TY - JOUR
T1 - Tritium and trees
T2 - A bomb peak perspective on soil water dynamics in semi-arid apple orchards
AU - Tao, Ze
AU - Evaristo, Jaivime
AU - Wang, Xia
AU - Chen, Guangjie
AU - Si, Bingcheng
AU - Siddique, Kadambot H.M.
N1 - Funding Information:
Professor Bing Si was funded by National Natural Science Foundation of China (41877017 & 42201051). Ze Tao was funded by Natural Science Foundation of Hebei Province (E2022201018). The soil samples were collected by Ze Tao, which was funed by National Natural Science Foundation of China (41877017 & 42201051). Samples measurements and further data processing were accomplished when Ze Tao was working in Hebei, which were funded by the National Natural Science Foundation of China (41877017 & 42201051) and Natural Science Foundation of Hebei Province (E2022201018). We thank Jingjing Jin, lab manager from the Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, for her assistance in performing sample analyses. We also extend our appreciation to Dong He, Yanli Fan, Peng Li, Wei Xiang and Xin Liu, for their assistance in the field.
Publisher Copyright:
© 2023 The Author(s)
PY - 2023/11
Y1 - 2023/11
N2 - Understanding the relationship between agroforest age and soil water dynamics is crucial for effective land and water resources management. However, the complexities of these dynamics, such as soil water recharge and depletion, hamper in-depth understanding, particularly in water-scarce regions. In this study, we examined soil water recharge and depletion in relation to the stand age of apple trees, a widely planted and representative deep-rooted agroforest, over four years in a semi-arid region on China's Loess Plateau (CLP). We collected soil cores to >20 m depth from four apple orchards (referred to as ‘agroforests’) with variable stand ages (established in 2008, 2005, 1998, and 1994). For comparison, we selected adjacent cropland as land use prior to agroforestry practices (‘control’). We measured soil water content and tritium distributions to model soil water dynamics and estimate water ages across different soil profiles. Our results show that recharge amounts (and depths) in shallow soils were 298.4 mm (7 m), 303.4 mm (6.6 m), 300.6 mm (5.4 m), and 483.1 mm (7.6 m), whereas deep soils had net depletions of 111.1 mm, 391.9 mm, 192.8 mm, and 108.9 mm for AP2008, AP2005, AP1998, and AP1994, respectively. The tritium peak depths, which indicate the 1963 bomb peak depth, significantly differed between agroforested and non-agroforested plots. In particular, agroforestation reduced the seepage velocity of soil water over 20 years. Furthermore, our tritium tracer water age model suggests that the age of transpired deep soil water exceeded 200 years in the oldest orchard. These findings highlight a complex interaction between newly infiltrated water and existing water, possibly due to variations in soil pore size distributions. The results of this study offer valuable insights into the ecohydrological impacts of agroforestation on the CLP and in similar climatic regions.
AB - Understanding the relationship between agroforest age and soil water dynamics is crucial for effective land and water resources management. However, the complexities of these dynamics, such as soil water recharge and depletion, hamper in-depth understanding, particularly in water-scarce regions. In this study, we examined soil water recharge and depletion in relation to the stand age of apple trees, a widely planted and representative deep-rooted agroforest, over four years in a semi-arid region on China's Loess Plateau (CLP). We collected soil cores to >20 m depth from four apple orchards (referred to as ‘agroforests’) with variable stand ages (established in 2008, 2005, 1998, and 1994). For comparison, we selected adjacent cropland as land use prior to agroforestry practices (‘control’). We measured soil water content and tritium distributions to model soil water dynamics and estimate water ages across different soil profiles. Our results show that recharge amounts (and depths) in shallow soils were 298.4 mm (7 m), 303.4 mm (6.6 m), 300.6 mm (5.4 m), and 483.1 mm (7.6 m), whereas deep soils had net depletions of 111.1 mm, 391.9 mm, 192.8 mm, and 108.9 mm for AP2008, AP2005, AP1998, and AP1994, respectively. The tritium peak depths, which indicate the 1963 bomb peak depth, significantly differed between agroforested and non-agroforested plots. In particular, agroforestation reduced the seepage velocity of soil water over 20 years. Furthermore, our tritium tracer water age model suggests that the age of transpired deep soil water exceeded 200 years in the oldest orchard. These findings highlight a complex interaction between newly infiltrated water and existing water, possibly due to variations in soil pore size distributions. The results of this study offer valuable insights into the ecohydrological impacts of agroforestation on the CLP and in similar climatic regions.
KW - Agroforest stand age
KW - Agroforests
KW - Soil water depletion
KW - Soil water recharge
KW - Transpiration water age
KW - Tritium
UR - http://www.scopus.com/inward/record.url?scp=85168851733&partnerID=8YFLogxK
U2 - 10.1016/j.catena.2023.107474
DO - 10.1016/j.catena.2023.107474
M3 - Article
AN - SCOPUS:85168851733
SN - 0341-8162
VL - 232
JO - Catena
JF - Catena
M1 - 107474
ER -