This study presents the evaluation of ten organic cover crops on soil fertility and macronutrient accumulation within their biomass. Field trials were conducted at the organic farm of Tennessee State University using a randomized complete block design with four replications under National Organic Program (NOP) management practices. The cover crops assessed includes barley, crimson clover, daikon radish, field peas, hairy vetch, mammoth red clover, medium red clover, tillage radish, white clover, and winter rye. Each plot measured 16 ft x 7 ft within a whole plot size of 190 ft x 63 ft. Cover crops were sown using a seed drill, adhering to USDA and SARE recommended seed rates. Soil Samples were collected at a foot depth both before and after cover crops termination to analyze the variations in soil properties such as pH, phosphorus, potassium, calcium, magnesium, zinc, iron, manganese, boron, sodium, and organic matter. Aboveground biomass was clipped from 1ft2 quadrants across all replications, dried at 60oC for 72 hours. Samples were grinded to a fine powder using a 1100-watt Ninja blender and analyzed for nitrogen and carbon content using Near-Infrared Spectroscopy (NIRS). Results indicated that most of the cover crops increased soil organic matter, phosphorus, sodium, magnesium, and iron. In contrast, declines were observed in soil pH, potassium, manganese, calcium, boron, zinc. Significant differences were observed in the nitrogen and carbon accumulation among cover crops. Hairy vetch showed the highest nitrogen (4.24%) and carbon (46.62%) content, while barley and daikon radish had the lowest nitrogen (1.55%) and carbon (40.66%) content, respectively. The carbon to nitrogen (C:N) ratio ranged from 11:1 to 30.1:1, with legumes generally exhibiting lower ratios (11:1 to 15.3:1) demonstrating higher decomposition and quicker nutrient release. In contrast non-legumes had the higher ratios (25.4:1 to 30.1:1), suggesting slower nutrient release. These findings highlight the short-term impacts of different organic cover crops on soil fertility and nutrient cycling. The variation in macronutrient accumulation and C:N ratios provides practical insights for the growers in selecting appropriate cover crops to enhance soil health and support sustainable agricultural systems.
