- Email: [email protected]
Respiration in broiler litter slurry surface applied to soil
Bioresource Technology60 (1997) 123-129 © 1997 Elsevier Science Limited All rights reserved. Printed in Great Britain 0960-8524/97 $17.00 ELSEVIER
P!I:S0960-8524(97)00017-5
RESPIRATION IN BROILER LITTER SLURRY SURFACE APPLIED TO SOIL T. T. A d a m s , a S. A. T h o m p s o n , a* M. L. C a b r e r a b & M. A. E i t e m a n a aDepamnent of Biological and Agricultural Engineering, The University of Georgia, Athens, Georgia 30602 USA hDepartment of Crop and Soil Science, The University of Georgia, Athens, Georgia 30602 USA
(Received 27 September 1996; revised version received 22 January 1997; accepted 27 January 1997) tivity (Tisdale et al., 1985). If CO2 is supplemented during high growth periods, a higher yield may be obtained (Dyakonova, 1954; Baker and Enoch, 1983; Acock and Allen, 1985). Leaves respond to higher CO2 concentrations not only at high light but also at low light levels (Acock and Allen, 1985). The mass flow of CO2 increases in leaves during constant intercellular concentration with increasing photon flux density (Keulen et al., 1989; Norman and Arkebauer, 1991). In addition to obtaining higher yields, the amount of carbon sequestered in the soil may be increased by increasing the CO2 levels within the canopy (Kimball, 1995). The average density of viable microorganisms in poultry pine-sawdust litter was measured to be 6.3 x 107/g dry material (Nodar et al., 1990). Aerobic heterotrophic bacteria were 1-6% of the population. Acidophile bacteria, aerobic spore-forming bacteria, actinomycetes and fungi were, respectively, 4.8 x 10 4, 8.1 × 10 4, 5.2 x 10 4 and 8.9 × 104 CFU/g dry material. High biochemical oxygen demand of the litter might lead to deficiencies in 02 which would explain why aerobic bacteria were only a small percentage of the microbial population. Ammonifiers and proteolytics, with average densities of 1.1 x 10 7 and 7.7 x 10 6 CFU/g dry material, respectively, were the most abundant microorganisms. The average density of the microbial population in poultry pine-sawdust litter was between the limits given for many soils (Alexander, 1967). In a comparison of manure slurries, Paul and Beauchamp (1989) found that poultry manure slurry (87% moisture) stored in a covered vessel produced high concentrations of volatile fatty acid (VFA) carbon and water soluble carbon (WSC), 14,490 mg kg- ~ and 17,404 mg kg- ~, respectively. Stevens and Cornforth (1974) concluded that VFAs were rapidly oxidized when anaerobically stored manure was exposed to oxygen. High concentrations of VFA have been measured in farm slurries (Cooper and Cornforth, 1978; Patni and Jui, 1985). Acetic, propionic and butyric acids were the dominant VFA, with lower concentrations of isobut'yric,
Abstract Respiration in broiler litter slurry that was surface applied to soil was examined for the purpose of determining the feasibility of enriching closed crop canopies with carbon dioxide. An estimated flux density of 1.11g C02 m -2 h -1 was calculated to be required from a ground source to obtain a maximum average increase in photosynthate of 23% for (73 plants. Litter, as received from the farm, was stored at 24°C for 72 days in a closed container (approximating conditions for deep stack storage). The stored litter was made into a slurry and stored at 24°C in a closed container for 23 days (approximating conditions in a manure storage pond). When stored slurry, inoculated 10% by volume with fresh litter slurry aged for seven days, was applied to soil at the rate of O.13ml cm -2 (12,8901ha -t) an average flux density of 5.32 g CO2 m - 2 h - i was measured. © 1997 Elsevier Science Ltd. INTRODUCTION
A significant portion of carbon provided to plants during photosynthesis is provided by evolution from the soil (Baldocchi, 1992). Monteith et al. (1964) found that soil respiration under a barley crop supplied about 22% of the carbon assimilated by the crop throughout the growing season. Denmead (1969) found that under a wheat crop, soil respiration accounted for about 43% of carbon assimilation during peak photosynthesis. Within closed plant canopies, the profile of average concentration of CO2 during photosynthesis shows a minimum at about 2/3 canopy height. The average minimum canopy CO2 concentration is lower than average atmospheric concentration (Monteith and Unsworth, 1990). Biscoe et al. (1975) concluded that all COg released at ground level will be used by the plant canopy during active photosynthesis. Increasing the CO2 available to plants has been widely recognized to increase growth and produc*Author to whom correspondence should be addressed. 123
124
T. T. Adams, S. A. Thompson, M. L. Cabrera, M. A. Eiteman
valeric and isovaleric acids. Animal manure is normally stored in ponds with a moisture content of 85-95% (Jantrania and White, 1985). CO2 production from poultry litter slurry applied to soil is correlated with WSC and VFA concentration (Paul and Beauchamp, 1989). VFAs are used as a carbon and energy source by facultative and aerobic bacteria. The production of CO2 in anaerobic digesters is higher when fresh feed is introduced by shock loadings (Water Pollution Control Federation, 1976). Increased CO2 generation could be a result of aerobic and/or facultative organisms in the feed which rapidly respire using the abundant VFAs accumulated in the digester until 02 depletion causes inhibition. In order to maximize the available carbon in poultry litter, an inexpensive, convenient and effective method is needed to prevent litter decomposition prior to the correct time for producing and applying the slurry. Storing biological wastes in a deep stack preserves nutrients until they are needed in the field (Bodrova and Ozolina, 1965). Currently, the value of CO2 respired from organic fertilizers is not quantified when the total value of nutrients is calculated. When compared to inorganic fertilizers, organic fertilizers applied to crops during the growing season are observed to produce higher yields even though nitrogen nutrients are lower (Nakamoto et al., 1994), a result that has confounded investigators. The objectives of the present study were to quantify the CO2 flux densities from slurries made from fresh and stored litter that were surface-applied to soil.
METHODS System description Soil columns A total of 18 different soil columns was used to study slurry treatment effects. Soil was collected from the top 15 inches of a fallow field mapped as Appling loam [clayey kaolinitic, thermic typic hapludults, (Perkins, 1987)] near Watkinsville, GA. The field was in corn the prior year. The soil was air dried and passed through a #6 ASTM Standard Sieve (3.35 mm square apertures) then wetted to 55% water filled porosity (WFP):
WFP = (volumetric water content/porosity x 100), porosity = (1 - bulk density/2.65). The soil was packed to a depth of 15 cm and bulk density of 1.55 g dry soil/cm3 into clear polystyrene tubes 20 cm in length with 4,45 cm inside diameter. Tube ends were fitted with rubber stoppers and soil was maintained at 24°C and 55% WFP gravimetrically by replenishing evaporated water. Light was provided by overhead fluorescent fixtures.
Broiler poultry litter Litter was obtained from a broiler poultry farm located in northern Georgia, USA. The broiler house was of standard open side construction where a second flock in their fifth week was being raised on pine-wood shavings on an earthen floor. Litter in the house was 0.10-0.15 m deep. Samples of the litter were collected down to the hard compacted clay soil at different locations within the house. Slurries Three slurries were prepared: Stored litter slurry: 27 kg of the collected litter was stored by placing the litter in triple lined polyethylene bags sealed in a container for 72 days at 24°C, approximating conditions of deep stack storage. Slurry was prepared using six parts deionized water to one part litter dry weight basis (14% solids). The slurry was stored in a 25-cm-diameter covered bowl with domed cover having a 0.6-cmdiameter vent. The slurry was stored for 23 days approximating conditions in a manure storage pond. Stored fractionated litter slurry: The same litter as in (1) above, was passed through a #6 ASTM Standard Sieve to produce a fractionated litter (Ndegwa et al., 1991). Slurry was made from this fractionated litter and stored as in (1). Fresh litter slurry: Litter as received from the farm with no storage was slurried as in (1) and aged in an open container for six days. Every second day, 12%, an arbitrary amount, of the total volume of the stored slurries was removed. Stored litter and deionized water of the same volume as that removed and in the same ratio as the original slurry was added in order to simulate a manure storage pond with influent and effluent withdrawal. Prior to soil application, slurries were passed through a #12 ASTM Standard Sieve (1.70 mm square apertures). The slurry after screening contained 7% solids.
Treatments Five slurry treatments were surface applied to soil columns: (1) stored litter slurry (SLS), (2) stored fractionated litter slurry (SFLS), (3) fresh litter slurry aged for six days (FLS), (4) stored litter slurry inoculated with 10% by volume fresh litter slurry aged in an open container for seven days (SLSI), and (5) stored litter slurry on wood chip mulch (SLSM). Control treatments were soil columns with deionized water application. Slurries were applied at the rate of 2ml per sample tube, 0.13 ml cm - - 2 (12,890 1ha-1). This volumetric amount was chosen as a result of the amount of WSC estimated to be required for microorganisms to respire 1.11 g m -2 h -I (Gale and Gilmour, 1986). The average BOD5 concentrations of stored slurries were measured to be approximately 100,000mg1-1. Three replications were performed for each treatment.
Respiration in broiler litter slurry surface applied to soil Poultry manure stored in contact with atmospheric oxygen has a lower VFA concentration, 440 mg kg-1, than manure slurry that is stored in a covered container, 14,490 mg kg-~ (Paul and Beauchamp, 1989). The litter for the stored litter slurry treatment (SLS) was stored with air excluded. The slurry was also stored in a covered container in an attempt to maximize VFA production prior to soil application. The WSC concentration of SLS was 5850 mg k g - ~. Fractionating litter concentrates nitrogen and phosphorus nutrients (Ndegwa et al., 1991). The SFLS treatment examined the effects of this pretreatment on microbial respiration. SFLS slurry had a higher WSC concentration, 6230 mg kg -~, than SLS slurry. The fresh litter slurry treatment (FLS) examined the effect of slurry made from litter fresh from the farm. The FLS treatment was aged in a container kept open to the atmosphere. The effect of slurry age was determined by conducting daily soil applications. The FLS treatment may have a more metabolically active aerobic microbial population. The SLS treatment contains metabolites from microorganisms growing in an oxygen limited environment. The inoculated stored litter slurry treatment (SLSI) examines the effect of a 10% by volume inoculation of the SLS with FLS. The inoculum may increase the rate of respiration by supplementing aerobic organisms that are known to be in low concentrations (1.1 × 10 6 CFU/g dry material) in litter (Nodar et al., 1990) and may have been further reduced by limiting air contact during storage. The FLS inoculum, aged for seven days, was applied to the SLS immediately after SLS was applied to soil. The stored litter slurry applied to mulch on soil (SLSM) treatment examined the effect of mulch on microbial respiration. Mulch can decrease moisture loss from soil by 50-70% and reduce soil surface temperatures, improving conditions for microbial growth in the field (Bussiere and Cellier, 1994). Slurry was applied to a 1 cm depth of wood chip mulch after the mulch was placed on the soil.
Analyses At selected time intervals after slurry application, soil columns were refitted with a rubber stopper containing a septum. The distance from the top of the slurry to the bottom of the stopper was used to calculate the head space volume for each gas sample collection. Gas samples from the head space were collected after a measured time (5-20 min depending on anticipated carbon dioxide concentration). A 3.0ml sample was removed with a syringe and injected into a 2.0 ml glass sample vial. Multiple samples were collected for a period of hours after slurry application. The stopper in the soil column was removed after each gas sample collection. Carbon dioxide concentration was measured using a
125
Varian Star 3600CX Gas Chromatograph with a Varian 8200CX Auto Sampler (Varian Analytical Instruments, Sugarland, TX). The rate of carbon dioxide production from the samples was determined by subtracting background CO2 from control sample tubes containing only soil. Three replications were performed for each treatment method. Total carbon in the slurries was measured by Dumas combustion analysis using an NA100 Carbon Analyzer (Carlo Erba Strumentazione, Milan, Italy). Water content in litter was determined by drying at 65°C for 48 h. Respiration rates between measurements were estimated by linear interpolation. Rates were integrated using the Romberg Method with Mathcad 3.1 (Mathsoft, 1992). Testing for significant differences between treatments was accomplished by using the Student-Newman-Keuls (SNK) ordered pair-wise test for sample means using SAS software (SAS Institute, 1985).
Calculating the carbon dioxide flux density in closed canopies In order to determine the flux density required of a ground source to enrich a crop canopy successfully with carbon dioxide, the biophysics occurring within a closed canopy was examined. For a local daytime wind speed of 1.36 m/s at the top of a short canopy during July 1993 in Athens, Georgia, the mean frequency of occurrence of atmospheric ramps which penetrate the canopy was estimated to be once every 50 s (Paw, U. et al., 1992; 1993). Quiescence within the canopy for these local conditions is predicted to occur from 59-64% of total time for crops such as cotton or soybean (Adams, 1994). An increase in net photosynthesis may be accomplished by increasing ambient and therefore leaf intercellular carbon dioxide concentration within closed plant canopies (Lawlor, 1987). The increase in net photosynthesis is linear between leaf intercellular carbon dioxide concentrations of 100 ppm and 400 ppm. The slope of the linearly increasing rate is 0.08/~mol C O 2 m - 2 S-- 1 per ppm of increased leaf intercellular carbon dioxide concentration in Ca leaves at 25°C and 1200 #mol quanta m - 2 s- t (Lawlor, 1987). Using a net photosynthesis model (Lawlor, 1987; Boote and Loomis, 1991; Jones, 1992) and the response of net photosynthesis to intercellular carbon dioxide concentration, an increase in net photosynthesis of 44% during quiescence and 23% averaged over total time was predicted for a closed crop canopy of C3 leaves for described local July conditions (Adams, 1994). The model assumed that the within canopy concentration of carbon dioxide was elevated to average atmospheric concentration by a ground source emission. Corresponding leaf intercellular concentrations of carbon dioxide were estimated by an equation correlating net photosynthesis with ambient and
126
T. T. Adams, S. A. Thompson, M. L. Cabrera, M. A. Eiteman
intercellular concentration and stomatal conductance (g' = 0.26 mol m -2 s -~) of water vapor (Boote and Loomis, 1991; Jones, 1992; Lawlor, 1987). To obtain the increase in canopy concentration, an estimated emission from a ground source of 7 /~mol CO2 m -2 s - I (1.11g CO2 m -2 h - j ) is required (Adams, 1994). Aphalo and Jarvis (1993) observed that a flux density of 6 #mol CO2 m - 2 s - ~ increased the intercellular carbon dioxide concentration in ivy leaves by 200 ttmol mol-J at a constant temperature of 20°C and photon flux density of 490/~mol quanta m - 2 s-~.
1.8 1.6
.,--.= ?
1.4-
~a =O
1.0-
O
0.8-
== O ==
0.6
[J
m
1.2-
0.40.20.0
RESULTS
1.5-
I
,
,
,
5
,
l
,
I
,
,
,
10
I
1
,
,
,
15
,
I
,
I 20
,
,
25
quent slurry applications and are shown in Fig. 3. Slurry was applied every two days up to the 10th application, whereafter slurry was applied every three days. A decrease in lag time resulted when slurry application was every three days. Based on these results it is believed that slurry solids may cause a delay in respiration due to their accumulation and the changing character of carbon compounds available for metabolism. The duration of high rates of respiration following slurry application to soil varied. Generally, optimum average carbon dioxide flux density, above 1 . 1 1 g m - 2 h -~, had a 6-8 h duration. Table 1 shows a comparison of total emissions over a 9.5 h period. SLS, SFLS, FLS and SLSI treatments had respiration rates that averaged higher than the 1.11 g m - 2 h -~ level. Only the stored litter slurry
0= 10-
.=. o
I
--
,=
•~
,
12
A
2.0-
,
Time (h) Fig. 2. Carbon dioxide production from a surface application of stored litter slurry (SIS) to soil, 0.131cm -2 (12,8901ha-J), three replications (mean plus and minus standard error).
3.0
~E
,
0
Carbon dioxide flux densities from broiler litter slurries surface-applied to soil columns were characterized to determine their value for canopy fertilization. Since the timing of respiration emission for the stated conditions was unknown, a number of single sample trials was undertaken to pinpoint the onset of significant flux. An emission peak of carbon dioxide from the stored litter slurry was observed after a short lag time (Fig. 1). Emissions were above the 1.11 g m - 2 h - ~ rate for approximately 8 h. After this initial trial, soil column head space gas samples on subsequent trials were obtained from replicates each hour after slurry application to observe emission characteristics. As shown in Fig. 2, results were similar to the initial trial. However, as additional slurry applications dried and accumulated on the soil surface, the timing and rate of carbon dioxide emission changed. High rates of respiration (greater than 1.11 g m -2 h -]) began from stored litter slurry after a lag time of 4.5 h on the third application of slurry to soil. Respiration lag times increased after subse-
2.5
,
6 ==
1.0-
0.5 ~JD +=
' ~ I ' ' ' t ' ' ' t ' ' ' I ' ' ' I ' ' ' L ' ' ' I I 1 I
0.0
0
2
4
6
8
10
12
14
0
' I' 2
Time
I'
I't'
4
6
8
I'
Slurry
Application=+
10
I' 12
14
(11)
Fig. 1. Carbon dioxide production from a surface application of stored litter slurry (SLS) to soil, 0.13 l cm -2 (12,890 1 ha- i), no replications.
Cumulative
Fig. 3. Lag in respiration after successive slurry applications for stored litter slurry (SLS) surface-applied to soil.
Respiration in broiler litter slurry surface applied to soil applied to a wood chip mulch on soil did not average more than the optimum carbon dioxide respiration level. A barrier between the slurry and the soil surface had the effect of reducing or delaying respiration, perhaps because of the isolation of the available carbon in the slurry from organisms in the soil. Variation in respiration rates between replicates might be attributable to respiration occurring in 'puffs' rather than as a steady emission. Evidence for this conclusion is that a high carbon dioxide emission rate from a soil column was often followed in the subsequent hour by a very low emission. This characteristic of respiration might be a result of synchronous metabolism and diauxic growth (Brock et al., 1994). As slurry made from fresh litter aged, the respiration rates changed. The highest emissions occurred on the sixth day. When fresh slurry, kept for seven days, was used as an inoculum for the stored litter slurry, the emissions were unexpectedly large and intermittent, causing a high variation in emissions. Gas samples collected 3 h after application showed flux densities of 6.30 and 10.63 g CO2 m - 2 h -~ for
S
--
4" ~'E~ 4
Fluxduration,eachsubdivision= 4 hours •~
3
o
2
/ A
/
Fluxrequiredfor max.canopyrespons~
/
1
I
Day 4
I
I
I
I
Day 7
Day of Application
I
I
Day 11 During
I
Day 22
35 Days of Incubation
Fig. 4.
127
two of the replicates, the third replicate indicated measurements were unexpectedly high in concentration and thus beyond gas chromatograph calibration limits. Gas samples collected after 6 h showed flux densities of 14.21 and 0.25 g CO2 m -2 h-~ for the first two replicates and again the third replicate was off scale. These results again indicate the high variability in the 'puffs' of microbial respiration. The high productivity of the inoculated slurry might be a result of the combination of a high availability of volatile fatty acids and other water soluble carbon compounds from the stored slurry, and a high number of organisms in the inoculum in a high state of metabolism. These results indicate that a detailed investigation of inoculated slurries is warranted. No significant difference at the 0.05 significance level existed between respiration rates from SLS, SLSM, SFLS and FLS treatments. A significant difference in respiration rates occurred from the SLSI treatment.
DISCUSSION If CO2 is supplemented under the canopy from a ground source, a closed canopy crop may produce a higher yield. The biophysics within closed crop canopies appears to offer the opportunity to enrich the canopy with a ground source of carbon dioxide to obtain an increase in net photosynthesis. An average increase of 23% in net peak photosynthesis was estimated for C3 plants with a closed canopy receiving a ground source carbon dioxide flux density of 1.11 g CO2 m - 2 h i. Flux of carbon dioxide from stored slurry and fresh litter slurry (aged for six days) surface applied to soil is greater than that required for estimated maximum benefit for C3 plants with closed plant canopies (1.11 g m -2 h - i ) . Elevated rates of carbon dioxide flux from respiration last for more than 6 h when the slurries are surface ap~plied to soil. Slurries are much easier to apply to a closed crop canopy than dry litter. The slurry, when screened to exclude
Table 1. Average carbon dioxide respired from slurry treatments integrated over a 9.5 h period, three replications applied to soil
Treatment
SLS SLSM SFLS FLS SLSI
Respiration lag (h)
Tot. C applied (g C m 2)
6 5 8.5 3.5 3
23.54 23.54 26.87 24.69 27.04
Tot. CO2-C released 1 (% of total C applied) 13.9"2 1.66b 12.67b 19.19b 50.93a
Ave. CO2 flux (g C02 m -2 h-~)
Ave. CO2 flux per g C applied
1.26 0.15 1.31 1.83 5.32
0.054 0.006 0.049 0.074 0.197
SLS: stored litter slurry; SLSM: stored litter slurry with mulch; SFLS: stored fractionated litter slurry; FLS: fresh litter slurry aged for six days; SLSI: stored litter slurry_inoculated with FLS aged for seven days.I Linear interpolation between measurements, integration over a 9.5 h period.2 Means with the same letter are not significantly different at the 0.05 significance level.
128
T. T. Adams, S. A. Thompson, M. L. Cabrera, M. A. Eiteman
large particles, may be pumped and sprayed on a field. The spraying of slurries on fields with developed crops is a commonly practiced, proven application method. If slurries are applied during daylight hours, the timing of slurry application is important since the respiration lag and delayed flux of carbon dioxide may result in much of the carbon dioxide being respired after dark. Lag time for broiler litter slurries may depend on the frequency of slurry application. By inoculating stored litter slurry with a fresh litter slurry allowed to age for seven days, the average flux density of carbon dioxide increased by 322% and the respiration lag time decreased to less than 3 h, conditions which may permit daily slurry applications. No significant difference in carbon dioxide rates occurred from slurries made from fresh and stored litter. Storing broiler litter under conditions of restricted air contact preserves carbon nutrients allowing slurries to be prepared and applied coincident with optimum crop growth periods. Additionally, storing poultry litter maintains the option of selling litter as a ruminant feed. Before utilizing biological waste slurries for the purpose of carbon dioxide enrichment, the fate of other slurry nutrients, specifically nitrogen and phosphorus compounds, must be examined to quantify their impact on crop nutrient requirements, and on soil and water quality. Additional processing of slurries may be required to control nitrogen and phosphorus transformations.
REFERENCES Acock, B. & Allen, L. H. (1985). Crop responses to elevated carbon dioxide concentrations. In Direct Effects of Increasing Carbon Dioxide on Vegetation, ed. B. R. Strain and J. D. Cure. U.S. Dept. of Energy, DOE/ER-0238, Dist. Category Uc-ll, Washington, D.C. pp. 100-116. Adams, T. T. (1994). Production of carbon dioxide from ensiled broiler litterY Master's thesis, The University of Georgia, Department of Biological and Agricultural Engineering, Athens, GA. Alexander, M. (1967). Introduction to Soil Microbiology. Wiley, New York. Aphalo, P. J. & Jarvis, P. G. (1993). The boundary layer and the apparent responses of stomatal conductance to wind speed and to the mole fraction of CO2 and water vapor in the ai~ Plant, Cell and Environ., 16, 771-783. Baker, B. N. & Enoch, H. Z. (1983). Plant growth and development. In C02 and Plants, ed. E. R. Lemon. AAAS Selected Symposium 84, Westview Press, Boulder, CO, pp. 122-123. Baldocchi, D. (1992). A Lagrangian random-walk model for simulating water vapor, CO2 and sensible heat flux densities and scalar profiles over and within a soybean canopy. Boundary-Layer Meteorol., 61, 113-144. Biscoe, P. V., Scott, R. K. & Monteith, J. L. (1975). Barley and its environment, III. Carbon budget of the stand. J. Appl. Ecol., 12, 269-293. Bodrova, E. M. & Ozolina, Z. D. (1965). Simultaneous Application of Organic and Mineral Fertilizers. Translated from the Russian and published pursuant to an agree-
ment with the U.S. Dept. of Agriculture, Jerusalem, pp. 72-100. Boote, D. J. & Loomis, R. S. (1991). Modeling crop photosynthesis - - From biochemistry to canopy. CSSA Special Publication No. 19, Crop Science Society of America, Madison, WI. p. 126. Brock, T. D., Madigan, M. T., Martinko, J. M. & Parker, J. (1994). Biology of Microorganisms. Prentice Hall, Englewood Cliffs, NJ, p. 176. Bussiere, F. & Cellier, P. (1994). Modification of the soil temperature and water content regimes by a crop residue mulch: experiment and modeling. Agricultural and Forest Meteorology, 68, 1-28. Cooper, P. & Cornforth, I. S. (1978). Volatile fatty acids in stored animal slurry. J. Sci. FoodAgric., 29, 19-27. Denmead, O. T. (1969). Comparative micrometeorology of a wheat field and a forest of Pinus radiata. Agricultural and Forest Meteorology, 6, 357-371. D'yakonova, K. V. (1954). Soil as a source of carbon dioxide for plants on irrigated and nonirrigated ciscaucasian chernozems. In Microorganisms and Organic Matter of Soils, ed. K. Greensburg (1970). Translated from Russian, Keter Press, Jerusalem. pp. 122-189. Gale, P. M. & Gilmour, J. T. (1986). Carbon and nitrogen mineralization kinetics for poultry litter J. Environ. Qual., 15, 423-426. Jantrania, H. G. & White, R. K. (1985). High solids anaerobic fermentation of poultry manure. In Agricultural Waste Utilization and Management, Proceedings of the Fifth International Symposium on Agricultural Wastes, ASAE, St. Joseph, MI. pp. 73-80. Jones, H. G. (1992). Plants and Microclimate, A Quantitative Approach to Environmental Plant Physiology. Cambridge University Press, Cambridge, pp. 90-116. Kimball, B. A. (1995). Update. Plant's CO2 diet doubled in world's largest study. Resource, 2, 7. Keulen, H. van, Goudriaan, J. & Seligman, N. G. (1989). Modelling the effects of nitrogen on canopy development and crop growth. In Plant Canopies: Their Growth, Form and Function, ed. G. Russell, B. Marshall and P. G. Jarvis. Cambridge University Press, Cambridge. pp. 83-104. Lawlor, D. W. (1987). Photosynthesis: Metabolism, Control, and Physiology. John Wiley, New York, pp. 127-137. Mathsoft (1992). Mathcad 3.1 User's Guide. Mathsoft, Cambridge, MA. Monteith, J. L., Szeicz, G. & Yabuki, K. (1964). Crop photosynthesis and the flux of carbon dioxide below the canopy. J. Appl. Ecol., 1, 321-337. Monteith, J. L. & Unsworth, M. H. (1990). Principles of Environmental Physics. Edward Arnold, London, pp. 113-269. Nakamoto, S. T., Leung, P. S. & Wanitprapha, K. (1994). The value of diluted poultry slurry. Biores. Technol., 48, 25-30. Ndegwa, P. M., Thompson, S. A. & Merka, W. C. (1991). Fractionation of poultry litter for enhanced utilizatiort Trans. ASAE, 34, 992-997. Nodar, R., Acea, M. J. & Carballas, T. (1990). Microbial populations of poultry pine-sawdust litter. Biological Wastes, 33, 295-306. Norman, J. M. & Arkebauer, T. J. (1991). Predicting canopy photosynthesis and light-use efficiency of canopies as affected by leaf and canopy traits. In Modeling Crop Photosynthesis - - From Biochemistry to Canopy, CSSA Special Publication 19, Crop Science Society of America, Madison, WI, pp. 75-94. Patni, N. K. & Jui, P. Y. (1985). Volatile fatty acids in stored dairy cattle slurry. Agricultural Wastes, 13, 159-178.
Respiration in broiler litter slurry surface applied to soil
Paul, J. W. & Beauchamp, E. G. (1989). Relationship between volatile fatty acids, total ammonia, and pH in manure slurries Biol. Wastes, 29, 313-318. Paw U, K. T., Brunet, Y., Collineau, S., Shaw, R. H., Maitani, T., Qiu, J. & Hipps, L. (1992). On coherent structures in turbulence above and within agricultural plant canopies Agric. For. Meteorol., 61, 55-68. Paw U, K. T., Brunet, Y., Collineau, S., Shaw, R. H., Maitani, T., Qiu, J. & Hipps, L. (1993). Corrigendum. On coherent structures in turbulence above and within agricultural plant canopie~ Agric. For. Meteorol., 63, 127. Perkins, H. F. (1987). Characterization data for selected Georgia soils. Special Publication 43, Georgia Agricul-
129
tural Experiment Station, The University of Georgia, Athens, GA. SAS Institute (1985). SAS User's Guide: Statistics, Version 5. SAS Institute, Cary, NC. Stevens, R. J. & Cornforth, I. S. (1974). The effect of aeration on the gases produced by slurry during storage. J. Sci. Food Agric., 25, 1249-1261. Tisdale, S. L., Nelson, W. L. & Beaton, J. D. (1985). Soil Fertility and Fertilizers. MacMillan, New York, pp. 36-38, 636-653. Water Pollution Control Federation (1976). Operation of Wastewater Treatment Plants. Manual of Practice 11. Lancaster Press, Lancaster, PA, pp. 264-266.
P!I:S0960-8524(97)00017-5
RESPIRATION IN BROILER LITTER SLURRY SURFACE APPLIED TO SOIL T. T. A d a m s , a S. A. T h o m p s o n , a* M. L. C a b r e r a b & M. A. E i t e m a n a aDepamnent of Biological and Agricultural Engineering, The University of Georgia, Athens, Georgia 30602 USA hDepartment of Crop and Soil Science, The University of Georgia, Athens, Georgia 30602 USA
(Received 27 September 1996; revised version received 22 January 1997; accepted 27 January 1997) tivity (Tisdale et al., 1985). If CO2 is supplemented during high growth periods, a higher yield may be obtained (Dyakonova, 1954; Baker and Enoch, 1983; Acock and Allen, 1985). Leaves respond to higher CO2 concentrations not only at high light but also at low light levels (Acock and Allen, 1985). The mass flow of CO2 increases in leaves during constant intercellular concentration with increasing photon flux density (Keulen et al., 1989; Norman and Arkebauer, 1991). In addition to obtaining higher yields, the amount of carbon sequestered in the soil may be increased by increasing the CO2 levels within the canopy (Kimball, 1995). The average density of viable microorganisms in poultry pine-sawdust litter was measured to be 6.3 x 107/g dry material (Nodar et al., 1990). Aerobic heterotrophic bacteria were 1-6% of the population. Acidophile bacteria, aerobic spore-forming bacteria, actinomycetes and fungi were, respectively, 4.8 x 10 4, 8.1 × 10 4, 5.2 x 10 4 and 8.9 × 104 CFU/g dry material. High biochemical oxygen demand of the litter might lead to deficiencies in 02 which would explain why aerobic bacteria were only a small percentage of the microbial population. Ammonifiers and proteolytics, with average densities of 1.1 x 10 7 and 7.7 x 10 6 CFU/g dry material, respectively, were the most abundant microorganisms. The average density of the microbial population in poultry pine-sawdust litter was between the limits given for many soils (Alexander, 1967). In a comparison of manure slurries, Paul and Beauchamp (1989) found that poultry manure slurry (87% moisture) stored in a covered vessel produced high concentrations of volatile fatty acid (VFA) carbon and water soluble carbon (WSC), 14,490 mg kg- ~ and 17,404 mg kg- ~, respectively. Stevens and Cornforth (1974) concluded that VFAs were rapidly oxidized when anaerobically stored manure was exposed to oxygen. High concentrations of VFA have been measured in farm slurries (Cooper and Cornforth, 1978; Patni and Jui, 1985). Acetic, propionic and butyric acids were the dominant VFA, with lower concentrations of isobut'yric,
Abstract Respiration in broiler litter slurry that was surface applied to soil was examined for the purpose of determining the feasibility of enriching closed crop canopies with carbon dioxide. An estimated flux density of 1.11g C02 m -2 h -1 was calculated to be required from a ground source to obtain a maximum average increase in photosynthate of 23% for (73 plants. Litter, as received from the farm, was stored at 24°C for 72 days in a closed container (approximating conditions for deep stack storage). The stored litter was made into a slurry and stored at 24°C in a closed container for 23 days (approximating conditions in a manure storage pond). When stored slurry, inoculated 10% by volume with fresh litter slurry aged for seven days, was applied to soil at the rate of O.13ml cm -2 (12,8901ha -t) an average flux density of 5.32 g CO2 m - 2 h - i was measured. © 1997 Elsevier Science Ltd. INTRODUCTION
A significant portion of carbon provided to plants during photosynthesis is provided by evolution from the soil (Baldocchi, 1992). Monteith et al. (1964) found that soil respiration under a barley crop supplied about 22% of the carbon assimilated by the crop throughout the growing season. Denmead (1969) found that under a wheat crop, soil respiration accounted for about 43% of carbon assimilation during peak photosynthesis. Within closed plant canopies, the profile of average concentration of CO2 during photosynthesis shows a minimum at about 2/3 canopy height. The average minimum canopy CO2 concentration is lower than average atmospheric concentration (Monteith and Unsworth, 1990). Biscoe et al. (1975) concluded that all COg released at ground level will be used by the plant canopy during active photosynthesis. Increasing the CO2 available to plants has been widely recognized to increase growth and produc*Author to whom correspondence should be addressed. 123
124
T. T. Adams, S. A. Thompson, M. L. Cabrera, M. A. Eiteman
valeric and isovaleric acids. Animal manure is normally stored in ponds with a moisture content of 85-95% (Jantrania and White, 1985). CO2 production from poultry litter slurry applied to soil is correlated with WSC and VFA concentration (Paul and Beauchamp, 1989). VFAs are used as a carbon and energy source by facultative and aerobic bacteria. The production of CO2 in anaerobic digesters is higher when fresh feed is introduced by shock loadings (Water Pollution Control Federation, 1976). Increased CO2 generation could be a result of aerobic and/or facultative organisms in the feed which rapidly respire using the abundant VFAs accumulated in the digester until 02 depletion causes inhibition. In order to maximize the available carbon in poultry litter, an inexpensive, convenient and effective method is needed to prevent litter decomposition prior to the correct time for producing and applying the slurry. Storing biological wastes in a deep stack preserves nutrients until they are needed in the field (Bodrova and Ozolina, 1965). Currently, the value of CO2 respired from organic fertilizers is not quantified when the total value of nutrients is calculated. When compared to inorganic fertilizers, organic fertilizers applied to crops during the growing season are observed to produce higher yields even though nitrogen nutrients are lower (Nakamoto et al., 1994), a result that has confounded investigators. The objectives of the present study were to quantify the CO2 flux densities from slurries made from fresh and stored litter that were surface-applied to soil.
METHODS System description Soil columns A total of 18 different soil columns was used to study slurry treatment effects. Soil was collected from the top 15 inches of a fallow field mapped as Appling loam [clayey kaolinitic, thermic typic hapludults, (Perkins, 1987)] near Watkinsville, GA. The field was in corn the prior year. The soil was air dried and passed through a #6 ASTM Standard Sieve (3.35 mm square apertures) then wetted to 55% water filled porosity (WFP):
WFP = (volumetric water content/porosity x 100), porosity = (1 - bulk density/2.65). The soil was packed to a depth of 15 cm and bulk density of 1.55 g dry soil/cm3 into clear polystyrene tubes 20 cm in length with 4,45 cm inside diameter. Tube ends were fitted with rubber stoppers and soil was maintained at 24°C and 55% WFP gravimetrically by replenishing evaporated water. Light was provided by overhead fluorescent fixtures.
Broiler poultry litter Litter was obtained from a broiler poultry farm located in northern Georgia, USA. The broiler house was of standard open side construction where a second flock in their fifth week was being raised on pine-wood shavings on an earthen floor. Litter in the house was 0.10-0.15 m deep. Samples of the litter were collected down to the hard compacted clay soil at different locations within the house. Slurries Three slurries were prepared: Stored litter slurry: 27 kg of the collected litter was stored by placing the litter in triple lined polyethylene bags sealed in a container for 72 days at 24°C, approximating conditions of deep stack storage. Slurry was prepared using six parts deionized water to one part litter dry weight basis (14% solids). The slurry was stored in a 25-cm-diameter covered bowl with domed cover having a 0.6-cmdiameter vent. The slurry was stored for 23 days approximating conditions in a manure storage pond. Stored fractionated litter slurry: The same litter as in (1) above, was passed through a #6 ASTM Standard Sieve to produce a fractionated litter (Ndegwa et al., 1991). Slurry was made from this fractionated litter and stored as in (1). Fresh litter slurry: Litter as received from the farm with no storage was slurried as in (1) and aged in an open container for six days. Every second day, 12%, an arbitrary amount, of the total volume of the stored slurries was removed. Stored litter and deionized water of the same volume as that removed and in the same ratio as the original slurry was added in order to simulate a manure storage pond with influent and effluent withdrawal. Prior to soil application, slurries were passed through a #12 ASTM Standard Sieve (1.70 mm square apertures). The slurry after screening contained 7% solids.
Treatments Five slurry treatments were surface applied to soil columns: (1) stored litter slurry (SLS), (2) stored fractionated litter slurry (SFLS), (3) fresh litter slurry aged for six days (FLS), (4) stored litter slurry inoculated with 10% by volume fresh litter slurry aged in an open container for seven days (SLSI), and (5) stored litter slurry on wood chip mulch (SLSM). Control treatments were soil columns with deionized water application. Slurries were applied at the rate of 2ml per sample tube, 0.13 ml cm - - 2 (12,890 1ha-1). This volumetric amount was chosen as a result of the amount of WSC estimated to be required for microorganisms to respire 1.11 g m -2 h -I (Gale and Gilmour, 1986). The average BOD5 concentrations of stored slurries were measured to be approximately 100,000mg1-1. Three replications were performed for each treatment.
Respiration in broiler litter slurry surface applied to soil Poultry manure stored in contact with atmospheric oxygen has a lower VFA concentration, 440 mg kg-1, than manure slurry that is stored in a covered container, 14,490 mg kg-~ (Paul and Beauchamp, 1989). The litter for the stored litter slurry treatment (SLS) was stored with air excluded. The slurry was also stored in a covered container in an attempt to maximize VFA production prior to soil application. The WSC concentration of SLS was 5850 mg k g - ~. Fractionating litter concentrates nitrogen and phosphorus nutrients (Ndegwa et al., 1991). The SFLS treatment examined the effects of this pretreatment on microbial respiration. SFLS slurry had a higher WSC concentration, 6230 mg kg -~, than SLS slurry. The fresh litter slurry treatment (FLS) examined the effect of slurry made from litter fresh from the farm. The FLS treatment was aged in a container kept open to the atmosphere. The effect of slurry age was determined by conducting daily soil applications. The FLS treatment may have a more metabolically active aerobic microbial population. The SLS treatment contains metabolites from microorganisms growing in an oxygen limited environment. The inoculated stored litter slurry treatment (SLSI) examines the effect of a 10% by volume inoculation of the SLS with FLS. The inoculum may increase the rate of respiration by supplementing aerobic organisms that are known to be in low concentrations (1.1 × 10 6 CFU/g dry material) in litter (Nodar et al., 1990) and may have been further reduced by limiting air contact during storage. The FLS inoculum, aged for seven days, was applied to the SLS immediately after SLS was applied to soil. The stored litter slurry applied to mulch on soil (SLSM) treatment examined the effect of mulch on microbial respiration. Mulch can decrease moisture loss from soil by 50-70% and reduce soil surface temperatures, improving conditions for microbial growth in the field (Bussiere and Cellier, 1994). Slurry was applied to a 1 cm depth of wood chip mulch after the mulch was placed on the soil.
Analyses At selected time intervals after slurry application, soil columns were refitted with a rubber stopper containing a septum. The distance from the top of the slurry to the bottom of the stopper was used to calculate the head space volume for each gas sample collection. Gas samples from the head space were collected after a measured time (5-20 min depending on anticipated carbon dioxide concentration). A 3.0ml sample was removed with a syringe and injected into a 2.0 ml glass sample vial. Multiple samples were collected for a period of hours after slurry application. The stopper in the soil column was removed after each gas sample collection. Carbon dioxide concentration was measured using a
125
Varian Star 3600CX Gas Chromatograph with a Varian 8200CX Auto Sampler (Varian Analytical Instruments, Sugarland, TX). The rate of carbon dioxide production from the samples was determined by subtracting background CO2 from control sample tubes containing only soil. Three replications were performed for each treatment method. Total carbon in the slurries was measured by Dumas combustion analysis using an NA100 Carbon Analyzer (Carlo Erba Strumentazione, Milan, Italy). Water content in litter was determined by drying at 65°C for 48 h. Respiration rates between measurements were estimated by linear interpolation. Rates were integrated using the Romberg Method with Mathcad 3.1 (Mathsoft, 1992). Testing for significant differences between treatments was accomplished by using the Student-Newman-Keuls (SNK) ordered pair-wise test for sample means using SAS software (SAS Institute, 1985).
Calculating the carbon dioxide flux density in closed canopies In order to determine the flux density required of a ground source to enrich a crop canopy successfully with carbon dioxide, the biophysics occurring within a closed canopy was examined. For a local daytime wind speed of 1.36 m/s at the top of a short canopy during July 1993 in Athens, Georgia, the mean frequency of occurrence of atmospheric ramps which penetrate the canopy was estimated to be once every 50 s (Paw, U. et al., 1992; 1993). Quiescence within the canopy for these local conditions is predicted to occur from 59-64% of total time for crops such as cotton or soybean (Adams, 1994). An increase in net photosynthesis may be accomplished by increasing ambient and therefore leaf intercellular carbon dioxide concentration within closed plant canopies (Lawlor, 1987). The increase in net photosynthesis is linear between leaf intercellular carbon dioxide concentrations of 100 ppm and 400 ppm. The slope of the linearly increasing rate is 0.08/~mol C O 2 m - 2 S-- 1 per ppm of increased leaf intercellular carbon dioxide concentration in Ca leaves at 25°C and 1200 #mol quanta m - 2 s- t (Lawlor, 1987). Using a net photosynthesis model (Lawlor, 1987; Boote and Loomis, 1991; Jones, 1992) and the response of net photosynthesis to intercellular carbon dioxide concentration, an increase in net photosynthesis of 44% during quiescence and 23% averaged over total time was predicted for a closed crop canopy of C3 leaves for described local July conditions (Adams, 1994). The model assumed that the within canopy concentration of carbon dioxide was elevated to average atmospheric concentration by a ground source emission. Corresponding leaf intercellular concentrations of carbon dioxide were estimated by an equation correlating net photosynthesis with ambient and
126
T. T. Adams, S. A. Thompson, M. L. Cabrera, M. A. Eiteman
intercellular concentration and stomatal conductance (g' = 0.26 mol m -2 s -~) of water vapor (Boote and Loomis, 1991; Jones, 1992; Lawlor, 1987). To obtain the increase in canopy concentration, an estimated emission from a ground source of 7 /~mol CO2 m -2 s - I (1.11g CO2 m -2 h - j ) is required (Adams, 1994). Aphalo and Jarvis (1993) observed that a flux density of 6 #mol CO2 m - 2 s - ~ increased the intercellular carbon dioxide concentration in ivy leaves by 200 ttmol mol-J at a constant temperature of 20°C and photon flux density of 490/~mol quanta m - 2 s-~.
1.8 1.6
.,--.= ?
1.4-
~a =O
1.0-
O
0.8-
== O ==
0.6
[J
m
1.2-
0.40.20.0
RESULTS
1.5-
I
,
,
,
5
,
l
,
I
,
,
,
10
I
1
,
,
,
15
,
I
,
I 20
,
,
25
quent slurry applications and are shown in Fig. 3. Slurry was applied every two days up to the 10th application, whereafter slurry was applied every three days. A decrease in lag time resulted when slurry application was every three days. Based on these results it is believed that slurry solids may cause a delay in respiration due to their accumulation and the changing character of carbon compounds available for metabolism. The duration of high rates of respiration following slurry application to soil varied. Generally, optimum average carbon dioxide flux density, above 1 . 1 1 g m - 2 h -~, had a 6-8 h duration. Table 1 shows a comparison of total emissions over a 9.5 h period. SLS, SFLS, FLS and SLSI treatments had respiration rates that averaged higher than the 1.11 g m - 2 h -~ level. Only the stored litter slurry
0= 10-
.=. o
I
--
,=
•~
,
12
A
2.0-
,
Time (h) Fig. 2. Carbon dioxide production from a surface application of stored litter slurry (SIS) to soil, 0.131cm -2 (12,8901ha-J), three replications (mean plus and minus standard error).
3.0
~E
,
0
Carbon dioxide flux densities from broiler litter slurries surface-applied to soil columns were characterized to determine their value for canopy fertilization. Since the timing of respiration emission for the stated conditions was unknown, a number of single sample trials was undertaken to pinpoint the onset of significant flux. An emission peak of carbon dioxide from the stored litter slurry was observed after a short lag time (Fig. 1). Emissions were above the 1.11 g m - 2 h - ~ rate for approximately 8 h. After this initial trial, soil column head space gas samples on subsequent trials were obtained from replicates each hour after slurry application to observe emission characteristics. As shown in Fig. 2, results were similar to the initial trial. However, as additional slurry applications dried and accumulated on the soil surface, the timing and rate of carbon dioxide emission changed. High rates of respiration (greater than 1.11 g m -2 h -]) began from stored litter slurry after a lag time of 4.5 h on the third application of slurry to soil. Respiration lag times increased after subse-
2.5
,
6 ==
1.0-
0.5 ~JD +=
' ~ I ' ' ' t ' ' ' t ' ' ' I ' ' ' I ' ' ' L ' ' ' I I 1 I
0.0
0
2
4
6
8
10
12
14
0
' I' 2
Time
I'
I't'
4
6
8
I'
Slurry
Application=+
10
I' 12
14
(11)
Fig. 1. Carbon dioxide production from a surface application of stored litter slurry (SLS) to soil, 0.13 l cm -2 (12,890 1 ha- i), no replications.
Cumulative
Fig. 3. Lag in respiration after successive slurry applications for stored litter slurry (SLS) surface-applied to soil.
Respiration in broiler litter slurry surface applied to soil applied to a wood chip mulch on soil did not average more than the optimum carbon dioxide respiration level. A barrier between the slurry and the soil surface had the effect of reducing or delaying respiration, perhaps because of the isolation of the available carbon in the slurry from organisms in the soil. Variation in respiration rates between replicates might be attributable to respiration occurring in 'puffs' rather than as a steady emission. Evidence for this conclusion is that a high carbon dioxide emission rate from a soil column was often followed in the subsequent hour by a very low emission. This characteristic of respiration might be a result of synchronous metabolism and diauxic growth (Brock et al., 1994). As slurry made from fresh litter aged, the respiration rates changed. The highest emissions occurred on the sixth day. When fresh slurry, kept for seven days, was used as an inoculum for the stored litter slurry, the emissions were unexpectedly large and intermittent, causing a high variation in emissions. Gas samples collected 3 h after application showed flux densities of 6.30 and 10.63 g CO2 m - 2 h -~ for
S
--
4" ~'E~ 4
Fluxduration,eachsubdivision= 4 hours •~
3
o
2
/ A
/
Fluxrequiredfor max.canopyrespons~
/
1
I
Day 4
I
I
I
I
Day 7
Day of Application
I
I
Day 11 During
I
Day 22
35 Days of Incubation
Fig. 4.
127
two of the replicates, the third replicate indicated measurements were unexpectedly high in concentration and thus beyond gas chromatograph calibration limits. Gas samples collected after 6 h showed flux densities of 14.21 and 0.25 g CO2 m -2 h-~ for the first two replicates and again the third replicate was off scale. These results again indicate the high variability in the 'puffs' of microbial respiration. The high productivity of the inoculated slurry might be a result of the combination of a high availability of volatile fatty acids and other water soluble carbon compounds from the stored slurry, and a high number of organisms in the inoculum in a high state of metabolism. These results indicate that a detailed investigation of inoculated slurries is warranted. No significant difference at the 0.05 significance level existed between respiration rates from SLS, SLSM, SFLS and FLS treatments. A significant difference in respiration rates occurred from the SLSI treatment.
DISCUSSION If CO2 is supplemented under the canopy from a ground source, a closed canopy crop may produce a higher yield. The biophysics within closed crop canopies appears to offer the opportunity to enrich the canopy with a ground source of carbon dioxide to obtain an increase in net photosynthesis. An average increase of 23% in net peak photosynthesis was estimated for C3 plants with a closed canopy receiving a ground source carbon dioxide flux density of 1.11 g CO2 m - 2 h i. Flux of carbon dioxide from stored slurry and fresh litter slurry (aged for six days) surface applied to soil is greater than that required for estimated maximum benefit for C3 plants with closed plant canopies (1.11 g m -2 h - i ) . Elevated rates of carbon dioxide flux from respiration last for more than 6 h when the slurries are surface ap~plied to soil. Slurries are much easier to apply to a closed crop canopy than dry litter. The slurry, when screened to exclude
Table 1. Average carbon dioxide respired from slurry treatments integrated over a 9.5 h period, three replications applied to soil
Treatment
SLS SLSM SFLS FLS SLSI
Respiration lag (h)
Tot. C applied (g C m 2)
6 5 8.5 3.5 3
23.54 23.54 26.87 24.69 27.04
Tot. CO2-C released 1 (% of total C applied) 13.9"2 1.66b 12.67b 19.19b 50.93a
Ave. CO2 flux (g C02 m -2 h-~)
Ave. CO2 flux per g C applied
1.26 0.15 1.31 1.83 5.32
0.054 0.006 0.049 0.074 0.197
SLS: stored litter slurry; SLSM: stored litter slurry with mulch; SFLS: stored fractionated litter slurry; FLS: fresh litter slurry aged for six days; SLSI: stored litter slurry_inoculated with FLS aged for seven days.I Linear interpolation between measurements, integration over a 9.5 h period.2 Means with the same letter are not significantly different at the 0.05 significance level.
128
T. T. Adams, S. A. Thompson, M. L. Cabrera, M. A. Eiteman
large particles, may be pumped and sprayed on a field. The spraying of slurries on fields with developed crops is a commonly practiced, proven application method. If slurries are applied during daylight hours, the timing of slurry application is important since the respiration lag and delayed flux of carbon dioxide may result in much of the carbon dioxide being respired after dark. Lag time for broiler litter slurries may depend on the frequency of slurry application. By inoculating stored litter slurry with a fresh litter slurry allowed to age for seven days, the average flux density of carbon dioxide increased by 322% and the respiration lag time decreased to less than 3 h, conditions which may permit daily slurry applications. No significant difference in carbon dioxide rates occurred from slurries made from fresh and stored litter. Storing broiler litter under conditions of restricted air contact preserves carbon nutrients allowing slurries to be prepared and applied coincident with optimum crop growth periods. Additionally, storing poultry litter maintains the option of selling litter as a ruminant feed. Before utilizing biological waste slurries for the purpose of carbon dioxide enrichment, the fate of other slurry nutrients, specifically nitrogen and phosphorus compounds, must be examined to quantify their impact on crop nutrient requirements, and on soil and water quality. Additional processing of slurries may be required to control nitrogen and phosphorus transformations.
REFERENCES Acock, B. & Allen, L. H. (1985). Crop responses to elevated carbon dioxide concentrations. In Direct Effects of Increasing Carbon Dioxide on Vegetation, ed. B. R. Strain and J. D. Cure. U.S. Dept. of Energy, DOE/ER-0238, Dist. Category Uc-ll, Washington, D.C. pp. 100-116. Adams, T. T. (1994). Production of carbon dioxide from ensiled broiler litterY Master's thesis, The University of Georgia, Department of Biological and Agricultural Engineering, Athens, GA. Alexander, M. (1967). Introduction to Soil Microbiology. Wiley, New York. Aphalo, P. J. & Jarvis, P. G. (1993). The boundary layer and the apparent responses of stomatal conductance to wind speed and to the mole fraction of CO2 and water vapor in the ai~ Plant, Cell and Environ., 16, 771-783. Baker, B. N. & Enoch, H. Z. (1983). Plant growth and development. In C02 and Plants, ed. E. R. Lemon. AAAS Selected Symposium 84, Westview Press, Boulder, CO, pp. 122-123. Baldocchi, D. (1992). A Lagrangian random-walk model for simulating water vapor, CO2 and sensible heat flux densities and scalar profiles over and within a soybean canopy. Boundary-Layer Meteorol., 61, 113-144. Biscoe, P. V., Scott, R. K. & Monteith, J. L. (1975). Barley and its environment, III. Carbon budget of the stand. J. Appl. Ecol., 12, 269-293. Bodrova, E. M. & Ozolina, Z. D. (1965). Simultaneous Application of Organic and Mineral Fertilizers. Translated from the Russian and published pursuant to an agree-
ment with the U.S. Dept. of Agriculture, Jerusalem, pp. 72-100. Boote, D. J. & Loomis, R. S. (1991). Modeling crop photosynthesis - - From biochemistry to canopy. CSSA Special Publication No. 19, Crop Science Society of America, Madison, WI. p. 126. Brock, T. D., Madigan, M. T., Martinko, J. M. & Parker, J. (1994). Biology of Microorganisms. Prentice Hall, Englewood Cliffs, NJ, p. 176. Bussiere, F. & Cellier, P. (1994). Modification of the soil temperature and water content regimes by a crop residue mulch: experiment and modeling. Agricultural and Forest Meteorology, 68, 1-28. Cooper, P. & Cornforth, I. S. (1978). Volatile fatty acids in stored animal slurry. J. Sci. FoodAgric., 29, 19-27. Denmead, O. T. (1969). Comparative micrometeorology of a wheat field and a forest of Pinus radiata. Agricultural and Forest Meteorology, 6, 357-371. D'yakonova, K. V. (1954). Soil as a source of carbon dioxide for plants on irrigated and nonirrigated ciscaucasian chernozems. In Microorganisms and Organic Matter of Soils, ed. K. Greensburg (1970). Translated from Russian, Keter Press, Jerusalem. pp. 122-189. Gale, P. M. & Gilmour, J. T. (1986). Carbon and nitrogen mineralization kinetics for poultry litter J. Environ. Qual., 15, 423-426. Jantrania, H. G. & White, R. K. (1985). High solids anaerobic fermentation of poultry manure. In Agricultural Waste Utilization and Management, Proceedings of the Fifth International Symposium on Agricultural Wastes, ASAE, St. Joseph, MI. pp. 73-80. Jones, H. G. (1992). Plants and Microclimate, A Quantitative Approach to Environmental Plant Physiology. Cambridge University Press, Cambridge, pp. 90-116. Kimball, B. A. (1995). Update. Plant's CO2 diet doubled in world's largest study. Resource, 2, 7. Keulen, H. van, Goudriaan, J. & Seligman, N. G. (1989). Modelling the effects of nitrogen on canopy development and crop growth. In Plant Canopies: Their Growth, Form and Function, ed. G. Russell, B. Marshall and P. G. Jarvis. Cambridge University Press, Cambridge. pp. 83-104. Lawlor, D. W. (1987). Photosynthesis: Metabolism, Control, and Physiology. John Wiley, New York, pp. 127-137. Mathsoft (1992). Mathcad 3.1 User's Guide. Mathsoft, Cambridge, MA. Monteith, J. L., Szeicz, G. & Yabuki, K. (1964). Crop photosynthesis and the flux of carbon dioxide below the canopy. J. Appl. Ecol., 1, 321-337. Monteith, J. L. & Unsworth, M. H. (1990). Principles of Environmental Physics. Edward Arnold, London, pp. 113-269. Nakamoto, S. T., Leung, P. S. & Wanitprapha, K. (1994). The value of diluted poultry slurry. Biores. Technol., 48, 25-30. Ndegwa, P. M., Thompson, S. A. & Merka, W. C. (1991). Fractionation of poultry litter for enhanced utilizatiort Trans. ASAE, 34, 992-997. Nodar, R., Acea, M. J. & Carballas, T. (1990). Microbial populations of poultry pine-sawdust litter. Biological Wastes, 33, 295-306. Norman, J. M. & Arkebauer, T. J. (1991). Predicting canopy photosynthesis and light-use efficiency of canopies as affected by leaf and canopy traits. In Modeling Crop Photosynthesis - - From Biochemistry to Canopy, CSSA Special Publication 19, Crop Science Society of America, Madison, WI, pp. 75-94. Patni, N. K. & Jui, P. Y. (1985). Volatile fatty acids in stored dairy cattle slurry. Agricultural Wastes, 13, 159-178.
Respiration in broiler litter slurry surface applied to soil
Paul, J. W. & Beauchamp, E. G. (1989). Relationship between volatile fatty acids, total ammonia, and pH in manure slurries Biol. Wastes, 29, 313-318. Paw U, K. T., Brunet, Y., Collineau, S., Shaw, R. H., Maitani, T., Qiu, J. & Hipps, L. (1992). On coherent structures in turbulence above and within agricultural plant canopies Agric. For. Meteorol., 61, 55-68. Paw U, K. T., Brunet, Y., Collineau, S., Shaw, R. H., Maitani, T., Qiu, J. & Hipps, L. (1993). Corrigendum. On coherent structures in turbulence above and within agricultural plant canopie~ Agric. For. Meteorol., 63, 127. Perkins, H. F. (1987). Characterization data for selected Georgia soils. Special Publication 43, Georgia Agricul-
129
tural Experiment Station, The University of Georgia, Athens, GA. SAS Institute (1985). SAS User's Guide: Statistics, Version 5. SAS Institute, Cary, NC. Stevens, R. J. & Cornforth, I. S. (1974). The effect of aeration on the gases produced by slurry during storage. J. Sci. Food Agric., 25, 1249-1261. Tisdale, S. L., Nelson, W. L. & Beaton, J. D. (1985). Soil Fertility and Fertilizers. MacMillan, New York, pp. 36-38, 636-653. Water Pollution Control Federation (1976). Operation of Wastewater Treatment Plants. Manual of Practice 11. Lancaster Press, Lancaster, PA, pp. 264-266.