Effect of Surface Straw Incorporation Rate on Water–Salt Balance and Maize Yield in Soil Subject to Secondary Salinization with Brackish Water Irrigation

Abstract

Secondary salinization induced by brackish water irrigation has forced agricultural development to increasingly rely on soil management. A two-year field experiment was conducted to explore the effects of different straw incorporation rates (SIRs) within 0 to 20 cm topsoil on the soil water–salt balance, maize yield production, and water use efficiency (WUE) under brackish water irrigation in a naturally non-saline area. Air-dried wheat straw was applied at the rates of 0, 4.5, 9.0, 13.5, and 18.0 t ha−1 (R0–R4) and two salinity levels of irrigation water with the salt content of 1.92 dS m−1 (SL) and 3.20 dS m−1 (SH) were applied for simulating the scenarios of secondary salinization. Results demonstrated that straw incorporation markedly increased the soil water content during two growing seasons, and SIR was directly correlated to the deep percolation, but inversely correlated to the soil water depletion, under both the SL and SH condition. Meanwhile, straw incorporation led to the increase in salt content within the straw incorporation zone, but the total mass of salt deposited in the 0–100 cm soil profile was comparatively reduced as SIR increased due to the increased deep percolation for salt leaching, and such relative alleviation was more pronounced under the SH condition. The significantly increased maize yield and its corresponding WUE were obtained in treatments with high SIR levels. Additionally, an exponential function was used to describe the trend of the yield-increasing rate as SIR increased, and the theoretical maximum of grain and biomass yield calculated from the fitting results were 6483 in 17,282 kg ha−1 under SL, and 5440 and 14,501 kg ha−1 under SH, respectively. Results in this study would be helpful in the adoption of straw incorporation and brackish water irrigation in ways that facilitate soil water availability and reduce the risk of soil salinization.

Soil Water-Salt Dynamics and Maize Growth as Affected by Cutting Length of Topsoil Incorporation Straw under Brackish Water Irrigation

“…As Figure 1 indicated, within the soil depth of 0-20 cm, the soil moisture content under L1 and L2 had greater values than that under CK during each stage of maize growth in 2017. The results in the present study were in agreement with the previous studies, which found that the soil moisture of the cultivated layer could be increased due to straw incorporation [39]. For example, the soil moisture content within 0-20 cm was 17.37%, 10.10% and 4.79% higher under L1, L2 and L3 than that under CK on average in 2017.…”

“…For all treatments, with the continuous irrigation of brackish water, the salinity in the soil has been accumulated at a fairly high level. Compared with the deeper soil, the salt accumulation in the 0-20 cm soil layer in each treatment was more obvious, which has been confirmed by the previous study [39]. Similar patterns were found in 2018, but the SAR of 0-20 cm (5.77, 7.04, 9.15 and 10.43) were obviously lower than that in 2017, and the effects of different lengths of straw incorporated into cultivated fields on soil salinity was more visible, which was likely induced by the impact of continuous straw incorporation [45].…”

“…Since most crops were sensitive to salinity in the early stages of growth, fresh water was applied at 30 mm in all treatments at pre-sowing to enhance germination. Since no suitable brackish water resource could be obtained near the study site, brackish water thus was designed with a salinity of 5 g NaCl L −1 , according to previous researches [38,39], which demonstrated that sodium and chloride were the primary ions of the brackish water resource. For all treatments, brackish water (5 g NaCl L −1 ) with a total amount of 320 mm was applied from seeding to full ripeness ( Table 2).…”

A meta-analysis of the effects of crop residue return on crop yields and water use efficiency

“…Similarly, Levy [44] and Zheng et al [45] reported that brackish water can decrease crop growth and yield, as salt damage makes it difficult for plant roots to absorb water. However, Lu et al [46] showed that applying brackish water increased corn yield and WUE under high crop residue return conditions. Therefore, long-term studies regarding the impacts of crop residue on crop yields under brackish irrigation are needed to identify effective methods of such irrigation.…”

Agroecological concepts and alternatives to the problems of contemporary agriculture: Monoculture and chemical fertilization in the context of climate change

“…The findings of this study indicated that the nitrification process in soil amended with urea was slowed by the application of P fertilizer, indicating that a synergistic feature of N and P nutrient management should be further investigated to slow N losses from agricultural systems. Furthermore, the most frequently form of nitrogen or sulfur fertilizer in soil is nitrates or sulfate (S) (Brito et al, 2007;Vandenberghe et al, 2012), which is likely to exacerbate secondary salinization in the soil layer (Lu et al, 2019;Shen et al, 2016). Increased secondary salinization may lead to a reduction in soil fertilizer availability, which would reduce the productivity of crops, like cotton (Osanai et al, 2017;Tian et al, 2018), sunflower (Aziz et al, 2019), and maize (Lu et al, 2019;Rajeshwar & Khan, 2010).…”