F. J. Larney

Inactivation of Giardia Cysts and Cryptosporidium Oocysts in Beef Feedlot Manure By Thermophilic Windrow Composting

Effects of composting manure on viability of Giardia cysts (GC) and Cryptosporidium cysts (CO) were determined in a two-year study with manure from feedlot cattle bedded on barley straw or woodchips. Each year, manure was deposited in 8 m × 2.5 m × 2 m windrows (one per bedding type) on a sheltered concrete pad. On day 0, porous bags containing 100 g of feces from confirmed Giardia- and Cryptosporidium-positive cattle (9 bags per retrieval day in Year 1; 3 per day in Year 2) were implanted in the windrows. Replicate bags were placed on the concrete pads as uncomposted controls. Windrow temperature and water content were measured and compost was turned mechanically twice each week. Fecal bags were retrieved and subsampled for enumerations of total and viable cysts and cysts after 1, 2, 3, 7, 10, 17, 24 and 31 days in 1998 and after 1, 2, 3, 7, 9, 16, 23, 30, 42, 56, 70 and 98 days in 1999. Windrow temperatures (TEMP) exceeded 55°C during the fourth week of composting, and remained above 50°C for 4 wk thereafter in 1999. Bedding material did not affect overall mean temperature in either year, but TEMP was higher with straw than with woodchip from day 10 to day 17 in 1998 (P < 0.05) and on day 16 and day 42 in 1999 (P < 0.10). In 1998, moisture content decreased from 62.2 to 43.2% during composting of woodchip manure and from 67.3 to 39.3% during composting of straw manure. In 1999, moisture content decreased from 61.0 to 31.8% for woodchip and from 64.5 to 28.6% for straw compost. Percentage of viable CO declined gradually over the 31 days in 1998. The following year revealed a rapid decline in viability of GC and CO once compost temperature exceeded 55°C and viabilities of GC and CO were reduced to zero after 42 days (straw compost) and after 56 days (woodchip compost). Exposure of CO and GC to temperatures > 55°C for a period of 15 days appears to be an effective method of inactivating Giardia cysts and Cryptosporidium cysts in feedlot manure.

Composting as a Means of Disposal of Sheep Mortalities

Four studies explored the feasibility of year-round composting of lamb and mature sheep mortalities within the arid climate of the Canadian prairies. In all studies, a ratio of 2:1:1 (manure : mortalities : chopped straw) was maintained, although depth of the mortality layer within the bin, number of layers of mortalities per bin, age of animal (lamb or mature sheep) and time of year (summer or winter) were varied. Composting neonatal lambs in the spring/summer was successful whether a single layer (n=15 lambs, weight 99.7 kg) or two, separated layers of mortalities (n=41 lambs, weight 198 kg) were added to a 2.4 m3 open bin. Residual bone, wool and soft tissues were negligible after the lamb compost had completed one heating cycle. In contrast, composting mature sheep in the fall/winter was more difficult due to: (1) over wet manure (31% dry matter) resulting in continuous anaerobic decomposition of carcasses; (2) fat/grease accumulation when composting a layer of carcasses 71 cm in depth (weight of sheep 1020 kg). For mature sheep mortalities, 2 heating cycles were required to eliminate soft tissues and wool. As compost in all studies heated in excess of 60°C in the primary and/or secondary bin, bacterial isolates taken after the compost completed the secondary heating cycle were all innocuous species. Provided that compost is protected from excessive moisture and compost is aerated by turning into a secondary bin, a 2:1:1 (manure:mortalities:straw) ratio allowed for year-round composting of lamb and mature sheep mortalities.

Soil salinity and sodicity after application of fresh and composted manure with straw or wood-chips

Limited information exists on the effect of fresh versus composted beef cattle manure containing straw or wood chips on salinity (EC), soluble salts (Ca, Mg, Na, K, Cl, SO4), sodicity (sodium adsorption ratio, SAR), and potassium adsorption ratio (PAR) status of soil in the Great Plains region of North America. A site on a clay loam soil under irrigated barley (Hordeum vulgare) in southern Alberta was used for this study. The treatments were three rates (13, 39, 77 Mg ha-1 dry material) of fresh manure (FM) or composted manure (CM) containing either straw (ST) or wood-chip (WD) bedding, one inorganic (IN) fertilizer treatment, and a control (CON) treatment. All treatments were applied in the fall of 1998, 1999, and 2000. Soil sampling was conducted in the fall of 1998, 1999, 2000, and 2001 prior to manure and fertilizer application. Our results indicated that applying CM to irrigated barley for 3 yr at rates up to 77 Mg ha-1 should not cause an increase in any of the salinity variables compared with FM. C...

Effects of age of cattle, turning technology and compost environment on disappearance of bone from mortality compost.

As residual bones in mortality compost negatively impact subsequent tillage, two studies were performed. For the first study, windrows of mature cattle or calves were placed on a base of barley straw and covered with beef manure. Windrows were divided into two sections and turned at 3-month intervals. Approximately 5000 kg of finished compost per windrow was passed through a 6mm trommel screen, with bones collected and weighed. Bone weight was 0.66% of mature cattle compost and 0.38% of calf compost on a dry matter basis, but did not differ after adjustment for weights of compost ingredients. In a subsequent study, four windrows were constructed containing mortalities, straw and beef manure (STATC) or straw, manure and slaughter waste (STATW). Also, straw, beef manure and slaughter waste was added to an 850 L rolling drum composter (DRUMW). Fresh bovine long-bones from calves were collected, weighed and embedded in the compost. Bones were retrieved and weighed when windrows were turned, or with DRUMW, after 8 weeks. Temperatures achieved followed the order STATW>STATC>DRUMW (p<0.05). Rate of bone disappearance followed a pattern identical to temperature, with the weight of bones in STATW declining by 53.7% during 7 weeks of composting. For STATC, temperatures were uniform over three composting periods, but bone disappearance was improved (p<0.05) when compost dry matter was lower (46%), as compared to 58%. Using a ratio of five parts manure to one part mortalities, results of this study demonstrated that residual bone was <1% of cured cattle compost and may be reduced by maintaining a high compost temperature and moisture content.

Open-Air Windrows for Winter Disposal of Frozen Cattle Mortalities: Effects of Ambient Temperature and Mortality Layering

After imposition of fees for disposal of cattle carcasses by the rendering industry, on-farm methods of mortality disposal are being investigated. Three open-air mortality compost windrows were constructed in January (JAN) and February (FEB) of 2004 in the cold, semiarid climate of southern Alberta, Canada. Windrow A included a base of barley straw a minimum of 46 cm thick, a layer of cattle mortalities (n=12) and a layer of stockpiled manure (minimum of 46 cm) covering the mortalities. Windrows B and C also had a bottom layer of barley straw, with windrow B containing 9 mortalities in 2 layers and windrow C containing 12 mortalities in 3 layers. Due to ambient temperatures > 0°C, carcasses (range 236 to 673 kg) were frozen at the time of windrow construction. Type ‘T’ thermocouples were embedded at the base of B and C windrows and temperatures within 120 cm of the surface were measured using a stainless steel dial probe. Windrows were turned 3 times at 3 mo intervals. Samples were collected from initial compost amendments and prior to each turning for determination of dry matter (DM), organic matter (OM), N, C and coliform bacteria. Ambient temperature was 13°C higher (P < 0.05) for the initial heating of FEB as compared to JAN compost, although the rate of compost temperature decline did not differ between replicates in this period. Days at maximum temperature did not differ between replicates and maximum temperatures in all windrows exceeded 55°C. After 3 heating periods and 9 mo, flesh was not evident and only fragments of bones (max wt. 740 g) were found. Results of this study demonstrate that ambient temperatures < 0°C and frozen mortalities provide no barrier to the use of open-air windrows for disposal of cattle mortalities. As well, stacking up to 3 layers of full-sized cattle mortalities in a windrow did not affect temperature profiles, residual flesh or bone, or analyses of the finished compost. Under the climatic conditions of southern Alberta, layering mortalities would reduce space requirements for large-animal mortality composting in a feedlot setting.

Short-Term Nitrogen Leaching Potential Of Fresh and Composted Beef Cattle Manure Applied to Disturbed Soil Cores

Although fresh beef cattle (Bos taurus) manure has traditionally been applied to cropland in southern Alberta, there has been a recent increase in application of composted manure to cropland in this region. Nitrogen leaching from fresh manure (FM) versus composted (CM) beef cattle manure application has not been investigated in this region. Our objective was to compare short-term (# 23 d) N leaching potential of NO3 -N and NH4 -N under increasing rates (0, 13, 39, 77 Mg ha−1 dry wt.) of FM and CM applied to a clay loam soil under uniform soil and simulated environmental conditions. Amendments were applied and incorporated into repacked 15-cm soil (surface Ah horizon) cores, incubated for 15 d, and then leached under constant-head and saturated conditions in the laboratory. An unamended control (CON) was also used. Leaching potential of NO3-N and NH4-N depended on how the N leaching variable was expressed: peak concentration vs flow-weighted mean concentration (FWMC) vs mass loss vs recovery in leachate. Peak concentrations of NO3-N were at least 90% greater for CM (125.8 mg L−1) than FM (66.3 mg L−1) and the CON (60.5 mg L−1) treatments. The FWMC of NO3-N was significantly (P # 0.05) greater for CM (21.0 mg L1) than FM (16.3 mg L−1). Recovery of NO3-N in leachate as a percentage of total N applied was significantly greater for CM (4.7%) than FM (0.8%). Peak concentrations of NH4-N, FWMC of NH4-N, mass loss of NO3 and NH4, and recovery of NH4, were similar between FM and CM. These results suggest that short-term N leaching potential of CM was greater than FM for peak concentration, FWMC, and recovery of NO3-N.

Biocontained Mortality Compost Using Liquid Manure

During disease outbreaks, composting has been used to safely dispose of carcasses and infectious solid manure. However, optimized methods have not been established to use liquid manure (> 80% water content, WC) from dairies as the substrate for mortality composting. In April of 2007, a 3×2 factorial study was conducted in wooden compost bins (240 × 240 × 140 cm) lined with 0.5 mm plastic to a height of 50 cm. Three levels (LO, 95 kg; MED, 236 kg; HI, 606 kg wet wt.) of liquid manure (91% WC) were applied to barley straw containing a single calf mortality (avg. wt 130 kg). Compost temperature and carcass degradation were evaluated in each bin over 52 d. As an indication of compost efficiency, viability of 4 types of weed seeds (wild buckwheat, Polygonium convolvulus L, BW; dandelion, Taraxacum officinale, DL; stinkweed, Thlaspi arvense L., SW; and wild oat, Avena fatua, WO) was determined from seeds retained at the laboratory (Control) or from those placed in sealed nylon bags (50 μm pore size) embedded at 3 locations in each bin. Initial C: N ratios ranged from 58:1 (HI) to 68:1 (LO), while initial WC was 64, 52 and 42% for the HI, MED and LO treatments, respectively. Rate of compost heating and peak temperature (58.6 vs. 46.5°C) was increased (P < 0.05) for HI as compared to LO. Rate of temperature decline was lower (P < 0.05) and calf decomposition was visibly superior for HI as compared to LO. Viability of WO was eliminated by all compost treatments, but that of BW increased (P < 0.05) in MED and LO as compared to Control. Although HI did not eliminate BW viability, this treatment showed the the most promise for incorporating liquid manure as a substrate in contained mortality compost.

Influence of Long-Term (9 yr) Composted and Stockpiled Feedlot Manure Application on Selected Soil Physical Properties of a Clay Loam Soil in Southern Alberta

ABSTRACT Land application of composted feedlot cattle (Bos taurus) manure may have differential effects on soil physical properties compared to stockpiled manure because of the differences in the composition, particle size, and decomposability of these materials. Our objective was to determine the effect of long-term (9 yr) composted (CM) versus stockpiled (SM) manure application on selected soil physical properties. Intact soil cores were taken from CM, SM, and unamended control treatments from a long-term field experiment in the fall of 2007. Soil bulk density, plant available water (PAW), and soil water retention and hydraulic conductivity at low (0–34 kPa) water potentials were determined on the soil cores. Water retention at the 0 to 10 cm depth was significantly (P ≤ 0.05) greater for SM than CM between -5 and -34 kPa, suggesting an increase in transmission and storage pores in the SM treatment. In contrast, water retention at the 10 to 20 cm depth was greater for CM than SM at -1 and -5 kPa, indicating an increase in transmission pores for this treatment. Based on the results of our study, application of CM instead of SM will likely not improve most soil physical properties measured, with the exception of water retention at certain water potentials in the top two depths. However, organic amendments will likely improve most soil properties measured compared to unamended soils.

Influence of long-term application of composted or stockpiled feedlot manure with straw or wood chips on soil cation exchange capacity

ABSTRACT The influence of annual applications of composted (CM) or stockpiled (SM) beef feedlot manure with straw (ST) or wood-chip (WD) bedding on cation exchange capacity (CEC) of a clay loam soil in southern Alberta was examined after 1, 8, and 15 years. The hypotheses in our study were that soil CEC should be greater for amended than unamended soils; manure type and bedding should have no effect on soil CEC; and soil CEC should increase with greater manure application rate. After fifteen applications, the CEC was significantly greater for amended than unamended soils. Manure type had no significant (P > 0.05) effect on soil CEC after fifteen applications, and the mean soil CEC was 5% greater for WD than ST. Mean CEC was significantly greater by 7 to 12% for the 77 than the 13 and the 39 Mg ha−1 rates after fifteen applications. The soil CEC was increased by 0.061 cmolc kg−1 for a unit increase in application rate (Mg dry wt. ha−1 yr−1), and 96% of the variation in CEC for amended soils could be explained by application rate. Overall, bedding, rate, or adjusting both bedding type and manure rate (but not manure type), may be possible practices for feedlot producers to manage soil CEC.

Transport of Residual Nitrogen and Carbon through Intact Soil Cores Amended with Stockpiled Feedlot Manure with Wood-Chip or Straw Bedding.

The environmental impact of using wood chips instead of straw bedding with feedlot manure on transport and leaching potential from feedlot manure is unknown. Our main objective was to determine if transport of total N, total organic N, NO-N, and nonpurgeable organic C (NPOC) to subsurface soil was lower for soils amended with feedlot manure if combined with wood chips compared with straw. A secondary objective was to compare transport of N and NPOC with organic amendments versus inorganic fertilizer. Stockpiled feedlot manure (SM) with wood chip (SM-WD) or barley straw (SM-ST) bedding at 39 Mg (dry wt.) ha, and inorganic fertilizer (IN) at 100 kg N ha, was applied annually for 13 yr to a clay loam soil in a replicated field experiment in southern Alberta, Canada. Intact soil cores were taken in fall 2011 (0-30 cm depth) from the three treatments, and the residual N and NPOC were eluted from the soil cores. Total N, total organic N, and NPOC were determined on filtered (1.0 μm) effluent samples that are primarily dissolved fraction but may contain some small particulate N and C. Peak concentrations, flow-weighted mean concentrations, and mass loss of total N, total organic N, NO-N, and NPOC were significantly ( ≤ 0.05) lower by 35 to 86% for SM-WD compared with SM-ST. Mean recoveries were also significantly lower for SM-WD than SM-ST by 0.07 to 8% (absolute difference). The transport behavior was similar for SM-WD and IN treatment, but solute transport was greater for SM-ST than for IN. Application of stockpiled feedlot manure with wood chips instead of straw bedding may be a beneficial management practice to reduce transport and leaching potential of N fractions and NPOC.