Nitrous Oxide Flux from Poultry-Manured Erosion Plots and Grass Filters after Simulated Rain

Adding carbon-rich materials to fields, like manure, may enhance denitrification. Grass filters, which are used to trap surface runoff from these fields, may also provide a carbon-rich environment that favors water infiltration and denitrification. Nitrous oxide (N2O) may be evolved these settings. It is a radiatively important trace gas and intermediate in the denitrification pathway and several other microbial processes. We measured N2O flux, after simulated rain, using a soil cover technique in poultry-manured plots and grass filters receiving their runoff. Intact soil cores were used to relate the N2O flux to the denitrification potential of the plots. Nitrous oxide fluxes were smaller in grass filters than in manured plots, even though more denitrifying bacteria were present. The average N2O flux in the three most dynamic erosion plots was 755 µg N2O-N m−2h−1, which was 39% of the maximal denitrification rate measured in acetylene-blocked, NO−3-amended soil cores. Nitrous oxide flux immediately after rainfall was greater than N2O flux measurements reported for similar agricultural settings

Filter Strip Length and Fecal Bacteria Trapping from Poultry Waste - An Update

Cheap, efficient, and environmentally sound waste disposal will be needed as Kentucky\u27s broiler industry expands. The filter strip length needed to protect water resources from contaminants in surface runoff is a pressing issue in waste management and water quality. In a previous Soil Science News and Views (Vol. 15, No. 8) we reported that grass filter strips as short as 15 feet can trap over 90% of the fecal bacteria eroding from land-applied and incorporated poultry waste during runoff following rainstorms. In this update, we provide some additional information and conclusions from that study on filter strip length, based on comparisons of filter strips receiving equal amounts of surface runoff

Nitrous Oxide Flux from Poultry-Manured Erosion Plots and Grass Filters after Simulated Rain

Adding carbon-rich materials to fields, like manure, may enhance denitrification. Grass filters, which are used to trap surface runoff from these fields, may also provide a carbon-rich environment that favors water infiltration and denitrification. Nitrous oxide (N2O) may be evolved these settings. It is a radiatively important trace gas and intermediate in the denitrification pathway and several other microbial processes. We measured N2O flux, after simulated rain, using a soil cover technique in poultry-manured plots and grass filters receiving their runoff. Intact soil cores were used to relate the N2O flux to the denitrification potential of the plots. Nitrous oxide fluxes were smaller in grass filters than in manured plots, even though more denitrifying bacteria were present. The average N2O flux in the three most dynamic erosion plots was 755 µg N2O-N m−2h−1, which was 39% of the maximal denitrification rate measured in acetylene-blocked, NO−3-amended soil cores. Nitrous oxide flux immediately after rainfall was greater than N2O flux measurements reported for similar agricultural settings

Trapping Fecal Bacteria and Sediment in Surface Runoff From Cropland Treated With Poultry Litter

Between 1991 and 1994 the broiler population exploded in Kentucky as the poultry industry began to expand. The Kentucky Department of Agriculture predicts that within four years annual broiler production could exceed 275 million birds. This may be good for Kentucky\u27s economy but it carries some important environmental consequences. If expansion continues as anticipated, the estimated waste production from broilers for processing could reach 300,000 tons per year (assuming each broiler house produces 150,000 birds per year and the yearly manure and litter production per house is approximately 160 tons)

The Effect of Organic Matter on Maximum Compactability of Soil

Bulk density is the weight of a given volume of soil expressed by soil scientists as grams per cubic centimeter (g/cm3). The higher the bulk density, the lower the volume of soil occupied by pore space, that volume of soil in which air and water reside. Because of this, there is much interest on the degree to which soil can be compacted. The Proctor test is a means of determining the maximum bulk density that can be attained in a soil sample. This maximum compactibility is widely used on highways and building foundations but has had little use in agricultural soils. In the fall of 1994 we began to determine maximum compactability on samples from plots and fields with variable land use history in Kentucky. This is a report of the preliminary results

Observations on the vibration of axially-tensioned elastomeric pipes conveying fluids

A study of the effect of axial tension on the vibration of a single-span elastomeric pipe clamped at both ends conveying fluid has been carried out both experimentally and theoretically. A new mathematical model using a penalty function technique and the method of kinematic correction and fictitious loads has been developed. The influence of flowing fluid and axial tension on natural frequencies and mode shapes of the system has been described using this model and compared with experimental observations. Linear and non-linear dynamic response of the harmonically excited pipe has also been investigated for varying flow velocities and initial axial tensions

Spectral geometry, homogeneous spaces, and differential forms with finite Fourier series

Let G be a compact Lie group acting transitively on Riemannian manifolds M and N. Let p be a G equivariant Riemannian submersion from M to N. We show that a smooth differential form on N has finite Fourier series if and only if the pull back has finite Fourier series on