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


     

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 Related articles in JEQ
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (7)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Wolkowski, R. P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Wolkowski, R. P.
Agricola
Right arrow Articles by Wolkowski, R. P.
Related Collections
Right arrow Municipal Waste
Published in J. Environ. Qual. 32:1844-1850 (2003).
© 2003 ASA, CSSA, SSSA
677 S. Segoe Rd., Madison, WI 53711 USA

TECHNICAL REPORTS

Waste Management

Nitrogen Management Considerations for Landspreading Municipal Solid Waste Compost

Richard P. Wolkowski*

Department of Soil Science, University of Wisconsin-Madison, 1525 Observatory Drive, Madison, WI 53706-1299

* Corresponding author (rpwolkow{at}wisc.edu).

Received for publication May 20, 2002.

   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 NOTES
 RESULTS AND DISCUSSION
 CONCLUSIONS
 REFERENCES
 
Many municipalities have examined composting as an alternative to landfilling for the management of organic solid waste materials. Ultimately these materials will be land-applied and therefore some knowledge of nutrient availability will be necessary to optimize crop yield and minimize environmental risk. Field studies were conducted in 1993 and 1994 on a silt loam and a loamy sand soil in Wisconsin to determine the effect of municipal solid waste compost (MSWC) on corn (Zea mays L.) yield, plant nutrient concentration, and soil nitrate N content. Municipal solid waste composts with ages of 7, 36, and 270 d were applied at rates of 22.5, 45, and 90 Mg ha-1 to small plots. Rates of commercial nitrogen (N) fertilizer, ranging from 0 to 179 kg N ha-1, were applied to separate plots to determine the N availability from the MSWC. Treatments were applied in the spring and incorporated before planting corn. The 270-d MSWC increased corn whole-plant dry matter and grain yield at each location in both years above the 7- and 36-d MSWC. Rate of MSWC only affected grain yield at the loamy sand site in 1994. Municipal solid waste compost had minimal effect on the levels of plant nutrients in the whole-plant tissue measured at physiological maturity. Nitrate N measured in the top 90 cm of soil was higher throughout the growing season in treatments receiving recommended N fertilizer when compared with any of the MSWC treatments. It was estimated that 6 to 17% of the total N in the 270-d MSWC became available in the first year. The land-application of mature MSWC at the tested rates would be an agronomically and environmentally admissible practice.

Abbreviations: MSW, municipal solid waste • MSWC, municipal solid waste compost


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 NOTES
 RESULTS AND DISCUSSION
 CONCLUSIONS
 REFERENCES
 
THE REMOVAL OF NONDEGRADABLE MATERIALS (e.g., glass, plastic, and metal) from the municipal solid waste (MSW) stream by residential recycling programs provides an opportunity to use the remaining, primarily organic material to produce a compost of reasonable quality (Hyatt, 1995). Several municipalities in the USA and others worldwide have adopted composting MSW as a means to divert material from landfills, while producing a soil amendment that can be land-applied to field crops. Compost application is generally perceived to be beneficial to the soil and crops because of improved soil structure, increased cation exchange and water holding capacity, and the addition of plant nutrients (Kerner et al., 2000).

Concerns have been raised with respect to the land application of MSWC based on the physical and chemical composition of the material. These include the issues of phytotoxicity, the uncertain plant nutrient value of the material, and the environmental consequences of the movement of contaminants into plants and ground water. In their review of the chemical properties of MSWC, He et al. (1992) concluded that the benefits of using these materials transcend the concerns; however, there are concerns from the accumulation of heavy metals over time (Fricke and Vogtmann, 1994).

Composts must be "mature" to limit the risk of crop growth and yield reduction from N immobilization caused by high C to N ratios (Sims, 1990; Mamo et al., 1998). Immature compost may also contain high concentrations of organic acids that interfere with root function and thereby impair plant growth (De Vleeschauwer et al., 1981; Jimenez and Garcia, 1992). Wong and Chu (1985) noted that these toxicity effects diminish as the time of composting increases, presumably because of lower organic acid concentrations in the material, indicated by reductions in the C to N ratio. Chefetz et al. (1998) suggested that monitoring specific constituents of the dissolved organic matter of a MSW may be a reasonable method to determine the point where the risk of phytotoxity is minimal.

Recent initiatives in nutrient management planning will require an improved assessment of the N supplying capacity of organic amendments so that proper credit can be taken where application is made. The availability of N from a MSWC in the year of application has been shown to be in the range of 10% (Mamo et al., 1998). This is much lower than the N availability estimated for dairy manure cited by Motavalli et al. (1989) and the regulated availability for organic N in sewage sludge for which the value is 25% (Wisconsin Department of Natural Resources, 1995). Therefore, application of relatively high rates of MSWC will be needed to supply crop N need to produce yields similar to those found with recommended rates of commercial fertilizer (Mays et al., 1973; Mamo et al., 1998, 1999). High rates of MSWC may not be acceptable to regulatory agencies because of the concern of excessive N loading and therefore supplemental commercial N fertilization will be needed to maximize yield at lower MSWC rates. This will certainly be the case with materials having high C to N ratios. Erickson et al. (1999) noted that soil NO3–N decreased in the year of application with increasing rates of MSWC having a C to N ratio of 40 in the year of application. They found that in the year following application the organic N in the MSWC mineralized to supply approximately one-third of the corn N need. The poor synchrony between when N is mineralized and when a crop demands N may subject some of the N to loss by leaching or denitrification. Once the availability of N from a MSWC is known, N nutrition can be optimized and leaching minimized by an application program having lower MSWC rates that will require some supplemental N fertilizer (Mamo et al., 1999).

The objective of this study was to determine the response of corn to varying rates and maturities of MSWC. The study was designed to assess the effect of these treatments on the yield, nutrient uptake, and soil nitrate N content. The N availability of the mature MSWC was also determined.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
NOTES
 RESULTS AND DISCUSSION
 CONCLUSIONS
 REFERENCES
 
Small plot field studies were conducted at the University of Wisconsin Arlington Agricultural Research Station (43°19' N, 89°21' W) and on a private farm near the city of Portage, Wisconsin (43°29' N, 89°23' W) in 1993 and 1994. The soils at the Arlington and Portage sites are a Saybrook silt loam (fine-silty, mixed, superactive, mesic Oxyaquic Argiudoll) and a Boyer loamy sand (coarse-loamy, mixed, semiactive, mesic Typic Hapludalf), respectively. Each field had been in a nonleguminous crop and had not received manure for the previous four seasons. The initial soil tests, as determined according to University of Wisconsin-Extension procedures (Kelling et al., 1998), were pH 7.0, organic matter 62 g kg-1, 115 mg P kg-1, and 180 mg K kg-1 for the Arlington site; and pH 5.4, organic matter 11 g kg-1, 60 mg P kg-1, and 100 mg K kg-1 for the Portage site. Available P and exchangeable K were both determined following extraction with the Bray-P1 test.

Municipal solid waste compost materials were obtained from the Columbia County (Wisconsin) Recycling and Composting Facility. This facility employs a process that consists of mixing solid waste collected from residential and small commercial sources for approximately 7 d in a rotating vessel, followed by windrow composting in an open-sided building. Glass, plastics, metals, and other noncompostable materials were presumably separated and collected elsewhere by recycling, but inevitably some of these inert materials are found in the collected waste. Windrows were managed to maintain an internal temperature in a range of 60 to 65°C and were mechanically turned with a machine specifically designed for windrow turning every 2 to 3 d. Several ages of MSWC were prepared based on the time from introduction into the vessel. Material that was 270 d old was considered mature because it did not reheat after turning. Materials were passed through a 1-cm screen before application. Inert material composition was determined on the screened MSWC by hand-sorting six, 200-g grab samples (dry-matter basis) of each MSWC material. Samples were collected from materials of all ages on the day of application. It was likely that the composition of the initial material was different and may have contributed to variability in analysis. Nutrient and metal concentration in the MSWC were measured via inductively coupled plasma (ICP) following nitric–perchloric acid digestion (Schulte et al., 1987).

Studies at both locations were set up in a split-plot treatment arrangement containing four replications. Individual plot size was 3 m (four corn rows) by 10.5 m. Municipal solid waste compost age was the main plot treatment (straight from the vessel or 7, 36, or 270 d in the windrow). Rate of application was the subplot treatment (22.5, 45, and 90 Mg dry matter ha-1). Nitrogen fertilizer was applied to separate plots at rates of 45, 90, 134, and 179 kg N ha-1 as ammonium nitrate to develop the N response curve necessary to calculate first-year N availability. A control treatment was also established (no compost or N fertilizer). Starter fertilizer was applied with the planter to all plots to supply 13 kg N, 24 kg P, and 45 kg K ha-1. The N contained in the starter was not included in the N rates described above.

Municipal solid waste compost and N fertilizer were applied by hand in the spring shortly before planting with the exception that the N fertilizer at the Portage site was applied uniformly between rows in a broadcast manner when the corn was at the V6 growth stage. Preplant applied materials were incorporated by double disking, then chisel-plowed and disked again to create a seedbed. Dates of compost application for Arlington were 30 Apr. 1993 and 18 Apr. 1994, and for Portage were 27 Apr. 1993 and 19 Apr. 1994. Corn (‘3578’; Pioneer Hi-Bred International, Des Moines, IA1) was planted in all cases within a few days of compost application in 75-cm rows. Standard crop protection chemicals, including corn rootworm insecticide and herbicides, were applied to both sites at label-recommended rates in each season. All yield, plant tissue, and soil measurements were taken from the middle two out of four rows of the plots.

Whole-plant dry matter content was determined at physiological maturity by cutting 10 randomly selected plants from all plots at ground level that were weighed, chopped in a stationary chopper, and subsampled to determine dry matter content and nutrient concentration. Grain yield was determined by harvesting the middle two rows of each plot with a small plot combine. Reported grain yields are adjusted to 155 g kg-1 water content. Profile soil samples were taken to a depth of 90 cm in 30-cm increments from the control, the 22.5 and 90 Mg ha-1 rates of all MSWC treatments, and the 179 kg N ha-1 fertilizer treatment. Samples were taken 14, 28, 56, and 112 d after the MSWC application. Samples were frozen immediately, then later air-dried and ground, and analyzed for nitrate N with a Lachat Auto-Analyzer, Quickchem Method 12-107-04-1-3 (Lachat Instruments, Milwaukee, WI) following extraction with 2 M KCl. The soil nitrate N contents for the 30-cm increments were added and are reported as the total for the 90-cm depth.

Data for the MSWC treatments were analyzed with an analysis of variance for a split-plot design using SAS procedures (SAS Institute, 1992). Where main effect significance was found at the P = 0.05 level, a Fisher's LSD is reported. Single degree of freedom contrasts were used for grain yield and soil nitrate data to compare the nonfertilized and fertilized controls (0 and 179 kg N ha-1) with the 270-d MSWC material applied at 90 Mg ha-1. A nitrogen fertilizer equivalence procedure was used to determine the first-year N availability from the 270-d compost treatments in each year (Motavalli et al., 1989). This procedure estimates the fertilizer or total MSWC N needed to produce an identical N uptake in the physiologically mature plant samples. These values were calculated for the three MSWC rates on yield response curves developed for each location and year. The fertilizer equivalency was then calculated by dividing the fertilizer N rate by the total N applied in the MSWC and then averaging these values.


   RESULTS AND DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 NOTES
 RESULTS AND DISCUSSION
CONCLUSIONS
 REFERENCES
 
Material Description
Table 1 shows the composition of the inert materials, the total concentration of selected plant nutrients and metals, and the C to N ratio in the compost used in 1993 and 1994. It should be recognized that different feed stocks were used to create the various aged materials so that they could all be land-applied on the same date. Glass comprised the largest inert material fraction in each of the composts. It is apparent that many individuals contributing solid waste to this facility did not recycle materials as effectively as anticipated. This might have been expected because of the voluntary nature of the recycling program. While the glass would be chemically inert, the amount found in these materials may discourage potential users of the material for aesthetic reasons and possible concerns associated with the health of livestock that may graze or be fed crops grown in areas treated with the material. The glass content of the compost tended to increase with the age of the material due to a concentrating effect from the loss of organic matter during composting. A similar phenomena was observed for the plastic fraction in 1994 and the "other" category. The other category was comprised of slowly or nondecomposable materials such as bones, pieces of rubber, and gravel. The metal content tended to decrease with age although the results are highly variable. This change may be the result of loss of mass via corrosion by organic acids during composting or changes in the feed stock composition. Clearly, more effective screening or other separation methods should be implemented to remove inert materials and enhance the quality of the final product.


View this table:
[in this window]
[in a new window]
  		Table 1. Inert material composition and the concentration of selected nutrients and metals in municipal solid waste compost applied to research plots at Arlington and Portage, Wisconsin, 1993–1994.{dagger}

 
The concentration of N, P, K, and S in the compost tended to increase with composting time (Table 1). The total N contents of the 36- and 270-d materials were slightly higher in 1994. In general, 99% of the N in the materials was in the organic fraction. The C to N ratio decreased as expected with time in the windrow and was found to be somewhat lower for all materials in 1994 for unknown reasons. The concentration of selected metals of the MSWC materials varied considerably, emphasizing the need for an analysis before application. Each of these was below the ceiling concentrations established for heavy metals in sewage sludge (USEPA, 1993) and therefore is considered a minimal health risk when applied to field crops.

Growing Season Conditions
Table 2 gives the average monthly temperature and precipitation totals for the 1993 and 1994 growing seasons as measured at National Oceanic and Atmospheric Administration weather stations located within 3 km of each site. The growing season of both years at Arlington was cooler and wetter than normal. Monthly average temperatures at the Portage location were closer to normal, although precipitation was generally higher than the 30-yr average. These conditions appear to have affected the corn yield potential in 1993 such that grain yields were 2 to 3 Mg ha-1 lower than measured in 1994. The above-average precipitation may have leached a greater amount of nitrate N deeper into the soil profile, especially on the sandy soil at Portage.


View this table:
[in this window]
[in a new window]
  		Table 2. Average monthly temperature and precipitation for the growing season recorded near municipal solid waste compost (MSWC) research locations, 1993 and 1994.

 
Total Dry Matter Yield and Nutrient Concentration
Table 3 shows the effects of MSWC on the total corn dry matter production at physiological maturity for both locations and years of the study. The age of the MSWC significantly affected total dry matter yield in both years at both locations. Severe stunting was observed throughout the season, and dry matter yield was depressed where the 7- and 36-d material was applied. This response may have been due to a combination of N immobilization because of the relatively high C to N ratio, and growth inhibition from high concentrations of organic acids (De Vleeschauwer et al., 1981; Jimenez and Garcia, 1992). The 7- and 36-d materials had an odor of acetic acid; however, the organic acid content of the materials was not measured. Dry matter production was not affected by MSWC rate and the interaction between material age and rate was not significant.


View this table:
[in this window]
[in a new window]
  		Table 3. Main effect of municipal solid waste compost (MSWC) application on the total corn dry matter production measured at physiological maturity, 1993–1994.

 
Table 4 shows the main effect of compost age and rate of application on the whole-plant nutrient concentration of corn at both locations in 1993. Similar results were observed in 1994, but are not shown. The N concentration in whole-plant tissue increased slightly with material age at the Portage location, but was unaffected at the Arlington location that had a much higher soil organic matter content. The effect of MSWC age on N concentration in the whole-plant at physiological maturity was not as great as it may have been if measured earlier in the season. It was apparent from visual crop symptoms expressed by the early vegetative growth that N deficiency existed for both the 7- and 36-d material throughout the growing season. Presumably a flush of mineralization that occurred toward the end of the growing season increased the plant-available N in these treatments, with little additional increase in dry matter production, resulting in a higher tissue N concentration. Nitrogen concentration where 270-d compost was applied may have been lower because of dilution in a greater amount of dry matter. Calculation of the mean total N uptake (product of dry matter and N concentration) shows a trend for greater N removal in 1993 by the 270-d MSWC (112, 115, and 159 at Arlington and 140, 157, and 195 kg N ha-1 at Portage from the 7-, 36-, and 270-d treatments, respectively).


View this table:
[in this window]
[in a new window]
  		Table 4. Main effect of the application of three ages of municipal solid waste compost (MSWC) on the whole-plant nutrient concentration at Arlington and Portage, Wisconsin, 1993.

 
The concentration of P and Mg decreased as the age of the MSWC increased at both locations in 1993 (Table 4) and 1994 (data not shown). This response may also be attributed to a dilution effect as the total amount of P applied by the 270-d material was substantially greater because of a higher P concentration in the material. All treatments received 24 kg P ha-1 in the starter at planting. This treatment was made to limit the response of the crop to P and should have supplied adequate P for the crop according to Wisconsin soil test recommendations (Kelling et al., 1998). Levels of the other plant nutrients were occasionally affected by MSWC age; however, these differences were not significant and did not demonstrate an identifiable trend related to nutrient or location. The rate of MSWC application had minimal effect on the concentration of plant nutrients in the whole-plant tissue (Table 4). This is indicative of the low level of available nutrients in the material and demonstrates the slow mineralization of nutrients in the year of application. No consistent interactions between MSWC age and rate of application were observed with respect to the nutrient concentration of the whole-plant tissue.

Grain Yield and Nitrogen Equivalency
Figure 1 shows the relationship between MSWC age and rate of application on corn grain yield for Arlington and Portage, respectively for both years of the study. The statistical significance levels for these comparisons are shown in Table 5. Compost age affected grain yield at both locations in both years. The 7- and 36-d compost depressed grain yield, when compared with the mature 270-d compost. There were interactions for grain yield response between MSWC age and rate in 1993 at both locations (P > F = 0.03 and 0.10 for Arlington and Portage, respectively). Yield at both locations in 1993 decreased as the 7-d MSWC rate increased. The C to N ratios for all materials were somewhat higher in 1993 compared with 1994 and coupled with the wetter, cooler conditions in 1993 the N immobilization effect may have been more significant in that year. The interaction between compost age and rate was not significant in 1994. Corn grain yields were highest with the 270-d compost at both locations. Table 5 also shows the single degree of freedom contrasts between the control vs. 179 kg N ha-1 and the 179 vs. 90 Mg ha-1 270-d treatments. In 1994, the 90 Mg dry matter ha-1 rate 270-d MSWC application produced grain yields equivalent to those where the recommended rate of 179 kg N ha-1 as fertilizer alone was applied. These yields were 8.8 ± 0.5 and 12.4 ± 1.0 at Arlington and 9.5 ± 0.2 and 10.5 ± 0.9 at Portage in 1993 and 1994, respectively.



View larger version (63K):
[in this window]
[in a new window]
  		Fig. 1. Corn grain yield as affected by municipal solid waste compost (MSWC) rate and maturity at Arlington and Portage, Wisconsin, 1993–1994. Control grain yields (Mg ha-1) for Arlington were 6.5 ± 1.0 in 1993 and 8.8 ± 0.5 in 1994, and 179 kg N ha-1 grain yields were 9.6 ± 1.0 in 1993 and 12.4 ± 1.0 in 1994. Control grain yields (Mg ha-1) for Portage were 5.6 ± 1.0 in 1993 and 9.5 ± 0.2 in 1994, and 179 kg N ha-1 grain yields were 6.0 ± 1.2 in 1993 and 10.5 ± 0.9 in 1994.

 

View this table:
[in this window]
[in a new window]
  		Table 5. Significance level of corn grain yield effects measured at the Arlington and Portage municipal solid waste compost (MSWC) compost studies, 1993–1994.

 
Municipal solid waste compost rate affected yield at Portage in 1994 where grain yields at the 45 and 90 Mg ha-1 treatments were greater than those when 22.5 Mg ha-1 was applied. Grain yield at Portage was affected more by MSWC rate and was more responsive to the use of 270-d MSWC presumably because of the lower organic matter content at the Portage site. A nitrogen equivalency procedure described by Motavalli et al. (1989) was used to estimate the first-year availability of N from the 270-d MSWC. The MSWC N availability was estimated to be 6 and 13% for Arlington and 10 and 17% for Portage in 1993 and 1994, respectively. These estimates of first-year N availability compare favorably with those reported from a similar climatic region by Mamo et al. (1998). Nitrogen availability from the MSWC may have been lower in 1993 because of lower mineralization resulting from the cooler, wetter conditions.

Soil Nitrate
Table 6 shows the effect of MSWC age and rate on the soil profile nitrate N content measured at several times during the growing season in 1993. Single degree of freedom contrasts were made between control vs. 179 kg N ha-1 and 179 vs. 90 Mg ha-1 270-d treatments. Levels in the control at Arlington were relatively high because of the high soil organic matter content and possible carryover from the previous crop. Data are shown for the 22.5 and 90 Mg ha-1 rate for materials of all ages, as well as the control and recommended N treatment. The corn N recommendation for these soils is 179 kg N ha-1. These measurements demonstrate that N availability as indicated by the level of soil inorganic N from the MSWC was relatively low compared with commercial N fertilizer applied at the recommended rate. Nitrogen immobilization was suspected where either the fresh or six-week-old material was applied, as soil nitrate levels were generally lower in these treatments when compared with the control. Soil nitrate N levels were always considerably higher where 179 kg N ha-1 as commercial fertilizer was applied. The soil nitrate N content was lower at 56 d at Portage, presumably because of a combination of leaching following heavy rains in loamy sand soil and plant uptake. Under the conditions of this study, it is apparent that immature MSWC immobilizes N and will not supply the total crop N need. Fertilizer N represents a greater risk of N leaching below the rootzone than does the MSWC treatment. It is suspected that most of the N not removed by the crop remains in an organic form, which will be slowly mineralized in subsequent years. Second and third year N credits for more easily mineralized materials such as manure are 10 and 5% of the initially applied N (Kelling et al., 1998) and 12 and 6% of the organic N for municipal biosolids (Wisconsin Department of Natural Resources, 1995). It would be expected that residual N availability from composts would be lower because of the recalcitrant nature of the organic matter.


View this table:
[in this window]
[in a new window]
  		Table 6. Effect of municipal solid waste compost (MSWC) and N fertilizer application{dagger} on the soil nitrate N content in the surface 0.9 m measured at several times after application, Arlington and Portage, Wisconsin, 1993.

 

   CONCLUSIONS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 NOTES
 RESULTS AND DISCUSSION
 CONCLUSIONS
REFERENCES
 
The land application of several different ages of MSWC to corn was studied in Wisconsin for two growing seasons. All materials contained relatively high levels of glass, which should be removed to improve quality. Use of MSWC had a moderate effect on the concentration of plant nutrients in the corn at physiological maturity. Application of 270-d MSWC increased yield as MSWC rate increased and resulted in corn grain yield near that obtained with recommended N fertilizer. First-year N availability of the 270-d MSWC ranged between 6 and 17%. The 7- and 36-d MSWC reduced yield, even at low rates of application. Soil nitrate N was usually lower where MSWC was applied, presumably because of slow mineralization from the material. The land application of mature MSWC appears to be a reasonable, beneficial reuse of municipal solid waste. Consideration should be given to metal accumulation from consecutive applications and loading of large amounts of organic N that may be converted to nitrate N and leached from the root zone. Knowledge of its relative nutrient supply capacity will give planners the ability to supplement MSWC treatments with other N-containing materials to optimize yields.


   ACKNOWLEDGMENTS
 
Appreciation is extended to Eileen Norby and the members of the Wisconsin Solid Waste Research Council for their financial support of this work and to Mr. William Casey of the Columbia County Recycling and Composting Facility for the preparation of the various composts.


   NOTES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 NOTES
RESULTS AND DISCUSSION
 CONCLUSIONS
 REFERENCES
 
1 Mention of product or company name does not constitute endorsement by the University of Wisconsin-Madison to the exclusion of others. Back


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


Related articles in JEQ:

This Issue in Journal of Environmental Quality

JEQ 2003 32: 1577-1582. [Full Text]  



This article has been cited by other articles:


Home page
 J. Environ. Qual.Home page
T. C. Flavel and D. V. Murphy
Carbon and Nitrogen Mineralization Rates after Application of Organic Amendments to Soil
J. Environ. Qual., January 3, 2006; 35(1): 183 - 193.
[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 Related articles in JEQ
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (7)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Wolkowski, R. P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Wolkowski, R. P.
Agricola
Right arrow Articles by Wolkowski, R. P.
Related Collections
Right arrow Municipal Waste

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