Paranitrophenol in the Adams–Evans (AE) buffer used for determining lime requirement (LR) is considered a hazardous chemical due to its toxicity. The Moore–Sikora (MS) buffer, which mimics AE soil‐buffer pH, was developed without hazardous chemicals and is currently used for routine soil testing at Clemson University. The MS buffer was designed by considering probable chemicals with pKa values in the desired pH range, potential reaction of the components with soil, and longevity of the buffer during storage. Boric acid, 3‐(N‐morpholino)propanesulfonic acid (MOPS), and 2‐(N‐morpholino)ethanesulfonic acid hydrate (MES) were considered for the new buffer. Once chemicals were identified, a technique of finding appropriate concentrations was utilized by using an equation that could predict the acid titration of a buffer and refining pKa and concentration values until a match was found with measured pH titrations of the AE buffer. The MS buffer contains 212, 131, and 34.8 mmol L−1 of B(OH)3, MOPS, and MES, respectively. The buffer also contains 200 mmol L−1 KOH and 1 mol L−1 KCl. The MS buffer was compared with the AE buffer for determining soil‐buffer pH values on 222 South Carolina soils and 41 North American Proficiency Testing Program soils. The MS soil‐buffer pH was strongly related to AE soil‐buffer pH (r2 > 0.98). Soil‐buffer pH was slightly less with MS buffer than AE buffer, with a mean difference of 0.03 pH units. The lower soil‐buffer pH with MS buffer caused a slightly higher LR than the AE buffer, with a mean difference of 0.34 Mg ha−1 on South Carolina soils. Forty‐four percent of the samples indicating a need for lime did not have a difference in LR between the two buffers. The slightly higher LR with the MS buffer on some of the samples is not expected to raise soil pH too high above target pH values.
A screw press separator was temporarily installed on a commercial swine farm in Horry County, South Carolina. The separator had a 0.5 mm screen and was operated with a single 40 kg weight on each pressure plate arm. Prediction equations were developed from the data to describe the removal of total solids (TS), total volatile solids (VS), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), ammonium nitrogen (NH 4-N), organic nitrogen (organic-N), and total phosphorus (TP). Separated solids were analyzed to determine the percent total solids and the concentration of major plant nutrients. The concentration of total potassium (TK) in the separator influent and effluent was the same within measurement error. The removal of TS, VS, N, and P was found to vary significantly with the TS concentration of the influent manure. Therefore, building management and the methods used to implement the machine in the manure handling system would have a significant impact on separator performance. The prediction equations were used to calculate separator performance for a typical pit-recharge swine building based on observed characteristics on the cooperator's farm. The screw press would be capable of removing 14.
Broiler farms produce large amounts of litter that is typically spread on nearby cropland or is sold to other farmers for use as a fertilizer substitute. Burning litter biomass to provide energy for space heating in broiler houses or for off-site electric generation has been viewed as an attractive alternative to land application and a source of renewable energy. A large litter sample was obtained from a commercial broiler farm following clean-out to evaluate the energy content, ash yield, and characteristics of ash following combustion. Litter ash was evaluated as a possible lime substitute and fertilizer. The energy content of the broiler litter was 14,425 kJ/kg DM and had an ash content of 24.7% dry basis. Broiler litter ash contained large amounts of Ca and a pH of 11.6, however the calcium carbonate equivalency (CCE) was only 32.4% on a dry basis. It was determined that broiler litter ash should not be used as a liming agent since it would result in excessive application of P 2 O 5, K 2 O, Cu, Zn, and Na. Small applications of litter ash, on the order of 2 t/ha or less, can provide the P or K needs of a crop and can serve as a source of key micronutrients without application of large amounts of Zn, Cu, or Na. A 1-MW litter fueled electric power plant would provide enough P 2 O 5 in litter ash to fertilize only 1600 ha at a rate of 100 kg P 2 O 5 /ha. It was also estimated that only 59% of the electrical generating capacity would be available for use by the distribution system over and above the electricity required by the broiler houses that supply litter to the plant. The amount of litter produced on broiler farms is theoretically adequate to provide enough heat to eliminate the purchase of propane for space heating but is limited by heating system efficiency. The amount of land needed to accommodate the ash from an on-farm litter furnace was estimated to be about 20 ha per broiler house. Many technical and economic obstacles need to be overcome to see large scale use of litter as a source of biomass fuel.
ABSTRACT. Maintenance and control of liquid levels in anaerobic lagoons
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