Study on Water and Salt Transport under Different Subsurface Pipe Arrangement Conditions in Severe Saline–Alkali Land in Hetao Irrigation District with DRAINMOD Model

Abstract

As an effective method to improve saline–alkali land, the drainage from subsurface pipes has been extensively studied in typical arid and semi-arid agricultural areas (Hetao Irrigation District). However, there are few studies on the improvement of subsurface pipe layout and the long-term soil salinization control in the process of leaching and soil amendment with subsurface pipes in this area. This study investigated the water and salt migration in the process of amending the heavy saline soil. Field experiments growing sunflowers and numerical model calculation were combined in this research. It was found in the field experiment that the salt concentration in the surface pipe drainage was positively correlated with the salt content in the soil and the depth of the pipe, while it was negatively correlated with the amount of irrigation water and the spacing of crops. Thus, the soil desalting rate (N) and salt control rate (SCR) were positively correlated with the depth of the pipe, and they were negatively correlated with the spacing. The leaching effect of irrigation would decrease when the soil salt content decreased. On the basis of field experiments, the DRAINMOD model and drainmod equation were used to calculate the water and salt migration in 38 different field plots during 2019 and 2020. When N was the same, the soil salinity in several plots with large burial depth could be controlled below the salt tolerance threshold of sunflowers during the growth period in the second year. The quantitative relationship between N and SCR, soil salt content before leaching, water amount of leaching, pipe spacing and buried depth was already established. These results can help develop strategies for desalination and salt control in the soil in the arid and semi-arid areas with the optimal layout of subsurface pipes.

Effect of Water Conservation and Nitrogen Reduction on Root Growth and Yield in Spring Maize in Typical Sand Interlayered Soil

“…In the study by Zou, the maximum rooting depth of maize roots at the grain filling stage was 100 cm, whereas the maximum rooting depth was limited to the depth of the sand layer in the present study. Generally, roots increase their surface area to absorb water and nutrients to meet the normal growth needs of crops [58][59][60][61]. In this study, we found that RL in the horizontal and vertical directions was significantly correlated with yield and WUE, with the highest correlation observed in NR20.…”

Spatiotemporal Absorption Features of Yellow Willow Water Usage on the Southern Edge of the Semi-Arid Hunshandak Sandland in China

“…The lack of isotope data with high temporal resolution along the soil-plant-atmosphere axis and the effects of isotope fractionation complicated our analysis of yellow willow water sources. To increase the accuracy of water source identification, future studies should examine the isotope fractionation mechanisms in yellow willow water sources [49], specifically the differences between various plant tissues and soil layers [50][51][52][53], and consider other models and/or data correction factors. To more precisely record short-term changes in the isotopic compositions of soil, plants, and atmospheric water, high-precision isotope analyzers should be employed with a higher sample frequency.…”

ECWS: Soil Salinity Measurement Method Based on Electrical Conductivity and Moisture Content

“…Soil salinity is a major factor affecting soil fertility and crop yield [40,41], and one of the most important indicators for assessing the degree of soil salinity [42]. The measurement of soil salinity is very important for the improvement of saline soils, so through the combination of soil bulk conductivity, soil solution conductivity, and volumetric water content, the ECWS model of soil salinity has been proposed, which is very important for soil salinity monitoring.…”