now, the suitability of this S-Index for Irish soils has never been tested. Indirect-S provides a generic characterisation of SPQ for a particular soil horizon, using simplified and modelled information (e.g. texture and SWRC derived from pedo-transfer functions), whereas Direct-S provides more complex site-specific information (e.g. texture and SWRC measured in the laboratory), which relates to properties measured for that exact soil horizon. Results showed a significant correlation between S-Indirect (Si) and S-Direct (Sd). Therefore, the S-Index can be used in Irish soils and presents opportunities for the use of Si at the national scale. Outlier horizons contained >6% organic carbon (OC) and bulk density (Bd) values

Aggregate stability (AS) is a key factor controlling soil erosion risk and compaction. The main objective of this work was to explore the impact of soil physical and chemical properties on AS in Mollisols, using Le Bissonnais method. To achieve this goal, 16 soils were selected to represent a range in soil physicochemical properties. Sand, Mg and organic carbon contents explained a high proportion of variability in AS. Crop rotations that increased soil C would aid in preventing losses in AS, although a decreasing response was observed for two of the evaluated mechanisms of AS. [ABSTRACT FROM AUTHOR]

Purpose: Many studies evaluate the effect of successive applications of chicken manure on soil attributes. In Brazil, the commercialization of this waste is common, implying on its sporadic use instead of many applications at the same area. The short-term effects of a single application of chicken manure and the role of its composting on soil structural stability are not fully understood. This study investigated application of in natura (uncomposted) and composted chicken manure on the structural stability of a Rhodic Ferralsol after a short period following single application. Methods: The experiment was performed in a Rhodic Ferralsol in Londrina, Paraná. Brazil. We applied in natura and composted chicken manure at doses of 4.5, 9.0, 13.5, and 18.0 Mg ha−1 plus a control without application. Soil samples were collected after 185 days at the 0.0–20.0 cm layer for laboratorial analysis. Results: The composting of chicken manure did not affect soil structural stability. Chicken manure did not alter water-dispersible clay (x ¯ = 21.7 %) , but increased the mean weight diameter of water-stable aggregates (MWD = 5.43 + 0.068 × dose) through the agglomeration of aggregates with 0.5–4 mm into 8–19 mm. Conclusion: Even after a short period of 185 days, the application of chicken manure increases the structural stability of Rhodic Ferralsols and its composting, in the way performed by many farmers, is not associated with the improvement of soil structural stability in short-term. However, other advantages arise from the composting of the manure and need to be considered prior its use. [ABSTRACT FROM AUTHOR]

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For cassava farming, conventional soil preparation is traditionally used. However, in recent years, some producers have been showing interest in adopting no-tillage system. We evaluated the cassava yield in conventional tillage or no-tillage systems with marandu grass straw, as well as the straw decomposition and the physical and chemical soil attributes. A completely randomized design with five treatments and four replicates was used. The treatments were no-tillage (NT 0% - no-grazing pasture; NT 25%, NT 50%, NT 75% - grazing intensities to obtain an intake of 25%, 50% and 75% of forage mass, by animals) and conventional tillage (CT 50% - grazing intensity to obtain an intake of 50% of forage mass, before tillage). The soil tillage did not influence fresh and dry weight of cassava roots, with averages of 31.84 and 10.88 Mg ha-1. After 448 days of cassava planting, straw decomposition did not differ between treatments, with an average value of 53%. The half-life time of straw was 221, 218, 263 and 321 days to treatments NT 0%, NT 25%, NT 50%, NT 75%, respectively. We observed that soil physical quality was improved in no-tillage treatment NT 50%, when compared to CT 50%. The residual straw of Marandu grass did not influence the cassava yield in no-tillage, when compared to conventional tillage. Part of the forage available in the pasture can be used for animal feed, before cassava planting. [ABSTRACT FROM AUTHOR]

Soil degradation causes low land productivity. To tackle soil degradation, soil management practices have been implemented in the study area. However, less attention has been given to the management of physical soil quality. Hence, the objective of this study is to evaluate soil physical properties of long-used cultivated lands. Twelve Land Mapping Units (LMUs) were identified by overlaying slope and soil maps. Twelve composite and 12 undisturbed soil samples were collected from the 12 LMUs, and soil physical properties analyzed. Soil bulk density varied from 1.22 g cm−3 in LMU3 to 1.68 g cm−3 in LMU4. Available water capacity ranged from 0.09 in LMU4 to 0.17 in LMU3. Stability index (SI) values ranged from a low of 3.58 at LUM10 to 62.5 at LMU3; stability quotient (SQ) values ranged from 79.4 at LMU9 to 2782.8 at LUM3. Highest and lowest soil crust index values were found to be 1.53 in LMU5 and 0.29 in LMU9. This study indicated that poor soil management practice in the study area has caused soil physical degradation. Therefore, this study provides insight into improved land management of long-used cultivated land in the semi-arid region of the study area and other similar environments. [ABSTRACT FROM AUTHOR]

Highlights • Critical moisture for crop in each phenological stage was added as the lowest limit of LLWR. • Water uptake in soil profile improved with deep tillage, intercropping and additional gypsum. • Soil physico-chemical conditioning was important to maintain plant water status. • Unlike plants aerial growth, average yield of first years are the same among management systems. • Intercropping with Brachiaria reduces soil moisture but not lead water stress to Coffee plants. Abstract Water determines the success of coffee farming, since it influences the phenology of the plant and, consequently, its productivity, product quality and commercial viability. The Least Limiting Water Range (LLWR) associated with the monitoring of soil water content (θ) distinguishes management systems as to their effectiveness in supplying water to plants. The need for developing better management systems –in Brazilian rainfed farming– that promote water uptake by coffee plant radicular systems at lower soil depths where water is more available, inspired this study. This work had as an objective to evaluate the availability of water in soil through LLWR limits in association with leaf water potential, as well as growth and yield of coffee plants, in the Cerrado region of Southeastern Brazil over 4 years. The management systems evaluated were: CV-0 (conventional management with coffee interrow maintained with bare soil); G-28 (conservation management, with maintenance of Brachiaria in interrow, ridging and additional application of 28 Mg ha−1 gypsum applied in the rows) and G-7 (same as G-28, except for an additional application of 7 Mg ha−1 of gypsum). θ was monitored every 15 days. Critical moisture for coffee crop in each phenological stage was added as the lowest limit of LLWR. In all evaluated management systems, θ was below the critical moisture as measured at the soil depths of 0.20 m and 0.60 m. At 1.00 m depth in the CV-0 management system, the greatest value of θ was found, which caused the assumption of smaller water uptake. Regardless of the management adopted, the leaf water potential reached -1.16 MPa in August 2010, but that did not cause water stress high enough to reduce productivity. At 0.60 m depth, the lowest value for θ between rows was observed for the G-28 management system. Plants showed a more accentuated initial growth in the CV-0 management system. Each management system showed distinct behavior regarding productivity of the evaluated crops: in 2011, CV-0 had the highest productivity, but, in 2012, productivity was greater for G-7 and G-28. [ABSTRACT FROM AUTHOR]

Abstract Hard-setting soils become hard and compact during drying, and are therefore difficult or impossible to cultivate unless they are re-wetted. This study was done to quantify the hard-setting behavior on nine soils with a wide range of texture (from sandy loam to silty clay). Repacked soil cores were prepared with least disturbance of soil aggregates (05‒4 mm). Water retention curves of the soils were measured in the matric suction range 10–15,000 hPa in different bulk densities (1.20–1.70 Mg m−3). Single-porosity van Genuchten-Mualem and dual-porosity Dexter models were fitted to the water retention data. Dexter's indices of soil physical quality (S) and hard-setting (H Dexter) were calculated using the van Genuchten-Mualem parameters. Soil physical quality indices S 1 and S 2 (slopes of water retention curve at first and second inflection points, related to matrix and structural pore spaces, respectively) and new hard-setting indices (H 1 and H 2 related to matrix and structural pore spaces, respectively) were also calculated from the parameters of dual-porosity model. Tensile strength (Y) of the soil samples prepared at different bulk densities was also measured from near-saturation to oven-dry. Slopes of relationships between Y and water content were used as soil strength-based hard-setting indices. A larger slope means that the soil is more susceptible to hard-setting. The H Dexter , H 1 and H 2 increased with an increment in the bulk density, whereas the S , S 1 and S 2 decreased. Significant positive relationships between hard-setting indices (H Dexter and H 1) and calcium carbonate content were observed. Negative linear relations were derived between S , S 1 and S 2 , and bulk density and positive linear relations were obtained between H Dexter , H 1 and H 2 , and bulk density. Soil hard-setting and physical quality indices were significantly correlated with relative bulk density. Positive relationships were observed between soil strength-based hard-setting indices and relative bulk density, and the correlations between these indices and H 2 and S 1 were significantly positive and negative, respectively. These findings confirmed that the new proposed indices enable prediction of soil hard-setting behavior using only water retention data with no need to measure soil mechanical strength. Highlights • Hard-setting increased (physical quality decreased) with increment in bulk density. • Positive relation between soil hard-setting and calcium carbonate was observed. • Negative relations between hard-setting indices and clay content were obtained. • Structural pores (susceptible to compaction) mainly govern soil physical quality. • Significant correlations between strength-based and calculated hard-setting indices were obtained. [ABSTRACT FROM AUTHOR]

Abstract In subhumid Southeastern USA, rapid decomposition of initially low cotton residue limits the benefits of no-tillage system in regard to the soil quality. Long-term addition of cover crops may compensate the low cotton residue and further improve the soil physical quality under no-tillage system. We examined the long-term (34 yr) effect of two cover crop species, hairy vetch (Vicia villosa), and winter wheat (Triticum aestivum L.), and no cover crop, applied on conventional tillage and no-tillage on soil hydro-physical properties and cotton yield. Research was conducted on a Lexington silt loam in Jackson, TN, during 2015 and 2016. Soil physical properties including bulk density, cone penetration resistance, in-situ soil moisture content, wet aggregate stability, water infiltration and field-saturated hydraulic conductivity, soil water retention characteristics, and dry aggregate size distribution were measured. Bulk density assessed before the annual tillage did not differ significantly between no-tillage and conventional tillage systems. Cone penetration resistance showed a greater horizontal consistency of maximally resistant zones (>2 MPa) under tilled managements, indicating a possible presence of a plow pan immediately below the plowed soil layer. Differences in field soil moisture content among tillage and cover crops were more evident in drier periods of the growing seasons, resulting in 28.6% and 36.4% greater moisture content in vetch cover crop and no-tillage than no cover crop and conventional tillage, respectively. No-tillage and vetch cover crop also increased the wet aggregate stability by 13% at 0–15 cm. Results showed a significant tillage × cover crop interaction in soil hydraulic properties. Our result demonstrates that long-term incorporation of cover crops, particularly vetch with no-tillage, significantly improved the initial infiltration rate, cumulative infiltration, and field-saturated hydraulic conductivity and increased the mean weight diameter of aggregates by promoting the macroaggregation. Improvement in soil physical properties was associated with an increase in cotton lint yield under cover crop and no-tillage management. Highlights • Thirty-four years of no-tillage improved soil physical properties. • Thirty-four years of cover crops also improved soil physical properties. • Long-term combined cover crops and no-till further improved soil quality. • Managements with improved soil quality also increased cotton yield. [ABSTRACT FROM AUTHOR]

The multi-height (low, L = 3 cm; intermediate, M = 100 cm; high, H = 200 cm) Beerkan run methodology was applied on both a minimum tilled (MT) (i.e., up to a depth of 30 cm) and a no-tilled (NT) bare loam soil, and the soil water retention curve was estimated by the BEST-steady algorithm. Three indicators of soil physical quality (SPQ), i.e., macroporosity (Pmac), air capacity (AC) and relative field capacity (RFC) were calculated to assess the impact of water pouring height under alternative soil management practices. Results showed that, compared to the reference low run, M and H runs affected both the estimated soil water retention curves and derived SPQ indicators. Generally, M–H runs significantly reduced the mean values of Pmac and AC and increased RFC for both MT and NT soil management practices. According to the guidelines for assessment of SPQ, the M and H runs: (i) worsened Pmac classification of both MT and NT soils; (ii) did not worsen AC classification, regardless of soil management parameters; (iii) worsened RFC classification of only NT soil, as a consequence of insufficient soil aeration. For both soil management techniques, a strong negative correlation was found between the Pmac and AC values and the gravitational potential energy, Ep, of the water used for the infiltration runs. A positive correlation was detected between RFC and Ep. The relationships were plausible from a soil physics point of view. NT soil has proven to be more resilient than MT. This study contributes toward testing simple and robust methods capable of quantifying soil degradation effects, due to intense rainfall events, under different soil management practices in the Mediterranean environment.

Abstract The objective of this work was to evaluate the effect of irrigation and of the presence of brachiaria (Urochloa decumbens) between coffee (Coffea arabica) rows on coffee yield and on chemical and hydrophysical attributes of a Typic Haplustox. The study was conducted in the Cerrado region in Planaltina, Brasília, DF, Brazil, in a randomized complete block design, arranged in split-split plots, with four replicates. Water regimes (irrigated or rainfed) were assigned to the main plots, inter-row management systems to the subplots, and soil layers to the sub-subplots. The following soil attributes were determined: total organic carbon, total nitrogen, C/N ratio, carbon and nitrogen stocks, bulk density, aggregate stability, total porosity, macroporosity, low-retention microporosity, remaining microporosity, criptoporosity, and total and readily-available water, besides coffee yield. Irrigation of coffee plants, associated with brachiaria intercropped as a cover crop, increased coffee yield and favored chemical and hydrophysical soil attributes, improving soil structure and its ability to store water. Irrigation favors organic carbon stocks in the upper soil layers, whereas brachiaria favors soil physical attributes related to water availability to coffee.