Effects of different irrigation methods on micro-environments and root distribution in winter wheat fields

The irrigation method used in winter wheat fields affects micro-environment factors, such as relative humidity（RH） within canopy, soil temperature, topsoil bulk density, soil matric potential, and soil nutrients, and these changes may affect plant root growth.An experiment was carried out to explore the effects of irrigation method on micro-environments and root distribution in a winter wheat field in the 2007–2008 and 2008–2009 growing seasons.The results showed that border irrigation（BI）, sprinkler irrigation（SI）, and surface drip irrigation（SDI） had no significant effects on soil temperature.Topsoil bulk density, RH within the canopy, soil available N distribution, and soil matric potential were significantly affected by the three treatments.The change in soil matric potential was the key reason for the altered root profile distribution patterns.Additionally, more fine roots were produced in the BI treatment when soil water content was low and topsoil bulk density was high.Root growth was most stimulated in the top soil layers and inhibited in the deep layers in the SDI treatment, followed by SI and BI, which was due to the different water application frequencies.As a result, the root profile distribution differed, depending on the irrigation method used.The root distribution pattern changes could be described by the power level variation in the exponential function.A good knowledge of root distribution patterns is important when attempting to model water and nutrient movements and when studying soil-plant interactions.

The Response of Chickpea to Irrigation with Treated Waste Water

In a three-year study, the response of four cultivars of chickpea, Bulgarit, WIR-32, Jordan and ICC 11293 to irrigation with TW （treated wastewater） and FW （freshwater）, using surface and subsurface drip irrigation was investigated. Wastewater generated from Al-Quds university campus included black, grey and storm water was treated by small scale pilot plant. The wastewater pilot plant consists of tailored made secondary biological activated sludge process with daily capacity of 50 m3. The influent and effluent chemical and biological quality parameters were routinely monitored and analyzed. The data reveal that the average values for BOD, COD and EC for the effluent are 50 ppm, 136 ppm and 1.4 mS/cm over 2 years period. The results of chickpea growth parameters and the chemical and biological analysis of the seeds and leaves indicate that the cultivars Bulgarit and ICC 11293 can be irrigated with TW without any loss in yield and quality. Factor analysis reasonably favored Bulgarit Cultivar irrigated with treated effluent over other cultivars. WIR-32 and Jordan cultivars showed significant reduction in their growth parameters when irrigated with TW as compared with FW. Surface and subsurface drip irrigation gave similar results in most cases. Soil analysis in this study showed no significant difference between irrigation with TW and FW.

Effect of Water Resources Allocation on Groundwater Environment and Soil Salinity Accumulation under Climate Change

The combined surface and groundwater allocation practice by wells and canals had contributed to the safety of groundwater environment and agriculture sustainable production. The typical area in the People＇s Victory Canal irrigation district was taken as a case, drawing together the irrigation district agriculture water consumption and precipitation from 1954 to 2014 in the People＇s Victory Canal irrigation district, ratios of surface to groundwater irrigation amount, dynamic of groundwater depth and hydrochemical characteristic of groundwater from 2008 to 2014 in the research area, the relationship between groundwater depth and ratio of surface to groundwater irrigation amount was analyzed, in order to ascertain the influence of precipitation on ratios of surface to groundwater irrigation amount and its effect on soil and groundwater environment. The results indicated that positive correlation between the ratios of surface to groundwater irrigation amount and annual precipitation was appeared, affected by climate change, average irrigation amount from surface in the recent 5 years was 2.90 x 108 cubic meters, accounted for 75.52% of total irrigation amount, on the other hand, decreasing tendency of precipitation was obvious, and groundwater depth dynamic in upstream of the branch canals was more dramatic than downstream because of surface water irrigation infiltration, under the unified condition of water use efficiency, ratio of surface to groundwater irrigation amount was negative correlation with area of the groundwater depth beyond 11 m, meanwhile, groundwater depth demonstrated negative correlation with the ratio of surface to groundwater irrigation amount, moreover, alkaline trend of groundwater hydrochemistry during the normal season in the research area was obvious because of phreatic evaporation and the agricultural irrigation from wells, along with irrigation from surface inflow of Yellow River, quality of groundwater hydrochemistry during the dry season was ameliorative greatly. Consequently, it was very important to the agriculture sustainable production that well-canal combined irrigation patterns alleviated extremely alkaline trend of the groundwater hydrochemistry and played a positive role of root layer soil salinity leaching.

Sharp Expansion of Intensive Groundwater Irrigation,Semi-Arid Environment at the Northern Bekaa Valley Lebanon

This research focuses on the sharp expansion of groundwater irrigation in the Northern Beqaa, using Landsat satellite images and other auxiliary GIS relevant data sources. Topographic maps were used to assess the location and size of the irrigated area in the early 1960s as the initial years of agriculture expansion analysis. The first available Landsat image of the area was of the year 1972 followed with a series of accessible Landsat images until 2009. In the 1960s, agricultural practices were only limited to areas of surface water resources and open channels next to urban settlements. In the Early 1980s, farmers discovered the agricultural potential of the area. Only 3% of the area was cultivated before the 1970s. The cultivated area reached about the 20% in late 1990s. Weather conditions, shallowness of groundwater tables, low fuel costs and market opportunities have led to an agricultural boom in the area considered as prone to desertification and of low productivity by national authorities. The area is however poorly understood from its hydro geological characteristics and exposed to intensive and unsustainable use of its natural resources.

Use fuzzy interface systems to optimize land suitability evaluation for surface and trickle irrigation

In this study fuzzy logic system was used for optimization parametric evaluation system in surface and trickle irrigations.This study was performed on a surface area of 5175 ha in fathali region located in Ardabil province of Iran.It was indicated that for trickle and surface irrigation respectively an area of about 2941.35 ha(56.77%)and 159.81 ha(3%)of the lands is“highly suitable”and an area of about 246.43 ha(4.7%)and 312.69 ha(6%)is“moderately suitable”.About 797.1 ha(15.4%)and 2744.17 ha(53.02%)were respectively“marginally suitable”for trickle and surface irrigations.“Currently not suitable”suitability included about 737.58 ha(14.2%)and 1746.05 ha(33.7%)and“Permanently not suitable”suitability matched 458.54 ha(8.86%)and 212.28 ha(4.1%)in the zone under study.According to the results,there is a major difference between the“highly suitable”lands obtained through the two methods and the area of“highly suitable”lands in the trickle method is about 18 times of the area of“highly suitable”obtained through the surface irrigation method.As a result,considering the gradual changes of soil parameters,fuzzy evaluation leads to more accuracy compared to the parametric non fuzzy method.By and large,it can be said that fuzzy method,shows higher qualities about the suitability of lands for trickle irrigation.

A two-dimensional Richards equation solver based on CVODE for variably saturated soil water movement

A numerical model of two-dimensional soil water movement under surface drip irrigation condition was developed. The physical process of soil water movement is described by 2D Richards equation,and the upper boundary condition is depicted by the improved moving ponded area boundary. The partial differential equation(PDE) is transformed into ordinary differential equations(ODEs) through spatial semi-discretization and numerically solved by an ordinary differential equation solver(CVODE) . The numerical and field experiments indicate the good performance of the model in terms of accuracy and efficiency. The model provides a useful tool for long-term simulation of soil water movement under surface drip irrigation. Also,the model can serve as a general 2D Richards equation solver for variably saturated soil water movement,which is named as TIVS model(Tsinghua Integrated Variably Saturated soil water movement model).