The Effect of Multi-Years Reclaimed Water Irrigation on Dryland Carbon Sequestration in the North China Plain

Yanbing Chi,Qiang Zheng,Shumei Ren,Ning Ma,Peiling Yang

doi:10.3390/w13223260

Abstract

Reclaimed water is an alternative water source which could alleviate the shortage of water resources in agricultural systems. Many researchers have studied the effect of reclaimed water on soil environment, crop yield, etc. However, carbon sequestration in reclaimed water irrigated agricultural systems is less studied. This study investigates methane uptake and photosynthesis in reclaimed water irrigation systems contributing to carbon sequestration estimation and analyzes the important factors impacting them. The results show that CH4 uptake is related to soil water-filled pore space (WFPS) with a quadratic and it has the highest uptake when WFPS is between 40 and 50%. Long-term reclaimed water irrigation could significantly decrease (p < 0.05) CH4 uptake and macroaggregate stability in the topsoil. However, reclaimed water had no significant impact on photosynthesis in comparison. The type of fertilizer is an important factor which impacts CH4 emission from soil; urea had a lower CH4 uptake and a higher CO2 emission than slow-released fertilizer. Overall, reclaimed water irrigation could effectively decrease soil carbon sequestration. A soil wetted proportion level of 40–50% was recommended in this study for favorable methane oxidation. Slow-released fertilizer in reclaimed water irrigated agriculture could better control soil carbon emission and soil carbon absorption.

Highlights

Agricultural CH4 production from soil plays an important role in global radiation and the greenhouse effect
Dryland carbon sequestration is necessary for global carbon balance, which includes CH4 uptake and photosynthesis
PC2 were higher than AF treatments, and RW treatments in PC1 were higher than CW treatments

Summary

Introduction

Agricultural CH4 production from soil plays an important role in global radiation and the greenhouse effect. Some studies showed that CH4 contributes 18% of global radiation [1,2], and its greenhouse effect capacity is 26 times that of CO2 [2]. Most studies showed that dryland CH4 uptake accounts for 6% of the total global methane consumption, and it is a very important part of CH4 sink [5,6]. The soil carbon sequestration could be impacted by many factors, such as temperature, soil water content, fertilizer, soil environment, etc. Temperature can significantly promote the activity of methane oxidizing bacteria and increase methane production [7]. Soil moisture can control bacteria activity and affect the soil oxygen content.

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Results

Discussion

Conclusion