MICRONUTRIENT STATUS OF MANURE

 

S. M. Combs, J. B. Peters and Ling S. Zhang

Department of Soil Science

University of Wisconsin-Madison

 

 

Animal feeds are routinely enriched with supplements to minimize potential for mineral deficiency, enhance feed efficiency or suppress disease.  Most swine and poultry are housed in confinement without access to soil or forage that enhances the need for feed additives.  Under practical feeding conditions it is usually necessary to provide supplemental sources of several macrominerals (Ca, P, Na, Cl, K, Mg and S) and trace minerals (As, Co, Cr, Cu, Fe, I, Mn, Mo, Se, Zn and others) to meet dietary requirements (NRC for Dairy Cattle, 1988, NRC for Swine, 1998 and NRC for Poultry, 1994).  The effects of diet on manure composition are much less quantified than the digestibility of nutrients in feeds.

 

In addition to the presence of trace elements in manure from supplementation, manure is increasingly being treated with chemical additives to control odor, adjust pH, precipitate suspended solids or enhance biological treatment (Day and Funk, 1998).  Amendments such as alum (Al2(SO4)3) and Fe salts are used effectively in swine manure systems to precipitate solids.  Poultry producers can choose from several amendments (alum, phosphoric acid, TSP, lime, gypsum, Fe salts and others) to minimize NH4 volatilization by altering pH or inhibiting microbial-aided uric acid decomposition.

 

Manure used to repeatedly supply major nutrients to crops has the potential to elevate soil concentrations of these elements.  The accumulation of P in excess of crop needs is a common example.  The objective of this limited study was to determine the major nutrient (N, P, K, Ca, Mg, Na and S) and trace element (Zn, Cu, Fe, Mn, B, Se, Co, Cr and As) content of dairy, swine and poultry manure and evaluate potential soil management impacts.  Manure samples submitted by producers to public soil testing labs in the NCR-13, SERA-6 and NEC-67 regions were split and analyzed by the UW Soil and Plant Analysis Lab-Madison.

 

Elemental Composition – ‘as is’

 

            Average concentrations and associated statistics for 87 dairy, 10 swine and 24 poultry manure samples are given on an ‘as is’ or wet basis in Table 1.  Knowing the ‘as is’ trace element concentration in manure may be more practical when considering the quantity potentially spread.  Swine and poultry manure contained similar amounts of Zn, Cu and Mn (0.5–1.1 lb/wet ton) and was approximately 10-100 times higher than determined in dairy manure (0.01–0.06 lbs/wet ton).  Liquid swine manure had about 6 times (0.6 lbs/1000 gal) as much Cu and about 10 times more Zn (1.03 lbs/1000 gal) than liquid dairy manure.   Total Fe and Al content of swine (especially solid) ranged up to 40 times (19 lbs Fe/wet ton) more than either dairy or poultry.

 

Swine and poultry manure also contained about 10 times more Se (0.002 lbs/wet ton) than dairy.  Liquid dairy manure has only 0.008 lbs Se/1000 gal Monogastic animals (poultry, swine) excrete Se primarily in urine but ingested Se is excreted mainly in feces of ruminants (dairy cattle) (Mayland, 1989).

 

Swine and poultry manure had 0.01 to 0.02 lb Cr/l000 gal while liquid dairy had 10 times less.  Less than 3% of ingested Cr is actually absorbed by swine (NRC for Swine, 1998). Similar differences were noted for Co.

 

Comparisons

 

Table 2 compares the results of this study on a dry weight basis to other estimates of elemental concentrations in manure and sewage sludge, (Capar et al., 1978; Peterson and Kelling, 1987; Dick and Chen, 1997). Changes in specialized feeding practices (i.e. Se, As), greater therapeutic use of trace elements (i.e. Cu, Zn) and management (litter, no litter) have contributed to changes in manure composition.  This study showed about the same Zn and slightly higher Cu concentrations than reported by Peterson and Kelling (1987) for solid swine manure.  Substantially more B (489 mg/kg dry wt) in solid swine manure was estimated by Peterson and Kelling (1987) than this study showed (30 mg/kg dry wt).   Selenium concentrations in solid dairy manure were about 2 times (0.58 mg/kg dry wt) higher than reported by Capar et al. (1978) (0.35 low fiber diet, 0.30 high fiber diet).  This difference may show the influence of recently increased allowable supplemental Se levels (NRC for Dairy Cattle, 1988).  Determined Cr concentrations in solid dairy manure were about 10 times and Co 2 to 3 times less than reported by Capar et al. (1978).

 

Most notable differences among reported results were evident for poultry

(Table 2).  Dick and Chen (1997) determined high levels of Cu (477 mg/kg dry wt) similar to this study (437 mg/kg dry wt) that were substantially greater than the 20-30 mg Cu/kg dry wt indicated by others.  Similar trends were evident for Zn, As and Mn.  Most poultry producers are reported to feed an excess of CuSO4 causing a weight gain in broilers related to possible reductions in pathogens contained in litter (Moore, 1998).

 

Comparing the trace element composition of manure to sewage sludge may put manure concentrations in better perspective (Table 2).  Manure and sewage sludge (means from 16 cities) have similar levels of most macro-elements (P, K, Ca, Mg, Na) and some trace elements (Mn, Al, As).  However, concentrations of Fe, Co and Se are about 2 times, Zn and Cu about 4 times and Cr 100 to 200 times greater in sewage sludge than manure.  Recent technology advances in recovery of trace elements prior to discharge probably has decreased trace element levels in sewage sludge that is currently land applied.

Table 1.  'As-is' total nutrient and trace element content in selected dairy, swine and poultry  manure.

                                                                                                               Total Concentration * (wet weight basis)

                                                         N   P2O5     K2O       Ca       Mg         S        Fe        Al       Na             Zn         B       Mn       Cu                                                        Se       Co       Cr       As

        Dairy solid                                                                                                          lbs/ton wet ton

                                  average           8.4       4.7       2.8       6.2       2.6       0.9       0.5       0.5       0.2             0.03      0.01      0.06      0.01                                    0.0002       0.0003    0.001   0.0001

                                         sd           1.5       1.5       1.6       6.9       2.6       0.2       0.5       0.5       0.2             0.03      0.00      0.04      0.01                                    0.0001       0.0003    0.001   0.0001

                                       max          13.5       9.8      10.4      51.8      17.6       1.4       3.1       2.4       1.1             0.17      0.03      0.19      0.08                                    0.0009       0.0020    0.005   0.0001

                                       min           5.5       2.4       1.2       2.5       0.8       0.6       0.1       0.1       0.1             0.01      0.01      0.02      0.00                                    0.0001       0.0001   0.0001   0.0005

        Swine solid

                                  average          24.0      47.6      29.2      26.5       6.6       5.3      19.0      14.4       6.7             0.79      0.04      1.09      0.50                                     0.002        0.003    0.010   0.0024

                                         sd           4.2      12.0       5.9       7.1       1.2       1.2       4.1       2.2       1.5             0.21      0.01      0.12      0.18                                     0.001        0.001    0.002   0.0009

                                       max          27.6      60.2      36.6      33.9       7.5       6.8      23.9      16.3       8.6             1.02      0.05      1.30      0.72                                     0.003        0.005    0.013   0.0039

                                       min          17.0      31.5      23.2      17.2       4.8       3.9      14.7      11.3       5.3             0.53      0.03      0.99      0.33                                     0.002        0.002    0.008   0.0016

        Poultry all **

                                  average          59.9      55.9      39.2      64.8       7.6       7.5       3.0       2.6       7.8             0.48      0.08      0.61      0.66                                     0.002        0.003    0.014   0.0330

                                         sd          18.1      17.9      11.2      11.2       1.9       2.3       4.3       3.0       3.0             0.17      0.05      0.27      0.39                                     0.001        0.001    0.009   0.0510

                                       max          94.8      90.4      55.4    191.9      10.6      10.7      21.8      12.7      12.3             0.83      0.30      1.13      1.34                                     0.004        0.005    0.033   0.1730

                                       min          22.6      21.6      14.5      23.9       3.7       2.7       0.5       0.4       1.7             0.17      0.02      0.15      0.02                                     0.001        0.001    0.001   0.0002

        Dairy liquid ***                                                                                                    lbs/1000 gal

                                  average          27.3      10.5      21.1      15.1       5.3       2.2       0.9       0.7       3.3             0.11      0.03      0.11      0.12                                    0.0010        0.001    0.002   0.0003

                                         sd          10.3       4.7      10.5       8.8       3.0       1.0       0.7       0.6       1.8             0.06      0.02      0.05      0.24                                    0.0004        0.001    0.001   0.0003

                                       max          50.2      19.6      39.8      36.8      14.7       3.9       3.4       3.0       7.7             0.23      0.06      0.20      1.19                                    0.0020        0.004    0.005   0.0010

                                       min          11.1       3.4       6.8       5.2       1.9       0.8       0.2       0.2       0.6             0.02      0.01      0.03      0.01                                    0.0002       0.0003    0.001   0.0001

        Swine liquid *

                                  average          69.4        36.8        25.1        21.8          7.4          5.3          2.5       2.4       4.6             1.03      0.06      0.23      0.62                                     0.002        0.003    0.026   0.0024

                                         sd          19.1      15.6      12.2       9.9       3.1       1.5       2.8       3.6       1.8             1.30      0.03      0.12      0.55                                     0.001        0.003    0.016   0.0025

                                       max          95.9      63.3      41.8      35.6      10.7       6.7       7.4       8.7       7.3             3.34      0.09      0.41      1.45                                     0.004        0.008    0.042   0.0067

                                       min          42.1      25.2       8.3      12.7       4.1       3.9       0.7       0.4       2.4             0.24      0.03      0.10      0.08                                     0.001        0.001    0.004   0.0004

                                          * Plant available concentrations depend on animal type, nutrient, application method and number of years of previous

                                          ** Includes unspecified 'chicken', and 'poultry' manure samples.

                                          *** Liquid manure <15% DM.

Table 2.Comparison of determined solid manure and sewage sludge total nutrient and trace element content on a

dry weight basis.

 

 

Dairy

Swine

Poultry

 

 

 

 

 

Peterson

 

Peterson

 

 

 

Peterson

Dick

Sewage

Nutrient

UW

Capar et. al.*

 

and

UW

and

UW

Capar et. al

 

and

and

Sludge

 

 

low fiber

high fiber

Kelling**

 

Kelling

 

litter

no litter

Kelling

Chen***

****

 

----------------------------------------------------------------------------------------% (dry wt)------------------------------------------------------------

N