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Carbon and Nitrogen Pools in Deep Soil Horizons at Different Landscape Positions
Author(s) -
Singh Gurbir,
Schoonover Jon E.,
Williard Karl W.J.,
Kaur Gurpreet,
Crim Jackie
Publication year - 2018
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/sssaj2018.03.0092
Subject(s) - nitrogen , carbon fibers , total organic carbon , chemistry , nutrient , soil horizon , agronomy , soil carbon , soil water , soil organic matter , environmental science , zoology , environmental chemistry , soil science , biology , mathematics , organic chemistry , algorithm , composite number
Core Ideas Total C and total N were greater at shoulder position for alfalfa than in the other two land uses. No observed differences for total C among land uses at backslope and footslope positions. Labile pools of C and N showed differences with land use and topographic positions. In general, labile C and N pools followed alfalfa > black walnut plantation > corn–soybean. Labile and bulk pools of carbon and nitrogen (C and N) play different functional roles in soil organic matter dynamics and nutrient cycling. The objectives of this study were to evaluate the (i) effects of land use [corn ( Zea mays L.)–soybean [ Glycine max (L.) Merr.], alfalfa ( Medicago sativa L.), and black walnut ( Juglans nigra L.) plantation] and (ii) vertical distribution of labile [potassium permanganate oxidizable carbon (POXC), water extractable organic carbon (WEOC), water extractable nitrogen (WEN)] and bulk [total carbon (TC), total nitrogen (TN)] pools of C and N in soil to a depth of 105 cm at different topographic positions within a watershed. Alfalfa had 10.02 to 14.86 Mg ha −1 greater TC than corn–soybean and black walnut plantation on the shoulder position in the surface horizon (0–15 cm), whereas the subsurface horizon (15–105 cm) showed no significant differences for TC measured at all topographic positions. Soil POXC was significantly higher in alfalfa than corn–soybean in the surface layer of 0 to 15 cm by 1748.6, 1904.03, and 2878.67 kg ha −1 at the shoulder, backslope, and footslope positions, respectively. However, no differences were observed for POXC at the shoulder position when all subsurface layers were combined at 15‐ to 105‐cm depth. In general, the labile pools of C and N showed differences with land use and topographic positions and followed alfalfa > black walnut plantation > corn–soybean. The study results suggest that for accurate assessment of land use on C and N gains and/or losses both bulk and labile pools should be measured including the entire root zone depth. Topographic differences should be accounted for assessing C and N pools at the watershed scale.