Loamy sand soil approaches organic carbon saturation after 37 years of conservation tillage

Abstract

Conservation tillage is reported to increase soil organic carbon (SOC) and total nitrogen (TN) contents, but long-term (>30 yr) field results quantifying the responses in Coastal Plain Ultisols are sparse. The distribution, accumulation, and topsoil storage of SOC and TN after 37 yr of crop production using conventional (CvT) or conservation tillage (CnT) on a Norfolk loamy sand (fine-loamy, kaolinitic, thermic, Typic Kandiudults) were quantified. Soil samples were collected annually from the 0−5-, 5−10-, and 10−15-cm depth increments beneath corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and cotton (Gossypium hirsutum L.) crops. Overall, SOC and TN accumulation in the 0−5-cm depth were highest for Norfolk soil under CnT. Focusing on total long-term changes for the 0−15-cm sampling depth beneath various corn crops shows that CnT and CvT sequestered 24.7 and 21.4 Mg C ha −1 , respectively. Between 1978 and 2016, there was a highly significant (P < .0001) exponential increase in SOC within the top 5-cm soil depth. However, the exponential curves began to plateau suggesting the Norfolk topsoil was approaching its organic carbon (OC) storage capacity. These field measurements strongly indicate that additional topsoil SOC increases with current tillage and crop management practices are limited. or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer.This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Root‐zone enrichment of carbon, nitrogen, and soil‐test biological activity under cotton systems in North Carolina

“…tobacco, peanut, and potatoes) and the predominance of sandy soil texture. Accumulation rates of TSN and STBA have rarely been reported in the literature (Franzluebbers and Stuedemann, 2003;Novak et al, 2020), so how root-zone enrichment of TSN and STBA in this study compares in other regions or studies remains unclear.…”

“…All rights reserved. Wallace, 2008;Novak, Watts, Bauer, Karlen, Hunt, & Mishra, 2020). Change in SOC concentration with time, soil depth, and management is often mirrored by proportional change in total soil N (TSN), although C:N ratio may vary by soil type (Franzluebbers, Langdale, & Schomberg, 1999;Sainju, Senwo, Nyakatawa, Tazisong, & Reddy, 2008a).…”

Soil health assessment after 40 years of conservation and conventional tillage management in Southeastern Coastal Plain soils

“…The (Novak et al, 2020). Cover crop alongside winter fallow were introduced in 2015 as a split-plot within each main tillage plot, resulting in a total of 20 experimental subplots.…”

“…Annual crop residue retention in the tested soils under corn, soybean, and cotton was estimated and ranged from 3.3 to 6.7 Mg ha −1 (Karlen et al, 1984), from 4.0 to 6.2 Mg ha −1 (Hunt et al, 2004), and from 2.8 to 6.5 Mg ha −1 (Hunt et al, 1998), respectively, all of which were higher than cover crop biomass inputs ranging from 0.4 to 3.1 Mg ha −1 (Hunt et al, 1998). It is therefore possible that SOC approached its storage capacity after long-term crop residue returns (Novak et al, 2007(Novak et al, , 2020Poeplau & Don, 2015).…”

Contrasting carbon and nitrogen responses to tillage at different soil depths: An observation after 40‐year of tillage management

“…or soybean [Glycine max (L.) Merr.]. The experimental soil is primarily Norfolk loamy sand (fine-loamy, siliceous, thermic Typic Kandiudults) (Novak et al, 2007(Novak et al, , 2020Ye et al, 2020) with 7.6 ± 0.2% clay and 14.1 ± 1.5% silt. Fertilizers and lime were applied according to soil testing results conducted by Agricultural Service Laboratory of Clemson University and recommendation guidelines provided by Clemson University extension services (Clemson University, 1982).…”