Biochar Added to a Potting Mix Decreased Bell Pepper Transplant Size, While Increasing Nutrient Retention

Biochar, a carbon rich material derived from the pyrolysis of biomass, has shown beneficial chemical and physical when added to the soil. Research into the use of biochar to increase plant productivity and growth has been on the increase over the past decade. Some research has focused on using biochar as an alternative to sphagnum peat moss, but little of this work has been done to determine if biochar can be used in vegetable transplant production. It was the goal of this project to explore the possibility of supplementing an over-the-counter potting mix (Jiffy Mix® Growers Choice #901, Lorain, OH) with biochar. Biochar was added to the potting mix at the following rates on a weight by weight (w/w) basis: 0%, 20%, 40%, 60%, and 80%. Bell pepper Capsicum annuum L. ‘Paladin’ was seeded and grown in three sizes of cell flats (50, 72, and 98) at each of the five biochar ratios. Plant height and biomass were reduced as biochar rates increased, as well as when the cell size was reduced. Growth decreased at differing rates within both factors, showing less reduction in smaller cell sizes and at the higher biochar rates. Nitrate found in the potting mix was leached except in the 60% and 80% biochar mixes. The 60% and 80% biochar mixes had higher levels of nitrates at the end of the experiment than in the beginning. These results indicate that both rate and cell size are important factors for consideration if biochar is used in transplant production.