SUN Jinjin1，3，5，MA Bin2，4，LI Fujie2，4，HAN Feng2，4，YAO Guodong2，4，WANG Yugang1，3，5
（1. State Key Laboratory of Desert and Oasis Ecology， Xinjiang Institute of Ecology and Geography， Chinese Academy of Sciences， Urumqi 830011， China；2. Urumqi Comprehensive Survey Center on Natural Resources， Urumqi 830057， China；3. University of Chinese Academy of Sciences， Beijing 100049， China；4. Key Laboratory of Natural Resource Coupling Process and Effects， Field observation and research station of water Resources and ecological effect in lower Reaches of Tarim River Basin，， Korla 841000， China；5. National Fukang Desert Ecosystem Field Science Observation and Research Station， Chinese Academy of Sciences， Fukang，831505， China）
Abstract
Objective Global saline-alkali land is extensive， with China alone having approximately 99 million hectares of such land， exacerbated by climate change and improper agricultural practices， posing a primary constraint on agricultural development in arid regions. Gypsum is recognized as an economical and environmentally friendly chemical amendment for saline-alkali soils. This study investigates the impact of desulfurized gypsum on the physicochemical properties of 0-40 cm soil in desert saline-alkali areas of Xinjiang， aiming to elucidate its role in soil improvement. Furthermore， this research aims to reveal the quantitative relationship between the application rate of desulfurized gypsum and soil organic and inorganic carbon content and reserves， as well as the influence of various environmental factors on soil improvement processes. These findings will provide a scientific basis for the amelioration and carbon sequestration of saline-alkali soils in arid regions， thereby mitigating the adverse effects of soil salinization on agricultural productivity.
Methods The study was conducted in the downstream area of the Tarim River， situated at the northeast edge of the Taklimakan Desert. This region experiences a continental， warm-temperate， extremely arid desert climate， characterized by abundant solar radiation， sparse and unevenly distributed precipitation， large diurnal temperature fluctuations， frequent sandstorms， and suspended dust. The average annual precipitation is approximately 60 mm， with an average annual water surface evaporation of approximately 2 500 mm. The experimental design involved the subdivision of a 10 m × 10 m plot into 30 smaller plots measuring 100 cm × 100 cm each. Each plot was surrounded by waterproof plastic barriers to prevent interference during irrigation， with isolation belts between plots. The desulfurized gypsum application rates varied between 0 and 50 t·hm-2 across six treatment levels， based on the soil Na+ and Mg2+ exchange capacity. A control group was included at 0 t·hm-2. Each treatment consisted of five experimental plots， including three for soil profile sampling and two for backfilling to mitigate the impact of sampling. The upper 20 cm of soil was loosened， desulfurized gypsum was applied and thoroughly mixed， and the land was leveled. Soil drilling was conducted at seven time points （after 1，2，3，5，7，21， and 42 d） post-treatment to obtain layered soil samples at depths of 0~20 cm and 20~40 cm. A range of soil parameters， including pH， electrical conductivity （σ）， organic carbon content （wO）， inorganic carbon content （wi）， soil bulk density， and soil water content （ws）， were analyzed. Soil samples were prepared and tested under standard methods. Differences in soil properties were analysed using one-way ANOVA and the least significant difference （LSD） method for comparison. The relationship between soil carbon density and environmental factors was investigated using the Mantel test.
Results and Discussion The study investigated the effects of different application rates of desulfurized gypsum （0，10，20，30， 40， and 50 t·hm-2） on soil improvement and carbon sequestration in the 0~40 cm soil layer. Results revealed a significant reduction in soil pH within the 0~20 cm layer following desulfurized gypsum application， accompanied by increased soil salinity compared to the control treatment. Additionally， soil organic carbon storage peaked at an application rate of 40 t·hm-2， exhibiting a 0. 029 kg·m-2 increase over the control. Compared to the control， soil inorganic carbon storage increased by 0. 211 kg·m-2 and 0. 182 kg·m-2 with application rates of 10 and 40 t·hm-2 of desulfurized gypsum， respectively， while the remaining treatments showed lower inorganic carbon storage than the control. The impact of desulfurized gypsum on soil carbon sequestration was most pronounced within 0~7 days after application， with the greatest effect observed at an application rate of 40 t·hm-2. Furthermore， correlation analysis indicated that changes in soil carbon storage were significantly associated with soil pH， soil salinity， precipitation， and evapotranspiration.
Conclusion After the addition of desulfurized gypsum， the pH of the amended soil layer （0~20 cm） significantly decreased， exhibiting an inverse relationship with soil pH changes. Conversely， soil salinity increased with higher desulfurized gypsum application rates， particularly evident in the 0~20 cm layer， whereas the impact on the 20~40 cm layer was minimal. Within the 0~20 cm layer， treatment with 40 t·hm-2 of desulfurized gypsum resulted in higher organic carbon and inorganic carbon content compared to other treatments. Carbon content decreased with increasing soil depth. Over time， desulfurized gypsum initially promoted inorganic carbon sequestration， but later stages of treatment showed an inhibitory effect on soil carbon sequestration. Furthermore， the study revealed that changes in soil carbon density were influenced by various factors， with significant correlations observed between soil pH， soil salinity， precipitation， evapotranspiration， and carbon storage. From the perspective of the improvement effect and carbon sequestration of saline-sodic soils， flue gas desulfurized gypsum application rate of 40 t·hm−2 can significantly reduce soil pH and has significant carbon sequestration.
Keywords：saline-soline soils； flue gas desulphurization gypsum； soil improvement； soil carbon sequestration
Get Citation:SUN J J， MA B， LI F J， et al. Effects of applying flue gas desulfurized gypsum on improvement and carbon sequestration in saline-sodic soils［J］. China Powder Science and Technology，2024，30（3）：1−12.
Received:2024-03-06.Revised:2024-04-19,Online:2024-04-25。
Funding Project:中国地质调查局地质调查项目，编号： DD20220887、 DD20220871；新疆“天山英才”计划项目，编号：2023TSYCLJ0048）；国 家自然科学基金项目，编号：42371126。
First Author:孙金金（1995—），女，博士研究生，研究方向为土壤碳循环。E-mail：sunjinjin22@mails. ucas. ac. cn。
Corresponding Author:李福杰（1993—），男，工程师，研究方向为干旱区自然资源要素耦合过程。E-mail：Lifujie@mail. cgs. gov. cn。
DOI：10.13732/j.issn.1008-5548.2024.03.001
CLC No:TB44 Type Code:A
Serial No:1008-5548（2024）03-0001-12
