Differential Influence of No-Tillage and Precipitation Pulses on Soil Heterotrophic and Autotrophic Respiration of Summer Maize in the North China Plain

Yunfeng Qiao,Zhao Li,Chao Tian,Fadong Li,Zhaoxin Li,Kun Du,Peifang Leng

doi:10.3390/agronomy10122004

Abstract

It is important to strengthen the studies on the response of soil respiration components to tillage practices and natural precipitation in cropland. Therefore, soil heterotrophic respiration (RH) and autotrophic (RA) respiration were monitored by a root exclusion method in the North China Plain (NCP). The tillage practices included no-tillage (NT) and conventional tillage (CT), and the study periods were the summer maize growth stages in 2018 and 2019. RH, RA, soil water content and temperature were measured continuously for 113 days by an automatic sampling and analysis system. The soil RH values on bright days and rain-affected days were higher under NT in 2018 (14.22 and 15.06 g CO2 m−2 d−1, respectively) than in 2019 (8.25 and 13.30 g CO2 m−2 d−1, respectively). However, the RA values on bright days and rain-affected days were lower under NT in 2018 (4.74 and 4.97 g CO2 m−2 d−1, respectively) than in 2019 (5.67 and 6.93 g CO2 m−2 d−1, respectively). Moreover, NT decreased RH but increased RA compared to CT in 2019. Compared to bright days, the largest increase in both RH and RA after rain pulses was under CT in 2019 (6.75 and 1.80 g CO2 m−2 d−1, respectively). Soil water content and soil temperature were higher in 2018 than in 2019. Moreover, NT increased soil water content and decreased soil temperature on bright days compared to CT in 2019. Furthermore, soil temperature accounted for more variations in RH on bright days and rain-affected days, but soil water content had a greater influence on RA on bright days. However, after precipitation, higher soil water content decreased RA under NT in 2018, while soil water content was positively related to RA under CT in 2019. This study determined the differential response of RH and RA to tillage practices and natural precipitation pulses, and we confirmed that excessively dry soil increases soil carbon loss after rain events in the NCP.

Highlights

Soil respiration (RS ) in cropland is a critical source of increasing atmosphere CO2 [1]
We suggest that the response of RH and RA to precipitation was limited by background respiration on bright days, as highlighted by the previous study [12]
We suggest that to decrease soil respiration in the North China Plain (NCP), cropland transform from tillage to no-tillage practices should not be conducted in the dry year, and we encourage proper but not excessive irrigation during summer maize growth stages under low annual precipitation conditions

Summary

Introduction

Soil respiration (RS ) in cropland is a critical source of increasing atmosphere CO2 [1]. RH is positively correlated with net primary productivity and is essential for assessing terrestrial carbon emissions to the atmosphere [3]. Conservation tillage practices, such as no-tillage (NT), tend to decrease RH and RA when compared to conventional tillage (CT) because of having a lower soil disturbance, which affects the soil water content and temperature and has a significant impact on RH and RA [4,5]. To further understand the response of soil CO2 emissions to NT, it is critical to explore the influence of short-term NT on RH and RA

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Methods

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Discussion

Conclusion