Agronomy Journal Grow Your Career With ASA
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Published online 17 August 2005
Published in Agron J 97:1304-1313 (2005)
DOI: 10.2134/agronj2004.0277
© 2005 American Society of Agronomy
677 S. Segoe Rd., Madison, WI 53711 USA
This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF) Free
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (9)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Bittman, S.
Right arrow Articles by Bounaix, F.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Bittman, S.
Right arrow Articles by Bounaix, F.
Agricola
Right arrow Articles by Bittman, S.
Right arrow Articles by Bounaix, F.
Related Collections
Right arrow Forage Management
Right arrow Best Management Practices
Right arrow Nitrogen
Right arrow Nutrient Management
Right arrow Air Pollution
Right arrow Soil Fertility and Productivity
Right arrow Animal Waste

Production Papers

Surface-Banding Liquid Manure over Aeration Slots

A New Low-Disturbance Method for Reducing Ammonia Emissions and Improving Yield of Perennial Grasses

Shabtai Bittmana,*, Laurens J. P. van Vlieta, C. Grant Kowalenkoa, Sean McGinnb, Derek E. Hunta and Frederic Bounaixa

a Pacific Agri-Food Res. Cent., Agric. and Agri-Food Canada, Box 1000, Agassiz, BC, V0M 1A0 Canada
b Lethbridge Res. Cent., Agric. and Agri-Food Canada, 5401-1 Ave. South, Lethbridge, AB, T1J 4B1 Canada

* Corresponding author (bittmans{at}agr.gc.ca)

Received for publication November 15, 2004.

   ABSTRACT
TOP
 NOTES
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 CONCLUSIONS
 REFERENCES
 
Low-disturbance methods for applying slurry manure on forages are needed that can maximize crop response and minimize loss of nutrients to the environment. A new implement [Aerway SSD (subsurface deposition slurry applicator)] that bands manure over aeration-type slots was assessed relative to conventional broadcasting and surface banding. The comparison was based on immediate and residual crop responses to single and multiple applications of dairy slurry by tall fescue (Festuca arundinacea Schreb.) and orchardgrass (Dactylis glomerata L.). Also, ammonia emissions were compared using both semiopen chamber and micrometeorological (integrated horizontal flux) methods. The aeration slots without manure generally did not have a significant effect on yield or N uptake. Averaged over all harvests, surface banding increased yield and N uptake over broadcasting by 6.9 and 6.8%, respectively. The SSD increased yield and N uptake over surface banding by 4.4 and 7.5%, respectively. The relative effectiveness of the techniques on yield varied among experiments. In the ammonia volatilization trials (micrometeorological method), loss of applied total ammoniacal N in the 2 wk after application ranged from 36 to 61% for broadcast manure compared with 17 to 32% for SSD-applied manure. With both micrometeorological and semiopen chamber, ammonia emissions from applied manure were 46 to 48% lower with the SSD than with broadcasting. Emissions from surface-banded manure (chamber method) averaged 33% greater with surface banding than with the SSD. The results indicate that the SSD manure applicator reduced ammonia loss and increased yield and N uptake relative to broadcasting and surface-banding techniques.

Abbreviations: SSD, subsurface deposition slurry applicator (Aerway SSD, Holland Equipment Ltd., Norwich, ON, Canada) • TAN, total ammoniacal nitrogen


   INTRODUCTION
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 CONCLUSIONS
 REFERENCES
 
LIVESTOCK MANURES are typically rich in undigested nutrients that are returned to the land for reuse by crops. The goal when applying manure on the land is to utilize the nutrients and reduce application of manufactured fertilizers without contaminating the environment. There is frequently a need to apply manure, particularly slurries, to perennial forages. These crops often take up more nutrients than annual crops and can conveniently receive several applications over the growing season each time the crop is harvested. By applying manure over the growing season, storage facilities can be continually emptied, reducing the need for application in autumn and for wintertime storage capacity. Also, because of year-round vegetation cover and typically deep roots of perennial forages, the risk of runoff and leaching of manure nutrients during winter from forage stands will be less than from bare soil or cover crops after harvest of annual crops.

The traditional method for spreading liquid manure on forage crops, surface broadcasting with a splashplate applicator, is rapid and inexpensive. However, broadcasting of manure is typically uneven, especially under windy conditions (Huther, 1988). Broadcast manure may also damage grass swards (Christie, 1987; Prins and Snijders, 1987; Wightman et al., 1997) and contaminate standing plants with microorganisms that can impede silage fermentation (Anderson and Christie, 1995; Steffens and Lorenz, 1998). Surface-applied manure is also prone to runoff into waterways (Uusi-Kamppa and Heinonen-Tanski, 2001). Crop response to broadcast application of slurry manure is often inconsistent (Bittman et al., 1999), and this probably discourages farmers from using slurry as a primary nutrient source. Inconsistent crop response is largely attributed to volatilization of ammonia, which is influenced by manure properties, soil attributes, and weather conditions (Stevens and Laughlin, 1997; Sommer and Hutchings, 2001). Volatilization of ammonia is reduced by minimizing the surface exposure of manure with the air and improving contact with the soil (Sommer and Hutchings, 2001). There is more ammonia loss after broadcasting of liquid manure on stubble than on bare soil, particularly if the manure has high dry matter content, because of increased exposure to the air (Frost, 1994). The amount of manure ammonia lost to the atmosphere is negatively related to rate of infiltration of manure into the soil; infiltration is enhanced by injection or incorporation of manure (Sommer and Hutchings, 2001). However, despite conserving ammonia, injection of manure may reduce yield of perennial grasses (Rees et al., 1993; Tunney and Molloy, 1986; Prins and Snijders, 1987). The yield reductions are attributed to the cutting of roots during injection (Rees et al., 1993), drying of the soil (Prins and Snijders, 1987), and anaerobic and toxic conditions from concentrating the manure in the injection slots (Tunney and Molloy, 1986). The yield reduction is greater with multiple applications over the season (Prins and Snijders, 1987). Manure injection may not be practical on stony or sloped land or on farms lacking access to powerful tractors. The direct ground injection (DGI) system forces finely separated manure under pressure into the soil with little soil disturbance (Morken and Sakshaug, 1998). Surface-banding slurry manure with drag-shoe or drop-hose implements is a compromise between injection and broadcasting. Surface-banding implements apply manure more uniformly than splashplates (Huther, 1988) and place the manure beneath grass canopies so that little adheres to and contaminates foliage. Slurry manure applied by surface banding typically supports higher yields than slurry applied by broadcasting (Lorenz and Steffens, 1997; Stevens and Laughlin, 1997; Bittman et al., 1999). Also, by delivering manure under the grass canopy, more time is available for spreading manure without contaminating the grass as it regrows (Bittman et al., 1999). Although injection conserves more ammonium N, surface banding and broadcasting may be more economical than injection (Rodhe and Rammer, 2001).

Placing slurry into narrow vertical slots has been shown to reduce ammonia loss compared with surface application (Frost, 1994). The effect of such vertical slots created with aeration-type implements is frequently benign on productivity of forage stands, based on studies conducted in Scotland (Douglas et al., 1995), Alberta (Malhi et al., 2000), and Manitoba (Chen et al., 2001). In contrast to these studies, aeration of compacted soil improved yield of perennial ryegrass (Lolium perenne L.) in Wales (Davies et al., 1989) but reduced yield on commercial timothy (Phleum pratense L.) fields in Nova Scotia (Gordon et al., 2000). None of the published studies examined the effect of repeated aeration treatments for more than one cut per year, which might be required for multiple manure applications. Douglas et al. (1995) suggested that aerating soil might improve infiltration of manure, but Gordon et al. (2000) and Chen et al. (2001) found that aeration before broadcasting dairy slurry did not reduce ammonia loss or improve yield. Unless there is surface crusting, aeration slots that cover less that 3% of the surface area of a field are unlikely to help infiltration of manure into the soil. To increase the amount of manure that infiltrates via aeration slots and to benefit from the advantages of banding, a manure applicator was designed that bands the slurry directly over the row of slots made by an aerator (Aerway SSD, Holland Equipment Ltd., Norwich, ON, Canada). This applicator can reduce odor emission from swine manure relative to surface broadcasting (Lau et al., 2003). The objective of our study was to compare three methods of applying liquid dairy manure on grass: conventional broadcasting, surface banding, and surface banding over aeration-type soil openings. The study examined volatilization of applied ammonia and yield and N uptake by two grass species, tall fescue, and orchardgrass.


   MATERIALS AND METHODS
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 CONCLUSIONS
 REFERENCES
 
The trials were conducted at the Pacific Agri-Food Research Centre at Agassiz in south coastal British Columbia (49°10' N, 125°15' W). The soils at the experimental sites are silty to sandy loam with about 6% organic matter, belonging to the Monroe series, described as an Eutrochrept of moderately good drainage derived from medium-textured stone-free Fraser River deposits. Weather data were collected within 0.5 km of all trials (Table 1). In 2000, crop response trials were conducted on a 5-yr-old stand of ‘Maximize’ tall fescue. In 2001, crop response trials were conducted on 3-yr-old stands of tall fescue (Fuego) and orchardgrass (Profile). The treatments in all yield trials comprised three manure application methods: broadcasting, surface banding, and surface banding over aeration slots.


View this table:
[in this window]
[in a new window]
  		Table 1. Weather conditions during the day of, day after, week after, and 2 wk after application of manure for the yield and micrometeorological trials in 2000 and 2001.

 
The "surface banding over aeration slots" application method (SSD treatment) was considered subsurface deposition and used a prototype Aerway SSD applicator (Fig. 1) . In this implement, the slurry is pumped under low pressure (under 0.1 MPa) from a liquid manure tank to a chopper distributor (Vogelsang, Essen, Germany), which homogenizes and divides the slurry evenly into separate equal-length hoses that deliver the manure to soft rubber emitters or nozzles positioned 2 cm above the soil surface. The emitter openings are oval and oriented parallel to the direction of travel to produce narrow bands, typically 5 cm wide. The emitters are positioned directly behind ground-driven aeration units, spaced 19 cm apart, which results in approximately 11 slots m–2. The aeration units consist of four tapered tines, measuring 15 cm wide (at the base) and 20 cm long, mounted at 90° angles from one another. The tines have a slight (2.5°) twist along their lengths that creates some lateral soil movement as the tines roll through the soil. The size of the aeration slots can be varied by adjusting tine depth (using depth control wheels) and offset angle (0–10°). In our study, the tine depth was 18 cm and the offset angle 2.5°. At these settings, the volume of each aeration slot was about 0.24 L while the combined slot volume per ha (26000 L) could accommodate about a third of the applied slurry.



View larger version (33K):
[in this window]
[in a new window]
  		Fig. 1. Schematic of the SSD liquid manure applicator. The implement places narrow bands of manure on the soil surface directly over a line of intermittent vertical slots created with aeration tines to assist infiltration.

 
Conventional surface banding was also done with the SSD implement by lifting the tines out of the ground and lengthening the emitters. Broadcasting was done with a commercial splashplate applicator. All applicators were calibrated before use. The slurry was obtained from an uncovered lagoon on an intensively managed dairy farm that uses wood-chip bedding in a free-stall barn. The manure properties and application rates are shown in Table 2.


View this table:
[in this window]
[in a new window]
  		Table 2. Composition and application rates of dairy slurry manure in yield and ammonia emission trials in 2000 and 2001.

 
Crop Response Trials
In all trials, treatments were applied on a recently harvested area. In year 2000, three trials were initiated on 24 May, 24 July, and 11 September. The May trial was harvested on 7 July, 30 August, and 19 October, the two latter harvests to determine carryover effect of the May treatments. The July trial was harvested on 30 August and 19 October, the latter harvest also to test the carryover effect of manure treatments. The September trial was harvested only on 19 October, which was effectively the end of the growing season. A fourth trial was conducted in 2000 to test the effect of multiple treatments (called Multiple). This Multiple trial received manure on each of the three application dates and was harvested on all above harvesting dates. There were two nonmanured controls, one aerated and one nonaerated. Each trial in 2000 was designed as a randomized complete block with four blocks. In year 2001, trials on both grass species were initiated on 21 May and 17 July. The May trial was harvested on 9 July and 11 September, and the July trial was harvested only on 11 September. A Multiple trial was treated on both 21 May and 17 July and harvested on both 9 July and 11 September. To conserve space in 2001, treatments for all application dates (i.e., trials) were fully randomized, rather than grouped, within each block so that the same nonaerated control plots could be used for all trials. Each harvest was analyzed as a randomized complete block with the same control treatment. Dates of treatments and harvesting are summarized in Table 3.


View this table:
[in this window]
[in a new window]
  		Table 3. Schedule of manure applications and grass harvesting for trials conducted in year 2000 and 2001 at Agassiz, BC.

 
All plots were about 3.5 by 10 m with a representative 1.5- by 7-m strip harvested using a sickle-bar harvester. Harvested herbage was weighed fresh and sampled for dry matter and total N content determination. The samples were weighed, dried at 60°C until constant weight, and then reweighed. These samples were ground through a 1-mm mesh and then analyzed using an automated dry-ash method (FP-428 Nitrogen Determinator, LECO Corp., St. Joseph, MI) to determine concentration of total N. Nitrogen uptake was calculated as the product of yield and total N concentration.

Ammonia Volatilization Trials
Both mass balance (micrometeorological) and semiopen chamber methods were used to measure ammonia volatilization. The micrometeorological method required large plots, so these trials were conducted separately from the crop response trials. The semiopen chambers were used on both the micrometeorological trials and the crop response trials. The micrometeorological trials were conducted on 16 May and 2 August in 2000 and on 9 May and 9 August in 2001. These trials compared splashplate- and SSD-applied manure in plots measuring 20 by 20 m. Large plastic sheets were laid on sides of the trial before manure application and quickly removed after application to exclude manure from outside the plot areas. The treatments were completely randomized in 2000 and randomized in complete blocks in 2001; three replicates were used in both years. The plots were all oriented in the same direction, and there was at least 60 m between plots. Three semiopen chambers were used for each plot and on untreated areas.

The micrometeorological ammonia flux density procedure followed the integrated horizontal flux-mass balance approach described by McGinn and Janzen (1998). Immediately after manure application, a mast was erected on the middle of each edge of the square plots for supporting passive ammonia samplers at heights of 0.25, 0.5, 1.0, and 3.0 m. Two passive flux samplers were placed at each height and oriented at 90° to edge of plot, with the stainless steel disc end of one sampler facing toward the plot and the other facing away. A passive flux sampler unit consisted of a pair of glass tubes (100 mm long, 7 mm i.d., and 10 mm o.d.) connected together by a small piece of silicon tubing, plus a 10-mm-long glass tube covered on one end by a stainless steel disc with a precise 1-mm hole at its center to control air flow. Before use, the glass tubes were coated on the inside with a solution of 3% oxalic acid in acetone and then quickly dried with ammonia-free air. After exposure in the field, the ammonia was extracted from the glass tubes with deionized water and analyzed by a Tecator flow injection analyzer (Kowalenko and Yu, 1996). Weather stations were positioned between each pair of plots and consisted of a datalogger (Model 21X, Campbell Scientific, Logan, UT), cup anemometers (Model 014A, MetOne, Grant's Pass, OR), and temperature sensors (Model 108, Campbell Scientific) mounted at the same heights as the passive flux samplers, and a wind vane (Model 24A, MetOne) mounted at 1-m height. The datalogger recorded wind speed, wind direction, and temperature every 5 s and averaged measurements over 30-min periods. The semiopen chambers and passive samplers were changed at 1, 2, 3, 7, and 14 d after manure application. The micrometeorological trials were analyzed as completely randomized designs in 2000 and randomized complete block designs in 2001.

The semiopen chamber method followed Marshall and Debell (1980). Three chambers were installed in each plot immediately after manure application by pushing them into the soil and sealing with a 3-cm ridge of sand. For the control and splashplate plots, the chambers were placed randomly in the plot areas. For the surface banding and SSD treatments, each chamber was centered over a manure band (and covered only that band). The effective manure sampling area was adjusted for the amount of manure covered. For each SSD plot, one chamber was centered over an opening, one was centered between openings, and one was placed midway between these positions to determine if there was an effect of chamber position. Chambers consisted of white PVC cylinders (66 cm high and 31 cm i.d.). After the chambers were installed, a polyurethane foam sorption pad (2.5-cm thick and 32-cm diam.) was inserted into the chambers 26 cm above the soil (held by a narrow rod), creating an effective volume of 20 L between the soil surface and the lower pad. A second sorption pad placed near the top of the chamber prevented deposition of ambient ammonia to the lower pad. A piece of corrugated polyvinyl was arched loosely over the chamber tops to protect from rain but allow air flow over the chamber. The foam sorption pads were cleaned with deionized water, squeezed to remove water, and soaked with a 100-mL solution of 0.7 M H3PO4 and glycerine (2:1) before use in chambers. A preliminary trial had shown that using more absorbent solution did not alter ammonia capture. To extract ammonia, each pad was rinsed three times in 600 mL of deionized water, and the storage bag was rinsed with 100 mL of deionized water; all extractant was combined and adjusted to 2000 mL. The ammonium concentration in this solution was determined using a Tecator flow injection analyzer (Kowalenko and Yu, 1996). The chamber pads were replaced 1, 2, 3, 7, and 14 d after manure applications (referred to as shifts). The quantity of ammonia absorbed on the sides of the chamber was found to be less than 1 and 5% of trapped ammonia in Shifts 1 and 2, respectively, and hence was ignored. Values for nonmanured controls were subtracted from the treated plots before analysis. The control treatments were not included in the statistical analysis but are presented in the tables. The data from the semiopen chamber trials were analyzed as randomized complete block designs.

Significance level for all comparisons was set a priori at P < 0.05%.


   RESULTS
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 CONCLUSIONS
 REFERENCES
 
Crop Response
In 2000, there was no evidence that aerating the soil (without manure) in May, July, or September affected yield or N uptake of tall fescue in any of the immediate or subsequent harvests (data not shown). The May and September aerations were followed by relatively wet periods while the July aeration was followed by a relatively dry period (Table 2). In 2001, none of the aeration treatments significantly affected yield of any orchardgrass harvests, with the exception that aeration under moist conditions in May (Table 2) significantly decreased yield and N uptake of the September harvest by 0.22 Mg ha–1 and 4.5 kg ha–1, respectively (data not shown). In contrast, aeration in May significantly increased the July yield and N uptake of tall fescue by 0.15 Mg ha–1 and 2.6 kg ha–1, respectively, while the multiple aeration treatment significantly increased the combined yield of the two harvests by 0.39 Mg ha–1 and N uptake by 7.7 kg N ha–1 (data not shown).

Manure consistently increased yield and N uptake over the control (unmanured) plots in the first harvest after application, regardless of trial, season, or application technique (Tables 4–9). In both May application trials (Single and Multiple) in 2000, manure produced about 16% higher yields when applied with the SSD than with the splashplate applicator (Table 4). The yield of the surface-banded treatment was intermediate, not significantly different from either splashplate or SSD treatments. The splashplate-applied manure (May) also produced significantly lower yield than the SSD and surface-banding treatments in the two subsequent untreated harvests (residual); in these harvests, there was a carryover effect of manure applied by both banding treatments but not by broadcasting. No yield differences due to application methods were found in August and October harvests subsequent to July and September applications, respectively. However, in the October harvest after the July application, yield was significantly greater for the SSD than the splashplate while surface banding was intermediate and not significantly different from the other methods. There were no differences among application methods in the August and October harvests in the Multiple trial.


View this table:
[in this window]
[in a new window]
  		Table 4. Effect of dairy slurry manure spread as single spring, summer, and autumn treatments and in all three seasons (Multiple), using three applicators, on immediate and residual dry matter yield response by tall fescue in 2000.

 

View this table:
[in this window]
[in a new window]
  		Table 9. Effect of dairy slurry manure spread as single spring, summer, and autumn treatments and in all three seasons (Multiple), using three applicators, on immediate and residual N uptake response by tall fescue in 2001.

 

View this table:
[in this window]
[in a new window]
  		Table 5. Effect of dairy slurry manure spread as single spring, summer, and autumn treatments and in all three seasons (Multiple), using three applicators, on immediate and residual dry matter yield response by orchardgrass in 2001.

 

View this table:
[in this window]
[in a new window]
  		Table 6. Effect of dairy slurry manure spread as single spring, summer, and autumn treatments and in all three seasons (Multiple), using three applicators, on immediate and residual dry matter yield response by tall fescue in 2001.

 

View this table:
[in this window]
[in a new window]
  		Table 7. Effect of dairy slurry manure spread as single spring, summer, and autumn treatments and in all three seasons (Multiple), using three applicators, on immediate and residual N uptake response by tall fescue in 2000.

 

View this table:
[in this window]
[in a new window]
  		Table 8. Effect of dairy slurry manure spread as single spring, summer, and autumn treatments and in all three seasons (Multiple), using three applicators, on immediate and residual N uptake response by orchardgrass in 2001.

 
A similar pattern to that found in 2000 was observed for yield of orchardgrass in 2001 (Table 5). Manure increased herbage yield in the first harvest after all applications. In the July harvests after both May applications (Single and Multiple), yield with SSD-applied manure was significantly greater than broadcast manure while surface banding was intermediate and not significantly different. For the single May application, this effect carried over to the September harvest and was evident in the combined yield. There was no significant yield difference due to application methods for either July application (Single and Multiple). All manure applications enhanced yield of tall fescue in 2001 (Table 6). Tall fescue yields responded more to the SSD applicator than the splashplate only in the spring application of the Multiple treatments; no significant differences due to method were found in either the spring or summer treatments.

There was little difference in the N concentration (data not shown) of the herbage due to method of manure application in any of the trials, so the differences in N-uptake values largely reflect changes in herbage yield in all trials. In the 2000 trial, N uptake was often greater for the SSD than the splashplate, but the difference was significant only in the July harvest of the Multiple trial (Table 7). In 2001, greater N uptake for the SSD than the splashplate was also observed for most orchardgrass harvests (Table 8) but only one tall fescue harvest (Table 9). Surface banding promoted greater N uptake than the splashplate only in the first harvest of the Multiple trial and the October harvest after the May application in 2000, a May application on orchardgrass in 2001, and a May application on tall fescue in 2001. The SSD was superior to the splashplate in one tall fescue harvest in 2000 (30 Aug. 2000), one orchardgrass harvest (9 July) in 2001, and one tall fescue harvest on the same date in 2001.

Overall, tall fescue yield was significantly better with the SSD than the splashplate treatment in five of nine harvests in 2000 (Table 4). In 2001, orchardgrass yields responded significantly better to SSD than splashplate-applied manure in three of five harvests (Table 5) while tall fescue responded more in one of five harvests (Table 6). Grass yields were never greater from splashplate-applied manure than from SSD-applied manure in any of the trials. Nitrogen uptake was greater with the SSD than the splashplate in 15 of 19 measurement periods although the difference was significant in only four harvests (Tables 6–9). It is noteworthy that in 2000, plants recovered 19 kg ha–1 more N from SSD than from splashplate treatment under multiple applications where about 275 kg NH4–N ha–1 had been applied (about 7% improved recovery) and 14 kg ha–1 more from the 92 kg NH4–N ha–1 in spring-applied manure (15% improved recovery).

Ammonia Emissions
With the micrometeorological method, loss of ammonia N in the 2 wk after broadcast slurry application ranged from 19.7 kg ha–1 in August 2001 to 44.1 kg ha–1 in May of 2000 (Table 10). This represented losses of 36 to 61% of applied total ammoniacal N (TAN). In contrast, loss of ammonia N from SSD-applied slurry ranged from 14.2 to 18.7 kg ha–1 or 17 to 32% of applied TAN. About 85% of emissions occurred in the first 24 h after manure application for both methods of application, so conservation of ammonia largely occurred during this period. It was perhaps surprising that greater losses were observed in the May applications (56 and 61% of TAN) than the August application (36–41%), especially in 2001 when temperatures, wind, and sunshine hours were much greater, on both the day of application and the next day, in August than in May (Table 2). The total emissions for the SSD over 2 wk of sampling were 35 to 58% (average 52%) of that by broadcast manure (Table 10). Difference between the SSD and splashplate seemed to be somewhat greater for spring than for summer application. This may be related to relatively rapid infiltration in August even without aeration, probably because the soils were drier in August than in May. In the 2 wk before manure application, the water deficits (evapotranspiration minus precipitation) were 15 mm (2000) and –4.9 mm (2001) in spring compared with 35 mm (2000) and 28 mm (2001) in August.


View this table:
[in this window]
[in a new window]
  		Table 10. Effect of applicator on ammonia N emission from liquid dairy manure applied to orchardgrass stands in spring and summer of 2000 and 2001, measured by micrometeorological and semiopen chamber techniques.

 
In the SSD plots, no differences in ammonia emission were found between the chamber positions (centered on a slot, centered midway between slots and halfway between these positions) at all treatment shifts. This indicated that there were no more ammonia emissions from the manure-filled slots than from the manure bands on the soil surface. Because there was no difference due to chamber position, the data from the three chambers were pooled (Table 11). On average, emissions measured with the semiopen chamber were about 30% those measured by micrometeorological, a proportion similar to that reported by Gordon et al. (2000). Similarly, emission values for CO2, CH4, and N2O measured with static vented chambers were only 12 to 22% of those measured with the micrometeorological technique (Sommer et al., 2004). Despite the difference in emission rates, we found the relative emissions by the application techniques were similar for the measurement methods, with SSD emissions averaging 48% lower than broadcasting rates using chambers compared with 46% lower using the micrometeorological method. Whereas in three of four experiments the proportion of ammonia lost in the first shift relative to all shifts was similar for the two methods, the chambers had lower first-shift rates and a slower rate of decline in emission rates in the May 2001 trial. Similarly, in the crop response trials, over 80% of ammonia emissions measured with chambers took place in the first 24 h. In these trials, emissions from the SSD averaged 60% less than broadcast manure, and the difference was significant in all five trials. The surface-banding treatment averaged 40% less emission than the broadcast manure treatment, and the difference was significant in four of five trials. Emissions from the surface-banding treatment averaged 33% more than the SSD treatment; although numerically different in all five trials, the difference was significant in only the two May trials and when averaged over all trials. As in the micrometeorological emission trials, the SSD and surface-banding treatments conserved more ammonia in the May than the July or September applications.


View this table:
[in this window]
[in a new window]
  		Table 11. Effect of method of dairy slurry application on tall fescue sod emissions of ammonia measured with the semiopen chamber technique.

 

   DISCUSSION
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
CONCLUSIONS
 REFERENCES
 
The general lack of effect of soil aeration on yield of tall fescue and orchardgrass is consistent with the results reported for perennial ryegrass on a clay loam soil in a humid climate (Douglas et al., 1995) and for bromegrass (Bromus inermis Leyss)–bluegrass (Poa pratensis L.) and bromegrass–alfalfa (Medicago sativa L.) mixed swards in a semiarid climate (Malhi et al., 2000). Even aggressive aeration, with the aerator set at 15° to direction of travel, did not affect the yield of timothy and alfalfa swards in sandy loam soil in southern Manitoba (Chen et al., 2001). In contrast to these studies, soil aeration improved yield of perennial ryegrass growing on a soil with a compacted surface layer over a more permeable layer (Davies et al., 1989) due to better drainage and increased mineralization of N from soil organic matter. However, where the compaction was consistent through the soil profile, aeration did not improve grass yield because the benefit of aeration was negated by disruption of natural biopores and by direct crop injury (Douglas et al., 1995). There was comparatively little soil compaction in our study (because our measurements were made between the tires of the manure tanker), but there was an indication that orchardgrass, a bunchgrass, may be more sensitive to aeration than slowly rhizomatous, tall fescue. Gordon et al. (2000) reported that aeration reduced herbage yield in Nova Scotia, but this may have been due to possible susceptibility of timothy, also a bunchgrass, which dominated the swards. Timothy was grown in association with alfalfa in Manitoba, so direct effect of aeration on timothy could not be deduced from the study of Chen et al. (2001). That even the multiple aerations did not negatively impact grass yield in our study, and that aeration can be performed on stony land (Davies et al., 1989; personal observation), suggests that the aeration tool can be used in fields and conditions where manure injectors may be unsuitable or damaging to swards. Direct evidence of injector damage to grass swards was reported by Prins and Snijders (1987) and surmised in other reports (Rees et al., 1993; Tunney and Molloy, 1986).

Since aeration did not generally affect yield, the difference in grass responses to manure application methods can be attributed to manure nutrient availability for the different methods. The increases in yield in some aeration applications in our trials contrast to reports of yield reduction due to aeration before spreading of slurry manure by Gordon et al. (2000). However, in their study, the slurry was broadcast whereas our method banded the manure over the aeration slots. The 5-cm-wide manure bands produced by the SSD applicator had 70% less exposed area for ammonia volatilization, and very little banded manure appeared to adhere to crop stubble and residue compared with surface broadcasting. Also, the banded manure rapidly filled the aeration slots that we calculated to hold about 26 m3 ha–1 or about a third of the applied volume. Further, we observed that the manure bands quickly soaked into the soil due to approximately 25% increased absorption surface in the slot walls (approx. 2500 m2 ha–1) and possibly some loosening of the soil due to lateral soil movement by the applicator leaving mainly solids on the soil surface. Grass roots seemed to proliferate along the faces of the manure-filled slots. This suggests a favorable environment at the slot–soil interface, but the overall effect of this root proliferation along the slots is not known. This contrasts with the report that roots could not explore the immediate area of the injected slurry due to anaerobic conditions and toxicity (Tunney and Molloy, 1986). The possibility that walls of the slots may be compressed with reduced infiltration must be considered particularly in fine-textured soils as observed with injection tools (Lund, 2001).

Increased yield and N uptake of the SSD manure treatment compared with the splashplate is probably due largely to reduced ammonia loss. Surface banding conserved about 40% of applied ammonia without the aeration openings, probably due to 70% reduction in exposed manure surface area and less manure left on stubble and residue (Sommer and Hutchings, 2001). The SSD conserved an additional 20% relative to the splashplate, due to rapid filling of the injection slots (26000 L ha–1) and soaking of the liquid fraction into the soil. Rapid infiltration has been shown to reduce ammonia emission (Sommer and Hutchings, 2001). Surface banding under a 20-cm-high grass canopy helps to conserve ammonia (Sommer et al., 1997), but this has not been tested with the SSD. There have been reports that ammonia initially conserved in banded manure is emitted after a several days (Thompson et al., 1990), but we found no evidence of significant emission from the SSD treatment after the first week. Surface broadcasting on aerated soil did not reduce ammonia emissions (Gordon et al., 2000) because the aeration openings covered less than 3% of the soil surface so that only that proportion of a thinly broadcast layer of slurry likely drained into the slots.

That the agronomic benefit of the SSD over the other methods was not consistent is not surprising based on previous studies on manure application. Misselbrook et al. (1996) reported that, while injection reduced ammonia volatilization loss without affecting denitrification, it reduced both yield and apparent N recovery compared with surface broadcasting. The yield reduction was attributed to poor slurry distribution, the narrow tines giving very high rates in narrow concentrated bands spaced 30 cm apart. Although ammonia volatilizes more under warm, windy conditions (Sommer and Hutchings, 2001), our trials suggest that the SSD benefited yield and ammonia conservation more in spring than in summer. Averaged over the two spring applications in 2000, the SSD plots recovered 9.4 kg ha–1 more N than the splashplate plots. Assuming 50% of applied TAN (92 kg ha–1) was lost with broadcasting and 25% lost with the SSD, 23 kg ha–1 of TAN was conserved by the SSD, so the recovery rate for conserved TAN was about 41%. A similar calculation for 2001 shows about 50% recovery of conserved TAN for orchardgrass and very little recovery for tall fescue, reflecting the difficulty of getting consistent results with manure application (Misselbrook et al., 1996). Although there appeared to be little benefit from the standpoint of yield or N uptake, the aeration applicator can be used several times in one year with no apparent harm to herbage production if required for environmental reasons.

Averaged over all harvests in this study, surface banding increased yield by 6.9% and N capture by 6.8% over broadcasting while aeration increased yield by 4.4% and N capture by 7.5% over surface banding. An economic analysis previously found no benefit for injection over broadcasting or surface banding (Rodhe and Rammer, 2001), but it is not known if the improvement in yield along with small increase in capture of N would cover the added application costs in our study. However, also important to farmers are the indirect economic benefits such as reduced crop contamination, more time to apply manure without damaging or contaminating the crop, more uniform application, and in many cases, less conflict with neighbors over odor (Lau et al., 2003). Reduced odor and ammonia emissions and reduced surface runoff with the SSD (van Vliet et al., unpublished data, 2002) are also in the public interest. By decreasing odor and runoff, the land area that can be safely treated with manure may be expanded. However, the deep tine openings may lead to greater loss of nutrients below the root zone under high rainfall (van Vliet et al., unpublished data, 2002) and increased emissions of N2O (Bittman, unpublished data, 2002). Further work is warranted to compare the SSD and surface-banding systems with shallow and deep injection on a variety of permanent grasslands.


   CONCLUSIONS
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 CONCLUSIONS
REFERENCES
 
There have been few reports of practical methods for applying liquid manure on perennial grasses that conserve ammonia and increase grass production. The benefits of injection techniques in conserving ammonia often do not translate into increased yield, possibly because of damage to the grass sward. The SSD manure applicator was shown to cause little or no damage to the grass sward even with two or three treatments in a growing season. The applicator conserved more ammonia than broadcasting and surface banding, probably because the aeration slots facilitated infiltration of the manure into the soil. Although yield benefits were not found in every trial, over all trials, the SSD applicator improved yield and N recovery by about 11% over surface broadcasting and 4% over surface banding.


   ACKNOWLEDGMENTS
 
The authors thank L. Birston, A. Friesen, E. Kenny, K. Krupp, A. Henderson, C. van Laerhoven, M. Schaber, and X. Wu for their technical assistance. We gratefully acknowledge the support of K. Tanner and Holland Equipment Ltd., Agriculture and Agri-Food Canada Matching Investment Initiative, and BC Investment Agriculture Foundation.


   NOTES
TOP
 NOTES
ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 CONCLUSIONS
 REFERENCES
 
Contribution 726.


   REFERENCES
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 CONCLUSIONS
 REFERENCES
 




This article has been cited by other articles:


Home page
 J. Environ. Qual.Home page
D. M. Butler, D. H. Franklin, M. L. Cabrera, A. S. Tasistro, K. Xia, and L. T. West
Evaluating Aeration Techniques for Decreasing Phosphorus Export from Grasslands Receiving Manure
J. Environ. Qual., May 1, 2008; 37(3): 1279 - 1287.
[Abstract] [Full Text] [PDF]

Home page
 J. Environ. Qual.Home page
L. J. P. van Vliet, S. Bittman, G. Derksen, and C. G. Kowalenko
Aerating Grassland before Manure Application Reduces Runoff Nutrient Loads in a High Rainfall Environment.
J. Environ. Qual., May 1, 2006; 35(3): 903 - 911.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF) Free
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (9)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Bittman, S.
Right arrow Articles by Bounaix, F.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Bittman, S.
Right arrow Articles by Bounaix, F.
Agricola
Right arrow Articles by Bittman, S.
Right arrow Articles by Bounaix, F.
Related Collections
Right arrow Forage Management
Right arrow Best Management Practices
Right arrow Nitrogen
Right arrow Nutrient Management
Right arrow Air Pollution
Right arrow Soil Fertility and Productivity
Right arrow Animal Waste

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
The SCI Journals Crop Science Vadose Zone Journal
Journal of Natural Resources
and Life Sciences Education		 Soil Science Society of America Journal
Journal of Plant Registrations Journal of
Environmental Quality		 The Plant Genome