Biochar's Effect on Plant Growth and Soil Nutrient Loss
Recent years have shown an increased interest in biochar, a high carbon compound made from pyrolyzed biomass. Biochar is a carbon negative product that has been suggested as a soil amendment. Studies have shown disagreement on the effect of biochar on plant growth and on anion leaching from biochar amended soils. Three experiments were conducted to investigate biochar’s effect on plant growth and on nitrogen and phosphorus leaching. Chapter one focuses on biochar’s effect on root growth. Bread wheat (Triticum aestivum L.) cv. Pavon 76 and Pavon 1RS.1AL were grown in a sandy loam soil amended with sand (50% by weight) and/or biochar (~1.5% by weight). Results indicated that the 1RS.1AL plants had more roots and deeper roots and biochar addition resulted in more root growth, likely due to changes in soil texture. A second study was conducted to investigate nitrogen and phosphorus leaching from Begonias (Begonia semperflorens ‘Viva’) grown in nursery conditions. Different amounts of biochar, ranging from 0% to 30% by weight, were incorporated into potting mix and the amount of nitrate, ammonium and phosphate leached from each pot was measured. No difference in plant growth was detected, but high rates of biochar did reduce the amount of nitrate, ammonium and phosphate leached. The last chapter investigated the biochar’s ability to adsorb nitrate, ammonium and phosphate when added to tall fescue (Festuca arundinacea) turf. Plots were either direct seeded or transplanted as sod with high, low or no biochar applied to the plots. Although plots with transplanted plants clearly leached more nitrate, ammonium and phosphate, the effect of biochar on leaching was less substantial. However, the results do seem to indicate that the biochar does reduce some leaching. Overall, the affect biochar had minimal effect plant growth in these experiments. The begonias showed no change in shoot growth. However, wheat plants tended to have more roots when grown with biochar. Additionally, when the results of the leaching studies for both the begonia experiment and the turf experiment are taken in aggregate, it’s clear that biochar can reduce the amount of nitrate, ammonium and phosphate leached.