Submitted to: Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2019
Publication Date: 6/4/2019
Citation: Novak, J.M., Sigua, G.C., Ducey, T.F., Watts, D.W., Stone, K.C. 2019. Designer biochars impact on corn grain yields, biomass production, and fertility properties of a highly-weathered ultisol. Environments MDPI. 6:64-79. https://doi.org/10.3390/environments6060064.
Interpretive Summary: Biochar is used as an amendment in agricultural soils to improve their ability to bolster important fertility properties. Biochars ability to improve soil fertility is explained by its composition of organic compounds which rebuilds soil organic carbon (SOC) levels and ash material comprised of plant nutrients like phosphorus and potassium. Biochars are expensive and there must be a financial realization that crops or biomass yields are significantly improved. Sandy soils in the Southeastern USA coastal plain region have marginal fertility characteristics, so we conceived a field experiment to determine if biochars applied to a sandy soil would improve both corn grain yields and corn biomass. We conducted this field experiment in South Carolina over three years by planting corn in plots treated with different types of biochars produced from wood and animal manures. We also measured plant available nutrient concentrations after soil extraction with reagents. We found that the biochars did increase plant available soil phosphorus and potassium concentrations. There was no increase, however, in corn grain yields or biomass production. It was speculated that the biochars did not work in our sandy soil because there were no prior soil fertility constraints that limited corn crop production.
Technical Abstract: There are mixed reports for biochars ability to increase corn grain and biomass yields. The objectives of this experiment were to conduct a three-year corn (Zea mays L.) grain and biomass production evaluation to determine soil fertility characteristics after designer biochars were applied to a highly weathered Ultisol. Amendments consisting of biochars and compost were produced from 100% pine chips (PC); 100% poultry litter (PL); PC:PL 2:1 blend; PC mixed 2:1 with raw switchgrass (Panicum virgatum; rSG) compost, and 100% rSG compost. All treatments were applied at 30,000 kg per ha to a Goldsboro sandy loam (Fine-loamy, siliceous, subactive, thermic Aquic Paleudult). Annual topsoil samples were collected in 5-cm depth increments (0 to 15-cm deep) and pH was measured along with Mehlich 1 phosphorus (M1 P) and potassium (M1 K) contents. After three years of corn production, there was no significant improvement in the annual mean corn grain or biomass yields. Biochar applied from PL and PC:PL 2:1 blend significantly increased M1 P and M1 K concentrations down to 10-cm deep, while the other biochar and compost treatments showed mixed results with modifying soil pH. Our results demonstrate that designer biochar additions did not accompany higher corn grain and biomass productivity.