Phenology, Nitrogen Status, and Yield of Red Clover (Trifolium pretense L.) Affected by Application of Vitamin B12, Humic Acid, and Enriched Biochar

Studies on vitamin B12's influence on the flowering and yield parameters of red clover (Trifolium pretense L.) are not well documented. A greenhouse experiment investigated the effect of the solo and combined application of vitamin B12 with humic acid and enriched biochar on the morphology, nitrogen status, and biomass yield of the shoots and roots of red clovers. Two levels of vitamin B12 (0, 20 mg pot(-1)) mixed with four growing media were laid out as a randomized complete block design. The results indicated that vitamin B12 markedly led to (A) a decrease in the flowering time by 5 days (100.2 to 95.9 days), while the co-application of B12 and humic acid resulted in further reduction (84.5 days); (B) an increased total number of stems (73.0 to 78.6 plant(-1)); (C) a boost in the root dry weight by 60% (3.8 to 6.4 g) while having no significant influence on the shoot dry weight; (D) a decrease in the leaf trichome density by 30% (49.0 to 35.0 plant(-1)); (E) a rise in the N content of the roots (107.8 to 173.3 mg plant(-1)), while having no influence on shoot N content. biochar's influence on the phenology and productivity of red clovers was minimal. The results highlighted the importance of the application of manure, which is naturally rich in vitamin B12 and humic acid, to forage crops, including red clover.