Norton pp. 1-9
Erosion models are needed in order to understand soil erosion mechanisms and resulting sediment transport and to determine the best soil conservation practices. Models based on erosion processes are driven by input data. We measured erodibility in rill and interrill areas for three Australian soils with high clay content and found that they were substantially different from the estimated values using proposed equations for the WEPP model. Use of the model outside its US database requires calibration with locally obtained data, which must be obtained experimentally in the field.
Modelling soil water movement has increased the demand for accurate measurement of soil hydraulic properties. Values of saturated hydraulic conductivity (K) obtained by using different hydraulic heads for artificially packed and undisturbed soil cores indicated a significant deviation from the conventional criterion for Darcy’s law that flux remains linear with hydraulic gradient. The study emphasis on defining the hydraulic head to be used for measuring K for studying water movement in soils to facilitate efficient utilization of water resources in agriculture.
Van Loo ,
De Neve pp. 14-22
Spatial organisation of the soil pore network may strongly influence soil microbial processes including C mineralisation. A direct correlation analysis was made between data on soil pore structure derived from X-ray computed tomography and C mineralisation quantified in an incubation study. The analysis revealed the positive role of larger pores (>150 µm pore neck diameter) for soil C mineralisation, presumably indirectly through their positive effect on aeration of smaller surrounding pores in which C mineralisation may actually take place. X-Ray CT visualisation of both water- and air-filled pore spaces will open up new possibilities to study the interplay of soil pore space, water distribution, and soil organic matter location on soil organic matter decomposition.
Behroozinezhad pp. 23-33
During past decades soil physician have eagerly looked for easy and fast methods to determine capillary conductivity K(θ) at various soil moisture contents. Theoretically, both bulk electrical conductivity (σb) and K(θ) should be closely related to water filled porosity. We showed that K(θ) may be determined reliably in undisturbed core samples at wide range of soil moisture content particularly in medium- and coarse-textured soils just by simple and rapid measurements of σb and particle size distribution.
McNeill pp. 34-40
The cation ratio of soil structural stability (CROSS) has been shown to be a good index of soil structural changes in salt-affected soils. However, additional factors such as clay mineralogy, organic matter and pH influence the effect of CROSS. We have shown that the distinctive way in which these components are associated, and the changes in soil chemistry affecting the net charge, are related to the effect of CROSS.
Wang pp. 41-49
Soil organic carbon (SOC) plays an important role in maintaining and improving soil fertility and quality, in addition to mitigating climate change. The spatial variation of SOC contents under different land use types was significant (P < 0.05). The mean SOC masses of grassland, forestland and cropland at a depth of 0–40 cm were 5.87, 5.61 and 5.07 kg/m2, respectively. Therefore, the carbon in the soils in the source area of the middle Dan River would increase with conversion from agricultural land to forest or grassland.
Zhou pp. 50-58
The long-term ‘Grain-for-Green’ eco-restoration program was initiated to promote vegetation restoration of low-yielding farmland in the China Loess Plateau region. The effects of land cover on runoff and sediment generation were investigated from a rainfall simulation study and the results showed that runoff and sediment production were significantly reduced in natural grassed hillslope than bare hillslope. The findings in this study have important implications for water-saving agriculture and erosion control in the hilly regions of the Loess Plateau.
Lin pp. 59-67
Impervious surfaces in urban areas hamper the exchange of material and energy between the soil and other environmental compartments, thereby having negative impacts on soil function and the urban environment. We found the sealing surface can reduce soil organic carbon content, as well as soil microbial activity and diversity. Therefore, semi-pervious pavement or other materials allowing exchanges of materials or energy could be considered in urban paved areas to reduce the negative effects of soil sealing.
We studied how addition of Carbon and Nitrogen affects microbial tolerance to salinity. High concentrations of easily available C increase the ability of microbes to tolerate high salinity. In saline soils, irrespective of the C substrate, N addition has no impact, or a negative impact, on microbial activity and growth.