Soil health, crop productivity, microbial transport, and mine spoil response to biochars

Biochar is being evaluated by scientists from the United States Department of Agriculture (USDA) Agricultural Research Service (ARS) for its potential to sequester soil C, to improve soil health, and to increase crop yields. ARS scientists from multiple locations such as Florence, SC, Kimberly, ID, Bowling Green, KY, Corvallis, OR, and St. Paul, MN, are conducting investigations with agronomic experiments at the laboratory, greenhouse, and field plot scales. To further expand biochars utility, ARS scientists have collaborated with United States Environmental Protection Agency (US EPA) investigators to reclaim mine-impacted soils. In the agronomic investigations, both positive and negative aspects of biochar application were revealed. In some experiments, biochars were reported to have no effect on crop yields, and minimal impact on movement of microbial pathogens through soil. In other experiments, biochars were reported to improve soil fertility, increase water retention, and bind with heavy metals in solutions and in mine spoil soils. This variation in biochars influence, substantiates and encourages further work on the designer biochar concept, which states that the biochars can be crafted for targeted agronomic and environmental purposes. There is a need to broadcast the successes and failures of biochar research reported by scientists from both agencies. Consequently, the objectives of this review are: to report on biochar effectiveness as a soil amendment; to ascertain its ability to modify soil properties, to evaluate its impact on soil leaching of microbes; and its potential capacity to help reclaim mine spoil sites

Grazing intensities and poultry litter fertilization levels on corn and black oat yield

The objective of this work was to assess the effect of poultry litter fertilization levels on corn and black oat yield using different grazing intensities, poultry litter levels (mixture of manure and bedding material) and a chemical fertilization level. The experimental design was a randomized complete block in a split-plot arrangement with four replicates. Black oat + ryegrass grazing intensities, characterized by different pasture sward management, with animal entrance at 25, 30 and 35-cm heights and exit at 5.0, 10 and 15-cm heights, were established at the main plots. After the grazing period, corn was grown at the subplots with four levels of poultry litter (0, 4,953, 9,907 and 14,860 kg ha-1), aiming to supply 0, 100, 200 and 300 kg ha-1 of nitrogen, and a treatment with chemical fertilizer, according to soil analysis. Grazing intensities had no effect on corn yield. Corn yield was 7,493, 8,458, 9,188, 10,247 and 11,028 kg ha-1, respectively, for the treatments without and with 4,953, 9,907 and 14,860 kg ha-1 of poultry litter, and the treatment with chemical fertilization. Poultry litter levels have a residual effect on the production of black oat grown in succession to corn

Does fertilizing corn with poultry litter enrich the grain with mineral nutrients?

Whether poultry litter (PL) increases concentration of selected mineral elements in corn (Zea mays L.) grain has not been well investigated. The objective of this study was to determine whether fertilizing corn with PL enriches the grain and other plant parts with selected mineral elements. Corn was grown in the field in northern Mississippi with no fertilization (UTC) or fertilization with 9 or 18 Mg ha–1 PL, or 202 kg ha–1 NH4NO3–N applied in the fall vs. spring. Poultry litter, regardless of application timing, increased soil total N and extractable P, K, Mg, Cu, Mn, and Zn by up to twofold relative to NH4NO3–N. Litter also increased concentration of N, P, Cu, and Zn in leaves and stems but did not particularly enrich the grain with any of the measured elements. Grain N, P, K, Mg, Fe, Mn, and Zn concentrations were highest in corn fertilized with 202 kg ha–1 NH4NO3–N applied in the spring. Poultry litter increased grain concentrations of these elements to equal those of the NH4NO3–N fertilized corn only if it also increased the N level in the plant and the grain. High positive correlation of grain N with grain P, K, Mg, Fe, Zn, and Mn suggests that conditions that increase grain protein level would also increase the levels of P, K, Mg, Fe, Zn, and Mn in the grain and that the level of mineral elements in corn grain is dependent on the level of N nutrition of the corn plant

Effect of turning frequency and season on composting materials from swine high-rise facilities

Composting swine slurries has several advantages, liquid slurries are converted to solids at lower moisture, the total volume and weight of material is reduced and the stabilized product is more easily transported off-site. Despite this, swine waste is generally stored, treated and applied in its liquid form. High-rise finishing facilities (HRFF) permit liquid slurries to be converted to solids which are partially decomposed underneath the HRFF and then finished in compost windrows. The purpose of this study was to evaluate the effect of turning frequency and ambient weather conditions on biological, physical and chemical properties of composted slurry-woodchip mixtures from HRFF. Compost trials were conducted in either fall (FT) or spring (ST) and piles were turned once or three times per week or upon compost temperature reaching 65 °C. Physical, chemical and microbiological characteristics were measured over the course of 112 (FT) or 143 (ST) days of composting. Total carbon, total nitrogen (N) and inorganic N decreased in all piles. Ammonium decreased while nitrate increased in all piles (including unturned), but total N losses were greatest in piles turned more frequently during the ST. Microbial populations of nitrifiers were dominated by ammonia-oxidizing archaea (3.0 X 10^3–4.2 X 10^6 cells g^-1 compost) but ammonia oxidizing bacteria (below detection to 6.0 X cells g^-1 compost) varied in response to turning and compost temperature; denitrifiers were present in high concentrations throughout the process. Swine HRFF materials composted well in windrows regardless of turning frequency and despite significant differences in starting materials and low initial C/N. Volume reduction, low moisture and low readily degradable organic matter suggest that the finished compost would have lower transportation costs and should provide value as a soil conditioner