Composting Unamended Chicken Manure - InfoHouseinfohouse.p2ric.org/ref/31/30805.pdf · egg producer in Ohio is composting unamended chicken manure. Studies were done to characterize

Compost Science & Utilization, (1998). Vol. 6, No. 2,272.35

Composting Unamended Chicken Manure

D.L. Elwell, H.M. Keener, D.S. Carey, and P.P. Schlak Department of Food, Agricultural, and Biological Engineering,

The Ohio State University/OARDC, Wooster, Ohio

Normally, manures are composted with amendments. However, a large commercial egg producer in Ohio i s composting unamended chicken manure. Studies were done to characterize this composting, both in situ and in pilot-scale vessels. While overly wet material can hamper initial operation, the general progression dries the material and produces a granular output that is below 20 percent (wet basis) moisture and can be bagged and/or sold commercially. A rewetting study on the present output material indicated it is incompletely composted. Further studies of initial and partially composted materials characterized heating, reaction rates, oxygen demand and ammonia output during composting. Very high ammonia production relative to more conventional -nanure composting operations is the most important result from this work. Retention and recapture of ammonia is the focus of research to be reported elsewhere.

lntroduction

Numerous studies have characterized composting of animal manures (Kirchmann and Witter 1989; Hansen et aI. 1991; Henry and White 1993; Inbar et al. 1993; Lo et al. 1993; Mahimairaja et al. 3994; Insam et al. 1996). Kroodsma et al. (1995) studied drying of unamended layer manure for odor control. Several chemical amendments have been studied for their effectiveness in reducing ammonia release during poultry manure and/or litter decomposition (Witter and Kirchman 1989a and 198913; Mahimairaja et al. 1994; Moore et al. 1996). However, little work has been reported on composting of unamended materials.

Daylay Egg Farm, Inc., West Mansfield, Ohio, a large, commercial egg producer, is presently composting pure chicken manure at their pullet growing facilities. They are also building a new, large, egg production facility (one million eggs per day before the end of 1997) that is to have facilities for composting 84,000 lbs/day (dry weight) of unamended chicken manure. Uncertainties with their present process relative to compost maturity and ammonia release have led them to cooperate with The

. Ohio State University/OARDC in studies of their present practices and for assistance in planning for future design considerations of ammonia scrubbing and reintroduc- tion of nitrogen compounds.

This paper presents various results relative to the Daylay systems. Temperature, moisture and oxygen data on the compost piles of their present system were collected at the pullet manure composting sites in order to better characterize composting activity as manure progressed through it. In addition, various test runs on manure/compost from three phases of their operation were made in our pilot-scale vessels to obtain more detailed data on decomposition rates and ammonia release rates. This information serves to characterize composting of unamended chicken manure.

Procedures

This study had two distinct parts: on-site data collection from several locations in the full-scale system; and off-site pilot-scale studies of materials obtained from three

22 cwnpow Sclence 8 U t i I i Z a t h spring 1998

1V

to VI

S;

S;

VI

E

C


~~

locations or phases of this system. The three phases involved in the pilot-scale tests were: Phase I, raw chicken manure collected from the input end of the composting system; Phase 11, partially composted manure collected after twelve days (three remixes, see below) into the full-scale process; and Phase 111, final output product from the full- scale system that was rewetted to test for maturity. The actual pilot-scale tests worked with Phases 111, I, and I1 in that order.

On-Site lnformation

Pullets are chickens being grown to production (egg laying) birds. This requires 18 weeks, and grows 40 gm chicks to 1.3 kg (2.9 lb) layers. The manure produced varies with time (Anonymous, 1992). At Daylay, there are presently two pullet growing facilities each of which has two buildings of cages separated by a composting unit. In one unit there are two composting alleys and in the other there is one alley.

Manure from the pullet raising operation is collected on belts that run under the chickens’ cages. These belts are driven a third of their total length each day, so that some of the manure remains on the belts for up to three days and therefore some drying of the manure occurs before it is collected. Manure thus amassed is conveyed by other belts to the head of one of the composting alleys. Each alley is 3.7 m (12 ft) by 85.3 m (280 ft) and has 0.9 m (3 ft) walls along its length with rails on which the turning machine rides. Normally, fresh manure is piled along the first 6.0 m (20 ft) of an alley with- out any treatment, but occasionally, when manure moisture level is too high for normal handling, drier material from later in the operation will be mixed into the fresh material. The initial material is thick and tends to form heavy clumps. A turning machine is directed into the output end of each alley once every three days, and the machine progresses along the length of the alley in 6 to 8 hours. Each turning/mixhg machine ex- tends the width of an alley and uses a rotating axle with beater bars to mix the material and move it to the center of the alley where it is lifted and conveyed back along the alley by a belt to be dropped onto a newly forming pile 6.0 m (20 ft) further toward the output end of the system. After turning, an open space at the head of the alley is avail- able for fresh input material. Exhaust air from the pullet houses (which run along both sides of the compost alleys) picks up moisture from the compost piles and drying occurs as the material progresses toward the output end of each alley. This drying, in com- bination with the mixing and composting that occurs, results in the material becoming less clumped and eventually granular as it progresses toward the output end.

Data on properties of the material in the alleys were collected at various times during the summer of 1996. Temperatures were measured by inserting hand held, dial type probes into the pile at 20 ft intervals. At the same times and locations, samples of the composiing material were collected, weighed, Oven dried (95°C for 48 hrs) and moisture levels and densities were determined. Toward the end of the summer, two sets of oxygen levels in the piles were obtained. A portable oxygen analyzer (Teledyne Brown Engineering Analytical Instruments) was connected to a four foot long, specially made probe for these measurements. Readings were taken at the same 20 ft intervals and were made just prior to and at various time intervals after turning of the material.

Pilot-Scale Tests

The pilot-scale system has been described in detail elsewhere (Elwell et ul. 1994; Hansen et al. 1989). Briefly, it consists of four, 208 liter (55 gallon) vessels each of

Compost Science a Utilization Spring1998 23

D.L. Elwell, H.M. Keener, D.S. Carey and P.P. Schlak

which is insulated with 5.0 cm (two inches) of polystyrene on all sides, equipped with a perforated metal plenum to distribute air flow uniformly through it, supplied with air by thermostatically controlled (high/low flow) fans, and instrumented for temperature (five locations), air flow rate, oxygen uptake, carbon dioxide production and ammonia release measurements. Mixing of materials was done manually. Moisture content of the material was determined from oven drying as described above.

A brief, initial, investigative test (April 15 to 24,1996; run 1) was made on rewetted (to 35 and 45 percent moisture, wet basis [wb]) output product (phase 111) from the full-scale system. In addition, ammonium sulfate was added to two of the vessels (one of each moisture level) in this initial run in order to get some indication of ammonia retention if recaptured ammonia were added back during the composting process. Results of this initial investigation indicated (see below) that ammonia evo- lution was significant once composting activity was high. Thus, to more fully characterize the composting that actually occurred in the full-scale system, more extensive pilot-scale tests were made on the initial, raw chicken manure (run 2, phase I; June 13 to 28, 1996), and then on material that had been partially composted during twelve days in the full-scale system (run 3, phase 11; August 6 to 23,1996). In each of these latter two cases, material was shoveled from the composting alley (at the appropriate distance from its input end) and put into plastic garbage cans. The cans were taken to the OARDC campus in Wooster the next morning and put into the research vessels. Except for some water addition to two of the vessels in run 3 (see Figure 9), there was no treatment of these materials.

Other tests on the Daylay manure/compost have since been run (Carey 1997). These tests involve various factors related to ammonia retention and the reintroduc- tion of recaptured ammonia as ammonium sulfate, and the results of this work will be presented in a later article (Carey et al. 1998).

Data and Laboratmy Information

Temperature, carbon dioxide and oxygen concentrations, and fan operating data were collected hourly or more often and recorded electronically as described elsewhere (Elwell et aI. 1994). Ammonia concentrations were obtained using boric acid traps and titration back to original acidity (Hansen et al. 1991; Bremner and Mul- vaney 1982), usually on a daily basis. Air flow rates through the compost were determined from manually read pressure drops across orifice plates. All these data were processed through computer programs specifically written for this purpose (Keener et al. 1993; Marugg et al. 1993). Material samples collected at various times from both the full-scale system and from the pilot-scale vessels were analyzed for pH, ash content, totai carbon content, avaiiabie nitrogen content, C/N ratio, and various nutrient contents at the Research and Extension Analytical Laboratory on the OARDC campus.

?r

Results

On-Site Information

From the turning/remixing information given above, an approximate conversion

Temperatures were measured along one of the composting alleys at five of 20 ft. along an alley to three days of composting can be made.

Spring 1998

Fii a\\

- PB w Pkk

Ru -

CdI


-Vessel 1 - -Vessel 2 -Vessel 3 - -Vessel 4

70

60

50

40

30

20

10

0 O 5 10

Time (days)

Figure 2. Temperature histories of the top probe in each of the four vessels used in run 1. This was a preliminary study of rewetted output (phase 111) material from the full-scale system; material in vessels 1 and 2 was at 45 percent (wb) moisture while that in 3 and 4 was at 35 percent, vessels 2 and 4 had also had ammonium sulfate added. The times when vessels 1 and 2 were on high fan are indicated.

time for even the wetter materials to begin to heat. Once the wetter two vessels began to heat, however, they warmed rapidly to 60°C and the high fans were switched on in both cases. Dry solid losses for this period corresponded well to activity as suggested by Figure 2, with Vessels 1 to 4 showing 6.0,3.1,1.0 and -2.7 percent loss, respectively. For Vessels 1 and 2, these values are not drastically below those for similar periods for the phase I and phase I1 materials. Reaction rates for these two vessels, depending on the active time interval chosen, would be roughly 0.01 and 0.005 kg/kg.day. This indicates the output (phase 111) material from the full- scale operation retained significant potentia1 for at least brief activity and was not fully mature.

Amounts of 0.7N hydrochloric acid used to titrate the boric acid traps to neu- trality in run 1 could not be converted to ammonia release values due to lack of adequate air flow data. However, the measured peak acid usage corresponded to roughly one third the maximum ammonia release rate for run 2. Thus, these results indicated the "finished" compost can release substantial quantities of ammonia once it is reactivated. Further, the Vessels 2 and 4 results suggested that recaptured ammonia introduced into the composting piles as ammonium sulfate will best be retained when activity is kept low due to dry conditions. A lower pH, however, should affect this latter conclusion (Kirchmann and Witter 1989; Ekinci 1997). Further study has been undertaken (Carey 1997) and will be published shortly (Carey et al. 1998).

Second Pilot-Scale Study: Composting of Raw Manure

For this test, run 2, all four vessels were filled with nominally the same raw, phase I, material. Initial moisture values ranged from 67 to 73 percent moisture (wb). This small difference was critical, and vessel 1, which tested at the highest moisture level, quickly became plugged so that the fans could not push air through it. Remixing did not cure this problem, and attempts to operate this vessel were suspended after the second remix.

Figure 3 shows temperature histories of the top probe in the remaining three vessels of this run. The downward spikes at days 4, 8 and 11 are the result of emptying each vessel for remixing. This figure also shows the fan histories for

r

Fii HI

til rii C(C

Cfl r tt 01 k;

ni

s11

26 compost science S. Utilization

D.L. Elwell, H.M. Keener, D.S. Carey and P.P. Schlnk

40

0 5 10

Time (days)

Figure 5. Dry solids losses during run 2

15

Figure 8 shows cumulative ammonia production amounts. This material is very active in its ammonia production due to its low C/N ratio, and these values are much higher than typically observed in similar studies (Hansen et al. 1989,1991; Mahimairaja et al. 1994; Moore et nl. 1996). However, Kirchmann and Witter (1989) have reported approximately 38 percent ammonia loss within 20 days from their lowest C/N mix- ture, and this is comparable to the present results. These values are consistent with the change in total nitrogen content between initial and final material samples, Table 2, and represent a substantial reduction in potential fertilizer value for the output material from the system.

TABLE 2. Final properties of the materials used in the pilot-scale studies

Total Total Ash Nitrogen Carbon C/N

Ratio (99 (74 (a,) . __ pH - . . . .

Vessel

Phase I, Run 2 2 9.0 t 00 25.75 t 0.93 395 k 0.02 31.75 t 101 8.1 t 0.0 3 9 1 t 0 0 27.96 k 0.70 5 18 t 0.31 2973 t 064 6 1 t 0.0 4 5 1 5 0 0 26.58 2 1.21 5 04 t 0.62 3 2 1 9 t 058 6 1 t 0.7

Phase 11, Run 3 1 8.6 t 0.0 25.50 +. 0.57 5.54 t 0.50 3305 t 093 6 1 t 0.7 2 8 6 t 0.0 28.05 f 0.64 5 35 t 0.25 32.78 t 0.33 6 1 t 0.0 3 8 6 t 0.0 27.10 +. 071 5.26 t 028 33.34 t 028 61 t 0.7 4 8.8 k 0.0 29.25 t 0.49 535 t 027 32.77 t 030 6.1 t 00

Phase 111, Run 1 I 8 1 f 0.0 29.92 t 1.03 5.12 2 0 14 3008 t 1.66 6.1 +. 0.0 2 8.0 t 0.0 32.50 t 105 4.99 k 006 2751 t 074 6 1 & 0.7 3 8 2 k 0.0 25.77 2 0.33 507 k 0.00 3321 t 0.36 7 1 I?: 0.0 4 7.9 * 0.0 26.68 f 0.17 5.74 t 0.20 3061 t 033 51 +_ 0.0

All values based on one random sample tested in duplicate. Run 2 and Run 3 are each full replicates, therefore all measured _____-I __I-

properties can be averaged within them. Run 1 vessels cannot be averaged because each vessel was an individual test. s

28 compost wence (L utilization Spnng 1998


Third Pilot-Scale Study: Composfing of 12 Day Old Material

The third pilot-scale study was conducted on material that was taken from the full- scale system after twelve days of composting. All four vessels were run using the same material. While this material was somewhat lumpy, much of it was broken up into smaller bits, and those lumps that did exist tended to be less than 5 cm across. This material was also significantly drier than the raw manure had been, and measured initial (Le. start of this run) moistures averaged 56.0 +- 2.2 percent. Thus, there was no ten- dency for the material to collapse and plug the vessels.

Temperature histories for run 3 were similar to those shown in Figure 3 for run 2. Initial temperatures were somewhat elevated since the material was warm when it ar- rived. After 12 days of composting in run 2, the raw material had begun to cool even under low fan aeration and had lost considerable activity. However, after the same amount of time in the full-scale system, that is at the start of this pilot-scale run, the material was fully active. It reached the 60°C high fan cut-in temperature very rapidly (about an hour in one case) and maintained significant high fan cooling for 6 to 15 days. This suggests that relatively little composting had occurred in the full-scale system during the first 12 days.

Figure 9 shows moisture level histories, and Figure 10 shows dry solid loss histories for run 3, phase TI material. Here the reaction rates are 0.038 & 0.016 kg/kg.day for the first 2.9 days and 0.011 3.0.002 kg/kg.day for the entire 16.9 day period. These values, however, are dependent on an assumption about the initial "moisture content" being partly composed of volatile organic compounds (VOCs) that were driven from the drying samples at 95°C. As in Elwell et al. (1996), energy and carbon dioxide production balances for this run did not correspond well to the initial, observed dry matter losses but, rather, suggested that more "dry" (Le. not water) matter should have been present initially and shouId have decomposed very readily. This did not seem to be an artifact of the calculations since reasonable correspondence was obtained for aH run 2 and all other run 3 results. In order to obtain similar correspondence for the initial run 3 period, initial moistures for all four vessels were set to 50.0 percent. This amounts to assuming 3.8 to 9.1 percent of the initial wet weight of these materials was VOCs, and it would imply significant anaerobic activity in the full-scale system. Further investigation of this hypothesis is planned for future studies.

Figure 7 shows that air flow per unit of initial mass was less for run 3 (phase 11, post 12 day material) than for run 2 (phase I, "raw" material). When air flow rates are considered (Figure 6), and values for run 3 are adjusted in time by an addition of 12 days and adjusted to the initial mass that would have been present at the start of run 2 (multiplied by 0.7; based on the approximate dry solids loss at 12 days shown in Fig- ure 5), then it appears these two runs were fairly equivalent to two parts of a true se- quence and that material activity was continually decreasing both in the vessels and in the full-scale piles.

Figure 11 shows an example of oxygen and carbon dioxide levels for run 3. Rapid depletion of oxygen and build up of carbon dioxide are observed under low fan air flows well into the run. Similar results were obtained in run 2. Thus, maintenance of aerobic conditions appears to require air flows adequate for cooling for as long as cooling is needed.

Cumulative ammonia emissions for run 3 are shown in Figure 12. While these results are only roughly half as large as for the phase I raw material, very significant release of ammonia is shown here.

Compost Science d Utilization Spring1998 29

D.L. Elwell, H.M. Keener, D.S. Carw and P.P. Schlak

Discussion

The present Daylay operation clearly demonstrates composting unamended chicken manure is possible, as long as the manure is not too moist. In the actual operation of the system, some drying occurs on the collection belts, and this is important for initial functionality of the composting system. Addition of drier output material is also desirable under some circumstances.

It is difficult to interpret the cumulative effects of the pilot-scale runs relative to the complete processes in the full-scale system. Because of variations in the input manure with time, there is no reason to assume the initial, raw state of the partially composted manure (phase 11, run 3) or of the finished compost (phase 111, run 1) accurately matched the raw manure (phase I, run 2) actually studied. Further, the pilot-scale runs were strongly aerobic over most of their course, while the full-scale system became anaerobic for large portions of the active composting period. Thus, in particular, "summing" the results of run 3 (phase 11, partially composted material) onto those of run 2 (phase I, raw manure) combines numbers

1.5, I

0.0 1 J 0 5 10 15 20 25 30

Time (days)

Figure 6. Average, thermostatically controlled air flow rates for runs 2 and 3. Run 2 (phase I, raw material) data, the left most four points, have not been adjusted in any way. Run 3 (phase I1 material) data, have been adjusted as described in the text to account for time and decomposition that occurred in the full-scale system before this material was collected. The smooth curve is a second order regression to the nine data points.

Fii acc off

C:


50000

I 40000

60%

55%

50%

T 1

- J,

.c)

L

6 45%

e

40%

35%

30%

0 5 10 15

Tim. (days)

Figure 8. Cumulptive ammonia release during run 2.

0 2 4 6 8 10 12 14 16 18

Time (days)

Figure 9. Moisture histories for run 3. Values shown were from samples obtained prior to water addition. Water was added to vessels 2 and 4 at the first (day 3) and third (day 10) remixes. Amounts added were equal to 4.9 and 4.7 percent of the wet weight in the two vessels, respectively, at the first remix, and to 9.5 and 8.8 percent at the third remix.

Compost Science 8 Utilization Spring1998 31


30-

10 15 0 5 Time (days)

Figure 10. Dry solids losses during run 3. The initial period includes the adjustments discussed in the text.

for materials that were produced 42 days apart and that experienced a distinctly different first 12 days of composting. Nevertheless, there is good indication that general trends and approximate overall values (as below) can be determined. The airflow rates shown in Figure 6, and the fact that after a simple adjustment the two data sets can be fit to a reasonable trend line as shown, particularly support this assertion.

Figure 5 dry solids losses were 29.9 k 3.6 percent for phase I material. Averag- ing the final ash values shown in Table 2 for the phase i vessels and dividing by the initial value in Table 1 indicates that 33.8k4.9 percent of the initial phase I material had been consumed. These figures are consistent and indicate that

25 3 20

W

C .o 15

E! g 10

u

-id

u C 0 0 5

0 0 5 10 15

Time (days)

Figure 11. Oxygen and carbon dioxide readings for run 3, vessel 2. These values are for the outlet air stream from the compost, and they are reasonably representative of the readings for all vessels.

Spring 1998 32 Compost Science B utilization

ak in) 18 PE AU a c

fo, fla ret

Vi3

W:<

fat, P= reel

P" ac: tell in$( lic

Vi3

thc

coir

D.L. Elwell, H.M. Keener, D.S. Carey and P.P. Scklak

The 1.71 0.3 percent value for phase 11, however, both exceeds the calculated value of 0.5 k 0.5 percent and, if summed (after mass loss adjustment) with the previous value, suggests the nitrogen content of the output product should have been lower than was measured. The relatively steep slopes of the ammonia release curves, Figure 12, are consistent with the likely solution to this apparent problem. During anaerobic composting, ammonia volatilization is reduced by 90 percent or more (Kirchmann and Wit- ter 1989; Mahimairaja et al. 1994). Thus, ammonia would be retained in the full-scale system when anaerobic conditions existed that would have been released at the same time in the composting process from the aerobic, pilot-scale vessels. In particular, the phase I1 ammonia release values cannot (even for approximate considerations) be added to the phase I values.

While this leaves some ambiguity, about 4 percent of the initial phase I dry mass is lost as ammonia. For the new Daylay facility, this dry mass will be around 84,000 lbs/ day. Assuming pullet manure adequately represents layer manure, around 3300 lbs/day of ammonia will be released. This would be a significant environmen- tal burden and a considerable loss in potential fertilizer value. The new Daylay facility will have suIfuric acid scrubbing units to clean the air exiting from the composting facility to deal with these problems. Addition of the ammonium sulfate obtained from the scrubbing process back to the compost is being considered, and studies related to this have been undertaken and will be published shortly (Carey et al. 1998).

Acknowledgements

Research was supported by funding from Daylay Egg Farm, Inc., West Mans- field, Ohio, and by State and Federal funds appropriated to the Ohio Agricultural Research and Development Center, The Ohio State University. Use of trade names is for information only and implies neither endorsement of products mentioned nor criticism of similar ones not mentioned.

References Anonymous. 1992. Hy-line management guide. Chicks/Pullets/Layers. 4th edition. Bremner, J.M. and C.S. Mulvaney. 1982. Nitrogen - Total. In: Page, A.L., et al. (eds.). Methods of

Soil Analysis, Part 11. Agronomy Monograph 9595-622. ASA, Madison, Wisconsin. Carey, D.S. 1997. Minimizing nitrogen loss from poultry manure compost amended with am-

monium sulfate. Master’s thesis, The Ohio State University, Columbus, Ohio. Carey, D.S., H.M. Keener and D.L. Elwell. 1998. The effects of ammonium sulfate addition to

partially composted poultry manure. Submitted for publication. Ekinci, K. 1997. Evaluation of decomposition rate, air flowrate and ammonia control of short pa-

per fiber with broiler litter and additives - alum and sulfuric acid. Master’s thesis, The Ohio

Elwell, D.L., H.M. Keener, H.A.J. Hoitink, R.C. Hansen and J. Hoff. 1994. Pilot and full scale eval- uations of leaves as an amendment in sewage sludge composting. Compost Science and Uti- Zizaf ion, 2(2):55-74.

Elwell, D.L., H.M. Keener, and R.C. Hansen. 1996. Controlled, high rate composting of mixtures of food residuals, yard trimmings and chicken manure. Compost Science and Utilization, 4(1):6-15.

Hansen, R.C., H.M. Keener, and H.A.J. Hoitink. 1989. Poultry manure composting: an ex- ploratory study. Trans. ofthe ASAE, 32(6):2151-2158.

Hansen, R.C., C. Marugg, W.M. Keener, W.A. Dick and H.A.J. Hoitink. 1991. Nitrogen transfor- mations during poultry manure composting. ASAE Paper No. 914014. ASAE, St. Joseph, Michigan.

State University, Columbus, Ohio. E-

Spring 1998 34 compost Science 8 Utilization

4


Henry, S.T. and R.K. White. 1993. Composting broiler litter from two management systems. Trans. of the ASAE, 36(3):873-877.

Inbar, Y., Y. Hadar and Y. Chen. 1993. Recycling of cattle manure: The composting process and characterization of maturity. J. Environ. Qual., 223357463.

Insam, H., K. Amor, M. Renner and C. Crepaz. 1996. Changes in functional abilities of the mi- crobial community during composting of manure. Microb. Ecol., 31:77-87.

Keener, H.M., C. Marugg, R.C. Hansen and H.A.J. Hoitink. 1993. Optimizing the efficiency of the composting process. In: Hoitink, H.A.J. and H.M. Keener (eds.). Science and Engineering of Composting. Renaissance Publications, Worthington, Ohio, pp. 59-94.

Kirchmann, H. and E. Witter. 1989. Ammonia volatilization during aerobic and anaerobic manure decomposition. Plant and Soil, 115:35-41.

Kroodsma, W., N.W.M. Ogink and M.A. Bruins. 1995. An emission-controlled storage system for predried layer manure. Pp. 590-598. In. Ross, C.C. (ed.). Seventh International Symposium on Agricultural and Food Processing Wastes. ASAE, St. Joseph, Michigan.

Lo, K.V., A.K. Lau and P.H. Liao. 1993. Composting of separated solid swine wastes. J. Agric. Engng. Res., 54307-317.

Mahimairaja, S., N.S. Bolan, M.J. Hedley and A.N. Macgregor. 1994. Losses and transformation of nitrogen during composting of poultry manure with different amendments: An incuba- tion experiment. Bioresource Technology, 47:265-273.

Marugg, C., M. Grebus, R.C. Hansen, H.M. Keener and H.A.J. Hoitink. 1993. A kinetic model of the yard waste composting process. Compost Science and Utilization, 1(1):8-51.

Moore, P.A., T.C. Daniel, D.R. Edwards and D.M. Miller. 1996. Evaluation of chemical amendments to reduce ammonia volatilization from poultry litter. Poultry Sci., 75:315-320.

Witter, E. and H. Kirchmann. 1989a. Peat, zeolite and basalt as adsorbents of ammoniacal nitrogen during manure decomposition. Plant and Soil, 115:43-52.

Witter, E. and H. Kirchmann. 1989b. Effects of addition of calcium and magnesium salts on ammonia volatilization during manure decomposition. Plant and Soil, 115:53-58.

Compost Science 8 Utilization Spring1998 35

Documents

Composting Unamended Chicken Manure - InfoHouseinfohouse.p2ric.org/ref/31/30805.pdf · egg producer in Ohio is composting unamended chicken manure. Studies were done to characterize