HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Tester, C. F. Articles by Parr, J. F. Search for Related Content PubMed Articles by Tester, C. F. Articles by Parr, J. F. Agricola Articles by Tester, C. F. Articles by Parr, J. F.

Decomposition of Sewage Sludge Compost in Soil: III. Carbon, Nitrogen, and Phosphorus Transformations in Different Sized Fractions¹

ABSTRACT

A laboratory incubation study was conducted to determine the rate and extent of decomposition of sewage sludge compost in soil amended with compost fractions of various particle sizes. Cured compost was passed through a 6-mm screen and further fractionated with a 1-mm sieve. The three fractions of compost (<6 mm, 1 to 6 mm, and <1 mm) were mixed with a loamy sand at a rate of 89.6 metric tons/ha (dry wt) and incubated at 25°C. Rates of mineralization and decomposition were determined by monitoring CO₂ and NH₃ evolution and measuring changes in the organic and inorganic fractions of C, N, and P with time. A lime-treated soil was included as an appropriate control because the compost was produced from a lime-stabilized undigested (raw) sewage sludge.

Decomposition of the three compost fractions, as determined by CO₂ evolution, was directly related to the amount of carbon in the compost-soil mixtures. Cumulative CO₂ evolution was lowest from the compost that passed the 1-mm sieve and had the lowest C/N ratio. Approximately 8% of the compost C from all fractions evolved as CO₂ in 45 days of incubation. The quantity of N mineralized ranged from 3 to 13% for the different fractions, and the extent of N mineralization was inversely related to the C/N ratio. Ammonia evolution paralleled N mineralization in these mixtures. The amount of extractable P was nearly the same for all fractions and did not change during incubation. Although the <1-mm fraction contained a greater amount of total P than the other two fractions, it contained a smaller amount of extractable P. When the pH was adjusted to 6.6, decomposition of the native soil C increased 82%, but neither soil N mineralization nor the amount of extractable P was affected.

Key Words: laboratory incubation • mineralization • immobilization • volatilization • extractable P

¹ Contribution from the Biol. Waste Manage. and Organic Resources Lab., Beltsville Agric. Res. Center, Agric. Res., SEA, USDA, Beltsville, MD 20705. This research was supported in part by the Maryland Environ. Serv., Annapolis, Md., and by a grant from USEPA, Cincinnati, Ohio.

² Research Chemists, Plant Physiologist, and Microbiologist, respectively.

Received for publication March 30, 1978.