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Effect of reclaimed water quality and irrigation modes on cation exchange performances of red soil |
WANG Hui*, LUO Lipeng, LIU Chang, TAN Shuai, HU Chuanwang |
College of Water Resources and Civil Engineering, Hunan Agricultural University, Changsha, Hunan 410128, China |
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Abstract The original reclaimed water solution and its diluted 2, 4, and 6 times were selected as the irrigation water source, and irrigation with distilled water(CK)as control. Two irrigation modes named single irrigation with reclaimed water(4 treatments RW, RW-2, RW-4, RW-6)and alternate irrigation with reclaimed water and distilled water(4 treatments ARW, ARW-2, ARW-4, ARW-6)were used to study the effect on cation exchange performances of red soil. The results showed that compared with CK treatment, the exchangeable K+, Na+ and Mg2+ accumulated contents of each treatment under single irrigation mode increased by 121.08%, 520.65% and 16.22% on average, respectively, and decreased with the increase of dilution ratio of reclaimed water, the exchangeable K+ showed the most significant trend. Under alternate irrigation mode of reclaimed water and distilled water, the accumulated contents of exchangeable Na+ and Mg2+ increased by 997.45% and 18.89% on average, respectively, while exchangeable K+ did not accumulate. Under the two irrigation modes, the soil cation exchange capacity(CEC)of each treatment was not significantly higher than that of CK(p>0.05). Except for RW-4 and RW-6, the alkalinity(ESP)of the other treatments was significantly higher than that of CK(p<0.05), and ESP decreased with the increase of dilution ratio under the same irrigation mode. Under the same water quality alternative irrigation, the ESP was higher than that under single irrigation, showing weak alkaline or non-alkaline(ESP<10%). In the red soil region of Southern China, the potential risk of soil secondary salinization will be increased by using the alternative irrigation of reclaimed water and distilled water, while the single irrigation of reclaimed water can moderately reduce the risk.
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Received: 13 April 2020
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