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Effect of forage crop establishment on dissolved organic carbon dynamics and leaching in a hill country soil
Author(s) -
Chibuike Grace,
Burkitt Lucy,
CampsArbestain Marta,
Bishop Peter,
Bretherton Mike,
Singh Ranvir
Publication year - 2019
Publication title -
soil use and management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.709
H-Index - 81
eISSN - 1475-2743
pISSN - 0266-0032
DOI - 10.1111/sum.12497
Subject(s) - leaching (pedology) , dissolved organic carbon , agronomy , soil water , environmental science , agrochemical , nitrate , pasture , soil carbon , total organic carbon , environmental chemistry , chemistry , soil science , agriculture , ecology , biology , organic chemistry
Intensive agricultural activities could affect the dynamics and leaching of dissolved organic carbon ( DOC ) and nitrate from agricultural soils to receiving waters. This study investigated soil DOC dynamics immediately (0–12 days) after spraying a hill country perennial pasture with agrochemicals to establish a winter forage crop for supplementary feed production. Two treatments were examined—perennial pasture (without agrochemicals) and swede ( Brassica napobrassica Mill.) cropping (after spraying with agrochemicals), both growing on a Typic Eutrudept. Soil samples were collected from various depths down to 1 m, before the application of agrochemicals (day 0) and 1, 6 and 12 days thereafter. Dissolved organic carbon concentration below the surface soil (<5 cm) was generally not altered by the agrochemicals. This was further proved by the isotopic monitoring of DOC leaching on this soil. Conversely, the agrochemicals significantly ( p = 0.03) increased DOC concentration within the 0–5‐cm soil depth on day 1, due to the direct contribution of organic molecules and/or displacement of organic compounds at adsorption sites by the agrochemicals; and on day 6, due to root necromass decomposition. The increase of nitrate in soil solution at this depth (0–5 cm) on days 6 and 12 suggests that the agrochemicals may have also enhanced nitrogen (N) mineralization in the surface soil. However, the significantly ( p = 0.04) higher DOC /nitrate (molar ratio) of the agrochemical treatment suggests that the agrochemicals used for clearing out pasture before forage crop establishment could lead to a short‐term increase in surface soil denitrification.