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Residual Nitrogen Availability from Soils Treated with Sewage Sludge in a Field Experiment
Author(s) -
Stark S. A.,
Clapp C. E.
Publication year - 1980
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1980.00472425000900030036x
Subject(s) - loam , mineralization (soil science) , soil water , sewage sludge , nitrogen , zoology , chemistry , incubation , tonne , environmental chemistry , nitrogen cycle , field experiment , environmental science , sewage , agronomy , environmental engineering , biology , soil science , biochemistry , organic chemistry
In this experiment we determined the residual nitrogen availability from sewage sludges applied to a Hubbard sandy loam soil. In Study I, three sludge types—anaerobically digested (119, 237, and 466 metric tons/ha), aerobically digested (244 metric tons/ha), and mixed primary‐settled and waste‐activated (493 metric tons/ha)—were applied over a 3‐year period. Soil samples were collected from the field experiment 2 years after the final sludge application. Study II samples were obtained from plots of a field experiment in which an anaerobically digested sludge had been applied (63, 125, and 200 metric tons/ha) 4 years earlier. Several biological and chemical characteristics were examined as indexes of N availability. Cumulative N mineralization during aerobic incubation was approximately linearly related to time 1/2 for all treatments. Index values for Study I samples varied widely, hut in general, reflected the quantity of sludge added: total soil C (1.05 to 4.66%), total soil N (0.092 to 0.608%), indigenous inorganic N (12 to 266 µ g/g), N mineralized during 52 weeks of aerobic incubation (87 to 884 µ g/g) and during 16 weeks of anaerobic incubation (14 to 525 µ g/g), nitrogen mineralization potential, N o (126 to 1,010 µ g/g), and autoclave‐extractable N (76 to 441 µ g/g). The sludge application rate was more important than the sludge type in affecting N mineralization. The sludge‐treated soils from Study II had lower and less varied index values than those from Study I. The evaluation of N‐availability indexes was based on the degree of correlation between the index values and N uptake by irrigated, field grown maize ( Zea mays L.) (Study I) or sorghum‐sudangrass ( Sorghum vulgare sudanese L., var. ‘Trudan V’) grown in the greenhouse (Study II). Each index was useful in determining relative differences of N availability for this soil having received greatly differing organic N treatments from sewage sludge. Nitrogen mineralized during short and long periods of incubation correlated with plant N uptake equally well. The chemical indexes of N availability were as reliable as more time‐consuming incubation procedures for determining the N‐supplying capacity of soils.