Search

【Objective】 The aim of this paper is to propose a reasonable water and fertilizer application system for the Yellow River water drip irrigation project in the salinized irrigation area on the South bank of the Yellow River in Ordos Dalat Banner. 【Method】 The field drip irrigation experiment was carried out, and 3 irrigation quotas were set: high water W1 (1 500 m3/hm2), medium water W2 (1 200 m3/hm2) and low water W3 (900 m3/hm2). 2 fertilization levels: high fertilizer N1 (187.5 kg/hm2), low fertilizer N2 (150 kg/hm2). The local irrigation and fertilization were used as the control group CK. The effects of different water and fertilizer treatments on sunflower growth index, yield, soil salinity and soil moisture content were studied. The entropy method was used to calculate the weight of 5 indexes, including yield, water productivity, partial fertilizer productivity, average conductivity of 0 ~ 40 cm soil layer and fruit rate. The optimal water and fertilizer scheme was obtained by comprehensive evaluation of each treatment. 【Result】 There was little variability in sunflower growth trait indexes among treatments, but all were more favorable than the CK treatment. The yields of the two treatments with high water were significantly higher than the other treatments. Throughout the reproductive period of sunflower, W1N2 treatment had the lowest value of electrical conductivity in the 0~40 cm soil layer, 341.9 μS/cm, and W2N1 had the highest value of soil electrical conductivity under water and fertilizer conditions, 449.7 μS/cm. The increase in electrical conductivity at the beginning and end of the reproductive period in W1N1, W1N2, W2N1, W2N2, W3N1, W3N2, and CK was 62.2%, respectively, 29.4%, 58.9%, 52.9%, 83.9%, 56.3%, and 54.0%, respectively. For the water content of the 60~100 cm soil layer, there was no significant difference between the high water treatment and the medium water treatment, and there was a significant difference between both the high water and medium water treatments compared to the low water treatment. Water infiltration in the high water treatment was close to uniform infiltration. The depth of the wetted area formed by different irrigation quotas is also different, the larger the irrigation quota, the deeper the location of the wetted area and the larger the wetted range. The entropy value method was used to comprehensively evaluate each treatment, and the optimal result was the W1N2 treatment, and the worst result was the CK treatment. 【Conclusion】 The degree of soil salinity return decreased with the increase of irrigation quota, but too high irrigation quota would reduce crop activity and thus inhibit crop growth. The results of the comprehensive assessment of treatments showed that the irrigation quota for sunflower in the irrigation area on the South bank of the Yellow River in Darat Banner, Ordos, was about 1 500 m3/hm2, and the application of urea (46% nitrogen) was about 150 kg/hm2. During the reproductive period, water was irrigated 5~6 times and fertilizer was applied 2~3 times, and fertilizer was applied to the field with water.

【Objective】 Many arid and semiarid regions in North and Northwest of China are poor in freshwater but have saline groundwater. Efficient utilization of these saline waters is crucial for agricultural sustainability. This study seeks to experimentally identify the optimal alternation of freshwater and saline water for irrigating arable crops in areas with shallow groundwater. 【Method】 The experiment was conducted at a maize field from May to October in 2022 at an experimental site in Darat Banner, Erdos. It compared four irrigations: irrigating with saline water only (T1), irrigating with saline water twice followed by a freshwater irrigation (T2), irrigating with saline water once followed by one freshwater irrigation (T3), irrigating with freshwater only (CK). In each treatment, we measured water and salt distribution in the soil, as well as yield of the maize. 【Result】 Alternate irrigation significantly influenced soil moisture and salinity. T3 considerably increased root water uptake during the critical growth stage of the crop, manifested by the 0.75% to 1.3% reduction in water content in the 0~40 cm soil layer, and 2.02% to 3.71% increase in water content in the 40~100 cm soil layer. During the irrigation period, there were 58.45% and 63.98% of soils salinized in T2 and T3, respectively. Compared to CK, alternate irrigation reduced crop yield by 10% to 13%, but saved 33% to 50% of freshwater. Grain yield and water use efficiency of T3 were 90.26% and 23.2% higher than that of T1, respectively, despite its 7.2% reduction in grain yield compared to CK. Groundwater recharge during the reproductive period accounted for 21.74% to 25.55% of the water consumed by the maize. 【Conclusion】 Considering the effect of alternate irrigation on distribution of water and salt in soil, as well as the growth and water consumption of the maize, the most suitable irrigation method for maize in the saline soil is alternating saline water and freshwater(T3).

Assessing maize yield is critical, as it is directly influenced by the crop's growth conditions. Therefore, real-time monitoring of maize growth is necessary. Regular monitoring of maize growth indicators is essential for optimizing irrigation management and evaluating agricultural yield. However, quantifying the physical aspects of regional crop development using time-series data is a challenging task. This research was conducted at the Dengkou Experimental Station in the Hetao irrigation area, Northwest China, to develop a monitoring tool for regional maize growth parameters. The tool aimed to establish a correlation between satellite-based physical data and actual crop growth on the ground. This study utilized dual-polarization Sentinel-1A GRD SAR data, accessible via the Google Earth Engine (GEE) cloud platform. Three polarization descriptors were introduced: θc (pseudo-scattering type parameter), Hc (pseudo-scattering entropy parameter), and mc (co-polar purity parameter). Using an unsupervised clustering framework, the maize-growing area was classified into several scattering mechanism groups, and the growth characteristics of the maize crop were analyzed. The results showed that throughout the maize development cycle, the parameters θc, Hc, and mc varied within the ranges of 26.82° to 42.13°, 0.48 to 0.89, and 0.32 to 0.85, respectively. During the leaf development stage, approximately 80% of the maize sampling points were concentrated in the low-to-moderate entropy scattering zone. As the plants reached the big trumpet stage, the entire cluster shifted to the high-entropy vegetation scattering zone. Finally, at maturity, over 60% of the sampling points were located in the high-entropy distribution scattering zone. This study presents an advanced analytical tool for crop management and yield estimation by utilizing precise and high-resolution spatial and temporal data on crop growth dynamics. The tool enhances the accuracy of crop growth management across different spatial and temporal conditions. [ABSTRACT FROM AUTHOR]

The objective of this study is to assess the suitability of the AquaCrop model for growing maize using brackish water irrigation in Northwest China. Additionally, this study aims to examine how maize utilizes water in various soil layers when irrigated with varying water qualities. The AquaCrop model was calibrated and verified using experimental data from the years 2022 and 2023 in this research. (1) The findings indicated that the AquaCrop model effectively simulated the canopy cover, biomass, and yield of maize when irrigated with brackish water. The validation year's R2, MAPE, and RMSE values for canopy cover, biomass, and yield of maize were 0.95, 5.36%, and 4.77%, respectively. For biomass, the R2, MAPE, and RMSE values were 0.91, 16.61%, and 2.12 t·hm−2, respectively. For yield, the R2, MAPE, and RMSE values were 0.84, 3.62%, and 0.42 t·hm−2, respectively. (2) Irrigation with water of high mineral content, measured at 1.6 ds/m, as well as with fresh water over the whole reproductive period, resulted in an increased reliance on groundwater for maize cultivation. There was no notable disparity in the usage of various soil layers between the irrigation with alternating freshwater and brackish water. (3) The AquaCrop model simulated the effects of seven different irrigation water quality treatments. It was shown that using water with mineralization levels of 0.5 and 0.8 ds/m resulted in decreased freshwater use without causing a substantial decrease in maize yield and biomass. [ABSTRACT FROM AUTHOR]

The control of irrigation volume is of significant importance in arid regions of northwest China. Particularly, it has a crucial impact on the salinization of shallow groundwater areas. In 2022 and 2023, field experiments were conducted to test three distinct under-membrane irrigation treatments. These treatments were assigned water quotas of HW (27 mm), MW (22.5 mm), and LW (18 mm). The HYDRUS-2D model was integrated with a field experiment to accurately simulate the dynamic fluctuations of soil water and salt in the sunflower root zone. The model's performance was assessed and verified using real-field data from 2022 and 2023, and the simulation results closely matched the measured values. This research also used stable hydroxide isotopes to assess the water supply from various soil layers at different time intervals in sunflower plants. The results indicated that the three different levels of irrigation applied under the membrane had a significant impact on soil water content. Specifically, there was a significant difference in soil water content at a depth of 0–40 cm (p < 0.05), while there was little effect on the water content at a depth of 40–60 cm (p > 0.05). After irrigation, the average salt content in the top 0–20 cm of soil decreased by 7.0% compared to the medium and low irrigation levels, and by 10.8% compared to the medium irrigation level. Additionally, the medium irrigation level resulted in a 10.8% decrease in salt content compared to the low irrigation level, and a 4.1% decrease compared to the medium irrigation level. During the same period, the soil salinity levels at depths of 0–20 cm, 20–40 cm, 40–60 cm, and 60–100 cm in the area outside the membrane were measured to be 2.7~4.8 g·kg−1, 2.8~4.0 g·kg−1, 2.7~3.4 g·kg−1, and 1.7~2.6 g·kg−1, respectively. These levels decreased by 13.1~55.5%, 0.7~42.8%, −0.4~16.2%, and −72.7~7.5%, respectively. Following irrigation, the HW treatment mostly absorbed water in the 0–40 cm soil layer, while the MW and LW treatments absorbed water in both the 0–40 cm and 60–80 cm soil levels. The results indicated that the most optimal drip irrigation method beneath the membrane in this location was achieved when the amount of water applied was between 25–30 mm. This method demonstrated a combination of water conservation, high crop yield, and effective salt suppression. [ABSTRACT FROM AUTHOR]