Quantitative study on the fate of residual soil nitrate in winter wheat based on a 15N-labeling method.
A considerable amount of surplus nitrogen (N), which primarily takes the form of nitrate, accumulates in the soil profile after harvesting crops from an intensive production system in the North China Plain. The residual soil nitrate (RSN) is a key factor that is included in the N recommendation algorithm. Quantifying the utilization and losses of RSN is a fundamental necessity for optimizing crop N management, improving N use efficiency, and reducing the impact derived from farmland N losses on the environment. In this study, a 15N-labeling method was introduced to study the fate of the RSN quantitatively during the winter wheat growing season by 15N tracer technique combined with a soil column study. A soil column with a 2 m height was vertically divided into 10 20-cm layers, and the RSN in each layer was individually labeled with a 15N tracer before the wheat was sown. The results indicated that approximately 17.68% of the crop N derived from RSN was located in the 0-2 m soil profile prior to wheat sowing. The wheat recovery proportions of RSN at various layers ranged from 0.21% to 33.46%. The percentages that still remained in the soil profile after the wheat harvest ranged from 47.08% to 75.44%, and 19.46-32.64% of the RSN was unaccounted for. Upward and downward movements in the RSN were observed, and the maximum upward and downward distances were 40 cm and 100 cm, respectively. In general, the 15N-labeling method contributes to a deeper understanding of the fates of the RSN. Considering the low crop recovery of the RSN from deep soil layers, water and N saving practices should be adopted during crop production.
College of Agronomy & biotechnology, China Agricultural University/Key Laboratory of Farming System, Ministry of Agriculture, Beijing, China.|Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, Hebei, China.
Jing-Ting
JT
Zhang
College of Agronomy & biotechnology, China Agricultural University/Key Laboratory of Farming System, Ministry of Agriculture, Beijing, China.
Zhi-Min
ZM
Wang
Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, Hebei, China.
Shuang-Bo
SB
Liang
College of Agronomy & biotechnology, China Agricultural University/Key Laboratory of Farming System, Ministry of Agriculture, Beijing, China.
Ying-Hua
YH
Zhang
College of Agronomy & biotechnology, China Agricultural University/Key Laboratory of Farming System, Ministry of Agriculture, Beijing, China.
Shun-Li
http://orcid.org/0000-0002-4913-0645
SL
Zhou
Wuqiao Experimental Station, China Agricultural University, Hebei, China.
Lai-Qing
LQ
Lu
Wuqiao Experimental Station, China Agricultural University, Hebei, China.
Run-Zheng
RZ
Wang
D002681:China; D018556:Crops, Agricultural; D009566:Nitrates / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis; D012621:Seasons; D012987:Soil / Q000737:chemistry*; D014908:Triticum / Q000254:growth & development* / Q000378:metabolism
D009566:Nitrates; D012987:Soil; D009584:Nitrogen