Integrating winter cover crops to enhance soil organic matter, weed suppression, and nutrient cycling in organic management systems

Title : Integrating winter cover crops to enhance soil organic matter, weed suppression, and nutrient cycling in organic management systems

Abstract:

Organic farming emphasizes ecological balance, biodiversity conversation, and long-term soil health by eliminating synthetic chemicals and genetically modified organisms. However, weed pressure and nutrient unavailability remain persistent constraints in organic crop production. Cover crops are widely promoted as a sustainable strategy to enhance soil health and productivity. This study evaluated winter cover crops for biomass production, weed suppression efficiency, carbon (C), and nitrogen (N) contributions. A two-year (Yr. 2023-2025) field trials were conducted at certified organic farm at Tennessee State University, Nashville, TN, USA. The experiment followed a randomized complete block design with four replications, and included legume cover crops (crimson clover, while clover, medium red clover, mammoth red clover, Austrian winter peas, hairy vetch), grasses (barley, winter rye) and brassicas (tillage radish, daikon radish), and a no-cover crop control. Above-ground cover crop and weed biomass were quantified by 1-ft2 quadrant sampling, and dried biomass was analyzed for carbon and nitrogen concentrations using near-infrared spectroscopy. Data were analyzed using ANOVA with Tukey’s HSD test and Pearson correlation. Cover crop species differed significantly (p < 0.05) in all parameters. Fresh biomass was highest in hairy vetch (92,347 lb/ac) and lowest in barley (20,042 lb/ac), while hairy vetch also accumulated the highest dry biomass (15,682 lb/ac) and tillage radish exhibited the lowest (7,405 lb/ac). Weed biomass was lowest under hairy vetch (44 lb/ac) and highest in barley (1,045 lb/ac) and winter rye (915 lb/ac). Pearson correlation observed a strong negative relationship of -0.72 to -0.47 between cover crop and weed biomass. Nitrogen concentration was higher in legumes (3.2-4.0%) than in grasses and brassicas (1.2-2.0%), while carbon concentration ranged from 44-47% across species. These findings demonstrate that cover crop species selection strongly influences weed suppression and nutrient cycling, with high-biomass legumes providing superior multifunctional benefits for sustainable organic farming systems.

Biography:

Dr. Nandwani is a Professor of Organic Agriculture at Tennessee State University with over 25 years of experience in organic and sustainable agriculture. He provides leadership in programs such as the Transitional to Organic Partnership Program (TOPP), Urban Agriculture, and Sustainable Cropping Systems. He has organized numerous scientific conferences and training programs for farmers, researchers, and extension professionals and served as Chair, Organic Tropical and Subtropical Fruits workgroup of International Society of Horticultural Science (ISHS). Dr. Nandwani serves on several national and international boards, has edited multiple academic books, published over 300 articles, secured more than $25 million in grants, travelled globally and is a Fellow of the American Society for Horticultural Science.