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Land Disposal of Liquid Sewage Sludge: III. The Effect on Soil Nitrate
Author(s) -
King Larry D.,
Morris H. D.
Publication year - 1972
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/jeq1972.00472425000100040025x
Subject(s) - loam , cynodon dactylon , sewage sludge , nitrate , fertilizer , environmental science , agronomy , sewage , groundwater , chemistry , environmental engineering , soil water , soil science , biology , geology , geotechnical engineering , organic chemistry
A field experiment was conducted over a 2‐year period to determine the effect of liquid sewage sludge on soil nitrate content of a Cecil sandy clay loam (Typic Hapludults) to a 120‐cm depth. Periodic applications of four rates of sludge to coastal bermudagrass (Cynodon dactylon L. Pers.) supplied a total of 4.4, 8.8, 10.0 and 20.0 cm of sludge in 1969 and 2.5, 5.0, 10.0, and 20.0 cm in 1970. Respective amounts of N applied by the four rates were 1,037, 2,074, 2,580, and 5,160 kg/ha in 1969 and 492, 984, 1.970, and 3,940 kg/ha in 1970. A chemical fertilizer treatment supplied 364 kg/ha of N in 1969 and 489 kg/ha in 1970. The two highest sludge rates affected significant increases in soil nitrate in the 0‐ to 120‐cm profile. The other two sludge rates and the chemical fertilizer treatment did not increase soil nitrate and were deemed safe from the standpoint of potential groundwater pollution. At the 20‐cm rate 40% (287 kg/ha) of the NO 3 ‐N present in the 0‐ to 120‐cm profile in October 1970 could not be accounted for the following May. Of the N supplied by the 10‐ and 20‐cm applications, 17 and 9%, respectively, was recovered through crop uptake while 56 and 54% remained in the sludge crust that had accumulated on the soil surface.