Advanced Materials Research Vols. 955-959

Abstract: Characteristic curves of soil moisture, between water content and matrix suction, are the basis for solving the problems of water flow and solute movement in soils. The soil–water characteristics of five layers of depths, 0–12 cm, 12–24 cm, 24–36 cm, 36–48 cm, and 48–60 cm, were measured for a sandy loam soil from Daxing District of Beijing in the northern part of the North China Plain by a pressure membrane apparatus. Curves were fitted using the Van Genuchten model. The fit between measured data and modeled results was excellent. The soil-water characteristic curves showed the typical Sshape of the Van Genuchten model. Matrix suction decreased with an increase in soil moisture; at low suctions, soil moisture content changed to a greater extent with suction, but at high suction, changes in soil moisture content with changes in suction were small. Clay content was proportional to soil water storage capacity and was inversely related to the speed of dehydration.

Abstract: Today to estimate the size of the rainfall on soil erosion comprehensive index is rainfall erosion force.This paper, by using routine weather stations rainfall data, such as the daily rainfall data of rainfall erosion force simplified model is set up, estimate rainfall erosion force, on the soil erosion quantitative forecast and science develop soil and water conservation measures is particularly important.

Abstract: Matrix suction is very important in researching the properties of unsaturated soil. At present, there have been a lot of measurements of matrix suction. Basing on the physical principles of each kind of measurements, this paper divides them into indoor test method and field test method and evaluates them by equipment needed, operation steps, measurement range and matters needing attention.

Abstract: The hydraulic conductivity and correlated factors of undisturbed soil profile (0-20cm、20-40cm、40-60cm) are researched, by taking different forest types (cyclobalanopsis chungii, phyllostachys pubescens, bambusa multiplex var.nana, eucalyptus forests) in typical small watershed of Moufengshan area in Guangzhou of China as study objects. In conclusion, generally, the hydraulic conductivity is decreasing with an increase in profile depth. The variation ranges of hydraulic conductivity are 13.64-4.91, 8.16-2.96, 7.92-3.71, and 10.4-3.63m/d for phyllostachys pubescens, cyclobalanopsis chungii, bambusa multiplex var.nana, and eucalyptus forests respectively. In general, coefficients of permeability are found to be positively related to porosity and root density, and negatively related to dry density, whilst the correlation with root diameter remains uncertain. However, the degrees of correlation with dry density, root density, and root diameter vary substantially for different types of forest land, whereas an overall well correlation with porosity is presented.

Abstract: To discuss the relationship between the effect on soil improvement, soil phosphatase activity and catalase activity by applying biogas slurry, the soil was applied on biogas slurry and pig manure respectively which was from demonstration base of ecological mulberry field at Rongchang, the soil enzymes and nutrients factor were determined and analyzed at different times. The results show that biogas slurry and pig manure can increase the content of soil organic matter, TN, TP, available nitrogen, available phosphorus and available potassium, and improve the activity of soil enzymes. It can significantly improve the activity of acid phosphatase by applying biogas slurry, and have certain effect on alkaline and neutral phosphatase activity; it can effectively improve the soil catalase activity for long-term using.

Abstract: So far, the definitions of slope debris flow are cinders and divergent, even, some scholars equate it with the hill slope debris flow/landslide-induced debris flow and other similar terms. This article summarizes research on the slope debris flow, from the definition and classification of debris flow, study on the classification of slope debris flow , analyzes the formation conditions, properties and characteristics of slope debris flow, at last, use the definition method of attribute and kind, tentatively give the preliminary definition of the slope debris flow .

Abstract: The reclaimed water treated in a Harbin recycled water plant has been taken as a target of research, by using microbial traditional culture method and tablet coated counting method, discussing the influence of the reclaimed water irrigation on soil microbial community structure through the method of short-term indoor simulated soil column irrigation. The results shows that the reclaimed water irrigation can significantly increase the quantity of bacteria and actinomycetes in the surface 0-20 cm layer soil, but it has little affect on 20-40 cm and 40-60 cm layer soil. Microbial community structure and diversity were changed relatively with the irrigation of reclaimed water, which embodied the increase or decrease of dominant and subdominant groups, the disappearance of non-dominant groups sensitive to reclaimed water, the appear or disappear of the other part of the occasional groups.

Abstract: Land roughness is an important parameter of border irrigation in the surface water flow movement, it affects of the water movement process and affects irrigation efficiency, so it’s necessary combined with field surface other parameters to study irrigation field roughness to the irrigation efficiency. Agreement is good between simulated by SIRMOD model and measured values​​ through field trials the measured data of water flow advance and regression process, and indicating with SIRMOD model can simulate border irrigation process. Four kinds of typical field surface roughness of irrigation simulation by SIRMOD model and analysis of the results obtained: land roughness difference of water flow advance and regression process influence significantly, the water flow advance and regression process is better with the small land roughness, and the curve of water flow advance and regression becomes uneven, so irrigation efficiency significant reduction with the field surface roughness increases.

Abstract: Investigation on arsenic (As) accumulation in soil and agricultural products collected from the areas influenced by mine tailings and spoils around Shimen realgar mine, Hunan province, China, was carried out in this study. Water solubility, fractionation and bioavailability of As were determined as well to understand the environmental risk of arsenic releasing from farmland to water system this region. The results indicated that total soil arsenic concentrations varied from 18.9 to 932mg kg^-1 and the highest arsenic concentration exceeding 500mg kg^-1 in soils occurred only within 500m from these arsenic sources, and relatively low content (<40 mg="" kg="" sup="">-1) appeared in the areas far away (>3000m) from the pollution source. Arsenic content in dryland soils decreased with the distance from the mining arsenic ore, tailings and heaps increased. Through sequential extraction procedure (SEP), it was verified that the least arsenic amount occurred for exchangeable fraction with the percentage of 1.1%, then the organically bound fraction (1.6%), and much of the arsenic in the soils was associated with relatively immobile solid phases as residual fraction ranging from 87.5% to 93.3%. The fraction of mobile species, which potentially is harmful to the environment, was found to be higher in the soils with more AsT (total arsenic) content. Through statistical analysis, it was found out that arsenic content in plants was significantly correlated (R²=0.202; P<0.01) with exchangeable As among these five As fractions in soils. Comparing extracted arsenic content in soils using distilled water (H₂O-As), muriatic acid (HCl-As) and ammonium chloride (NH₄Cl-As), better positive relationship occurred significantly (R²=0.226; P<0.01) between NH₄Cl-As and arsenic in plant, indicating the bioavailability was most closely related to NH₄Cl-As rather than total As and other chemical solvents for extracting arsenic from soil.

Abstract: Taking the marsh meadow Deyeuxia angustifolia in San Jiang Plain of Northeast China as test material,a field experiment was carried out with treatments different in nitrogen supply (0,4,8g/m²) to investigate the effects the soil nutrient content.The results showed that difference among layers soil organic matter activity firstly increased and then decreased with increasing of nitrogen addition. Difference among layers soil total nitrogen contains were no significant differences. Soil total nitrogen contains reduced gradually in the 0-10cm layers,in the 10-20cm and 20-30cm layers firstly increased and then decreased. Difference among layers soil ammonium N contains were no significant differences.The 0-10cm and 20-30cm layers soil total NO_-³-N firstly increased and then decreased,10-20cm layers firstly decreased and then increased. Difference among layers soil nitrate N contains obviously different levels (p<0.05). With increasing of nitrogen addition, the 0-10cm and 10-20cm layers soil total phosphoru contains increased gradually,20-30cm layers firstly increased and then decreased. With increasing of nitrogen addition,difference among layers soil total potassium contains were no significant differences.