Pedosphere 30(5): 694--702, 2020
ISSN 1002-0160/CN 32-1315/P
©2020 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Short-term effects of biochar and gypsum on soil hydraulic properties and sodicity in a saline-alkali soil
Yue ZHANG1,2, Jingsong YANG1,2, Rongjiang YAO1,2, Xiangping WANG1,2, Wenping XIE1,2
1State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China)
2University of Chinese Academy of Sciences, Beijing 100049 (China)
ABSTRACT
      Salt and sodicity of saline-alkali soil adversely affect the construction of ecological landscapes and negatively impact crop production. The reclamation potential of biochar (BC, wheat straw biochar applied at 1% by weight), gypsum (G, 0.4% by weight), and gypsum coupled with biochar (GBC) was examined in this laboratory-based study by evaluating their effects on a saline-alkali soil (silt loam) with no amendment as a control (CK). Saline ice and fresh water (simulated rainfall) were leached through soil columns to investigate changes in salt content, sodium adsorption ratio (SAR), alkalinity, and pH of the leachate and the soil. Results showed that saturated water content and field water capacity (FWC) significantly increased by 4.4% and 5.6%, respectively, in the BC treatment after a short incubation time. Co-application of biochar and gypsum (GBC) increased soil saturated hydraulic conductivity (Ks) by 58.4%, which was also significantly higher than the sole addition. Electrical conductivity (EC) of the leachate decreased sharply after saline ice leaching; subsequent freshwater leaching accelerated the removal of the rest of the salts, irrespective of the amendment application. However, the application of gypsum (G and GB) significantly enhanced the removal of exchangeable Na+ and reduced leachate SAR. After leaching, the soil salt content decreased significantly for all treatments. The application of gypsum resulted in a significantly lower soil pH, exchangeable sodium percentage (ESP), SAR, and alkalinity values than those recorded for the CK and BC treatments. These results demonstrated that the co-application of gypsum and biochar could improve saline-alkali soil hydraulic conductivity and decrease leaching-induced sodicity over a short period.
Key Words:  field water capacity,saline ice,saturated hydraulic conductivity,sodium adsorption ratio,soil alkalinity
Citation: Zhang Y, Yang J S, Yao R J, Wang X P, Xie W P. 2020. Short-term effects of biochar and gypsum on soil hydraulic properties and sodicity in a saline-alkali soil Pedosphere. 30(5):694-702.
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