Abstract
Nitrate accumulated deep (>100 cm) in the regolith (soil and saprolite) threatens groundwater quality, but most studies focus only on nitrate nearer the surface (<100 cm). Surface soil management versus regolith interactions affect deep nitrate leaching, but their combined impact remains unclear. This study measured how deep nitrate accumulation was affected by crop practices including orchard/cropland planting years, regolith structure, and soil properties in highly weathered subtropical red soils. Deep nitrate storage varied from 43.6 to 1116.3 kg ha-1. Regolith thickness was positively correlated with nitrate storage (R2 = 0.43, p < 0.05). Reticulated red clay (110-838 cm) had 81% of the accumulated nitrate and overlapped with 79% of the nitrate accumulation layer. All of the nitrate accumulation parameters (except for peak depth (PD)) generally increased with the planting years. The difference in peak nitrate concentration (9.0-20.0 mg kg-1) with planting year gradient (3-58 years) varied by 2.2 times, and the difference in nitrate storage (43.6-425.7 kg ha-1) varied by 9.8 times. Texture and pH explain 41.6% of the variation in nitrate concentration. As soil management practices interact with deeper regolith to control the spatial pattern of nitrate accumulation, vulnerable regions could be identified to avoid high accumulation.
| Original language | English |
|---|---|
| Pages (from-to) | 13739-13747 |
| Number of pages | 9 |
| Journal | Environmental Science and Technology |
| Volume | 54 |
| Issue number | 21 |
| Early online date | 13 Oct 2020 |
| DOIs | |
| Publication status | Published - 3 Nov 2020 |
Bibliographical note
Funding Information:This study was financially supported by the National Natural Science Foundation of China (Nos. 41571130051, 41977003, and 41771251), the National Key Research and Development Plan of China (No. 2018YFE0107000), the Science and Technology Service Network Initiative of the Chinese Academy of Sciences (No. KFJ-STS-ZDTP-039), and the Second Tibetan Plateau Scientific Expedition and Research Program (STEP, No. 2019QZKK0306). It is also associated with the U.K. Natural Environmental Research Council China-UK critical zone observatory programme (NE/S009167/1 and NE/N007611/1). Special thanks go to our team members of Soils in Time and Space for their selfless help in the field investigation, laboratory analysis, and early discussion. We sincerely thank Prof. Jo Smith (University of Aberdeen), Dr. Longlong Xia (Institute of Meteorology and Climate Research, Atmospheric Environmental Research), and Dr. Delai Zhong (Hong Kong Polytechnic University) for their useful comments. Shunhua Yang received funds from the China Scholarship Council (No. 201802527019) for a 1-year study at the University of Aberdeen. During the writing of this manuscript, the world is painfully suffering from COVID-19. We are grateful to those who are dedicating themselves to fight against the virus and providing help in our daily life.