Published online 27 April 2005
Published in Agron J 97:668-673 (2005)
DOI: 10.2134/agronj2004.0008
© 2005 American Society of Agronomy
677 S. Segoe Rd., Madison, WI 53711 USA
Manure Management
Comparison of Phosphorus Uptake from Poultry Litter Compost with Triple Superphosphate in Codorus Soil
Lawrence J. Sikora* and
Nancy K. Enkiri
Anim. Manure and Byprod. Lab., Henry A. Wallace Beltsville Agric. Res. Cent., 10300 Baltimore Ave., Beltsville, MD 20705
* Corresponding author (sikoral{at}ba.ars.usda.gov)
Received for publication January 8, 2004.
 |
ABSTRACT
|
|---|
Nutrient management plans require that fertilizer equivalents of manures and composts be used in determining the total nutrient application to soils. The P nutrient content of manure composts has not been studied as extensively as N. In a growth chamber study using 15-cm pots, a Codorus silt loam soil (Fluvaquentic dystrochrepts) with less than 10 mg kg–1 Mehlich-3 extractable P was amended with poultry litter compost (PLC) or triple superphosphate (TSP) at rates of 0, 25, 50, 100, and 150 kg P ha–1. Nitrogen was supplied to be uniform across all treatments, taking into account the N mineralization rate of PLC. Fescue (Festuca arundinacea Schreb) was grown and harvested three times over 103 d. Yield of fescue was curvilinear related to rate of amendment, but yield was not affected by PLC or TSP. Models describing yield changes with rate were different for TSP and PLC. Phosphorus uptake was statistically the same for both treatments, and a single quadratic equation described P uptake with rate. These data indicate that PLC added to soils on a total P basis provided the same amount of fertilizer equivalents as TSP. The use of composted manure as a N source narrows further the plant available N/P ratio from that recorded in manures because N is immobilized and P is not. To use manure compost as source of P, more fertilizer N would be required to satisfy crops needs than if manure was used as a P source.
Abbreviations: PLC, poultry litter compost • TSP, triple superphosphate
|
INTRODUCTION
|
|---|
APPLICATION OF P in any form to land will be scrutinized because research shows that P from nonpoint sources has contributed significantly to enrichment of waterways (Taylor and Pionke, 2000). Phosphorus additions to soil must therefore be carefully monitored, and soils with excessive agronomic P levels should not have any additional P applied than is needed by the crop. Alternatively, the soils should be treated to reduce the soluble P content (Codling et al., 2000). Phosphorus site index, which provides farmers with recommendations on proper P application rates, is being adopted in several states. Phosphorus site indices vary by state, but factors are generally grouped by P source (fertilizer, manure, and compost) and where the amendment will be placed (proximity to waterways, erosion potential of the land, extractable P levels in the soil, etc.).
The growth of animal industries and siting of production units on small acreages create regional nutrient input vs. output concerns in the USA and in Europe (Sharpley et al., 1996). The poultry industry is an example of an animal business with operations concentrated on an area of land that is insufficient for the safe application of all the manure generated during production. If land-applied in excess of plant needs, poultry manure can be a source of P enrichment of watersheds (Pote et al., 1999; Sims et al., 1998). Although agricultural fields are the primary sources of nonpoint P pollution, only those fields that are highly erodible, near water, and high in total P become major sources of P enrichment (Sharpley et al., 1996). About 27% of the P applied to fields in the Chesapeake Bay watershed is in the form of manure while 73% is commercial fertilizer (Taylor and Pionke, 2000). Efforts have been made by states to minimize P pollution from land-applied manures with some states such as Maryland mandating legislation in the form of the Water Quality Improvement Act of 1998 (Maryland Dep. of Agric. Office of Resour. Conserv., 2002), which specifies nutrient management plans for farms above a certain animal density.
It is possible that composting would reduce P availability and decrease the potential for watershed pollution by poultry manure runoff. Composting reduces the N mineralization rate of organic materials because the C/N ratio of the compost is greater than that of the original organic material and because the N is a more recalcitrant form (Sikora and Szmidt, 2001). Only recently has information become available on the effect of composting on P mineralization and availability to plants. Dao et al. (2001) found little change in water and Mehlich-3 soluble P content in poultry manure before and after composting. The form of P added to soils may influence the amount of P uptake by plants or the amount and type of P runoff. Vadas et al. (2004) reported that runoff from poultry manure had higher levels of water soluble P than runoff from poultry manure compost. Preusch et al. (2002) monitored water and Mehlich-1 extractable P in two soils amended with poultry litter and the subsequent PLC from two sources in West Virginia. Composting did not consistently reduce water or Mehlich-1 extractable P levels in the final compost compared with the poultry litter. Preusch et al. (2002) suggested that maturity or stability of PLC may affect extractable P concentrations when composts were added to soils.
Vadas et al. (2004) found in comparing runoff from manure to composted manure, molybdate reactive P, total dissolved P, and total P concentrations in runoff from compost applications were about half those for manure. These data suggest that composting would reduce soluble P concentrations, which in turn should reduce fertilizer equivalents in soil amended with composts.
Sharpley and Moyer (2000) found that composting poultry manure decreased the total P by 67% and water extractable P by 73%. Most of this reduction can be accounted for by dilution with bulking agent before composting. However, DeLaune et al. (2000) found that composting poultry litter increased total P by an average of 44% and water extractable P by an average of 160%. Because P is conserved in the compost while mass is lost as a result of decomposition, P levels may also increase after composting. For accurate evaluation of losses and gain of P with composting, mass loss and bulking agent additions must be taken into account.
Phosphorus uptake from manures and composts may be similar based on recent research. Eghball and Power (1999) reported that P uptake by corn (Zea mays L.) from composted cattle manure was equal to P uptake from the uncomposted manure. Robbins et al. (2000) speculated that manure P was more available to plants than inorganic P fertilizer. Extractable P content of soils amended with manure, whey, or monocalcium P was positively correlated with soil organic C levels resulting from the amendments. Robbins et al. (2000) hypothesized that organic C in manure is more stable than organic C in whey and coats P adsorption and precipitation sites, allowing manure P to stay in solution longer.
Sikora and Enkiri (2003) showed in a growth chamber study that P uptake from PLC was linearly related to compost rate and was not significantly different from TSP amendments of the same P rates. The study was performed in a soil containing greater than 100 mg kg–1 Mehlich-3 extractable P, and no yield response to P amendments was recorded. Extractable P levels differed in a sandy loam soil vs. a silt loam soil amended with PLC (Preusch et al., 2002). To determine fescue response to PLC and TSP in a P-deficient soil, a study was conducted using Codorus soil that contained less than 10 mg kg–1 Mehlich-3 extractable P and less than 1.0 mg kg–1 water extractable P (Table 1).
|
MATERIALS AND METHODS
|
|---|
Production of Compost
Poultry litter compost was produced at the Beltsville Agricultural Research Center Composting Facility (Table 1). Poultry (turkey) litter was mixed with orchardgrass (Dactylis glomerata L.) hay in a 1:3 (v/v) mixture, placed in a 50-m windrow, and composted by the windrow method for 8 wk. The windrow was turned six times during the first 3 wk and five additional times for the remaining 5 wk using a self-propelled windrow turner. The first six turnings were accompanied with watering to maintain adequate moisture for composting. Mean high temperature was 60°C, and after 8 wk, the mean temperature of the windrow had declined to 38°C. Samples were taken at 8 wk with a shovel at four locations along the 30-m length of the windrow, combined into one sample, and mixed. A 1-kg subsample was screened through a 13-mm sieve followed by a 7-mm sieve and stored at 4°C until use.
Soil Incubation
A 7-d incubation study was conducted to determine the available N content of PLC so that accommodations could be made for differing available N contents of soil amended at different PLC rates (Bundy and Meisinger, 1994). Using methods previously described in Sikora and Enkiri (2003), 100 g of Codorus soil (fine-loamy, mixed, mesic Fluvaquentic Dystrochrepts) was amended with 1 g of PLC and incubated at 25°C and –33 kPa moisture content. Ammonium N and NO3–N were determined colorimetrically by flow injection analysis (Lachat Instruments, Milwaukee, WI). Two 5-g samples per flask were extracted with distilled water and Mehlich-3 extractant (Wolf and Beegle, 1995; Mehlich, 1984) following the procedure outlined above but with no adjustment of extractant pH. Orthophosphate P was determined colorimetrically by flow injection analysis. A 30-g sample was mixed with 30 mL 0.01 M CaCl2 and shaken on a rotary shaker for 1 h. After standing for 10 min, pH of the liquid was determined. Moisture contents of samples were determined by drying samples overnight at 105°C (Table 1).
Pot Study
Eighteen hundred grams of Codorus silt loam soil was amended with either TSP or PLC to provide five rates of P: 0, 25, 50, 100, or 150 kg P ha–1. Amendments were based on soil bulk density of 1.284 g cm–3 and 10000 m2 by 15-cm soil volume. The amount of plant available N provided by the compost was calculated, and sufficient NH4NO3 was added to provide a total of 120 mg N per pot (150 kg N ha–1). Potassium (as K2SO4) and Mg (as MgSO4) were both added at the rate of 125 kg ha–1. A micronutrient solution containing Zn as ZnSO4·7H2O, B as H3BO3, Cu as CuSO4·5H2O, and Mo as Na2MoO4·2H2O was added equaling amendment rates of 1.25, 2.5, 0.63, and 23 kg ha–1, respectively. The micronutrient content of PLC was not considered in the calculation of micronutrient needs for plant. Calcium oxide (1.47 g kg–1) was added to increase the pH of all treatments to 
6.5. The soil, dry amendments, and micronutrient solution were hand-mixed in large plastic bags, placed in 15-cm pots, brought to –33 kPa moisture, weighed, and equilibrated for at least 48 h before planting Kentucky 31 tall fescue (300 seeds/pot).
Pots were watered daily by manually adjusting the weight to –33 kPa and weighing and adding water to achieve the 0 time weight. The temperature of the growth chamber was maintained at 25°C during the 16 h of illumination and at 20°C for the 8-h dark period. Intensity of lights was approximately 600 µmol s–1 m–1, and the light source was a combination of high-pressure sodium and metal halide lamps. Relative humidity ranged from 62 to 72%. The fescue was clipped to a 2.5-cm height on Day 32, 68, and 103 after planting. Dry weight was determined after drying samples in a forced-air oven at 70°C for 5 d. Dried clippings were ground using a Glen Mills Inc. MicroHammer/Cutter Mill. Ground samples were analyzed for total N and P content after Kjeldahl block digestion by flow injection analysis (Lachat Instruments, Milwaukee, WI). After the third fescue clipping harvest, roots and crowns were separated from soil by hand, washed on a 2-mm sieve, dried, weighed, and analyzed using the same techniques as those for the clippings.
Statistical design of the experiment was a complete randomization with four repetitions. The three-factor treatment structure included P source, rate of P, and time. The PROC MIXED software program (SAS Inst., 1999) was used to examine treatment effects via ANOVA, regression, and analysis of covariance, modeling P source as a classification factor and rate and rate2 as regressors (i.e., covariates) with each coefficient having a single degree of freedom.
|
RESULTS
|
|---|
Soil Incubation Study
The 7-d incubation indicated that Codorus soil had 51.36 mg N kg–1 and, with PLC and lime added, 57.31 mg N kg–1 (Table 2). A 7-d incubation was considered a sufficient length of time because experience indicated that there was little difference between a 7- and 21-d incubation (data not presented). Net total mineral N at Day 0 was 4.64 mg N kg–1 soil or 7.59% of the PLC total N. After 7 d, mineralization of PLC equaled 5.95 mg N kg–1 soil or 9.75%. The mineralization of organic N in PLC was low, probably because the C/N ratio was 17.5 (Table 1). Allowances for the mineral N added as PLC were made when adding fertilizer N to equal a total N amendment of 150 kg ha–1.
Dry Weight
Fescue dry weight increased with increasing P amendment at lower rates of addition for both TSP and PLC (Fig. 1)
. At P rates greater than 50 kg ha–1, dry weight increases declined in the case of PLC and were negligible for TSP. Yields were largest in the first clipping and declined with later samplings. A two-way analysis of variance indicated that fescue dry weight was affected by rate and by the interaction of rate and P source but not by P source. (Table 3). Regressions indicated that the effect of rate on yield exhibited statistically significant linear and quadratic relationships for both P treatments. Analysis of covariance indicated the slope of the linear portion of TSP amendment was significantly greater than that of PLC (0.063 vs. 0.028), and the negative quadratic coefficient was also significantly greater, in absolute value, than PLC (–0.000335 vs. –0.000102), exhibiting a faster decline in fescue yield than from PLC. Comparison of the model regression equations (P > F 0.0001) to fescue dry weight is presented in Fig. 2
. Previous studies using a Sassafras soil with greater than 100 mg Mehlich extractable P and the same two P sources indicated no yield response to increasing P levels but a linear increase in P uptake with increasing P from either source (Sikora and Enkiri, 2003). In the P-deficient Codorus soil, P amendment rate determined dry weight yield. The 150 kg P ha–1 TSP treatment produced 40.1% greater yield, and the 150 kg P ha–1 PLC treatment produced 48.0% greater yield than the control in the Codorus soil. Sikora and Enkiri (2003) recorded an average 30% increase in P uptake over the control at the 150 kg P ha–1 rate in the Sassafras soil.
View larger version (64K):
[in this window]
[in a new window]
|
Fig. 1. Cumulative fescue dry weight yield (mean and standard error) for three harvests as affected by poultry litter compost (PLC) or triple superphosphate (TSP) treatment.
|
|
View this table:
[in this window]
[in a new window]
|
Table 3. Two-way ANOVA testing the effects of treatment (poultry litter compost or triple superphosphate) and rate on fescue dry weight yield and P uptake.
|
|
View larger version (26K):
[in this window]
[in a new window]
|
Fig. 2. Cumulative dry weight (DW) after 103 d from poultry litter compost (PLC) and triple superphosphate (TSP) treatments. Model equations describing response are plotted.
|
|
Phosphorus Uptake
Phosphorus uptake was greatest in the first fescue clipping and declined with subsequent clippings (Fig. 3)
. Data indicated that P source did not influence P uptake, but P rate did (Table 3). Analysis of covariance showed that P uptake by fescue from both TSP and PLC had statistically similar linear and quadratic parameters (Table 4). Similar to yield data, cumulative P uptake was linearly related to rate at low P levels and slowly declined at higher rates of P amendment. Because both treatments had a similar relationship to P uptake, a single quadratic model describing P uptake by TSP of PLC resulted: P uptake = 2.28 + 0.060 x rate – 0.000239 x rate2 (P > F 0.0001). Comparison of model regression equation to cumulative P uptake by fescue is presented in Fig. 4
. The 150 kg P ha–1 rate resulted in a 300% increase in P uptake over the control, or no P amendment. Sikora and Enkiri (2003) recorded a 30% increase in P uptake with the 150 kg P ha–1 in P-sufficient Sassafras soil.
View larger version (64K):
[in this window]
[in a new window]
|
Fig. 3. Cumulative P uptake by fescue (mean and standard error) for three harvests as affected by poultry litter compost (PLC) or triple superphosphate (TSP) treatment.
|
|
View this table:
[in this window]
[in a new window]
|
Table 4. Analysis of covariance testing the effects P source (poultry litter compost or triple superphosphate), rate, and rate x P source on dry weight of fescue clippings. Rate and rate2 are covariates with single degrees of freedom, and P source is a classification variable.
|
|
View larger version (22K):
[in this window]
[in a new window]
|
Fig. 4. Cumulative P uptake by fescue from poultry litter compost (PLC) and triple superphosphate (TSP) over 103 d. Model equation is plotted to represent both PLC and TSP treatments that were not significantly different.
|
|
Mean separation analysis was conducted to determine the significant differences in individual treatments (Table 5). The 25 kg P ha–1 amendment for both treatments resulted in a significant increase in yield and P uptake. Yield data for the 100 and 150 kg P ha–1 rates were not different while the yields for 25 and 50 kg ha–1 rates with one exception were grouped together. In examining the P uptake mean separation analyses, a clearer separation was seen with only 50 TSP grouped with the 100 and 150 kg P ha–1 amendments of both treatments. The 25 and 50 kg P ha–1 amendment rates were also not significantly different from each other but greater than control soil.
View this table:
[in this window]
[in a new window]
|
Table 5. Mean comparisons of treatment that include P sources [poultry litter compost (PLC) or triple superphosphate (TSP)] at a 25, 50, 100, or 150 kg P ha –1 amendment rate.
|
|
Root and Crown Yields and Phosphorus Uptake
Yields from harvesting root and crown material (henceforth referred to only as roots) from all the pots were 40 to 60% greater than yields of clippings (data not presented). They ranged from 8.4 g per pot for control plants to 10.06 g per pot for 150 kg P ha–1 as TSP and 10.86 g per pot for 150 kg P ha–1 as PLC. In general, the response to treatment was the same as the clippings with increasing yield and P uptake with increasing P amendment. Variation was higher for roots than for clippings and was attributed to the difficulty in harvesting roots by hand from the Codorus soil. Therefore, the root and clippings data were not combined in the statistical analyses. Sikora and Enkiri (2003) found that in fescue grown in a sandy Sassafras soil with excessive extractable P, P uptake by roots was similar to the P uptake by clippings. In the Codorus soil, more P was found in the roots than in clippings.
|
DISCUSSION
|
|---|
Preventing P loss from surface soil focuses on defining, targeting, and remediating those areas with high soil P levels and with high runoff potential (Gburek and Sharpley, 1998). Nutrient management plans require accurate N and P fertilizer equivalents assigned to manures and composts applied to all soils, but especially soils with high runoff potential. Very few studies have looked closely at P availability of composts because composts were often considered a source of organic matter and not a source of nutrients. We evaluated the P availability of composted poultry manure in a P-deficient Codorus soil and found that it was equal to TSP in yield production and P uptake. Similar P uptake results were recorded in a P-sufficient Sassafras soil. McCoy et al. (1986) showed that biosolids compost made from biosolids containing large amounts of Fe and Al provided very little fertilizer P to corn. They concluded that the Fe and Al added at the treatment plant to condition the biosolids was the major factor in determining P availability and not composting. Our studies would indicate also that composting had little effect on P availability. Dao et al. (2001) demonstrated in the laboratory that extractable P levels in poultry manure were not influenced by composting, but when industrial byproducts containing high percentages of Fe or Al were added to poultry litter before composting, extractable P levels were reduced immediately after addition, and subsequent compost treatment had no further effect on P extractability. These data suggest that to reduce soluble P in manures, additions of metals such as Fe and Al may be required.
Dao (1999) discussed the need to increase the soluble or plant available N/P ratio of manures applied to land to be more in line with crop uptake. Crop uptake of N vs. P is approximately 7:1 (Buckman and Brady, 1969) while the ratio in manures may be as low as 3:1 (Dao, 1999). When manures are applied to land based on the N requirement of the crop, more P is applied than is needed, resulting in P enrichment of soil with all of the possible negative consequences related to this addition. Our data demonstrate that composting can exacerbate this consequence because composting will immobilize N (Sikora and Szmidt, 2001) but does not affect P availability as documented in this study. When amending soils with composts vs. manure, compost amendments based on N requirements will add greater excess of P. Alternatively, compost amendments that are based on P requirements would require higher N fertilizer additions than manure because composting reduces the N fertilizer value of the product.
Management options are available that will increase the N/P ratio of manures. Reduction of P in animal diets is one way to reduce P in manures. Studies have indicated that reducing the supplemental diet inorganic P in feeds to 0.23% from 0.45% will reduce total and water soluble P content in manures (Vadas et al., 2004). Another option is to add P-binding metals such as Fe and Al to manures. Dao et al. (2001), DeLaune et al. (2000), and Codling et al. (2000) showed convincingly that addition of metals reduces soluble P levels in poultry litter, which also reduces P runoff from surface-applied manure. Composting as a treatment process has shown mixed results in reducing soluble P levels in manures. Sharpley and Moyer (2000) found that poultry manure compost had 33% of the total P and 27% of the soluble P found in the manure. This decrease was attributed mainly to dilution with bulking agents. However, these results would suggest that the highly mobile P fraction is reduced after composting manure. Dao et al. (2001) found that composting did not reduce extractable P. Sikora and Enkiri (2003) showed that PLC P was as available to fescue as TSP in a P-sufficient soil. Some explanation for differences is the treatment and storage of manure and composts. Preusch et al. (2002) monitored water and Mehlich-1 extractable P in two soils amended with poultry litter and the subsequent compost from two sources in West Virginia. Composting did not consistently reduce water or Mehlich-1 extractable P levels compared with litter. Their data, however, did suggest that the more stable compost had lower extractable P concentrations in amended soils (Preusch et al., 2002). Gagnon and Simard (1999) found that increasing composting duration and sheltering the compost process from the weather changed the P mineralization curves obtained when the compost was incubated with soil. Even though the fescue uptake data recorded suggest that composting does not affect P uptake because the compost P is as available TSP, soluble P appears to be affected by biological factors such as maturity of the compost. Further research is required to determine the reasons for this discrepancy.
|
CONCLUSIONS
|
|---|
Our data indicated that poultry manure compost is equal to TSP in providing P to fescue in the P-deficient Codorus soil. Composting does not affect the plant available P in the same manner as it does plant available N. Similar results were found when fescue was grown in a P-sufficient Sassafras soil amended with TPS or PLC. There was no yield response to P additions (Sikora and Enkiri, 2003). A linear P uptake response to PLC addition was recorded in Sassafras soil while, in the Codorus soil, a quadratic relationship was seen. Compared with the control Sassafras soil, the 150 kg P ha–1 amendment rate resulted in a 30% greater P uptake. In Codorus soil, the P uptake with the 150 kg P ha–1 application rate was approximately 300% greater than the control. Dry weight yield in the Codorus soil at 150 kg P ha–1 rate was approximately 30% greater than the Codorus soil control. These data suggest that nutrient management plans and calculations for P site index application of compost as a P source can be calculated using the total P content of the compost and assume the plant response is the same to TSP. The use of composted manure as a N source narrows further the plant available N/P ratio from that recorded in manures because N is immobilized and P is not. To use manure compost as source of P, more fertilizer N would be required to satisfy crop needs than if manure were used as a P source.
|
REFERENCES
|
|---|
- Buckman, H.O., and N.C. Brady. 1969. The nature and properties of soils. The Macmillan Co./Colliere-Macmillan Limited, London.
- Bundy, L.G., and J.J. Meisinger. 1994. Nitrogen availability indices. p. 951–984. In R.W. Weaver, R.W.S. Angle, P. Bottomly, D. Bezdicek, S. Smith, A. Tabatabia, and A. Wollum (ed.) Methods of soil analysis. Part 2. Microbiological and biochemical properties. SSSA Book Ser. 5. SSSA, Madison, WI.
- Codling, E., R.L. Chaney, and C.L. Mulchi. 2000. Use of aluminum- and iron-rich residues to immobilize phosphorus in poultry litter and litter-amended soils. J. Environ. Qual. 29:1924–1931.[Abstract/Free Full Text]
- Dao, T.H. 1999. Co-amendments to modify P extractability and N:P ratio in feedlot manure and composted manure. J. Environ. Qual. 28:1114–1121.[Abstract/Free Full Text]
- Dao, T.H., L.J. Sikora, A. Hamasaki, and R.L. Chaney. 2001. Manure phosphorus extractability as affected by aluminum and iron by-products and aerobic composting. J. Environ. Qual. 30:1693–1698.[Abstract/Free Full Text]
- DeLaune, P.B., P.A. Moore, Jr., T.C. Daniel, D.R. Edwards, J.L. Lemunyon, and P. Fredericks. 2000. Effects of chemical and microbial amendments on ammonia volatilization from poultry litter during composting. USDA-ARS, Poultry Prod. and Product Safety Res. Unit, Fayetteville, AK.
- Eghball, B., and J.F. Power. 1999. Phosphorus- and nitrogen-based manure and compost applications: Corn production and soil phosphorus. Soil Sci. Soc. Am. J. 63:895–901.[Abstract/Free Full Text]
- Gagnon, B., and R.R. Simard. 1999. Nitrogen and phosphorus release from on-farm and industrial composts. Can. J. Soil Sci. 79:481–489.
- Gburek, W.J., and A.N. Sharpley. 1998. Hydrologic controls on phosphorus loss for upland agricultural watersheds. J. Environ. Qual. 27:267–277.[Abstract/Free Full Text]
- Maryland Department of Agriculture Office of Resource Conservation. 2002. Nutrient management in Maryland [Online]. Available at http://www.mda.state.md.us/nutrient/nutmgmt.htm (verified 3 Jan. 2005). Maryland Dep. of Agric. Office of Resour. Conserv., Annapolis.
- McCoy, J., L.J. Sikora, and R.R. Weil. 1986. Plant availability of phosphorus in sewage sludge compost. J. Environ. Qual. 15:403–409.[Abstract/Free Full Text]
- Mehlich, A. 1984. Mehlich 3 soil test extraction: A modification of Mehlich 2 extractant. Commun. Soil Sci. Plant Anal. 15:1409–1416.
- Pote, D.H., T.C. Daniel, D.J. Nichols, A.N. Sharpley, P.A. Moore, Jr., D.M. Miller, and D.R. Edwards. 1999. Relationship between phosphorus levels in three ultisols and phosphorus concentrations in runoff. J. Environ. Qual. 28:170–175.[Abstract/Free Full Text]
- Preusch, P.L., P.R. Adler, L.J. Sikora, and T.J. Tworkoski. 2002. Nitrogen and phosphorus availability in composted and uncomposted poultry litter. J. Environ. Qual. 31:2051–2057.[Abstract/Free Full Text]
- Robbins, C.W., L.L. Freeborn, and D.T. Westermann. 2000. Organic phosphorus source effects on calcareous soil phosphorus and organic carbon. J. Environ. Qual. 29:973–978.[Abstract/Free Full Text]
- SAS Institute. 1999. SAS/STAT users guide. Version 8. SAS Inst., Cary, NC.
- Sharpley, A.N., T.C. Daniel, J.T. Sims, and D.H. Pote. 1996. Determining environmentally sound phosphorus levels. J. Soil Water Conserv. 51:160–166.
- Sharpley, A.N., and B. Moyer. 2000. Phosphorus forms in manure and compost and their release during simulated rainfall. J. Environ. Qual. 29:1462–1469.[Abstract/Free Full Text]
- Sikora, L.J., and N.K. Enkiri. 2003. Availability of poultry litter compost P to fescue as compared to triple super phosphate. Soil Sci. 168:192–199.[CrossRef]
- Sikora, L.J., and R.A.K. Szmidt. 2001. Nitrogen sources, mineralization rates, and nitrogen nutrition benefits to plants from composts. p. 287–305. In P.J. Stoffella and B.A. Kahn (ed.) Compost utilization in horticultural cropping systems. Lewis Publ., Boca Raton, FL.
- Sims, J.T., R.R. Simard, and B.C. Joern. 1998. Phosphorus loss in agricultural drainage: Historical perspective and current research. J. Environ. Qual. 27:277–293.[Abstract/Free Full Text]
- Taylor, A.W., and H.B. Pionke. 2000. Inputs of phosphorus to the Chesapeake Bay watershed. p. 7–21. In A.N. Sharpley (ed.) Agriculture and phosphorus management: The Chesapeake Bay. Lewis Publ., Boca Raton, FL.
- Vadas, P.A., J.J. Meisinger, L.J. Sikora, J.P. McMurtry, and A.E. Sefton. 2004. Effect of poultry diet on phosphorus in runoff from soils amended with poultry manure and compost. J. Environ. Qual. 33:1845–1854.[Abstract/Free Full Text]
- Wolf, A., and D. Beegle. 1995. Recommended soil tests for macronutrients: Phosphorus, potassium, calcium and magnesium. p. 30–38. In Recommended soil testing procedures for the northeastern U.S. Northeast Reg. Bull. 493. 2nd ed. Univ. of Delaware Agric. Exp. Stn., Newark.
This article has been cited by other articles:
|
|
|
|
 
P. B. DeLaune, P. A. Moore Jr., and J. L. Lemunyon
Effect of chemical and microbial amendment on phosphorus runoff from composted poultry litter.
J. Environ. Qual.,
July 1, 2006;
35(4):
1291 - 1296.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
F. Zvomuya, B. L. Helgason, F. J. Larney, H. H. Janzen, O. O. Akinremi, and B. M. Olson
Predicting phosphorus availability from soil-applied composted and non-composted cattle feedlot manure.
J. Environ. Qual.,
May 1, 2006;
35(3):
928 - 937.
[Abstract]
[Full Text]
[PDF]
|
|
|
TOP
ABSTRACT
INTRODUCTION
