Open AccessLong‐term agricultural practice effects on carbon and nitrogen isotopes of soil organic matter fractions
Author(s) -
Desrochers Johan,
Brye Kristofor R.,
Pollock Erik D.
Publication year - 2022
Publication title -
agrosystems, geosciences and environment
Language(s) - English
Resource type - Journals
ISSN - 2639-6696
DOI - 10.1002/agg2.20232
Subject(s) - loam , tillage , crop residue , soil carbon , residue (chemistry) , chemistry , nitrogen , agronomy , organic matter , soil organic matter , conventional tillage , soil water , environmental chemistry , environmental science , soil science , agriculture , ecology , biology , biochemistry , organic chemistry
Understanding the effects of long‐term traditional and alternative agricultural management practice effects on carbon (C) and nitrogen (N) cycling and storage within particulate organic matter (POM) and light fractions (LF) within various soil aggregate‐size classes can be illuminated by isotopic 13 C/ 12 C (δ 13 C) and 15 N/ 14 N (δ 15 N) differences. The objective of this study was to evaluate the effects of residue level, residue burning, tillage, and irrigation on δ 13 C and δ 15 N values of the bulk‐soil, macro‐ (>250 μm) and micro‐aggregate‐(53–250 μm), coarse‐ (>250 μm), and fine‐ (53–250 μm) POM, and coarse‐ and fine‐LF in the top 10 cm following 13 yr of consistent management in a wheat ( Triticum aestivum L.)–soybean [ Glycine max (L.) Merr.] double‐crop system on a silt‐loam soil in eastern Arkansas. Various treatment combinations affected ( p < .05) δ 13 C values within the bulk‐soil and fine‐POM, as well as δ 15 N values within the bulk‐soil, macro‐aggregate, coarse‐LF, and fine‐LF fractions. Averaged across all other field treatments, macro‐aggregate δ 15 N was greater ( p < .01) in the no‐tillage (NT)‐low‐ (3.23%) compared with NT–high‐residue (3.05%) and CT‐high‐ and low‐residue combination, which did not differ and averaged 3.11%, indicating that more labile residue can be achieved in the NT–high‐residue treatment combination. Results showed significant variations in aggregate‐associated δ 13 C and δ 15 N, as affected by long‐term residue and water management practices that would otherwise not have been evident from simple, bulk‐soil analysis or a short‐term field study.