Soil Physical Properties

Alfalfa (Medicago sativa) is the basic forage resource for milk production in the flat Pampa of the Santa Fe Province of Argentina. However, the presence of microrelief with patches threatens the expansion of the area cultivated with alfalfa. The lower productivity in the patches is attributed to the inferior soil physical quality. The objectives of this study were to quantify indicators of soil physical quality and to establish the soil properties that would affect the alfalfa productivity in patches (PA) and normal areas (NA). Additionally, the macro and micro nutrient contents in both areas were determined. The experiment was carried out on an Aquic Argiudoll. Eighteen sampling sites, nine in NA and nine in PA were established. At each site, undisturbed soil samples (5 × 5 cm cores) were collected to measure soil bulk density (Bd), soil resistance to root penetration (PR), effective stress (σ), the water release curve and the least limiting water range (LLWR). Disturbed soil samp...

A two year field experiment was conducted to investigate the effect of different tillage methods on soil physical properties and crop yield of watermelon. Tillage treatments in the study were moldboard plow + two passes of disk harrow as conventional tillage (CT), two passes of disk harrow as reduced tillage (RT), one pass of disk harrow as minimum tillage (MT) and no-tillage (NT) as direct drilling method. The statistical results of the study indicated that tillage method significantly (P≤0.05) affected crop yield, fruit weight, fruit length, fruit diameter and total soluble solids, but there was no significant differences in other components such as number of plants per hectare, number of fruits per plant, root length and root dry matter. The maximum value of crop yield (21.11 t ha), number of plants per hectare (2730), fruit weight (5.15kg), fruit diameter (20.3cm), root length (42.0cm) and root dry matter (54.1%) was observed in case of CT treatment, while maximum value of numbe...

Changes in grassland management intended to increase productivity can lead to sequestration of substantial amounts of atmospheric C in soils. Management-intensive grazing (MiG) can increase forage production in mesic pastures, but potential impacts on soil C have not been evaluated. We sampled four pastures (to 50 cm depth) in Virginia, USA, under MiG and neighboring pastures that were extensively grazed or

field study was conducted at five villages of Botswana namely, Tsabong, Tshane, Mathathane, Motlhabaneng and Tsetsejwe during the periods of June to August 1999 and June to August 2000. The objective of the study was to assess and compare the soil physicochemical properties of soils at the five villages and to study the effect of cultivation on some soil physical properties. Parameters measured in the field included soil pH, organic carbon (OC), phosphorus (P), cation exchange capacity (CEC), exchangeable cations (Ca, Mg, K and Na), bulk density (BD), soil penetration resistance and infiltration rate. Soil pH, OC, CEC, Mg, Ca and BD were found to be significantly different in the five villages. The non-cultivated soil was found to have significantly lower bulk density, higher infiltration rate and higher penetration resistance compared to the cultivated soil. Soil from the Kgalagadi area was found to be significantly lower in nutrients in comparison with the soil from the Bobirwa ar...

Soil saturated hydraulic conductivity (Ks) is an important soil physical property. Some laboratory and field methods are expensive, time consuming and labour intensive. Indirect methods such as pedo-transfer functions (PTF) are available. Effective porosity or macroporosity (Øe) is approximately equals to porosity minus volumetric soil water content at the field capacity. According to Kozeny–Carman equation, Ks could be evaluated using Øe. Franzmeier estimated the Ks from Øe based on Ahuja et al. He found a strong relationship between Øe and Ks. This paper presents results of a study to characterize the effective porosity in lowland paddy fields and to show the possibility of using the effective porosity (Øe) in estimating the saturated hydraulic conductivity (Ks). Soil in lowland paddy fields forms its horizon as topsoil, hardpan and subsoil. Soil samples were collected randomly within a 2300-ha rice cultivation area where there are five dominant soil series. A total of 408 soil samples were taken from 136 sampling points and at three depths, namely, the topsoil, hardpan and subsoil. Ks values were measured in the laboratory using the falling head method. Soil bulk density and moisture content at −66 kPa were determined. The Øe was then calculated using the difference of the total porosity (Ø) minus the volumetric moisture content at −66 kPa. The Ks values ranged from 5.35×10−4 to 8.77×10−2 m day−1. The Db varied from 0.62 to 1.91 Mg m−3, and the values of the Dp ranged from 1.10 to 2.89 Mg m−3. The Ø ranged from 0.17 to 0.68 m3 m−3. The results of the Øe of the samples in this study were obtained by calculating the difference of the total porosity and volumetric moisture content at field capacity. For clayey soils, field capacity is taken at the suction of −66 kPa. The Øe varied from 0.05 to 0.55 m3 m−3, with the mean value of 0.24 m3 m−3. The regression equation of a power function shows a highly significant regression coefficient, r2 of 0.50 (n=400). This indicates that there is a strong relationship between Ks and Øe for the lowland paddy soils in the study area.

Soil physical properties play an important role in vegetation growth on rangelands as a result of the effects they have on the development of root systems. The goal of this research was to investigate the trampling effect of livestock grazing on soil physical properties (moisture, bulk density, infiltration rate and mechanical resistance) and vegetation cover. The experiment was conducted on three rangeland condition areas - the reference area, a moderately grazed area and a heavily grazed area - in the Lar rangelands (84 km northeast of Tehran) during the grazing season of 2000 and 2001. Soil moisture was reduced from both the reference area and the heavily grazed area throughout the grazing season to depths of 0-15 and 15-30 cm. Soil bulk density increased during the grazing season, being lowest in the reference area and highest in the heavily grazed area. Throughout the grazing season, bulk density was higher in the top soil layer (0-15 cm) compared to underlying layer (15-30 cm)...

Previous information shows that soil degradation is one of the major problems facing current agriculture and forestry at both global and Mediterranean region. Overuse of heavy machinery, intensive cropping, short rotations, intensive grazing, and inappropriate soil management leads to soil organic matter loss, soil compaction, and, therefore, runoff and erosion.
Although each soil presents specific problems, in developing improved land use and practices in agroecosystems, solutions should focus to:
1. reduce tillage that mixes soil horizons, causing loss of soil organic matter and destabilize the soil aggregates;
2. shorten the traffic of tillage machinery and performing the necessary soil management during periods in which the soil takes optimum moisture conditions;
3. maintain the surface of the ground covered with plant residues that diminish the soil temperature and protects the aggregates destruction by rain drops impact;
4. incorporate organic amendments that contribute to maintain an adequate level of soil organic matter content, contributing to stabilize the aggregates stability and the formation of new aggregates;
5. include rotation of species, particularly meadows that include leguminous species for favoring an increment of the soil organic matter.

Since soil management systems infl uence soil physical fertility, it is important to determine the effect of long-term organic fertilizer amendments on soil physical properties such as water-holding capacity. Addition of organic materials of different origins to soil has been one of the most common rehabilitation practices to improve soil physical properties. This is essential to sustaining the productivity of

Laurentide glaciers extended into north central Pennsylvania repeatedly during at least the last 2 million years. Early Pleistocene glaciation extended farther south into central Pennsylvania than any subsequent glaciation, reaching the West Branch Susquehanna River (WBSR) valley. Early Pleistocene ice dammed the northeast-flowing West Branch Susquehanna River at Williamsport, forming Glacial Lake Lesley, a 100-km-long proglacial lake. In this paper,

Site-specific crop management, well-established in some developed countries, is now being considered in developing countries such as Malaysia. The apparent electrical conductivity (ECa) of the soil can be used as an indirect indicator of a number of soil physical properties and even crop yield. Commercially available ECa sensors can efficiently develop the spatially dense data sets desirable in describing within-field spatial soil variability for precision farming. The main purpose of this study was to generate a variability map of soil ECa within a Malaysian paddy field using a VerisEC sensor. The ECa values were then compared with some soil variables within classes after delineation. Measured parameters were mapped using the kriging technique and their correlation with soil ECa was determined. The study showed that the VerisEC can determine soil spatial variability, and can acquire soil ECa information quickly. Spatial variability of shallow and deep ECa showed the same patterns. Estimation of soil properties based on ECa varied from one soil parameter to another and all could be estimated better by deep ECa. Cross-validation results showed that shallow and deep ECa, and also bulk density, gave more accurate estimates compared with other variables.