Drying-wetting cycles consistently increase net nitrogen mineralization in 25 agricultural soils across intensity and number of drying-wetting cycles

Tianhui Lu; Yuhan Wang; Hansong Zhu; Xiaorong Wei; Mingan Shao

doi:10.1016/j.scitotenv.2019.135574

Drying-wetting cycles consistently increase net nitrogen mineralization in 25 agricultural soils across intensity and number of drying-wetting cycles

Sci Total Environ. 2020 Mar 25:710:135574. doi: 10.1016/j.scitotenv.2019.135574. Epub 2019 Nov 18.

Authors

Tianhui Lu¹, Yuhan Wang², Hansong Zhu², Xiaorong Wei³, Mingan Shao⁴

Affiliations

¹ State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Research Center of Soil and Water Conservation and Ecological Environment, Ministry of Education, Chinese Academy of Sciences, Yangling 712100, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
² College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, PR China.
³ State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Research Center of Soil and Water Conservation and Ecological Environment, Ministry of Education, Chinese Academy of Sciences, Yangling 712100, PR China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, PR China. Electronic address: xrwei78@163.com.
⁴ State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Research Center of Soil and Water Conservation and Ecological Environment, Ministry of Education, Chinese Academy of Sciences, Yangling 712100, PR China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, PR China.

PMID: 31787285
DOI: 10.1016/j.scitotenv.2019.135574

Abstract

An increase in extreme weather events such as heavy rainfall and extreme drought causes intensive and frequent drying-wetting (DW) cycles, which have strong effects on the availability of nitrogen (N) for plant growth and development. How the effects of DW cycles on N turnover vary with the intensity and number of DW cycles and soil properties has not been clearly addressed, which hinders predicting soil biogeochemical cycles in a changing world. Herein, we examined the response of net N mineralization in agricultural soils measured at a standard temperature (25 °C) to DW cycles varying in intensity and number. A total of 25 soils differing in texture and organic matter content were collected to create a soil property gradient. We also established the relationships of DW cycle effects on net N mineralization to soil properties. The DW cycles significantly increased N mineralization by 11.05 ± 0.66 mg kg^-¹ (+81.7%), and the increase was consistent across DW intensities and numbers for most soils. The release of inorganic N was dependent on soil properties, while the regulation of soil properties on DW effects varied with DW intensity, with stronger regulation under intense DW cycles (60% to 0% field capacity) than under moderate DW cycles (100% to 20% field capacity). The effect of intense DW cycles on NH₄⁺ increased with clay content but decreased with soil pH and sand content. The effect on NO₃^- has opposite responses to these soil properties when compared with the effects on NH₄⁺. The effect on total inorganic N increased with soil pH and inorganic N concentration. These results indicated that DW cycles have the potential to increase N availability in agricultural soils and highlighted the underestimation of N availability predicted with averaged soil moisture instead of real-time soil moisture under changing soil moisture conditions.

Keywords: Inorganic N release; Intensity of drying-wetting cycles; Number of drying-wetting cycles; Soil moisture; Soil pH; Soil texture.