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ASAE Conference Proceeding

This is not a peer-reviewed article.

AMMONIA EMISSION FROM A GROUP-HOUSING FACILITY FOR DRY SOWS

M.G.A.M. van Assel donk

Research Institute for Pig Husbandry, Rosmalen, The Netherlands

, A. I. J. Hoofs

Experimental Farm for Pig Husbandry ?South and West Netherlands? Sterksel, The Netherlands

, N. Verdoes 1

In Swine Housing, Proc. First Int. Conf. (October 9-11, 2000, Des Moines, Iowa), pp. 182-187, St. Joseph, Mich.: ASAE. ,Pub. Date 2000/10/09 . ASAE Pub #701P0001

ABSTRACT

In 1998 a new law was enforced in the Netherlands, requiring that dry sows be housed in groups. Moreover, standards for floor space were increased. At the Experimental Farm for Pig Husbandry South and West Netherlands at Sterksel sows were given the space between the individual stalls as extra space. Ammonia emission in this compartment, where ground tubes were applied, was limited by applying inclined pit walls and by using metal tribar slats. The emission was, on average, 2.15 kg of NH 3 per sow place per year. This is an average reduction of 49% compared with traditional housing. The extra investment and yearly costs for this compartment in relation to traditional compartments were about NLG 190 and NLG 29 per sow place, respectively.

KEYWORDS: Ammonia emission, emitting surface, dry sows

INTRODUCTION

At the moment in the Netherlands emission poor housing systems are obliged in several regions and several cases. In future, all pig houses have to meet these standards. In recent years many emission poor housing systems were developed for individual housed sows. In 1998 a new law was enforced in the Netherlands, requiring that dry sows be housed in groups. Moreover, standards for floor space were increased: one sow should have at least 2.25 m 2 of floor space, 1.3 m 2 of that should be solid. To meet the new requirements, facilities with individual housing for sows must be adapted before 1 January 2008. Farmers are willing to adapt the buildings in an easy way.

At the Experimental Farm for Pig Husbandry South and West Netherlands at Sterksel sows were given the space between the individual stalls as extra space. Ammonia emission in this compartment was limited by applying inclined pit walls and by using metal tribar slats. The purpose of this research was defining ammonia emission according to the measuring protocol, mentioned in the assessment directives emission-poor facilities (Van der Hoek et al., 1996).

MATERIALS AND METHODS

Housing

The compartment consisted of two rows, each having 16 lockable individual stalls (figure 1). The compartment could be divided into 2 pens by means of a fence. Each pen consisted of 2 rows, each with 8 individual stalls. At both sides of the compartment there was a control passage of 55 cm width and a slatted floor, underneath of which was an air inlet channel. The individual stalls were 230 cm deep and 68 cm wide, including the elevated dry-feed hopper. The floor was solid from the front to 205 cm. The last 25 cm in the stalls and the space of 210 cm between the two rows were tribar slats with non-slip material (15 mm slat and 15 mm split). For each sow there was 1.39 m 2 of solid floor and 0.88 m 2 of slatted floor. In the slurry pit there were three manure channels, with inclined walls and a sewerage system. The manure from each channel could be removed separately. The angle of inclination of the walls in relation to the pit floor was 60 0 .

Figure 1: Plan of the compartment with individual stalls with extra space between the stalls (dimensions are in cm)

VanAsseldonk1_files/image1.wmf

Climate

Incoming air was cooled in summer and heated in winter through ground tubes. Fresh air entered the compartment through the air inlet channels under the control passages. A temperature of 20 0 C was targeted. The minimum and maximum ventilation capacity was set at 20 m 3 and 180 m 3 per sow place per hour, respectively. The range from minimum to maximum ventilation was 5 0 C.

Feed and drinking water supply

Twice a day the sows were fed feed (ME = 0.97; crude protein 159 g/kg) through a dispenser. The dose varied from 2.2 to 3.4 kg per sow per day, depending on the pregnancy stage. During feeding sows could drink water for 20 minutes through a drinking nipple in the dry-feed hopper.

Measurement of ammonia emission

Ammonia concentration of outgoing air is measured continuously by means of the B&K-monitor

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(Bruel and Kjaer), according to the measuring protocol of the Research Institute for Pig Husbandry (Van t Klooster et al., 1992). The ammonia concentration of outgoing air was sampled in the ventilation shaft. At the same moment the measuring and registration unit measured the temperature and registered the ventilation flow by a calibrated meaning fan. In period 2 (08-10-1999 through 08-11-1999) the ammonia concentration of in going air (background concentration) was measured by the NO x monitor.

Level of slurry and number of removals

Once a week the level of slurry was registered with a sounding rod. Also at the moment of removal the slurry level per manure channel was registered. Emitting surface immediately after removal was 0.38 m 2 at minimum per sow place.

RESULTS

Table 1 presents the emission figures for period 1 (01-08-1999 through 31-08-1999) and period 2 (08-10-1999 through 08-11-1999).

Table 1: Emission figures of the compartment with individual stalls with extra space between the stalls during a summer and a winter period.

Period 1

Period 2

Starting date

01-08-1999

08-10-1999

Final date

31-08-1999

08-11-1999

Number of observations (mean per day)

52

41

Temperature in the ventilation shaft ( o C)

23.9

21.5

Ventilation flow (m 3 /hour/ sow place )

99.4

37.8

Ammonia concentration of outgoing air (mg NH 3 /m 3 )

3.19

5.82

Background concentration (mg NH 3 /m 3 )

-

0.10

Ammonia emission of outgoing air not corrected for

background concentration (kg NH 3 /sow place/year)

2.53

1.79

Ammonia emission of outgoing air corrected for

background concentration (kg NH 3 /sow place/year)

-

.76

Ammonia emissions for periods 1 and 2 are presented graphically in figures 2 and 3.

Figure 2: Ammonia emission and temperature in period 1

VanAsseldonk1_files/image2.wmf

Figure 3: Ammonia emission and temperature in period 2

VanAsseldonk1_files/image3.wmf

Level of slurry and number of removals

In table 2 the data about the maximum slurry level per manure channel and the emitting surface at the moment of removal are presented.

Table 2: Slurry levels (cm) in the manure channels and average emitting surface area at the moment of removal

Period 1

Date of removal

Manure channel 1

Manure channel 2

Manure channel 3

Emitting surface per sow at moment of removal (slurry level = mean of three manure channels)

04-08-1999

9.5

11.5

11.5

0.52 m 2

17-08-1999

21.5

18

17.5

0.64 m 2

24-08-1999

17

16.5

16.5

0.60 m 2

27-08-1999

11

10

10

0.51 m 2

Period 2

Date of removal

Manure channel 1

Manure channel 2

Manure channel 3

Emitting surface per sow at moment of removal (slurry level = mean of three manure channels)

15-10-1999

14

12.5

14.5

0.56 m 2

22-10-1999

14

12.5

12.5

0.55 m 2

28-10-1999

16.5

13

13

0.57 m 2

03-11-1999

13.5

14

14

0.56 m 2

DISCUSSION

Ventilation system

The air entered the compartment indirectly through a space under the control passage. The air was supplied through ground tubes. In this way the amount of ventilation is expected to be lower than with ceiling ventilation, since fresh air is hardly mixed with dirty compartment air before it reaches the sows. The effect of reducing the ventilation flow on emission is, however, difficult to quantify.

Reducing emitting surface

Reducing the emitting slurry surface was realized in this research by using a partly solid floor in the individual stall and by inclining the pit walls. During the experiment the solid floor remained completely clean. Observations during and immediately after feeding showed that all sows left the individual stall to defecate on the slatted floor. The level of slurry determined the emitting slurry surface in the slurry channel. Voermans et al. (1995) states that reducing the emitting slurry surface by 10% results in a reduction in ammonia emission of approximately 8 8.5%.

The standard for ammonia emission by traditional housing, with an emitting slurry surface about 1.2 m 2 per sow place, is 4.2 kg of NH 3 per sow place per year. In research by Voermans and Hendriks (1996) ammonia emission was 2.16 kg of NH 3 per sow place per year in a compartment with a manure channel system with an emitting slurry surface of 0.4 m 2 per sow place. The emitting slurry surface in this research varied from 0.38 m 2 and 0.52 m 2 per sow place. The average ammonia emission was 2.15 kg of NH 3 per sow place per year and hence corresponds to ammonia emission measured in by Voermans and Hendriks (1996). The reduction of ammonia emission in this research compared with traditional individual stalls was 49%.

Significance to practice

An easy way to adapt an existing facility to group housing is to use the space between the individual stalls. This space should be sufficient to meet the requirement of a net floor space of 2.25 m 2 per sow. With a stall that is 0.65 m wide and 2 m deep this means that the space between two rows of individual stalls should be at least 3 m. With a single row of individual stalls the space behind the individual stalls should be at least 1.5 m. For functioning adequately, however, a space of 2 m is desirable.

ECONOMIC EVALUATION

Table 3 presents the extra investment and yearly costs for the compartment with individual stalls with extra space in relation to traditional housing.

Table 3: Extra investment and yearly costs per dry sow place

Investment costs

Yearly costs

Less for shallow pits

88.96

6.60

Extra for sewerage system

91.49

9.57

Less for concrete slats

57.04

7.39

Extra for metal slats

98.72

14.76

Extra for slurry storage in manure silo

(including covering)

148.23

18.71

Total

192.44

29.05

On the basis of the above assumptions the extra investment and yearly costs for the compartment with inclined pit walls and metal tribar-slatted floor in relation to the traditional compartment were NLG 192.44 and NLG 29.05 per sow place respectively (table 3).

CONCLUSIONS

Ammonia emission in the compartment for dry sows in individual stalls with extra space between the stalls, where ground tubes were applied, was, on average, 2.15 kg of NH 3 per sow place per year (partly corrected for background concentration). The reduction of ammonia emission compared with traditional individual stalls was 49%. The extra investment and yearly costs for this compartment in relation to traditional compartments were NLG 192.44 and NLG 29.05 per sow place, respectively.

REFERENCES

Hoek, K.W. van der, C.G.J. Leijen, H.J.M. Hendriks, W. Scherphof, A.M. van de Weerdhof, F. Jansen en J. Oosthoek, 1996. Beoordelingsrichtlijnen emissie-arme stalsystemen [in Dutch]

Klooster, C.E. van t, B.P. Heitlager en J.P.B.F. van Gastel, 1992. Measurement systems for emissions of ammonia and other gasses at the Research Institute for Pig Husbandry. Intern report P3.92. Research Institute for Pig Husbandry, Rosmalen, The Netherlands

Voermans, J.A.M., N. Verdoes and G.M. den Brok, 1995. The effect of pen design and climate control on the emission of ammonia from pig houses. Seventh International Symposium on Agricultural and Food Processing Wastes. Proceedings of the 7th International Symposium, June 18-20, Hyatt Regency Chicago, page 252 - 260

Voermans, M.P. en J.G.L. Hendriks, 1996. Het grupstalsysteem voor guste en dragende zeugen in relatie tot ammoniakemissie [in Dutch]. Report P1.158. Research Institute for Pig Husbandry, Rosmalen, The Netherlands