EQUINE BEDDING MATERIALS EFFECT ON PHYSICAL AND

CHEMICAL PROPERTIES OF COMPOSTED STALL WASTE

ABSTRACT

In recent years new bedding materials have been marketed to the

equine industry. Limited research has been conducted to evaluate

how composting impacts the physical and chemical properties of

these materials. In 2010, a study was conducted to evaluate the

effects that bedding materials have on the physical and chemical

properties of composted equine stall waste. Two bedding materials

were evaluated including a pelletized straw product and wood

shavings. Differences were observed in final mass, organic matter,

particle size distribution and several chemical parameters.

Composting resulted in significant reductions in final C:N ratio for all

bedding materials with the greatest reductions occurring in the

straw-based material. Bedding materials appear to influence the

physical and chemical properties of composted equine stall waste

and can have dramatic impacts on the potential of using composted

equine stall waste as a soil amendment.

INTRODUCTIONA typical 455 kg (1,000 pound) horse produces 0.023 m3 (0.82 ft3) of manure

per day weighing more than 22.7 kg (50 pounds). In addition to manure,

equine stall waste includes various bedding materials such as straw or wood

shavings. The amount of bedding added varies based on individual

management, but has been found to range from 2.7 kg per day for wood

shavings to more than 3 kg per day for straw (Komar, 2009). Disposal of this

waste material can be an issue, particularly on small farms with limited

available acres for spreading manure. Recently, composting of this waste

material has been suggested as a potential handling technique for small

equine operations. Much of the research comparing bedding materials’

impact on compost quality has been conducted using beef and dairy waste.

Limited research has been conducted to evaluate the impact that bedding

materials have on the chemical and physical characteristics of composted

equine stall waste.

MATERIALS AND METHODSA study was conducted at the Rutgers Equine Science Center in New

Brunswick, New Jersey to evaluate the chemical and physical characteristics

of two common equine stall bedding materials following an aerated

composting process. The bedding materials included a pelletized wheat

straw product and pine wood shavings. Compost piles were constructed on

May 12, 2010. Four replications of each of the bedding materials were

constructed and placed in a randomized complete block design for statistical

analysis. Digital thermocouples were used to monitor the temperature in the

center of each pile during composting. Physical and chemical properties of

the compost were evaluated using conventional laboratory procedures at the

beginning (day 1) and end of the composting process (day 100). Data were

subjected to analysis of variance and means separated using Fisher’s LSD

(P=.05).

RESULTS AND DISCUSSIONAll materials reached maximum temperatures during the first weeks of

composting. Among materials, only the pelletized straw maintained

temperatures above 55°C . This is in compliance with USEPA guidelines for

microbial decline of at least 15 days at 55°C. Temperatures were below this

threshold for the remainder of the experiment (Figure 1) reaching

temperatures near ambient by the conclusion of the trial. Composting resulted

in significant mass reductions for both bedding materials with numerical

differences observed between the straw and wood materials ( Figure 2.).

Organic carbon was reduced during composting for both materials suggesting

that composting occurred for both treatments (Figure 3.). Differences were

observed in available P with concentrations increasing for both materials

(Figure 4.). No differences were observed in K concentration following

composting (Figure 5.). TKN was greater in the pelletized straw material

following composting (Table 1.). Differences were observed in nitrate-N

following composting with the greatest increase occurring in the pelletized

straw. Particle size was reduced for both materials following composting

suggesting that organic C was degraded during composting (Table 2.)

CONCLUSIONSAs the equine industry continues to expand in New Jersey, manure

management will continue to be an important component of a well-managed

equine operation. Farms with limited acres will need to maximize the

effectiveness of their manure applications to ensure maximum crop yield

while minimizing the potential for environmental impact. Composting horse

stall waste appears to be a promising manure management strategy by

reducing manure volume while providing crop nutrients. Bedding type

appears to impact volume, as well as, the physical and chemical

characteristics of composted equine stall waste. More research is needed to

quantify the effectiveness of alternative bedding materials and to determine

their acceptance by the equine consumer.

Komar*, S.J.1,Williams, C. 2 , Westendorf, M. 3 , Miskewitz, R. 4 Mickel, R.C. 5 ,Bamka, W.J.61Extension Agent, Rutgers Cooperative Extension, Sussex County, Newton, New Jersey 07860, 2. Extension Specialist, Rutgers NJAES Cooperative Extension, New

Brunswick, New Jersey 08901, 3.Extension Specialist, Rutgers NJAES Cooperative Extension, New Brunswick, New Jersey 08901, 4.Assistant Research Professor,

Rutgers University, New Brunswick, New Jersey 08901, 5 Extension Agent, Rutgers Cooperative Extension, Hunterdon County, Flemington, New Jersey 08822, 6

Extension Agent, Rutgers Cooperative Extension, Burlington County, Westampton, New Jersey 08060

Treatment

TKN

%

Nitrate

Nitrogen

ppm

Ammonium

Nitrogen

ppm

Initial Final Initial Final Initial Final

Pelletized

Straw

1.76 2.34 a 9.45 321.94 a 6.07 3.45

Wood Shavings 1.3 1.39 b 9.5 7.67b 6.09 6.01

Effect of Composting on Nitrogen

Table 1. Bedding materials effect on various forms of nitrogen. Any two

means in a column with a different letter are different according to Ficher’s

LSD (P=.05)

Physical appearance of bedding materials after 100 days of composting.

Stall waste is often spread on pasture or hay land

making composting a potential solution for disposal.

Manure management will continue to be an important

consideration for equine operations in New Jersey

20

25

30

35

40

45

50

55

Pile T

em

pera

ture

(d

eg

rees C

)

_____ Wood

Shavings

Treatment> 1” >1/2” >1/4” >1/4”

Initial Final Initial Final Initial Final Initial Final

Pelletized

Straw 25 22 26 24 25 26 24 28

Wood

Shavings 26 22 27 28 25 20 24 26

Wood

Shavings

Pelletized Straw

Table 2. Percentage of material particle size before and after composting.

Any two means in a column with a different letter are different according to

Ficher’s LSD (P=.05)

Particle Size Distribution

0

100

200

300

400

Pelletized Straw Wood Shavings

Mas

s (K

g)

Dry Mass

Initial Final

Figure 2. Dry matter mass (Kg). Any column with an * is

significantly different according to Fischer’s LSD (P=.05)

0

20

40

60

80

100

Pelletized Straw Wood Shavings

%

Organic Carbon

Initial Final

Figure 3. Percent organic Carbon. Any column with an * is

significantly different according to Fischer’s LSD (P=.05)

0

50

100

150

Pelletized Straw Wood Shavings

PP

M

Available P

Initial Final

Figure 4. Available Phosphorus (PPM). Any column with an *

is significantly different according to Fischer’s LSD (P=.05)

0

20

40

60

80

100

Pelletized Straw Wood Shavings

PP

M

Available K

Initial Final

Figure 5. Available Potassium (PPM). Any column with an

* is significantly different according to Fischer’s LSD

(P=.05)

Figure 1. Temperature (°C) during 2010 composting cycle.