|SONG, PENG - China Agriculture University|
|ZHOU, BO - China Agriculture University|
|ZHOU, HONGXU - China Agriculture University|
|ZHAO, ZHIRUI - Chinese Academy Of Sciences|
|LI, YUNKAI - China Agricultural University|
Submitted to: Journal of Environmental Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/24/2019
Publication Date: 6/24/2019
Citation: Song, P., Feng, G.G., Brooks, J.P., Zhou, B., Zhou, H., Zhao, Z., Li, Y. 2019. Environmental risk of chlorine-controlled cloffing in drip irrigation system using reclaimed water: the perspective of soil health. Journal of Environmental Science and Technology. 232:1452-1464. https://doi.org/10.1080/08927014.2019.1600191.
Interpretive Summary: The use of chlorine to clean drip irrigation lines can impose a stress on soil bacteria. Unfortunately, the use of chlorine is necessary for drip irrigation lines where reclaimed or recycled wastewater is utilized, because wastewater can build up matter into the irrigation line thus clogging the line. Chemical chlorination is an effective method to control this clogging, but chlorination can be harsh and its effect on soil biological properties as well as soil health can be detrimental. Therefore, we used spring corn planted fields and various chlorine regimes to test the effect of chlorine on soil biology, harvest, and soil health levels over a two year period. A few approaches towards monitoring the soil biology were used including molecular and physiology based approaches in the root zone of the spring corn. The results showed that the content of soil bacteria significantly decreased by 17.7%~44.7%, 7.0%~47.3%, which indicated that the microbial community was reduced. Specific bacteria were more affected by the chlorine which reduced specific nutrient cycling activities in the soil, which led to a decrease in crude fat and protein in the harvested corn; however, corn yield wasn’t reduced. Shorter term use of chlorine appears to have less of an effect on soil biology. The research results can provide a reference for the management of reclaimed water network systems and soil health.
Technical Abstract: Chemical chlorination is an effective method to control the emitter bio-clogging in drip irrigation using reclaimed water, but the broad spectrum of strong oxidative bactericidal action of chlorine causes certain risks to soil microbial communities and even soil health. Therefore, we used spring maize as the research object, field chlorine experiment with drip irrigation using reclaimed water was carried out in two years, high-throughput sequencing technology combined with PLFAs (phosphospholipid fatty acids) technology was used, the biological bio-indicator of soil health (microbial community structure of soil) in the root zone of the spring maize were systematically studied on the effects of different chlorination modes under the drip irrigation using reclaimed water. The effects of microbial community structure on soil enzyme activity and spring maize yield and quality were analyzed. The results showed that the total amount of PLFAs labeled microbes and the content of bacteria significantly decreased by 17.7%~44.7%'7.0%~47.3%, which reduced the microbial community diversity. The relative abundance of Nitrospirae, Actinobacteria and Firmicutes decreased at the bacterial level. The changes of microbial community structure reduced urease, catalase and phosphatase activities, inhibited the conversion and absorption of nutrients in the soil, which led to a decrease in crude fat and protein by 2.2%-16.6% and 2.2%-14.1%, respectively. But the yield of spring maize didn’t significantly reduce. In comparison, long-term use of high concentration short duration chlorination mode was more likely to have adverse effects on soil health than low concentration long duration chlorination mode. The research results can provide a reference for the management of reclaimed water network systems and soil health.