L.M. Safley

Performance of a low temperature lagoon digester

Abstract 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.

Low-temperature digestion of dairy and swine manure

Abstract Laboratory anaerobic digesters were fed dairy and swine manure at the rates of 0.1 and 0.2 kg volatile solids (VS)/ m 3 -day over the temperature range of 10–23°C. The digesters were operated successfully with little indication of instability. Methane (CH 4 ) yield, (B, m 3 CH 4 /kg VS added) was determined to typically decrease linearly as temperature (T, °C) was decreased: Dairy at 0.1 kg VS/m 3 -day B=0.1153+0.0053T Dairy at 0.2 kg VS/m 3 -day B=0.0820+0.0063T Swine at 0.1 kg VS/m 3 -day B=0.2011+0.0053T Swine at 0.2 kg VS/m 3 -day B=0.3177+0.0044T Some increased performance was suggested for the lower loading rates compared with higher loading rates.

Anaerobic lagoon biogas recovery systems

Abstract Floating covers were placed on two anaerobic lagoons to study biogas production. One cover was approximately 370 m2 in size and was located on a lagoon receiving effluent from a poultry anaerobic digester. The second cover was 155 m2 and was located on a swine anaerobic lagoon. The liquid entering the swine lagoon had opportunity for considerable volatile solids (VS) loss prior to entering the lagoon. The poultry and swine lagoons had mean volumetric biogas production rates of 0·07 and 0·05 m3/m3-day, respectively. The areal biogas production rates were 0·16 and 0·13 m3/m2-day for the poultry and swine lagoons, respectively. The mean methane (CH4) concentrations were 64·8% and 62·0% for the biogas from the poultry and swine lagoons, respectively. Biogas production was determined to be a function of VS loading and lagoon temperature. Biogas production rates were reduced at lagoon temperatures below 13–15°C.

Fresh dairy manure characteristics and barnlot nutrient losses

Abstract Seven North Carolina milking herds were studied over a 30-month period to determine nutrient conservation between the time of manure excretion and land application. The relative amount of nutrients, urine and fecal fractions of manure, were determined in each. A simple mass balance, considering the inputs and outputs of a dairy cow, was used to estimate daily manurial nitrogen production. The average value was 0·361 kg of N per cow-day. Of the amount estimated in ‘as-exreted’ manure, 77% of the N, 102% of the P and 90% of the K was determined by mass balance to be removed from storage. Little, if any, nutrient loss was attributed to storage. Barnlot management with complete and frequent manure collection was found to be important. The farms in this study were found to dilute their manure by a factor of two by the time it was land applied.

Loss of nitrogen during sprinkler irrigation of swine lagoon liquid

Abstract 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.

Effects of dairy manure application rate and timing, and injector spacing and type on corn silage production☆

Abstract A 3-year field experiment was conducted with liquid dairy manure to determine the effects of application rate (80 and 160 m 3 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.

A greenhouse study on the response of corn (Zea mays L.) to manure from beef cattle fed antibiotics

Abstract Manure from beef cattle receiving the antibiotics lasalocid or monensin or no antibiotic, was used at rates equivalent to 0, 11, 22 and 44t ha −1 (dry weight) in a greenhouse study with corn ( Zea mays L.). Monensin manure was lower in organic N and P but higher in K than were the other manures. In two successive crops, yields with the antibiotic manures were equal to or greater than yields with the control manure at rates of 22t ha −1 or less. Both antibiotic manures suppressed yield at the 44t ha −1 rate in the first crop but not in the second.

Slurry dairy manure as corn nutrient source

Abstract Application of slurry dairy manure were made on five different farms in the Piedmonts region of North Carolina for three consecutive springs and two falls. The manure supplied sufficient nutrients to produce corn (Zea mays L.) silage yields comparable with commercial fertilizer applications at soil test recommendations. The calculated availability of manurial N varied between farms. Yield was usually not significantly different for fall and spring applications of manure, but sometimes the spring manure application resulted in greater yield. The use of a nitrification inhibitor in fall-applied dairy slurry did not give significant yield differences when compared with similar fall treatments that did not receive this material. For maximum manure utilization efficiency application rates should be below 224kg N ha −1 (80 m 3 manure ha −1 ). The slurry manure nutrient concentrations were found to vary considerably between farms and from season to season at a given farm, indicating the desirability of seasonal manurial analysis. Some test sites, due to previou manure and/or fertilizer applications, were found to be unresponsive to either manure or fertilizer applications. Nitrogen availability (NA) was found to vary with site; however, spring manure applications appear to give higher NA values.

Corrosion of galvanized steel in animal waste environments

Abstract 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.