Effect of Saline Water on Soil Acidity, Alkalinity and Nutrients Leaching in Sandy Loamy Soil in Rwamagana Bella Flower Farm, Rwanda

The necessity to saline and sodic waters is sometimes used for irrigating agricultural activities under certain circumstances, but it is important to note that the use of these waters comes with specific considerations and limitations. One way to decrease undesirable effects of sodic waters on the physical and chemical properties of soils is to apply organic and chemical amendments within the soil. This study aimed to assess the effectiveness of saline water on soil acidity, alkalinity and nutrients leaching in sandy loamy soil at Bella flower farm, in Rwamagana District, Rwanda. The water used was from the Muhazi Lake which is classified as Class I (Saline water quality). Column leaching experiments using treated soils were then conducted under saturated conditions. The soil under experimental was first analyzed for its textural classification, soil properties and is classified as sandy loamy soil. The t-test was taken at 1%, 5% and 10% levels of statistical significance compared to control soil. The results indicated that the application of saline water to soils caused an increase in some soil nutrients like increase of Phosphorus (P), Potassium (K+), Magnesium (Mg2+), Sulphur (S), CN ratio and Sodium (Na+) and decreased soil texture, physical and chemical properties and remained soil nutrients. Consequently, the intensive addition of saline water leachates to soil in PVC pipes led to decreased of soil EC through leaching and a raiser Soluble Sodium Percentage (SSP). The rate of saline water application affected the increase accumulation of SAR and Na% in the top soil layers. The study indicated that saline water is an inefficient amendment for sandy soil with saline water irrigation. The study recommends further studies with similar topic with saline water irrigation, as it accentuated the alkalinity levels.

Study on Relative Soil and Water Conservation Benefits of Ridge Tillage in Different Terrain Conditions in the Black Soil Area of Northeast China

Ridge tillage, which is a very common and important tillage measure in the black soil area of northeast China, has some soil and water conservation bene- fits, but has little attention. It is very important to explore the spatial distribution of the ridge direction of the arable land and its soil and water conservation benefits in different terrain conditions in the black soil area. So Binxian County of Heilongjiang Province was selected as the study area, and 168 field investigation units were ex- tracted by stratified sampling method and investigated. According to equations of slope gradient factor and slope gradient in ridge direction, and based on the soft- ware of Arcmap, SPSS and Excel, the investigation data of soil and water loss in Binxian County were analyzed and counted, The results show that in plain, hilly and mountainous areas, the average ground slope gradients are 1.92°, 6.20° and 8.27° respectively, and the average slope gradients along ridge direction are 1.33°, 4.52°and 6.45° respectively, which account for about 70%, 73% and 78% of the average ground slope gradients in the same terrain condition; the relative quantities of soil erosion in the present ridge tillage condition account for about 55%, 69% and 67% respectively of that in down-slope ridge tillage conditions, so the present ridge tillage has obviously relative soil and water conservation benefits. Based on these results, the reasons of the present ridge tillage status were analyzed, and some reform measures were proposed. The results could not only help to comprehend the spatial distribution and soil and water conservation benefits of ridge tillage in the black soil area of Northeast China, but also provide scientific references for the layout of local soil and water conservation measures.

IMPACTS OF DIFFERENT TYPES OF LAND USE ON PROCESSES OF SOIL AND WATER LOSS OVER PURPLE SOIL SLOPELAND

Based on natural precipitation observations, impacts of different types of land use on processes of soil and water loss over purple soil related slopeland were studied by simulated rainfall experiments. Measurement data revealed that rainstorms and slope length are the essential factors accountable for soil and water loss on purple soil slopeland for intense rill erosion can be caused on 10 meter long purple soil slopes by high intensity rainfall. Under circumanstances of rainstorms, annual hedge plants grown on slopeland of 25 degrees can cause a reduction of runoff by 22 43 percent and that of erosion induced sand content by 94 98 percent. Stone bund horizontal terraces can lead to a runoff reduction by 62 67 percent in comparison with steep slopelands and that of erosion induced sediment by 97.8 99 percent. Soil and water loss can be substantially decreased on steep slopes by hedge plants with a cost of only 10 20 percent that of the stone bund horizontal terraces. Hence it is an effective way to control soil and water loss in terms of slopeland amelioration and utilization in the Three Gorges Reservoir Area.

Soil and water loss in the Lancang River-Mekong River watershed (in Yunnan section, China) and its control measures

According to a lot of hydrological and environmental monitoring data, the condition of soil and water loss in the Lancang River Mekong River watershed (in Yunnan section, China) is described. The occurrence and development of soil and water loss is analyzed. The conclusion is that: (1) generally, the situation of soil and water loss in the Lancang River Mekong River watershed (in Yunnan section, China) is light, however, soil and water loss in some regions is serious, especially in the middle reach area of the river; (2) soil and water loss in the Lancang River Mekong River (in Yunnan section, China) watershed presents developing tendency and it is mainly caused by human beings. In accordance with these results, the control measures for soil and water loss are discussed.

Impact of soil texture and sweetpotato cropping system on soil erosion and nutrient loss in the Three Gorges Reservoir Area of the Changjiang River

This study investigated the impact of soil texture and sweetpotato cropping system on soil erosion and nutrient loss in the drought infield of the Three Gorges Reservoir Area of Changjiang River under field conditions. A factorial experiment was conducted in the study using five soil textures and two cropping systems. The lost soil during the crop season was recovered by a soil-blocking device and the dry weights for the total lost soil and its nutrient components, such as ammonium nitrogen, effective phosphorus, K^＋ and organic matter were analyzed. We found that soil texture significantly affected the dry weights of the total lost soil, effective phosphorus, K^＋, and organic matter, while sweetpotato cropping systems and interaction between soil texture and sweetpotato cropping system affected the dry weights of the total lost soil, the effective phosphorus and organic matter. Among the five soil textures tested, Da and Huang caused significantly less soil erosion and nutrient loss compared with the other three soil textures; intercropping sweetpotato with corn significantly reduced soil erosion and nutrient loss.

Risk Assessment and Change Monitoring of Soil and Water Loss in Ruijin City Based on RS and GIS

The land use information extraction technology for the high-resolution remote sensing images of the Gaofen No. 1 satellite was construc-ted. According to the spectral, band, texture and shape attributes, land use types were divided, and the changing laws of land use types were ana- lyzed. Aftewards,according to the Table of Grading Standard of Sooil Erosion Intensity（SL190-96）,as well as vegetation coverage index NDVI slope, the risks of soil and water loss were assessed. Meanwhile, the level, scale, location and scope of changes in the risks of soil and water loss were monitored by using spatial visualization and spatial statistical techniques. The results showed that the area of areas without soil erosion and moderate soil erosion areas decreased obviously from 2015 to 2017, and the decreases were up to 22.929 3 and 13.626 3 km2 respectively. The ar-ea of mild soil erosion areas increased fast, and the increase reached 31.140 0 km2. The area of extremely strong soil erosion areas increased by 7.267 4 km2. In the city, moderate and strong soil erosion areas reduced, while extremely strong soil erosion patches increased fast, which was mainly related to road construction and construction and development of orchards. The extremely strong soil erosion areas were distributed in the shape of a banded loop, surrounded the suburbs of the city, and shrank towards the center of Ruijin City. The constructed technology to monitor the changes in land use and soil and water loss, as well as the changing laws of land use and soil and water loss provide the theoretical basis and plan-ning basis of soil and water conservation for urban planning departments and soil and water conservation departments.

Substantive Characteristics of Water and Soil Conservation and Ecological Civilization Construction in China

Water and soil conservation is an important part of eco-civilization con-struction. It is a major part of eco-construction and lifeline of social and economy development. Therefore, water and soil conservation is of great significance in maintaining eco-safety. The research concluded status quo and characters of water and soil losses in China and analyzed water and soil conservation and construction of eco-civilization from the perspectives of water and soil conservation and con-struction of eco-civilization.

Chemical and Microbiological Parameters of Paddy Soil Quality as Affected by Different Nutrient and Water Regimes

A field experiment was conducted from 1999 to 2002 to compare and evaluate the effects of nutrient and water regimes on paddy soil quality by investigating soil chemical and microbiological parameters. Four nutrient regimes, a control, chemical fertilizers only (CF), chemical fertilizers with swine manure (SM), and chemical fertilizers with wheat straw (WS), and two soil moisture regimes, continuous waterlogging (CWL) and alternate wetting and drying (AWD), were investigated. With SM and WS total organic carbon and total nitrogen in the paddy soil were significantly higher (P < 0.05) than those with CF. A similar effect for organic amendments was observed in the soil light fraction organic C (LFOC), water-soluble carbohydrates (WSC), and water-soluble organic C (WSOC). CWL, in particular when swine manure was incorporated into the paddy soil, markedly decreased soil redox potential (Eh) and increased total active reducing substances (ARS). Meanwhile, as compared to CF, SM and WS significantly (P < 0.05) increased soil microbial biomass C (MBC) and mineralizable carbon, with differences in AWD being higher than CWL. In addition, SM and WS treatments significantly (P < 0.05) improved rice above-ground biomass and grain yield, with AWD being greater than CWL. Thus, for ecologically sustainable agricultural management of paddy soils, long-term waterlogging should be avoided when organic manure was incorporated into paddy soil.

Effect of Typical Vegetation Restoration Pattern on Soil and Water Conservation in Yuanmou Dry-hot Valley of Yunnan Province

In Yuanmou dry-hot valley of Yunnan Province,three typical vegetation restoration patterns including production forest transformed from sloping fields to terracing,ecological afforestation within the gully and ecological aforestation in gully head and slope were selected to compare their effects on soil and water conservation.Soil and water loss,soil infiltration rate and the soil moisture dynamics of soil profile with the depth of 0-100 cm of these three patterns and their controls were observed by established standard observation plots in rainy season.The results showed that the soil and water loss of ecological afforestation and production forest terrace reduced by over 30% and 60% compared with their controls（without growth of any vegetation）respectively,showing significant control effect on the soil and water loss.Vegetation restoration also apparently increased the infiltration rate of soil（increased by 100%-200%）.In rainy season,the soil moisture content of ecological afforestation and production forest terrace increased by over 30% and 100% compared with their controls.This indicated that vegetation restoration will not lead to soil aridity during the rainy season;vegetation restoration not only reduced the loss of surface water and soil fine particles,but also enhanced the infiltration of precipitation.These two effects made the soil moisture content increase throughout the profile.

Spatiotemporal features of soil and water loss in Three Gorges Reservoir Area of Chongqing

Soil and water loss has been the most serious eco-environmental problem in the Three Gorges Reservoir Area of Chongqing.In this paper the authors studied the spatiotemporal features of soil and water loss from 1999 to 2004 based on RS and GIS techniques.The results showed that:(1) The soil and water loss area decreased from 1999 to 2004.(2) Soil and water loss mainly exists in purple soil,yellow soil,limestone soil,paddy soil and yellow brown soil distributed areas.(3) The dry slope land and sparse woodland that are intensively influenced by human activities experienced most serious soil and water loss.(4) Soil and water loss in the study area indicated an obvious vertical differentiation characteristic.(5) There is a significant correlation between soil and water loss and slope.(6) There is no obvious correlation between soil and water loss and aspect.(7) Soil and water loss mainly exists in the values of R between 300 and 340 distribution area.The very-high soil and water loss has obvious correlation with R.

Soil nutrient loss due to tuber crop harvesting and its environmental impact in the North China Plain

Soil loss due to crop harvesting （SLCH） is a soil erosion process that signiifcantly contributes to soil degradation in crop-lands. However, little is known about soil nutrient losses caused by SLCH and its environmental impacts. In the North China Plain area, we measured the losses of soil organic carbon （SOC） and nitrogen as wel as phosphorus due to SLCH and assessed their relationship with soil particle size composition, agronomic practices and soil moisture content. Our results show that the losses by harvesting potato of SOC, total nitrogen （TN）, available nitrogen （AN）, available phosphorus （AP） and total phosphorus （TP） were 1.7, 1.8, 1.8, 15.9 and 14.1 times compared by harvesting sweet potato, respectively. The variation of SOC, N and P loss by SLCH are mainly explained by the variation of plant density （PD） （17–50%）, net mass of an individual tuber （Mcrop/p） （16–74%）, soil clay content （34–70%） and water content （19–46%）. Taking into account the current sewage treatment system and the ratio of the nutrients adhering to the tubers during transportation from the ifeld （NTRP/SP）, the loss of TN and TP by harvesting of potato and sweet potato in the North China Plain area amounts to 3% N and 20% P loads in the water bodies of this region. The fate of the exported N and P in the sewage treatment system ultimately controls the contribution of N and P to the polution of lakes and rivers. Our results suggest that a large amount of SLCH-induced soil nutrient export during transportation from the ifeld is a potential polutant source for agricultural water for vast planting areas of tuber crops in China, and should not be overlooked.

Root Function in Nutrient Uptake and Soil Water Effect on NO3^- -N and NH4^+ -N Migration

Root function in uptake of nutrients and the effect of soil water on the transfer and distribution of NO3^--N in arable soil were studied using summer maize （Zea mays L. var. Shandan 9） as a testing crop. Results showed that root growth and water supply had a significant effect on NO3^--N transfer and made NO3^--N distributed evenly from bulk soil to rhizosphere soil. Under a natural condition with irrigation, the difference of NO3^--N concentration at different distance points from a maize plant was smaller, while obvious difference of NO3^--N concentration was observed under conditions of limited root growth space without irrigation. Whether root growth space was restricted or not, the content of soil NO3^--N decreased gradually from 10 to 0 cm from the plant, being opposite to the root absorbing area in soils. When root-grown space was limited, changes of NO3^--N concentration at different distances from a plant were similar to that of water content in tendency. Results showed that NO3^--N could be transferred as solute to plant root systems with water uptake by plants. However, the transfer and distribution of NH4^--N were not influenced by root growth and soil water supply, being different to NO3^--N.

Arbuscular mycorrhizal fungi improved plant growth and nutrient acquisition of desert ephemeral Plantago minuta under variable soil water conditions

Desert ephemeral plants play an important role in desert ecosystem.Soil water availability is considered as the major restrictive factor limiting the growth of ephemeral plants.Moreover,arbuscular mycorrhizal fungi（AM fungi） are widely reported to improve the growth of desert ephemerals.The present study aimed to test the hypothesis of that AM fungi could alleviate drought stress of desert ephemeral Plantago minuta,and AM fungal functions reduced with the improvement of soil water content.A pot experiment was carried out with three levels of soil water contents（4.5%,9.0%,and 15.8%（w/w））,and three AM inoculation treatments（Glomus mosseae,Glomus etunicatum and non-inoculation）.The results indicate that mycorrhizal colonization rate decreased with the increase of soil water availability.Inoculation improved plant growth and N,P and K acquisition in both shoots and roots regardless water treatments.When comparing the two fungi,plants inoculated with G.mosseae performed better than those inoculated with G.etunicatum in terms of plant growth and nutrient acquisition.These results showed that ameliorative soil water did not suppress arbuscular mycorrhizal fungal functions in improving growth and nutrient acquisition of desert ephemeral Plantago minuta.

Effect of Polyacrylamide Application on Water and Nutrient Movements in Soils

An understanding of nutrient movement in soil is important for developing management strategies to minimize nutrient leaching and surface movement, thus improving nutrient uptake by plants, maintaining a sustainable soil system, and even protecting groundwater quality. Polyacrylamide (PAM) is known as one of soil conditioner that functions to stabilize soil structure, increase infiltration, and reduce surface runoff. This study assesses the effects of PAM on the vertical movement of soil-water and major/minor nutrients (NO3-N, NH3-N, T-N, PO4-P, T-P, K, Ca, Mg, and Fe) in soils. Saturated hydraulic conductivity (Ksat) increases with increasing PAM concen- trations up to 10 mg&middot;L-1 for sand and 20 mg&middot;L-1 for a mixture of sand and clay. Decreases in the loss of soluble nutrients, particularly NH3-N, PO4-P and T-P, are observed as PAM concentrations increase. In contrast, PAM concentration has no effect on nitrate and minor nutrient levels. These results indicate that the application of PAM may be a viable method for protecting water bodies from excessive nutrients and improving nutrient availability for plants.

A policy and technical measures for controlling soil and water loss in the Loess Plateau of China

Loess Plateau is the most serious region of soil and water loss in China and the world. The sediment carried into the Yellow River amounts to 1.6 billion tons every year. This paper reviews the factors and reasons for erosion in this area, and puts forward a comprehensive controlling policy on the basis of the principles of ecology and practise of Chinese scientists for 40 years. In conformity with the policy, a number of technical measures for controlling soil and water loss are suggested.

Topographic differentiation simulation of crop yield and soil and water loss on the Loess Plateau

De-farming slope farmland has been an effective measure in recent years for the improvement of the eco-environment and the mitigation of soil and water loss on the Loess Plateau. This paper, taking the Yangou Basin as a case study and using day-by-day mete- orological data of Yah＇an station in 2005, simulated and analyzed the quantitative relation between crop yield, soil and water loss and topographic condition with the aid of WIN-YIELD software. Results show that： 1） topographic gradient has important influence on crop yield. The bigger gradient is, the lower the crop yield. Yields of sorghum and corn decrease by 15.44% and 14.32% respectively at 25° in comparison to the case of 0°. In addition, yields of soya, bean and potato decrease slightly by 5.26%, 4.67% and 3.84%, respectively. The influences of topographic height and slope aspect on crop yield are slight. 2） Under the same topographic condition, different crops＇ runoff and soil loss show obvious disparity. Topographic gradient has important influence on soil and water loss. In general, the changing trend is that the soil and water loss aggregates with the increase of gradient, and the maximal amount occurs around 20°. The influence of topographic height is slight. Topographic aspect has a certain effect, and the fundamental characteristic is that values are higher at the aspect of south than north. 3） Topographic gradients of 5° and 15° are two important thresholds. The characteristic about soil and water loss with the variation of topographic gradients show that： the slope farmland with gradient less than 5° could remain unchanged, and the slope farmland more than 15° should be de-farmed as early as possible.

Impact of slash disposal on soil and water loss and the growth of planted seedlings

The three methods of slash disposal in this experiment were no treatment, strip piling and burning. The results obtained from this study showed that the soil erosion, water and nutrient loss were higher in the logged areas by burning than in the logged areas by no treatment and strip piling. The soil and water loss was not serious when the slope degree of the logged area was less than 16o. The survival rate of planted seedlings was higher and the growth was better in the logged areas followed by burning than in the logged areas by no treatment and strip piling. Burning should not be used when the slope was more than 23o.

Study on Soil and Water Loss Characteristic of the Railway Construction in Mountain Area

The factor of human project activity is often the immediate cause resulting in soil and water loss. The Baoji-Lanzhou second railway in construction is an example. The soil and water loss law caused by earth and stone mountain railway engineering construction in the northwestern China is studied systematically and that caused possibly by the road bed project, the road moat project, the field project, the tunnel project and the service road project in construction is probed. At the same time, the type, t...

Impact Assessment of Land-Use Changes on Nutrient Load in Song Cau Watershed Using Soil and Water Assessment Tool （SWAT） Model

The objective of this paper is to implement ＂Soil and Water Assessment Tool （SWAT）＂ model to assess the possible impact of land-use changes on nutrient yields from Song Cau watershed located in Northern Viet Nam. Organic nitrogen （N） as well as phosphorus （P） output due to nonpoint source erosion was estimated through SWAT. Parameters governing the mechanics of streamflow discharge, sediment yield, nitrogen, and phosphorus output in SWAT were calibrated in a distributed fashion. A five-year period of record for nutrient was used for model calibration, while a four-year period was used for model validation. Comparing measured versus simulated average monthly total N, and P loads for the calibration and validation periods; respectively, we found that SWAT model performed reasonably well for Song Cau watershed. Simulation results showed that monthly Nash-Sutcliffe coefficient of Efficiency （NSE） ranged from 0.65 to 0.83, observation＇s standard deviation ratio （RSR） and percent bias （PBIAS） ranged from 0.41 to 0.58 and -36.12 to 2.78, respectively. Additionally, SWAT simulation results also showed that land-use changes caused significant percentage of changes in sediment yield, total N, and P loads within Song Cau watershed.

The Effect of Land Use Change on Soil and Water Quality in Northern Iran

Rapid urbanization has led to extensive land-use changes,particularly in developing countries.This research is aimed to investigate the role of land use and its effect on soil and water quality in Ziarat watershed focusing on four land uses:forest,pasture,cultivated and urban development.Soil samples were taken from a depth of 0-30 cm on each land use and were analyzed by completely randomized split-plot design in two geographical directions.Results showed that bulk density(BD),electrical conductivity(EC),pH,calcium carbonate equivalent(CCE),and soil particle density(DS) of the soil samples in pastures,cultivated and urban areas increased and the mean weight diameter(MWD),soil porosity(F),organic carbons(OC),total nitrogen(TN),exchangeable cations(Ca 2+,Mg 2+,K +,Na +),cation exchange capacity(CEC) and soil microbial respirations(SMR) decreased,respectively in comparison with the forest soils.For water quality evaluations,sodium adsorption ratio(SAR),electrical conductivity(EC),pH,total dissolved solids(TDS),bicarbonate(HCO 3),chloride(Cl),total hardness(TH),calcium(Ca 2+),potassium(K +),sodium(Na +) and magnesium(Mg 2+) were investigated in two areas:Nahrkhoran and Abgir stations.Results showed that the concentration of TDS,EC and HCO 3 in Naharkhoran station is higher than that in Abgir station.On the other hand,the concentration of TDS,EC and HCO 3 in Abgir station are the relatively higher due to its location.Total hardness had the same trend during the study years except in the last three years;however,TH showed an increase of 25% TH in Naharkhoran for the last two years.Cl,K + and SAR in Naharkhoran station increased by 61%,22%,78% and 56% respectively,in comparison with Abgir station.This study demonstrated that the trend of soil degradation and mismanagement of land use may increase the frequency of urban floods and human health problems.