Soil health conditions under cotton production in North Carolina

Authors: Franzluebbers, Alan

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2020
Publication Date: 6/10/2021
Publication URL: https://handle.nal.usda.gov/10113/7709497
Citation: Franzluebbers, A.J. 2021. Soil health conditions under cotton production in North Carolina. Agronomy Journal. 113:2132-2149. https://doi.org/10.1002/agj2.20573.
DOI: https://doi.org/10.1002/agj2.20573

Interpretive Summary: Soils in the southeastern US have had a long history of cultivation and periods of rampant soil erosion and degradation. However, recent cultivation technologies have focused on conservation management that reduces soil erosion and improves soil functioning. This study aimed to assess the soil health condition for cotton production throughout the state of North Carolina. Using a stratified random sampling for sampling, 120 fields were sampled at depths of 0-4-, 4-12-, and 12-24-inch depths. Soil health condition was highly variable depending on inherent soil physical properties and management-dependent soil biological and chemical properties. Soil organic matter and its biologically active components were greater in fields managed with no tillage or strip tillage on a continuous basis compared with conventional disk tillage. Soil pH and soil-test K were not affected by tillage system. Cation exchange capacity was greater in fields managed with continuous conservation tillage than rotated with disk tillage for other crops. Soil-test P was lower with conservation tillage than with disk tillage, but all fields were rated adequate in soil-test P. Crop rotation sequence with high-disturbance crops like peanut, potato, and tobacco led to reduced soil organic matter. History of cover cropping and animal manure application had some positive effects on soil conditions. Overall, the soil health condition of cotton production in North Carolina is fair but shows great promise for improvement with more continuous use of conservation tillage to build soil-test biological activity from relatively low levels at present.

Technical Abstract: Soil organic C (SOC) and N fractions are considered important indicators of soil health due to their multifunctional roles in storing and supplying nutrients, enhancing soil physical properties, and feeding soil biological activity and the important roles it has on plant nutrition. The impact of widespread crop cultivation within a region has rarely been surveyed but could provide a snapshot of soil health condition when associated with a survey of historical management. Such a survey was conducted in North Carolina under cotton cultivation. Surface residue was collected, and soil was sampled at 0-10, 10-30, and 30-60 cm depths from 120 randomly selected fields. Soil properties varied by physiographic region of Piedmont, Coastal Plain, and Flatwoods. Conservation tillage was the dominant form of cotton cultivation, but its use throughout the rotation sequence, was an even greater determinant of its positive impact on soil organic C and N fractions. Soil-test biological activity averaged 138 and 92 mg/kg/3 d under continuous conservation tillage and frequent tillage, respectively, in the surface 10-cm depth, and the effect persisted into the 10-30-cm depth (19% greater) but with lower absolute values. Cover cropping and animal manure had smaller effects on soil organic fractions and routine soil chemical properties. Intermittent tillage in the rotation sequence was the largest impediment to sustained SOC and total soil N accumulation and soil microbial properties. This assessment illustrated positive soil health condition from farmer adoption of conservation tillage, but improvements are possible with more continuous practice of conservation approaches.