Document Type

Article

Publication Date

1-2022

Keywords

Lower Mississippi River Delta; wheat-soybean double-crop; organic matter; conventional tillage; soil

Abstract

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 13C/12C (δ13C) and 15N/14N (δ15N) differences. The objective of this study was to evaluate the effects of residue level, residue burning, tillage, and irrigation on δ13C and δ15N 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) δ13C values within the bulk-soil and fine-POM, as well as δ15N values within the bulk-soil, macro-aggregate, coarse-LF, and fine-LF fractions. Averaged across all other field treatments, macro-aggregate δ15N 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 δ13C and δ15N, 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.

Download

Share

COinS