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ARS Home » Southeast Area » Florence, South Carolina » Coastal Plain Soil, Water and Plant Conservation Research » Research » Publications at this Location » Publication #423722
Research Project: Innovative Technologies and Practices to Enhance Water Quantity and Quality Management for Sustainable Agricultural Systems in the Southeastern Coastal Plain

Location: Coastal Plain Soil, Water and Plant Conservation Research

Title: Impact of long-term supplemental irrigation on soil organic carbon and nitrogen in sandy soils under conservation tillage in the southeastern United States

Author
item Paye, Wooiklee
item STONE, KENNETH - Retired ARS Employee
item SZOGI, ARIEL - Retired ARS Employee
item Billman, Eric
item Shumaker, Paul

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/2025
Publication Date: 10/1/2025
Citation: Paye, W.S., Stone, K.C., Szogi, A.A., Billman, E.D., Shumaker, P.D. 2025. Impact of long-term supplemental irrigation on soil organic carbon and nitrogen in sandy soils under conservation tillage in the southeastern United States. Agrosystems, Geosciences & Environment. 8(4).Article e70221. https://doi.org/10.1002/agg2.70221.
DOI: https://doi.org/10.1002/agg2.70221

Interpretive Summary: Agricultural production in the southeastern Coastal Plain of the U.S. faces unique challenges due to sporadic short-term droughts and prevalence of sandy soils having low organic matter and water-holding capacities. This has led to the widespread adoption of supplemental irrigation as a risk reduction strategy against crop yield losses caused by unpredictable short-term droughts in the region. However, the impacts of supplemental irrigation on soil health in the Southeastern Coastal Plain have not been reported. This study compared soil health, carbon and nitrogen stocks of croplands receiving long-term (29-years) of supplemental irrigation with those under non-irrigated conditions. We found no difference in soil health and carbon and nitrogen storage between irrigated and non-irrigated conditions. Although irrigation is important in preventing drought-induced yield losses in the southeastern Coastal Plain region, our results showed that irrigating provided no benefit to soil health compared to a non-irrigated field.

Technical Abstract: Management practices that increase soil organic carbon (SOC) and nitrogen (N) stocks improve soil health, crop productivity and agricultural sustainability. While the role of irrigation in improving SOC and N accrual is well-recognized under semiarid conditions, our understanding of its impact on SOC buildup and N stocks in humid climates is limited. Our objective was to quantify the differences in soil carbon (C) and N fractions and the changes in SOC and N stocks between irrigated and rainfed conditions following long-term (29-years) supplemental irrigation in sandy soils under conservation tillage in the southeastern Coastal Plain of the U.S. We sampled four typical Coastal Plain soils under both irrigated and rainfed areas of the same experimental field. We found no significant difference in soil respiration (as 3day-CO2-C), microbial biomass carbon (MBC), hot water-extractable carbon (HWEC), inorganic N and labile organic N (LON) between irrigated and rainfed conditions. In addition, we found no difference in SOC and N stocks under the irrigated versus rainfed scenario. Irrigation is crucial in mitigating the effect of sporadic droughts on agricultural productivity in the southeastern Coastal Plain of the U.S. However, our results indicated that 29 years of supplemental irrigation had no significant impact on soil C and N fractions or SOC and N storage compared to rainfed conditions under continuous long-term conservation tillage.