Premium
Deep‐Soil Adsorption of Nitrate in a Japanese Andisol in Response to Different Nitrogen Sources
Author(s) -
Maeda Morihiro,
Ihara Hirotaka,
Ota Takeshi
Publication year - 2008
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2007.0212
Subject(s) - andisol , chemistry , nitrate , nitrogen , soil water , zoology , environmental chemistry , agronomy , environmental science , soil science , biology , organic chemistry
Nitrate adsorption in a deep Andisol with a high anion exchange capacity (AEC) needs to be studied for groundwater management. We evaluated N balances andNO 3 −content profiles under cropping in Andisol fields after 10 yr of repeated N additions of different N sources—swine compost (SC, N application rate of 800 kg ha −1 yr −1 ), coated urea (CU, 400 kg ha −1 yr −1 ), or NH 4 –N (AN, 400 kg ha −1 yr −1 )—and an unfertilized control (NF). The N losses from the 0‐ to 20‐cm layer of three N‐treated soils during the experiment were 2300 to 2700 kg N ha −1 , which were not significantly different ( P > 0.05). Nitrate‐N retention in deep‐soil profiles up to 450 cm was 1800 to 2300 kg N ha −1 irrespective of N source ( P > 0.05), and was 788 kg ha −1 in the NF treatment. On the other hand, the type of N source affected soilNO 3 −content profiles:NO 3 −from the two types of slow‐release N additions (SC and CU) remained within a depth of 60 cm, whereasNO 3 −in the 180‐ to 280‐cm layer was significantly higher in the AN treatment ( P < 0.05). Stepwise multiple regression analysis showed that the primary contributor to soilNO 3 −content was Al content derived from allophane and imogolite, followed by soil pH andSO 4 2 −with negative impacts. In Andisols of Ibaraki, Japan,NO 3 −leached from the root zones is retained by adsorption in deep layers, which may reduce the risk of groundwater contamination at least for 10 yr.