Madhav Dhakal 1,2, Dinesh Panday 1, Fatemeh Etemadi 1, Reza K. Afshar 1, Casey Lapham 1, Andrew Smith 1, Arash Ghalehgolabbehbahani 1
1Rodale Institute, Kutztown, Pennsylvania, USA
2Mississippi Water Resources Research Institute, Mississippi State University, Starkville, Mississippi, USA
Correspondance: Madhav Dhakal and Dinesh Panday, Rodale Institute, Kutztown, PA, USA. dinesh.panday@rodaleinstitute.org , dinesh.livingsoil@gmail.com
Abstract
Tillage and cover cropping influence N, crop yield, quality, and soil properties in organic systems. This study evaluated four N application rates (0, 50, 100, and 150 kg ha−1) in two industrial hemp (Cannabis sativa L.) types (grain and fiber) under conventional till (CT) and no-till (NT), with and without a legume cover crop (CC), in rotation with malt barley (Hordeum vulgare L.) from 2021 to 2024. Measurements included hemp biomass, grain and fiber yield, barley yield and grain quality, soil health indicators, and N use efficiency. Tillage was instrumental to hemp establishment, as NT with cover crop residue (NTCC) resulted in severe stand loss, preventing yield gains despite modest improvements in soil health indicators such as permanganate oxidizable carbon (POXC) and soil protein (typically 10–30 mg kg−1). Because all CCs were established under full tillage, CC biomass could not be compared across tillage systems. Under CT, CCs enhanced hemp biomass and grain yield, and N fertilization up to 100 kg ha−1 improved performance, whereas higher N provided no additional benefit. Barley crude protein and germination were unaffected by CC or N rate, although barley grain yield increased where hemp followed CC or higher N input, reflecting residual N rather than changes in soil C. No statistically significant differences in N use efficiency indices were detected among N rates. Soil health gains under NT did not translate into agronomic viability for hemp. Cover cropping and tillage should be integrated to optimize N use, productivity, and crop quality in organic hemp–barley systems.
Abbreviations: CC= cover crop, CT= conventional till, DON= deoxynivalenol, NC= no cover crop, NT= no-till, NUE= nitrogen use efficiency, POXC= permanganate oxidizable carbon, THC= delta-9-tetrahydrocannabinol
This material is based upon work supported by the Agriculture Research Service , under Grant/Award Number [NR212D37XXXXG001].
