Selected Soil Physical Properties Research Articles

Effect of tillage systems combined with plastic film mulches and fertilizers on soil physical properties in a wheat-agricultural site in southern Iraq

This study researches the influence of the three tillage systems (conventional, economical and mulch tillage) when combined with different soil plastic mulching and fertilizer applications on key selected soil physical properties (SPP) at 0-20 cm soil depth in a wheat agricultural site, during summer (from 1st June to 31st July 2015). SPP include soil porosity (Φ), volumetric soil water content 60 days after irrigation to field capacity (q60), and mean weight diameter of aggregates (MWD). The term mulch tillage refers here to a soil conservation practice where the soil surface is disturbed by tillage whereby crop residues are mixed with the soil and a certain amount of residues remain on the soil surface, while mulching refers to the placement of inorganic material over the top of a soil surface to protect it. Soil treatments included tillage system: conventional tillage using a combination of a mouldboard plough and a disc harrow (MP+DH), economical tillage using a rotary cultivator (RC), and mulch tillage using a chisel plough (MT+CP); soil plastic mulching: transparent mulching (TM), black mulching (BM) of 200 cm wide with 0.05 cm thick, and without mulching (WM); and fertilisers: composed organic fertiliser (CoF), no-composed organic fertiliser (NoF), and chemical fertiliser (ChF). The split–split-plot design under the randomized complete block design (RCBD) was established in 27 treatments with 3 replicated, to map Φ, q60, and MWD based on 81 soil samples from all treatments. Results showed that the different soil treatments have diverse impacts on SPP. MP+DH resulted in the higher q60 (0.22 cm3 cm-3), MWD (0.85 mm), and Φ (56.87%). Our findings showed that MT+CP obtained a higher MWD of 0.98 mm and lower Φ of 49% compared to other tillage systems. Soil mulching had significantly modified SPP, with BM resulting in the highest Φ (55.65%), q60 (0.35 cm3 cm-3), and MWD (1.06 mm). Results indicated no significant differences between fertiliser types on SPP. The CoF had a significant effect on MWD and related soil characteristics studied. These findings can help us to understand the individual and combined effects of the tillage system, mulching, and fertilization application on some soil characteristics in wheat agriculture. A further study with more focus on the influence of tillage depths and mulching types (plastic vs organic mulch for different crops) under a variety of soils and climatic conditions, as well as on soil thermal properties needs further investigation.

Spatial Variability and Mapping of Selected Soil Physical Properties under Continuous Cultivation

Assessments of Soil physical properties and estimation of their associated variability are essential for making site-specific decisions on soil and crop management This study examined the spatial variability of soil hydro-physical properties and variance structure at Sector F1 of the Jibia Irrigation project Katsina State, Nigeria. Grid sampling technique was used to obtain one hundred and forty-four (144) soil samples from 206 ha of land using Google earth. The grids were drawn using Google earth software at intervals of 150 m x 150 m. Surface soil samples (0 - 20 cm) were collected at grid intersection points. The collected soil samples were air-dried and passed through a 2mm sieve, and analyzed using standard laboratory procedures for physical parameters. The ArcGIS software package 10.3 was used to model the variance structure of Sand, Silt, Clay, Bulk density, Particle density, Percent total porosity and Organic Matter (OM). Results obtained revealed that the coefficient of variation (CV) ranged from 5.724% in particle density to 109% in clay. The Semivariogram showed that the range of spatial dependence varied from 0.342m for (Dry mean weight diameter) to 9.3m (Organic matter) for all measured soil properties. High Spatial dependency ratios were observed for Bulk density, Sand, Silt and clay contents. Particle density exhibited moderate spatial dependency (Nugget to sill ratio 0.25 – 0.75%). Wet Mean weight diameter and organic matter content have a weak spatial dependency. The results indicated that sandy textured soils dominated the greater part of the study area with low to moderate organic matter content. The soils being sandy-dominated has a high infiltration rate and low ability to retain moisture and nutrients were observed as the major characteristics of the soil of the study area.

Relating soil physical properties to other soil properties and crop yields

Soil physical properties can be related to other soil properties and crop yields, but their evaluations as soil health indicators relating to extensive soil properties and long-term crop yields need further exploration. We evaluated the long-term (14 and 36 year) effect of cropping systems and N fertilizations on selected soil physical properties and related them to 66 soil physical, chemical, biological, and biochemical properties and mean crop yields across years at two dryland farming sites in the semiarid region of the northern Great Plains, USA. Treatments were rotations of no-tillage and conventional tillage spring wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), pea (Pisum sativum L.), and fallow with or without N fertilization. Soil samples collected in April 2019 were analyzed for physical, chemical, biological, and biochemical properties and mean crop yields were determined. The average slake aggregate (ASA), wet aggregate stability index (WASI), and intact core available water holding capacity (IAWHC) were associated with most soil physical, chemical, biological, and biochemical properties and clay concentration was associated with nutrient concentrations. These parameters were also better related to mean crop yields across years than other soil physical properties. Because of the enhanced relationship with soil properties and crop yields and simple and inexpensive measurement, ASA can be used as a potential soil health indicator in dryland cropping systems in semiarid regions.

Effect of Conservation Tillage on Soil and Water Quality

Soil erosion from cropland has been recognized as a major problem in agricultural production. Conservation tillage is one of many conservation practices developed to reduce soil erosion. Meanwhile, many benefits from conservation tillage system beyond controlling soil loss have been reported. The objective of this work is to briefly review effect of conservation tillage on soil erosion and runoff, soil organic matter, selected soil physical properties, and water quality. Conservation tillage has inconsistent effects on surface runoff and soil loss due to differences in surface roughness and the rate of crop residue left on the soil surface. Increased soil organic carbon (SOC), mainly concentrated near soil surface, has been widely reported in the literature. However, SOC under conservation tillage is labile in topsoil and more recalcitrant in subsoil. Increased SOC leads to improved soil physical properties such as reduced bulk density, increased hydraulic conductivity and infiltration, and improved water retention capacity. Conservation tillage could improve water quality by reducing the total sediment, nitrate, ammonium, and phosphate in the runoff. However, conservation tillage may also facilitate nitrate leaching due to the increase of macropores in soil body.

Soil Compaction Effects on Soil Physical Properties and Soybean (Glycine max.) Yield in Ogbomoso, Southwestern Nigeria

Compaction is one of the major threats to soil sustainability as it can have negative effects on soil physical properties. Therefore, field experiments were conducted at Ladoke Akintola University of Technology Teaching and Research Farm, Ogbomoso, Southwestern Nigeria, in 2015 and 2016 to evaluate the influence of soil compaction on selected soil physical properties, growth, yield and nutrient uptake of soybean (Glycine max.). The experiment was arranged in a randomized complete block design and replicated three times. There were four treatments which consisted of 0 (no pass of tractor wheel), 4, 8, and 14 passes of tractor wheel totaling 16 treatments. Soil physical properties determined were; bulk density, total porosity, macroporosity and saturated hydraulic conductivity. While data recorded on soybean were plant height, stem girth, number of leaves, biomass and grain yield. Data collected were subjected to Analysis of Variance and significant means were compared using Least Significant Difference at 5% level of probability. Although not significant, soil physical quality decreased with increased levels of soil compaction in both years of study. Growth of soybean was significantly reduced by soil compaction with 14 passes producing the shortest plant (91.46, 29.10 cm) compared to the control (103.96, 30.27 cm), respectively, for 2015 and 2016. Grain yield of soybean significantly decreased by 12, 27, and 44% respectively, for 4, 8 and 18 passes of tractor wheel. The study indicates that soil compaction as a result of tractor wheel passes should be minimized on agricultural fields to reduce the adverse effects on soil physical properties, soybean growth and yield.

The Impact of Using Different Doses of Biomass Ash on Some Physical Properties of Podzolic Soil under the Cultivation of Winter Oilseed Rape.

This two-year study was focused on the effect of the application of different biomass ash doses on selected soil physical properties, i.e., soil moisture (SM), bulk density (BD), penetration resistance (PR), and soil stability in water measured by the content of readily dispersible clay (RDC), following control and mineral NPK fertilization in the cultivation of winter oilseed rape (Brassica napus L. var. napus). A one-factor field experiment conducted on podzolic soil (control, NPK, 100, 200, 300, 400, 500 kg K2O·ha−1) showed that the use of biomass combustion ash significantly improved soil moisture at all depths and variants, and especially at a depth of 30–35 cm in the 500 kg·ha−1 variant, i.e., by 2.99% v/v, compared to NPK. In turn, the moisture content in the 30–35 cm layer increased by 3.19% v/v in all variants in both years compared to the control. In 2020 and 2021, bulk density in the 0–5 cm layer treated with a dose of 500 kg·ha−1 exhibited a positive 0.15 and 0.12 Mg·m−3 decrease, respectively, compared to the control. In both years, the BD values in the 30–35 cm layer were reduced by 0.14 and 0.16 Mg·m−3 compared to the control. The PR values decreased in the treatments with doses of 300, 400, and 500 kg·ha−1, especially in 2021. The RDC content was found to decline in both years, i.e., 2020 and 2021, upon the application of even the lowest dose (100 kg·ha−1) in all the analysed layers. The reduction in the RDC content, especially in the 0–5 cm layer, is very important for soil structure stability and to protect the soil environment. This layer is most susceptible to crusting, which results in poor aeration and weak plant emergence during drought and/or periods of excessive moisture. It may also increase surface runoff and intensify soil erosion processes.

Rapid change in soil properties after converting grasslands to crop production

AbstractChanges to land management over the last 150 years, primarily the conversion of perennial grasslands to agricultural production dominated by annual row crops, have greatly changed soil properties and reduced the soil's ability to infiltrate and store water in the soil profile. Direct near‐term response at the time of conversion of an uncultivated remnant prairie to row crops is rare, especially responses that include repeated measurements on the same parcel of land and resampling of soils to a depth of 1 m to document rapid changes in soil organic carbon, nitrogen, and selected soil physical properties related to hydraulic properties. The objective of this research was to measure changes in soil chemical and physical properties after the conversion of perennial grassland to annual row‐crop production. A before‐and‐after approach was used to compare soil properties from a 0.31‐ha field in southwest Minnesota. Cultivation resulted in a negative shift in soil properties. Two years postcultivation, there was an overall reduction in soil organic carbon of 18.6 Mg ha−1 for the 0–1.0 m soil profile. Infiltration rates and soil sorptivity exhibited significant decreases following cultivation. The average decrease in the mean postcultivation infiltration and sorptivity rates were 0.30 mm s−1 and 0.12 mm s−0.5, respectively. Bulk density increased on average by 0.10 Mg m−3 between 0–0.2 m and 0.14 Mg m−3 between 0.2–1.0 m. This work provided a rare glimpse of the vast shift in soil properties, which occurred when the plow ripped through virgin prairie decades ago during the massive expansion of agriculture.

Effects of conservation tillage, phosphorus and variety on selected soil physical properties and cowpea productivity at Minna in Nigeria’s Southern Guinea Savanna

This study was conducted to evaluate the influence of conservation tillage, inorganic phosphorus fertilizer and variety on soil physical properties and cowpea productivity at Minna in the Southern Guinea Savanna of Nigeria. Three tillage practices (zero, reduced and ridged), three phosphorus rates (0, 30 and 60 kg P2O5 ha-1) and three cowpea varieties (IT93K-452-1, IT99K-573-1-1 and IT90K277-2) were factorially combined and laid out in randomized complete block design with three replications. Two crops of cowpea were cultivated sequentially. Soil and crop indices used for the evaluation were soil bulk density, soil organic carbon content, mean weight diameter, soil moisture content, haulm yield and grain yield. Conservation tillage significantly affected the four soil indices while phosphorus rates significantly affected soil organic carbon content, mean weight diameter and soil moisture content. There was varietal effect on soil organic carbon content and soil moisture content. Conservation tillage methods influenced haulm yield significantly but had no significant effect on grain yield. Phosphorus application and variety, on the other hand, significantly affected both haulm and grain yields. Notably, in the early harvest, application of 60 kg P2O5 ha-1 raised haulm yield from 2,489 kg ha-1 (untreated control) to 5,482 kg ha-1 , and grain yield from 614 kg ha-1 (untreated control) to 1,440 kg ha-1 , representing 120% and 135% increments for haulm and grain yields respectively. Farmers are advised to combine either zero or reduced tillage with 60 kg P2O5 ha-1 and IT99K573-1-1 for maximum haulm and grain yields.

Impact of Tillage Systems Equipped with Row Cleaners on Some Selected Soil Physical Properties under Wheat Cropping

Availability of improved tillage and herbicides during the last decades has enhanced the acceptance of conservation tillage. The main constrain to this type of tillage, particularly, zero tillage is high level of crop residue, which reduces seeding quality, soil temperature, etc. Accordingly, a study was initiated by equipping row cleaners with no-till system under wheat cultivation. For this purpose, a field experiment was laid in a split-split plot design with three types of row cleaners, three sub-treatments of travelling speed, and two sub- sub treatments of tillage depth. The results indicated that the soil temperature was highly affected by percent of residue left. Measurement of penetration resistance indicated that hard pan was not a potential limiting factor for the crop root development. The soil water was increased by 8.83%, 15.33% and 12.54% under no-till without row cleaner (M1), no-till with narrow row cleaner (M2) and no-till with wide row cleaner (M3) respectively compared to that under conventional tillage (CT). The percentage of soil loss reduction under M1, M2 and M3 were 53.11%, 59.62% and 50.51% compared to that under CT. The water losses were also reduced by 46.19%, 48.65% and 46.86% under these treatments as compared with CT.

Effects of four organic amendments on soil physiochemical properties and yield of maize (Zea mays) and cowpea (Vigna unguiculata) intercrop in Awka, southeastern Nigeria

Effects of four organic amendments on some soil physical and chemical properties were investigated in Awka, Anambra State in southeastern Nigeria. Over the years, use of synthetic materials in crop production has been a common practice globally. The attendant detrimental effects of the chemicals used in the formulation of these synthetics on animal and human health as well as the environment has made researchers to look out for a better agronomic practice that would not only improve productivity but at the same time sustain a healthy environment. Sole maize, sole cowpea and maize-cowpea intercrop (study area conventional practices) were planted using four soil organic amendments viz: cassava peel (CP), poultry manure (PM), pig waste (PW) and rice husk (RH) at the rate of 20 t ha–1 with the fifth as the control. The treatments were laid out in a 3 × 5 factorial in randomized complete block design and replicated four times. Data on the treatments’ effects on the selected soil physical properties (bulk density, total porosity, soil moisture) and chemical properties (soil pH, available phosphorus, cation exchange capacity (CEC), organic carbon, exchangeable bases and exchangeable acidity) were subjected to factorial analysis of variance using GenStat 2006 Edition. Results indicated that for sole maize, the amendments had significant effect onexchangeable Al3+and Na+; organic carbon, soil pH, available phosphorus and CEC but had no significant effect on Ca2+, H+, Mg2+ and K+ as compared to the control. For sole cowpea, compared to the plots with no amendment (control), all the chemical parameters analyzed differed significantly except organic carbon. Whereas, for maize-cowpea intercrop the treatments had no significant effect on Al3+, Na+, K+ and available phosphorus but differed significantly in exchangeable H+, Ca2+, Mg2+, organic carbon, soil pH, and CEC. There was a decrease in bulk density following the amendment. For sole maize, sole cowpea and maizecowpea intercrop; bulk density, total porosity and moisture content of the amended plots were significantly (p< 0.05) influenced. Organic amendments also significantly improved the growth and yield of maize and cowpea in both the sole and intercrop systems. Generally, poultry manure resulted in higher plant height,number of leaves and leaf area for maize; vine length, number of branches for cowpea as compared with other amendments. Hence, poultry manure was the most effective organic amendment in improving the soil physical and chemical properties as well as the growth and yield of cowpea and maize.
 Key words: Growth, maize-cowpea intercrop, soil physical and chemical properties, soil organic amendments

Variable tillage depth and chemical fertilization impact on irrigated common beans and soil physical properties

Common bean (Phaseolus vulgaris L.) is an important grain crop in the world. Despite suitable soil-climatic conditions and high export potential, irrigated common bean production in Ukraine under performs due to a lack of sustainable management practices. The objective of our study was to evaluate the temporal effects of nitrogeN–Phosphorus (N–P) fertilization rates and tillage depth on the growth, yield, and water-use efficiency of common beans and selected soil physical properties. A 2 × 3 factorial experiment in a completely randomized design with four replications was conducted (2014–2016) at the Agricultural Land Cooperative Farm in the Kherson region of southern Ukraine. The factors were tillage depth (shallow tillage 0–20 cm vs. deep tillage of 0–30 cm) and N–P fertilization (control, N45P45, and N90P90 kg/ha). While tillage depth showed a marginal impact on the growth and yield of common beans, the N–P fertilization, in contrast, exerted significant effects on beans. Grain yields consistently increased by 25–30 % under N45P45 and N90P90 compared to the control; however, the effects of both N45P45 and N90P90 on grain yields were statistically similar. Likewise, the crude protein content was significantly higher by 17 % under N90P90 when compared to the control. As expected, the water-use efficiency (WUE) was significantly higher by 22–27 % under N45P45 and N90P90 when compared with the control; however, the N45P45 and N90P90 effects on WUE were non-significant. A similar effect (25–33 %) of N–P fertilizer was observed on irrigation-use efficiency (IUE) of beans. Soil bulk density (ρb) decreased significantly by 3 % in response to the temporal effects of the 0–30 cm tillage depth than that of the 0–20 cm tillage depth. Likewise, the 0–30 cm tillage depth significantly increased water infiltration by 7 % compared to the 0–20 cm tillage depth. The boundary line technique to evaluate the relationship between N–P fertilization and grain yield indicating that N45P45 produces near maximum economic grain production (95 %) comparable with N90P90, suggesting a savings of 45 kg/ha of both nitrogen (N) and phosphorus (P) fertilizers. While the impact of N–P fertilization was equally effective under both tillage depths, our results recommended that shallow tillage (0–20 cm) can be equally effective for irrigated common bean production to avoid deep tillage (0–30 cm).

The Physical Properties of Soil in Palm Oil Agroforetrial System (Elaeis Guineensis Jacq.) with Aloes (Aquilaria Malacensis Lamk.) and In Palm Oil Monoculture System

Oil palm cultivation is generally carried out in monoculture. This has an impact on decreasing soil fertility, one of which is the physical properties of the soil. One of solutions that can be done to overcome this is the cultivation of oil palm plants with an agroforestry system. The purpose of this research was to compare the physical properties of soil agroforestry on oil palm (Elaeis gueneensis Jacq.) and aloes (Aquilaria malacensis Lamk.) with oil palm in monoculture. This research was conducted in Bukit Kemuning Village, Tapung Hulu District, Kampar Regency for 4 months from November – Februari 2020. Determination research the locations for agroforestry system and monoculture system using purposive sampling method. Soil samples were taken from 4 sampling point: palm circle, leaf frond piles, harvest path and aloes circle which were repeated 6 times on each land. The observation parameters are several soil physical properties (topsoil depth, bulk density, particle density, total pore space, moisture content, water holding capacity, permeability, infiltration, and soil resistance) and soil C-organic. Data from the observations of each parameter were analyzed statistically using the t test. The results showed that the agroforestry system increased C-organic content and improved selected soil physical properties (increase topsoil depth, total pore space, moisture content, water holding capacity, permeability, infiltration and decrease bulk density, particle density and soil resistance).

Effect of conservation agriculture on selected soil physical properties on a haplic cambisol in Alice, Eastern Cape, South Africa

ABSTRACT Conservation agriculture (CA) is believed to contribute to sustainable crop production. However, there are contrasting reports on its short-term effects on soil properties. An experiment was conducted to determine the effects of CA on bulk density (BD), porosity, mean weight diameter (MWD) and penetration resistance (PR) in a semiarid province of South Africa (SA). A split–split–plot design was used; the main treatment factor was allocated to tillage [(Conventional Tillage (CT) and No-Till (NT)], sub-factor of crop rotation [(Maize-Fallow- Maize (MFM), Maize–Oat–Maize (MOM and Maize–Vetch–Maize (MVM))] and sub-sub factor of residue management [(retention (R+); removal (R-) and biochar (B)]. No-tillage, significantly increased soil organic carbon (SOC) compared to CT at the 0–5 cm depth. Tillage, crop rotation and residue management significantly (P < 0.01) affected MWD at the 0–5 cm depth, but not (p > 0.05) on BD, porosity and PR. The lack of significant differences, in both NT and CT plots, between biochar applications and residue retention with respect to BD, MWD across seasons and PR, also show that biochar can potentially be used as a crop residue strategy in a CA system. However, there is a need to further tests and also explore the biochar crop residue retention combinations.

Parameter estimation for multiple post‐wildfire hydrologic models

AbstractPredictions of post‐wildfire flooding and debris flows are needed, typically with short lead times. Measurements of soil‐hydraulic properties necessary for model parameterization are, however, seldom available. This study quantified soil‐hydraulic properties, soil‐water retention, and selected soil physical properties within the perimeter of the 2017 Thomas Fire in California. The Thomas Fire burn scar produced catastrophic debris flows in January 2018, highlighting the need for improved prediction capability. Soil‐hydraulic properties were also indirectly estimated using relations tied to soil‐water retention. These measurements and estimates are examined in the context of parameterizing post‐wildfire hydrologic models. Tension infiltrometer measurements showed significant decreases (p &lt; .05) in field‐saturated hydraulic conductivity (Kfs) and sorptivity (S) in burned areas relative to unburned areas. Wildfire effects on soil water‐retention were dominated by significant decreases in saturated soil‐water content (θS). The van Genuchten parameters α, N, and residual water content did not show significant wildfire effects. The impacts of the wildfire on hydraulic and physical soil properties were greatest in the top 1 cm, emphasizing that measurements of post‐fire soil properties should focus on the near‐surface. Reductions in Kfs, θs, and soil‐water retention in burned soils were attributed to fire‐induced decreases in soil structure evidenced by increases in dry bulk density. Sorptivity reductions in burned soils were attributed to increases in soil‐water repellency. Rapid post‐fire assessments of flash flood and debris flow hazards using physically‐based hydrologic models are facilitated by similarities between Kfs, S, and the Green–Ampt wetting front potential (ψf) with measurements at other southern CA burned sites. We suggest that ratios of burned to unburned Kfs (0.37), S (0.36), and ψf (0.66) could be used to scale unburned values for model parameterization. Alternatively, typical burned values (Kfs = 20 mm hr−1; S = 6 mm hr−0.5; ψf = 1.6 mm) could be used for model parameterization.

Effects of altitudinal gradient and soil depth on selected soil physical properties in Hakim Gara shrub land of Harari Region (Eastern Ethiopia)

The study was conducted to investigate the effects of altitudinal gradient and soil depth on selected soil physical properties in Hakim Gara shrub land of Harari Region of Eastern Ethiopia which is good for oilseed crops groundnut, sunflower, safflower and niger. Soil samples were collected along altitudinal gradients of the land features between 2001 and 2113 m above sea level at 0-20 and 20-40 cm depths. The soil texture was mainly loamy and loamy sand except at a few sites that had silt loamy textural class. Bulk density and particle density at different soil depths exhibited increasing trend between the range from 1.12 to 1.40 g/cm3 and 2.35 to 2.65 g/cm 3, respectively in all sampling sites. While there was decreasing trend in total porosity between 52.12 to 46.17 %. Clay, silt and total porosity were positively correlated with altitude while sand content, bulk density and particle density were negatively correlated with altitude. Sand content, bulk density and particle density also were positively correlated with soil depth from that bulk density was significantly correlated with depth while clay, silt, and total porosity were negatively correlated with soil depth.

Tillage and crop rotation effects on soil carbon and selected soil physical properties in a Haplic Cambisol in Eastern Cape, South Africa

The effects of tillage and crop rotation on the soil carbon, the soil bulk density, the porosity and the soil water content were evaluated during the 6&lt;sup&gt;th&lt;/sup&gt; season of an on-going field trial at the University of Fort Hare Farm (UFH), South Africa. Two tillage systems; conventional tillage (CT) and no-till and crop rotations; maize (Zea mays L.)-fallow-maize (MFM), maize-fallow-soybean (Glycine max L.) (MFS); maize-wheat (Triticum aestivum L.)-maize (MWM) and maize-wheat-soybean (MWS) were evaluated. The field experiment was a 2 × 4 factorial, laid out in a randomised complete design. The crop residues were retained for the no-till plots and incorporated for the CT plots, after each cropping season. No significant effects (P &amp;gt; 0.05) of the tillage and crop rotation on the bulk density were observed. However, the values ranged from 1.32 to1.37 g/cm&lt;sup&gt;3&lt;/sup&gt;. Significant interaction effects of the tillage and crop rotation were observed on the soil porosity (P &amp;lt; 0.01) and the soil water content (P &amp;lt; 0.05). The porosity for the MFM and the MWS, was higher under the CT whereas for the MWM and the MWS, it was higher under the no-till. However, the greatest porosity was under the MWS. Whilst the no-till significantly increased (P &amp;lt; 0.05) the soil water content compared to the CT; the greatest soil water content was observed when the no-till was combined with the MWM rotations. The soil organic carbon (SOC) was increased more (P &amp;lt; 0.05) by the no-till than the CT, and the MFM consistently had the least SOC compared with the rest of the crop rotations, at all the sampling depths (0–5, 5–10 and 10–20 cm). The soil bulk density negatively correlated with the soil porosity and the soil water content, whereas the porosity positively correlated with the soil water content. The study concluded that the crop rotations, the MWM and the MWS under the no-till coupled with the residue retention improved the soil porosity and the soil water content levels the most.

Soil Physical Properties Spatial Variability under Long-Term No-Tillage Corn

Spatial variability of soil physical and hydrological properties within or among agricultural fields could be intrinsically induced due to geologic and pedologic soil forming factors, but some of the variability may be induced by anthropogenic activities such as tillage practices. No-tillage has been gaining ground as a successful conservation practice, and quantifying spatial variability of soil physical properties induced by no-tillage practices is a prerequisite for making appropriate site-specific agricultural management decisions and/or reformulating some management practices. In particular, there remains very limited information on the spatial variability of soil physical properties under long-term no-tillage corn and tropical soil conditions. Therefore, the main objective of this study was to quantify the spatial variability of some selected soil physical properties (soil surface temperature (ST), volumetric water content (θv), soil resistance (TIP), total porosity (θt), bulk density (ρb), organic carbon, and saturated hydraulic conductivity (Ksat)) using classical and geostatistical methods. The study site was a 2 ha field cropped no-tillage sweet corn for nearly 10 years on Oahu, Hawaii. The field was divided into 10 × 10 and 20 × 20 m grids. Soil samples were collected at each grid for measuring ρb, θt, and soil organic carbon (SOC) in the laboratory following standard methods. Saturated hydraulic conductivity, TIP at 10 and 20 cm depths, soil surface temperature, and θv were also measured. Porosity and ρb have low and low to moderate variability, respectively based on the relative ranking of the magnitude of variability drawn from the coefficient of variation. Variability of the SOC, TIP, and Ksat ranges from moderate to high. Based on the best-fitted semivariogram model for finer grid data, 9.8 m and 142.2 m are the cut off beyond which the measured parameter does not show any spatial correlation for SOC, and TIP at 10 cm depth, respectively. Bulk density shows the highest spatial dependence (range = 226.8 m) among all measured properties. Spatial distribution of the soil properties based on kriging shows a high level of variability even though the sampled field is relatively small.

The Influence of Concrete Grinding Residue on Soil Physical Properties and Plant Growth

Diamond grinding is a concrete pavement maintenance technique, and concrete grinding residue (CGR) is the byproduct. Concrete grinding residue deposited along roadsides affects soil chemical properties, but impacts of CGR on soil physical properties and plant growth are rarely studied. In this study, a controlled field experiment was performed to determine the influence of CGR on selected soil physical properties (i.e., bulk density [ρb], saturated hydraulic conductivity [Ks], and water infiltrability [It]) and on plant biomass and plant coverage under four application rates (0, 2.24, 4.48, and 8.96 kg m−2). Field measurements were performed before the CGR applications, and 1, 7, and 12 mo after the CGR applications. No significant CGR effects on soil physical properties were detected. The ρb was relatively stable for all of the treatments, whereas some nonsignificant variations (e.g., 10–30% of mean Ks values and mean It values among four CGR rates) were found. Plant biomass with a CGR rate of 2.24 kg m−2 tended to be 10 to 40% larger than biomass in the control treatment, whereas plant biomass with a CGR rate of 8.96 kg m−2 tended to be ∼10% smaller than the control treatment. Concrete grinding residue had no significant effects on plant coverage, richness, Simpson's diversity, and evenness. Thus, CGR applications up to 8.96 kg m−2 did not significantly affect soil physical properties and plant growth in this controlled field study. This study can serve as a reference for results obtained from roadsides in Minnesota and Iowa that receive CGR applications.Core Ideas Concrete grinding residue (CGR) was evaluated in a controlled field study. CGR applications &lt;8.96 kg m−2 did not significantly affect soil physical properties. CGR applications did not significantly affect plant biomass and community properties. The results provided a reference for diamond grinding in Minnesota and Iowa.

Effects of biochar and phosphorus fertilizer rates on soil physical properties and wheat yield on clay textured soil in middle Nile Delta of Egypt

ABSTRACTBiochar has not been adequately used by farmers to improve the clay textured soil productivities in the world. Therefore, the objective of this study is to investigate the effect of the co-application of biochar with different rates of phosphorus (P) fertilizer on selected soil physical properties and wheat yield on clay textured soil over two growth seasons. Biochar treatments occupied the main plots at a rate of 0.0 and 10 t ha−1, while the sub-plots were devoted to phosphorus rates at rates of 0%, 50%, 100%, and 150% of recommended P fertilizers. Biochar (10 t ha−1) and P at different rates decreased soil bulk density significantly. Meanwhile, it increased aggregate stability, saturated hydraulic conductivity and soil water retention significantly at (p < .05), and it improved the grain yield of wheat. More grain yields in the soil treated with biochar than untreated soil under all P application rates for both years were probably caused partially by more nutrients (N, P, and K) were applied from biochar itself. Grain yield of wheat in the soil-amended biochar and P did not increase significantly between the application at 50%, 100% and 150% P. The results of this study indicate that phosphorus blends with biochar can be used to decrease the bulk density of clay textured soils and to improve crop production in these soils.

Differences in Selected Soil Physical Properties along Three Toposequences in Ohafia, Abia State, Nigeria

Some physical properties of soils were studied along three toposequences in Ohafia area in Abia State, Southeast Nigeria. Transect technique was used to align soil profiles cutting across three major units of summit, midslope and footslope. Soil particle sizes, soil bulk density and soil total porosity were evaluated in each of the topographic units. Coefficient of variation was used to estimate differences among these soil properties along the toposequence. Results indicated low variation (less than 15% coefficient of variation) except in silt content of midslope soils. There were differences in the thickness of horizons with increasing thickness towards footslope in all toposequences. The percentage of sand was highest at the summit and decreases towards the footslope while the values of silt, clay and total porosity were highest at the footslope and decreases towards the summit. Therefore appropriate agronomic practices are recommended for improvement of soil physical properties and at the summit.