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【Objective】 A pre-planting border irrigation in spring coupled with a drip irrigation in summer during crops growth season is an irrigation technique to reduce soil salinity and safeguard crops growth in the salt-affected soils in the Hetao Irrigation District in Inner Mongolia. This paper investigates the impact of different combinations of irrigation amounts in the dual irrigations on changes in soil water and salt, as well as the growth of sunflower. 【Method】 The field experiment compared two spring (S) irrigation amounts: 95 mm and 135 mm, and three summer (W) irrigation amounts: 68, 100 mm and 135 mm. In each treatment, we measured the spatiotemporal changes in soil water and salt, as well as crop growth characteristics. 【Result】 ① The soil water content in the S135W135 treatment was the highest among all treatments during the experimental period, with the average soil water content and saturation being 17.10% and 75.53%, respectively. The coefficient of variation of soil water content in the S95W135 treatment was 22.40%, the lowest among all treatments. ② Depending on the summer irrigation amount, the desalination rate of the 0-80 cm soil layer under S135 and S95 varied from 32.64% to 50.50% and 21.8% to 38.87%, respectively. Although the spring irrigation amounts did not significantly affect immediate post-irrigation salt content, the S135W100 and S95W135 combinations showed deeper leaching depths and higher desalination rates (40.77% and 33.37%, respectively) than other treatments. ③ Aboveground dry matter production was significantly higher in the S95W135 and S135W100 combinations than in other combinations, surpassing the S135W135 combination by 10.55% and 9.94%, respectively. The S135W100 combination achieved the highest water use efficiency at 21.59%, an increase of 13.03% compared to S135W135. 【Conclusion】 Reducing spring irrigation by 30% to 95 mm combined with a summer drip irrigation of 135 mm is the most efficient irrigation scheme for sunflower cultivation in the salt-affected soils in the Hetao Irrigation District.

【Objective】 Flume is a device to measure water flow in open channels. The purpose of this paper is to propose a bionic technology to optimize wing-shaped flume in attempts to reduce the head loss across the flume and improve the critical submergence degree for channels in areas with small topographic gradient. 【Method】 The experiments compared 15 flow conditions. The change in water levels from the inlet to the outlet of the flumes was measured. These enabled us to analyze the hydraulic parameters including water head loss, backwater height, Frude number and critical gradient, and to compare the performance of the original wing-shaped flume and the optimized imitation pigeon wing section curve type flume. 【Result】 The average error of the optimized imitation pigeon wing section curve type flume is 1.28%, meeting the requirements. Compared with the original wing-shaped flume, the critical submergence degree working condition, the average backwater height and the average head loss of the optimized flume are reduced by 7.46% and 5.81% respectively, the flow in the upstream became smoother with the Fr

【Objective】 Irrigation in Hetao Irrigation District relies on water diverted from the Yellow River, and it has a direct consequence for physicochemical properties of both soil and groundwater. The purpose of this paper is to study the impact of spring irrigation on depth and physicochemical properties of the groundwater. 【Method】 The experiment was conducted on a saline-alkali soil. We measured the changes in groundwater table, typical cation and anion ions, EC, pH, and other factors in the groundwater before and after the spring irrigation. The impacts of the irrigation on changes in groundwater depth and its physicochemical properties were analyzed using statistical methods. 【Result】 The irrigation increased the concentrations of TDS, Ca2+, K+ + Na+, SO42- and Cl-, especially K+ + Na+ + and Cl- which not only had the largest coefficient of variation but also varied most erratically over space. Along with rock weathering and evaporation crystallization, cation exchange was another factor that modulated the change in chemical composition of the groundwater. After the irrigation, chemical composition of the groundwater shifted from Na-Mg-Cl-SO4-HCO3 type and Na-Cl-SO4-HCO3 to Na-Cl-SO4 type. Depending on irrigation amount and region, it took 10~20 day for the groundwater to respond to the irrigation, with the groundwater table rising by 1.197~2.142 m at a daily rate 0.079 8~0.169 m/d. 【Conclusion】 Spring irrigation increased the average TDS content of grounded by 15.6%, indicating a salt leaching, but it also raised the groundwater table giving rise to soil salinity. Therefore, to alleviate soil salinization, spring irrigation amount should be reduced, and drainage system should be improved in the region.

Biochar is a widely recognized soil amendment used to improve soil physicochemical properties and crop productivity. However, its compositive effects on soil water, fertilizer, and carbon in cropping systems are not extensively understood. A two-year field study was conducted to investigate the influence of integrating maize-residue-derived biochar on evapotranspiration, water and fertilizer utilization efficiency, soil organic carbon (SOC) content, and soil carbon emissions in maize farming, employing drip irrigation in conjunction with film mulching. The treatments included the following three biochar amendments: 15 (B15); 30 (B30); and 45 (B45) t ha−1. Biochar was exclusively incorporated prior to sowing during the initial year of the experiment, and no biochar was used as a control (CK). After two years, the biochar amendments, especially B30, improved crop water productivity and the partial factor productivities of nitrogen, phosphorus, and potassium fertilizer. Relative to CK, the biochar amendments significantly reduced soil CO2 and CH4 emissions during crop growth by 17.6–40.6% and −1.21–268.4%, respectively, averaged across two years. The best treatment effect was achieved by adding 15 t ha−1 of biochar. The biochar needed replenishing in the third year for B30 and in the fourth year for B45 to increase the SOC content by 20 g kg−1. An application rate of 22 metric tons per hectare of biochar is proposed to optimize water and fertilizer utilization efficiency, alongside augmenting the soil organic matter content, within maize farming under drip irrigation and mulching practices on sandy loam soil. However, the biochar must be added at 20 t ha−1 in the third year to counterbalance soil carbon losses and improve SOC. [ABSTRACT FROM AUTHOR]

【Background】 The wide distribution of saline and alkali soils in Ordos of Inner Mongolia is a main abiotic factor hindering crop growth. Their remediation is a prerequisite for developing sustainable agriculture in this region. Subsurface drain is a technology widely used to alleviate salt accumulation and enhance salt leaching. 【Objective】 The objective of this paper is to experimentally study the effects of subsurface drain on salt dynamics in soils heavily affected by salinity and alkalinity. 【Method】 The experiment was conducted from May to October 2015 at Dalat Banner, with the drains spaced 18 m apart and buried in a depth varying from 1.2 m to 1.5 m; the depth of the drainage ditches was 1.8~2.0 m. In each treatment, we measured soil salt distribution up to 1.0 m deep, the change in groundwater table and salinity, as well as the quality of the irrigation water and drainage water, salt ion data and their relationship. 【Result】 ①Spatial variation of salt in the top 0~100 cm soil was moderate with a coefficient of variation of 25%~75%; the majority of salt was accumulated in regions proximal to the soil surface. ②The drains dropped the groundwater table by 50~60 cm and reduced soil salinity by approximately 10%, compared with data measured before experiment. ③At the end of the experiment, the main salt ions in the soil were K++Na+, SO42- and Cl-, while in the groundwater they were K++Na+, Cl- and HCO3-. ④Irrigating using the Yellow river water increased HCO3- in soil by 56% and the decreased of other salt ions, with SO42-, K++Na+ and Cl- reduced by 36%, 34% and 31% respectively. Leaching of the irrigation water increased ion contents in both drainage water and groundwater, especially the drainage water whose salinity was 3.43 times that of groundwater. 【Conclusion】 Subsurface drains can control the groundwater depth and reduce soil salt content; it facilitates leaching of SO42-, K++Na+ and Cl- from the soil. However, care should be taken to avoid an increase in HCO3- and its consequence for soil alkalization when irrigating with the Yellow river water.

【Background and objective】 Water scarcity in arid areas in northern China is a bottleneck holding their socioeconomic development. Since agricultural irrigation is a major water user in these areas, improving irrigation water use efficiency is essential to ameliorating water shortage, an fundamental issue in which is evaluation of agricultural water use efficiency. This paper is to present a new method to evaluate water use efficiency in irrigation districts. 【Method】 The method is based on the principle component analysis (PCA) and grey relation analysis (GRA) evaluation index system; it considered water use level, current situation of engineering projects, management level and irrigation technologies in irrigation district. An comprehensive evaluation model coupling PCA, GRA and the technique for order preference by similarity to ideal solution (TOPSIS) was derived to evaluate water use efficiency in five large irrigation districts in Inner Mongolia that rely on Yellow river for irrigation. 【Result】 The ranking of water use efficiency obtained from the coupled PCA and GRA-TOPSIS was the same as that calculated from GRA-TOPSIS for all five irrigation districts. It was also consistent with that calculated from the fuzzy matter element analysis (FMA), indicating that the coupled PCA and GRA-TOPSIS is reliable and accurate to evaluate water use efficiency in irrigation districts. The extreme difference of the coupled PCA and GRA-TOPSIS, the GRA-TOPSIS and the FMA method was 0.501, 0.448 and 0.500, respectively, with their associated coefficients of variation being 0.699, 0.450, 0.921, respectively. The large coefficient of variation of the coupled PCA and GRA-TOPSIS makes it more effective to differentiate the water use efficiency between irrigation districts. Overall, results obtained from the coupled PCA and GRA- TOPSIS model accurately described the water use situation in all irrigation districts and the model is hence reliable. 【Conclusion】 Coupling PCA and GRA- TOPSIS model improved evaluation accuracy of agricultural water use efficiency in irrigation district.

A 3-year field experiment was conducted to determine the impact of corn residue-derived biochar on soil organic matter (SOM), soil nutrients, corn yield and partial factor productivity of synthetic fertilizer in Hetao Irrigation District, Inner Mongolia of China. Three rates of biochar, 15 (B15), 30 (B30) and 45 (B45) t ha−1, and a non-biochar control (B0) were applied to a corn field one time at the first crop growing season under film-mulched with drip-irrigation. Relative to B0, the B30 led to a significant increase in SOM at top 30 cm soil layer (15.3%) and partial factor productivity of fertilizers (12.8%) as averaged across 3 years. Amendment in B30 also increased the available nutrients in the soil (nitrogen, phosphorus and potassium), corn yield and economic benefit. In contrast, the first year showed the largest improvements for corn yield and economic benefit for B30, followed by the second year and the third year. The corn grain yield has potentially increased when the SOM and the available phosphorus were increased when compared to the available nitrogen and potassium. A single biochar amendment at the rate of 30 t ha−1 can be adequate for the corn production in 3 years under dry climatic conditions. [ABSTRACT FROM AUTHOR]

Pulsed eddy current (PEC) technique has been used to detect corrosion under insulation (CUI) for decades, but whether and how the wire mesh laid in the insulation layer affects the detection remains ambiguous. This paper touches on this issue for the first time. The insulated structure was simplified to a carbon steel plate covered by a cladding with an air gap representing the insulation layer, in which the wire mesh was situated. Finite element simulations were performed on the simplified model and found that the aluminium or stainless steel wire mesh had little effect on eddy currents in the plate, while the mild steel wire mesh could cause a considerable increase in the probe footprint and a significant drop of the eddy current density. For the mild steel wire mesh, the magnetic permeability and wire diameter were the main factors affecting the probe footprint and eddy current density. Afterwards, simulations were conducted to analyse the effect of the mild steel wire mesh on the PEC probe performances for evaluating the CUI depth and found that the mild steel wire mesh led to decreases in both the PEC signal amplitude and decay rate. The simulation results were finally verified by experiments. [ABSTRACT FROM AUTHOR]