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ASAE Conference Proceeding

This is not a peer-reviewed article.

On-Farm Demonstration of Effectiveness of Export and Import of Composted Dairy Manure through Turfgrass Sod

D. M. Vietor, T. L. Provin, F. J. Jacoby, S. E. Feagley, R. H. White, T. L. Carpenter, and C. L. Munster

Pp. 494-499 in Total Maximum Daily Load (TMDL) Environmental Regulations II, Conference Proceedings, 8-12 November 2003 (Albuquerque, New Mexico, USA), ed. Ali Saleh. ,8 November 2003 . ASAE Pub #701P1503

ABSTRACT

The best management practice of moving manure P and N with turfgrass sod across watershed boundaries was evaluated. The export and import of manure P or N with sod and soil-test P concentration in sod were related to P loading and runoff water quality. Up to 274 kg ha -1 of soil P and 72% of applied manure P were removed in a single sod harvest from a dairy waste application site. Total dissolved P (TDP) losses in runoff after import of manure-grown sod on an 8.5% slope were directly related to soil-test P of sod. Variation of soil-test P in samples of imported sod extracted in water, 10 mM CaCl 2 , and Olsen, Mehlich III, and acidified ammonium acetate-EDTA solutions accounted for > 77% of variation of TDP concentration in runoff of simulated rain. The soil-test P values could be used alone or as a component of a P index to evaluate impacts of manure-grown sod imports on water quality.

KEYWORDS. Composted dairy manure, Phosphorus, Turfgrass sod, Phosphorus export, Phosphorus import, Phorphorus loss in runoff, On-farm research.

Introduction

A TMDL issued for impaired segments of the Upper North Bosque River in Texas includes a mandate for a 50% reduction in average total-annual loading of P. Phase I of the TMDL implementation plan includes provisions for export of 50% of dairy-generated manure outside of watersheds surrounding impaired river segments. Export of manure P through turfgrass sod provides a best management practice (BMP) for transport of raw and composted manure from confined animal feeding operations (CAFOs) outside impaired watersheds (Vietor et al., 2002). The large economic value of turfgrass sod could pay the costs of manure composting, application, and export through sod. Plot-scale studies have documented export of up to 286 kg ha -1 of the manure P applied prior to a sod harvest (Vietor et al., 2002). The P accumulated in soil after long-term manure or wastewater applications could similarly be removed in sod, but exports of soil P remain to be quantified.

The finite land area available for sod production and a direct relationship between manure P rate and export through sod motivate CAFOs and composting facilities to apply high manure P rates. The high manure rates can improve soil physical properties and provide P and other nutrients for the transplanted sod (Vietor et al. 2002). Yet, import of manure residues with sod can contribute to P loading and nonpoint source pollution on receiving watersheds. Both positive and negative impacts of high manure P rates and export in sod need to be evaluated for importing as well as exporting watersheds.

The impact of imports of manure-grown sod on receiving watersheds can be assessed through analyses of soil within transplanted sod (Vietor et al., 2002). Extractable P concentrations in sod can be related to concentrations and losses of P in surface runoff and integrated with transport factors to evaluate impacts on water quality (Sims et al., 2000). Yet, relationships between soil-test P and runoff P vary among soil types and P extraction methods (Pote et al., 1999). Research is needed to identify one or more analytical methods and indicators of potential impacts of manure-grown sod on water quality of importing landscapes.

Two on-farm demonstrations were established to: i.) Quantify annual exports and imports of manure P and N through sod produced near CAFOs and ii.) Quantify and relate TDP concentrations in surface runoff from manure-grown sod to soil-test indicators of P in sod.

MATERIAL AND METHODS

Pack Dairy. ‘Tifway’ bermudagrass and ‘Reveille’ bluegrass were established in 3 x 6 m plots on a waste-application site (fine, mixed, thermic Udic Paleustalfs) in a randomized complete block design with two replications. Three treatments comprised a control without manure and one rate of composted dairy manure with and without N fertilizer for each turf species (Table 1). A high soil-test P (acidified ammonium acetate-EDTA [AAAE]) (Hons et al., 1990) for controls exceeded 500 mg P kg -1 soil, which requires a P reduction component in nutrient utilization plans for dairy CAFOs in Texas. Tifway was sprigged during April 2000 and manure was applied in September 2000 and August 2001. Reveille was seeded and manure applied in February and October 2001. Tifway sod was harvested during August 2001 and May 2002. Reveille sod was harvested during October 2001 and May 2002. Turfgrass clippings were returned to plot surfaces.

Table 1. Manure and fertilizer P and N applied to turfgrass sod produced on waste-application site of the Pack Dairy during 2000 to 2002.

Reveille bluegrass

Tifway bermudagrass

Treatment

2001

2002

2001

2002

Manure

Fert .‡

Manure

Fert.

Manure

Fert.

Manure

Fert.

N

P

N

N

P

N

N

P

N

N

P

N

------------------------------------ kg ha -1 --------------------------------

Control

0

0

50

0

0

0

0

0

50

0

0

0

Comp. Manure

359

192

0

135

105

0

413

186

0

384

172

0

Comp. Manure + N

353

183

150

135

106

150

428

201

150

384

172

200

Total N and P applied as composted dairy manure on turfgrass sod at specified rates.

.‡ Ammonium nitrate (34-0-0) provided N at specified rates.

Stoney Point AgriCorp., Inc. Tifway bermudagrass sod was grown on a sandy loam soil at four rates of feedlot manure. Manure was incorporated to provide total P rates of 200, 400, and 800 kg ha -1 before sprigging of Tifway in April, 2000. The highest manure rate (2400 kg P ha -1 ) was not incorporated. Sod was harvested during August, 2000 and transplanted to 1.5 x 2 m plots on an 8.5% slope of sandy-clay loam soil (fine, smectitic, thermic Ruptic-vertic Albaqualf). Sod from each P rate was sampled and analyzed to quantify P and N amounts imported on runoff plots.

Simulated rain was applied to imported sod 21 and 328 d after transplanting according to procedures of the NRCS Phosphorus Benchmark Soils Project. A 1 x 1 m metal frame with flume was driven into sod and subtending soil to capture and sample runoff (Torbert et al., 1999). Runoff of water applied through a Tlaloc 3000 rain simulator (Joern’s Inc., West Lafayette, IN) was weighed and sampled at 5-min intervals over a 35-min period of runoff. Mean total runoff depths for sod grown at the four P rates were 36 and 44 mm at 21 and 328 d after sod import. Soil was sampled to a 7.5-cm depth of each plot after the second application of simulated rain.

Sample analysis. Plant and soil components of sod samples were separated and analyzed for each harvest date on the Pack Dairy and for sod harvested from Stoney Point (Vietor et al., 2002). Manure, sod, and runoff filtrate (<1.4 µm) and sediment samples were digested through Kjeldahl procedures (Parkinson and Allen, 1975). The P in digests was analyzed through Inductively Coupled Plasma Spectroscopy (ICP) and total N was measured by a Technicon Autoanalyzer II. In addition, seven methods were used to extract soil P of transplanted sod before and after simulated rain applications. The methods comprised Mehlich III (Mehlich, 1984), Bray I (Bray and Kurtz, 1945), Olsen (Olsen et al., 1954), TAMU (AAAE) (Hons et al., 1990), 1 N KCl, 10 mM CaCl 2 , and distilled water. The ICP was used to measure P in soil extracts. Soil NO 3 -N was extracted in 1 N KCl and analyzed in a Lachat 8000 Autoanalyzer fitted with a cadmium reduction column.

RESULTS AND DISCUSSION

Pack Dairy. Exports of soil and manure P through two harvests of each Reveille and Tifway sod demonstrated the effectiveness of this BMP. The 250 to 274 kg ha -1 of soil P removed in each harvest of control plots indicated turfgrass sod exports can achieve P reductions required for soils that exceed environmental thresholds ( Tables 2 and 3) (TCEQ, 2002). The soil component, which includes turf clippings and manure, accounted for >85% of P exported through sod cut to a 2.5-cm depth. Exports of P through the plant component of sod did not increase with manure P rate. In addition, supplemental N fertilizer did not increase mean P or N content of plants (Tables 2 and 3). Despite the high initial soil-test P, manure applications increased mean P export in sod 19% for Reveille and 50% for Tifway (Tables 2 and 3). If total P in sod of control plots is subtracted from that in sod of manure treatments, 32% of applied manure P was exported in Reveille sod and 74% in Tifway sod.

The large amounts of manure and soil P and N exported with sod can be both beneficial and hazardous to landscapes on which sod is imported. Large N requirements will likely necessitate N fertilizer inputs during establishment of manure-grown sod, but the manure P imported with sod can eliminate P fertilizer applications for several years. Although runoff losses of manure P tend to be less than fertilizer P when rain occurs soon after application, one or more indicators of potential runoff loss of manure P from imported sod is needed. The TAMU method (AAAE) indicated 61 % of total P in soil of Reveille sod and 44% in Tifway sod were available to plants, but soil-test P results for TAMU or other methods need to be related to potential runoff loss from imported sod.

Stoney Point. Manure P rates from 200 to 2400 kg P ha -1 resulted in P exports in sod ranging from 161 to 503 kg total P ha -1 . Total dissolved P (TDP) in runoff of simulated rain applied 21 and

Table 2. Mean concentration and export of N and P forms in soil and plant components of two harvests of ‘Reveille’ bluegrass sod grown with and without composted dairy manure or fertilizer on a waste-application field. See table 1 for details about treatments.

Concentration in sod components

Export through sod components

Treatment

Soil

Plants

Soil

Plant

Total

Total N

Total P

NO 3 -N

STP

Total N

Total P

Total N

Total P

Total N

Total P

Total N

Total P

----------------------------- g kg -1 -------------------------

------------------------ kg ha -1 harvest -1 ------------------------

Control

2.72

1.05 b

0.030

0.62

12.3 b

2.28 b

556

213 b

187

36.8

742

250 b

Manure

3.03

1.23 ab

0.028

0.75

14.5 ab

2.70 ab

625

251 a

194

38.8

819

290 a

Manure + N

3.13

1.35 a

0.028

0.81

18.5 a

2.98 a

626

269 a

211

34.1

837

303 a

P level

0.06

0.05

n.s.

0.07

0.05

0.05

0.09

0.01

n.s.

n.s.

n.s.

0.04

Soil-test P extracted in acidified ammonium acetate-EDTA.

Numbers followed by the same letter within column are not significantly different (P=0.05).

Table 3. Mean concentration and export of N and P forms in soil and plant components of two harvests of ‘Tifway’ bermudagrass sod grown with and without added manure or fertilizer on a waste-application field. See table 1 for details about treatments.

Concentration in sod components

Export through sod components

Treatment

Soil

Plants

Soil

Plant

Total

Total N

Total P

NO 3 -N

STP

Total N

Total P

Total N

Total P

Total N

Total P

Total N

Total P

----------------------------- g kg -1 -------------------------

-------------------- kg ha -1 harvest -1 ------------------------

Control

3.87

1.29

0.029 b

0.49 b

17.5

2.62

714

237

250

37.3

964

274

Manure

4.49

1.79

0.029 b

0.79 a

16.8

2.78

890

359

244

40.5

1134

399

Manure+N

4.79

1.85

0.045 a

0.79 a

18.4

2.85

1011

393

227

35.0

1239

428

P level

n.s.

n.s.

0.01

0.07

n.s.

n.s.

n.s.

n.s.

n.s.

n.s.

n.s.

n.s.

Soil-test P extracted in acidified ammonium acetate-EDTA.

Numbers followed by the same letter within column are not significantly different (P=0.05).

327 d after transplanting of sod were directly related to P extracted from the soil component of sod samples (Fig. 1 and 2). Similar to Pote et al. (1999), variation of soil-test P accounted for a large portion of variation of TDP concentration in simulated runoff regardless of the method used or date of measurement. Large R 2 values indicated soil P extracted in 10 mM CaCl 2 and distilled water could be used alone or as a component of a P index to predict impacts of manure-grown sod imports on water quality (Sims et al., 2000). Simulated rain application on manure alone previously indicated water extractable P was related to the potential for land-applied manure to enrich surface runoff P (Sharpley and Moyer, 2000).

494-499tmdl_files/image1.gif

494-499tmdl_files/image2.gif

Figure 1. Relationship between soil-test P determined through specified methods for imported sod layer and mean total dissolved P concentration in simulated runoff 21 d after transplanting of Tifway bermudagrass sod. Manure P rates of 200, 400, 800, and 2400 kg ha -1 were applied during sod production to provide the range of soil-test P in sod layer transplanted to an 8.5% slope.

Soil-test P of sod grown at the lowest manure rate (200 kg P ha -1 ) was “very high” compared to the range of plant-available P typically quantified through Bray I, Olsen, Mehlich III, and TAMU methods. In addition, the pH range of sod and soil samples (7.8 to 8.8) was above optimum for Bray I. At the high manure P rates applied to sod, dilute solutions of strong acids and chelates for Mehlich III and TAMU (AAAE) methods desorbed and dissolved much larger P amounts than water, CaCl 2 , and KCl (Fig. 1 and 2). Yet, variation of soil-test P for these two methods accounted for a large portion of variation of TDP in simulated runoff. The relationship between Olsen soil-test P and TDP in runoff 21 d after sod imports was similar to the TAMU method at high manure rates (Fig. 1). In contrast, Olsen soil-test P was comparable to water and salt extractions, including Bray I, for soil sampled to 7.5 cm at 328 d after sod was transplanted (Fig 2). Similar to the trend of TDP concentration in runoff (Fig. 1 and 2), increasing manure P rate increased TDP mass losses in runoff 21 and 328 d after sod was transplanted. TDP losses in runoff were 0.52, 0.80, 1.52, and 1.66 kg P ha -1 21 d after import of sod grown at the respective manure P rates (Table 1). At 328 d after transplanting, TDP losses in runoff were 0.38, 0.57, 0.70, and 0.66 kg P ha -1 . The particulate fraction of P in simulated runoff averaged 10% and 20% of the mass loss of TDP in simulated runoff 27 and 328 d after transplanting of sod and was similar among the four manure P rates. Less than 0.8 % of total P imported in sod was lost as TDP and particulate P during two runoff events.

494-499tmdl_files/image3.gif

Figure 2. Relationship between soil-test P and mean total dissolved P concentration in simulated runoff 328 d after transplanting of Tifway bermudagrass sod.

Acknowledgements.

Supported in part by the USGS National Water Resources Institute and the Texas Advanced Technology Program.

REFERENCES

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