@article{bicudo_safley_westerman_1999, title={Nutrient content and sludge volumes in single-cell recycle anaerobic swine lagoons in North Carolina}, volume={42}, DOI={10.13031/2013.13256}, abstractNote={Fifteen single-stage anaerobic lagoons representing four types of swine production farms (farrow-to-feeder, 
crossing, farrow-to-finish, and finish) were monitored during two years to evaluate performance. Lagoon liquid and 
sludge were characterized for all sites. Lagoon loading rates, percent of lagoon volume occupied by sludge, sludge 
accumulation and age of lagoon at the time of evaluation were determined. The mean annual lagoon liquid Total Kjeldahl 
Nitrogen (TKN) increased with increase in average daily live animal weight per cubic meter (LAW/m3) of lagoon volume, 
and the rate of increase depended upon the type of production farm. The monthly supernatant TKN concentration varied 
as much as 50% over two years for the same lagoon, generally showing a cyclic pattern with highest concentration in 
mid-summer. Of the nutrient mass contained in the lagoon, about 30% of TKN and more than 90% of Total Phosphorus 
(Total-P) and volatile solids (VS) were contained in the sludge. The accumulation of TKN and Total-P in the sludge 
increased linearly with time. Sludge accumulation was found to be impacted both by age of lagoon and loading rate. 
Based on total sludge accumulated and the age of lagoon, it was determined that sludge accumulated at an approximate 
rate of 0.003 m3/yr per kg of LAW. This is higher accumulation rate than reported from a study in Missouri, but lower 
than reported by a study in South Carolina. It is approximately 25% of the value predicted by ASAE Engineering Practice 
EP 403.2 and ASAE DATA D384.1. Additional data is needed on sludge accumulation rates in swine lagoons and 
characterization of sludge, especially considering likely changes in swine nutrition to improve nutrient utilization and 
reduce nitrogen and phosphorus excretion.}, number={4}, journal={Transactions of the ASAE}, author={Bicudo, J. R. and Safley, L. M. and Westerman, P. W.}, year={1999}, pages={1087–1093} }
 @article{safley_1994, title={Best management practices for livestock production}, volume={49}, number={2}, journal={Journal of Soil & Water Conservation}, author={Safley, L. M., Jr.}, year={1994}, pages={57} }
 @article{safley_westerman_1994, title={LOW-TEMPERATURE DIGESTION OF DAIRY AND SWINE MANURE}, volume={47}, ISSN={["0960-8524"]}, DOI={10.1016/0960-8524(94)90116-3}, abstractNote={Laboratory anaerobic digesters were fed dairy and swine manure at the rates of 0.1 and 0.2 kg volatile solids (VS)/ m3-day over the temperature range of 10–23°C. The digesters were operated successfully with little indication of instability. Methane (CH4) yield, (B, m3 CH4/kg VS added) was determined to typically decrease linearly as temperature (T, °C) was decreased: Dairy at 0.1 kg VS/m3-day B=0.1153+0.0053TDairy at 0.2 kg VS/m3-day B=0.0820+0.0063TSwine at 0.1 kg VS/m3-day B=0.2011+0.0053TSwine at 0.2 kg VS/m3-day B=0.3177+0.0044T Some increased performance was suggested for the lower loading rates compared with higher loading rates.}, number={2}, journal={BIORESOURCE TECHNOLOGY}, author={SAFLEY, LM and WESTERMAN, PW}, year={1994}, pages={165–171} }
 @article{safley_westerman_kim_carr_1992, title={CORROSION OF GALVANIZED STEEL IN ANIMAL WASTE ENVIRONMENTS}, volume={40}, ISSN={["0960-8524"]}, DOI={10.1016/0960-8524(92)90119-I}, abstractNote={Specimens of seven different types of steel plate] were subjected to animal waste environments to determine resistance to corrosion during a 49-month trial. The metal types included: unpainted cold-rolled steel (BS), cold-rolled steel covered with epoxy paint (ECS), batch galvanized (BG), Galfan 60 (GF-60), Galfan 90 (GF-90), stainless steel (SS) and drawing quality galvanized (DQ). Specimens were exposed to dairy, swine and poultry manure in the following situations: manure collection pit, animal housing area, suspended over an anaerobic lagoon and submerged in an anaerobic lagoon. The manure collection pit environments caused the greatest amount of corrosion. Only the SS and BG specimens did not suffer metal loss for either the swine, dairy or poultry manure pits. All other metal types suffered appreciable metal loss in manure pit environments with the exception of GF-90 in the swine and dairy manure pits. Very little metal loss was observed on any of the specimens in the animal housing areas or those submerged in the anaerobic lagoons. Of the specimens positioned above the anaerobic lagoons only BS and ECS suffered metal loss.}, number={1}, journal={BIORESOURCE TECHNOLOGY}, author={SAFLEY, LM and WESTERMAN, PW and KIM, MM and CARR, DS}, year={1992}, pages={53–61} }
 @article{safley_barker_westerman_1992, title={LOSS OF NITROGEN DURING SPRINKLER IRRIGATION OF SWINE LAGOON LIQUID}, volume={40}, ISSN={["0960-8524"]}, DOI={10.1016/0960-8524(92)90112-B}, abstractNote={Irrigation experiments were conducted using center pivot and big gun equipment to determine losses of nitrogen that occur during sprinkler irrigation. Anaerobic lagoon liquid was irrigated onto bare ground and nitrogen losses were evaluated for different application rates. The pH of the applied lagoon liquid was found to increase during irrigation. TKN losses occurring during sprinkler irrigation using the center pivot were found to range from 14·9% to 43·4%. Of this amount 53·5–100% was accounted for in volumetric loss (evaporation and drift). Ammonia-N losses occurring during sprinkler irrigation (center pivot) were found to range from 13·9% to 37·3%. Volumetric loss of the liquid during sprinkler irrigation accounted for 62·2–100% of the ammonia-N loss. Due to the sampling technique used it was not possible to estimate volumetric losses for the big gun equipment. However, pH and concentration changes in the irrigated liquid were similar to those observed in the center pivot tests.}, number={1}, journal={BIORESOURCE TECHNOLOGY}, author={SAFLEY, LM and BARKER, JC and WESTERMAN, PW}, year={1992}, pages={7–15} }
 @article{safley_westerman_1992, title={PERFORMANCE OF A DAIRY MANURE ANAEROBIC LAGOON}, volume={42}, ISSN={["1873-2976"]}, DOI={10.1016/0960-8524(92)90086-D}, abstractNote={A single-stage anaerobic lagoon treating dairy manure was studied for approximately four years (April 1987–April 1991). A portion of the lagoon was covered to gather data on biogas production and quality. Methane concentrations in the biogas exceeded 80% throughout the evaluation period. The following relationship between CH4 concentration and sludge temperature was determined: CH4 = 89·514e−0·00381T where CH4 is the per cent CH4 concentration and T is the temperature (°C). Influent and lagoon liquid concentrations for several parameters were monitored. The installation of a separator to process the waste stream going into the lagoon approximately one and a half years into the study reduced the vs loading rate by 17%. Chemical oxygen demand, total solids, volatile solids and volatile fatty acid reductions exceeded 80% (influent compared to lagoon liquid concentrations).}, number={1}, journal={BIORESOURCE TECHNOLOGY}, author={SAFLEY, LM and WESTERMAN, PW}, year={1992}, pages={43–52} }
 @article{safley_westerman_1992, title={PERFORMANCE OF A LOW-TEMPERATURE LAGOON DIGESTER}, volume={41}, ISSN={["0960-8524"]}, DOI={10.1016/0960-8524(92)90188-4}, abstractNote={An earthen digester was constructed to treat the separated liquids from flushed dairy cattle manure. A floating cover was used to harvest the biogas produced. Satisfactory digester performance was found for both winter and summer conditions. However, biogas production was found to fluctuate seasonally with reduced biogas production being noted during the winter. Mean methane (CH4) yield was found to be 0·39 m3 CH4/kg volatile solids (VS) added. Mean biogas concentrations was 68·9% CH4 and 28·3% carbon dioxide (CO2). The loading rate during the period of study (31 October 1988–25 March 1991) was 0·12 kg VS/m3 -day.}, number={2}, journal={BIORESOURCE TECHNOLOGY}, author={SAFLEY, LM and WESTERMAN, PW}, year={1992}, pages={167–175} }
 @article{safley_westerman_1990, title={PSYCHROPHILIC ANAEROBIC-DIGESTION OF ANIMAL MANURE - PROPOSED DESIGN METHODOLOGY}, volume={34}, ISSN={["0269-7483"]}, DOI={10.1016/0269-7483(90)90014-J}, abstractNote={A comprehensive literature review was conducted on psychrophilic anaerobic digestion and design of anaerobic digesters for treating animal manures. Anaerobic digestion of caged layer manure was studied in the laboratory at low temperatures (14–23°C). The digesters were operated to determine combinations of temperature and loading rate that gave acceptable methane yield. Acceptable methane yield was obtained for loading rates ranging between 0·15 kg VS/m day and 0·57 kg VS/m3 day for temperatures of 14°C and 23°C, respectively. The resulting data along with that taken from similar tests documented in the literature was found to approximate the van't Hoff-Arrhenius equation. This equation is then suggested as a technique for determining suitable loading rates for psychrophilic digesters based on data for digesters operated at higher temperatures.}, number={2}, journal={BIOLOGICAL WASTES}, author={SAFLEY, LM and WESTERMAN, PW}, year={1990}, pages={133–148} }
 @article{safley_westerman_king_1989, title={EFFECTS OF DAIRY MANURE APPLICATION RATE AND TIMING, AND INJECTOR SPACING AND TYPE ON CORN-SILAGE PRODUCTION}, volume={28}, ISSN={["0269-7483"]}, DOI={10.1016/0269-7483(89)90084-0}, abstractNote={A 3-year field experiment was conducted with liquid dairy manure to determine the effects of application rate (80 and 160 m3 ha−1), application timing (fall and spring), injector spacing (0·48 and 0·96 m) and injector type (chisel and sweep) on corn (Zea mays L.) silage yield and nitrogen (N) recovery. Harvested N was increased over control plots by chisel injection, narrow injector spacing, spring manure applications, and the high rate of manure application. Silage yield was adversely affected by drought which occurred in the last 2 years of the experiment. Several main factors increased the quantity of N that was not recovered in harvested N or inorganic N in the 0–30 cm layer of soil: chisel > sweep (17%); high > low application rate (109%). Fall application at the low rate generally resulted in lower yield than did 168 kg N ha−1 applied as commercial fertilizer in the spring. There was no significant difference in silage N content between treatments receiving either manure or commercial N fertilizer. Manurial N concentration combined with application rate was determined to have more influence on silage yield than application timing or injector spacing or type.}, number={3}, journal={BIOLOGICAL WASTES}, author={SAFLEY, LM and WESTERMAN, PW and KING, LD}, year={1989}, pages={203–216} }
 @article{safley_nelson_westerman_1983, title={Conserving manurial nitrogen}, volume={26}, DOI={10.13031/2013.34098}, abstractNote={ABSTRACT NITROGEN in manure can be lost by ammonia volatilization, nitrate leaching, and denitrification. Such loss can reduce the value of manure as a source of crop nutrients. This paper reviews past practices in attempting to conserve nitrogen by adding chemicals to manure. Results of two recent experiments are reported. In one, three chemicals—gypsum, super-phosphate, and phosphoric acid—were added to manure to produce a stable ammonium compound. Results indicated that superphosphate and phosphoric acid are effective in conserving ammonia but are not cost effective. In the second study a nitrification inhibitor was found to be effective in conserving manurial nitrogen—especially for manure applied in the fall.}, number={4}, journal={Transactions of the ASAE}, author={Safley, L. M. and Nelson, D. W. and Westerman, P. W.}, year={1983}, pages={1166} }