EFFECTS OF HORTICULTURAL CHARCOAL ON THE CROP YIELD AND HEALTH OF EARLY GIRL TOMATOES

Horticultural charcoal (biochar) is a common soil amendment used by home gardeners. Biochar is believed to moisturize and enrich soil, allowing for healthier plants and larger crop yields. The hypothesis was that the combination of biochar and soil enriching fertilizer would be the most effective means for growing healthy plants with a higher crop yield. Tomatoes were chosen because they are common plants in both farms and home gardens. The common hybrid Early Girl® tomato was chosen for its early ripening trait and its popularity among gardeners in colder climates such as here in northern Vermont. Sixteen established plants were purchased at the same time and separated into four groups of four: a control group of garden soil with no added fertilizer or biochar, a garden soil group supplemented with biochar, a garden soil group supplemented with fertilizer, and a garden soil group supplemented with a combination of biochar and fertilizer. The plants were monitored on a weekly basis for leaf dimensions, plant height, and crop yield. Each plant received the same amount of water, sunlight, staking and weeding. The results show that biochar combined with fertilizer was the least effective method for growing the plants. The fertilized plants were the strongest and healthiest plants, with large leaves and a crop yield 18% larger in mass than the control. The biochar plants were similar in size to the control plants and produced a crop yield 13% higher than the control. The control plants were the third best performing plants with large, healthy leaves and stems but a slightly lower crop yield than the fertilized plants. The biochar and fertilizer plants were the lowest performing plants, with weak stems, stunted plants, and a crop yield 47% smaller in mass than that of the fertilized plants. Further testing with more groups and a larger variety of plants will be done in the next growing season.