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Cumulative Effects of Nitrogen, Phosphorus, and Potassium Fertilizer Additions on Soil Respiration, pH, and Organic Matter Content
Author(s) -
Van Cleve Keith,
Moore Terry A.
Publication year - 1978
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1978.03615995004200010026x
Subject(s) - organic matter , chemistry , soil organic matter , phosphorus , agronomy , nitrogen , nitrification , zoology , potassium , fertilizer , soil respiration , soil water , environmental science , soil science , biology , organic chemistry
Cumulative effects of annual additions of NH 4 NO 3 (111 kg/ha N), treble superphosphate (55 kg/ha P), and KCl (111 kg/ha K) on aspen ( Populus tremuloides Michx.) soil respiration, pH, and soil organic matter content were examined. Total fertilizer additions from fall 1969 through spring 1975 were 777 kg/ha N and K and 385 kg/ha P. The main effect of N and P additions was to increase soil biological activity by up to 42% and 33%, respectively, with the greatest increases occurring at the 15‐ to 30‐cm soil depth. For K, a 21% reduction in soil biological activity occurred at 0‐ to 15‐cm, while a 20% increase was found at 15‐ to 30‐cm. Fertilization with N and P increased but K showed no effect on surface soil organic matter content. Subsurface soil (15‐ to 30‐cm) organic matter content was not affected by any treatment. Higher soil organic matter content probably resulted largely from greater aspen growth response to N. Increased soil biological activity was attributed to a combination of increased soil organic matter content and improved levels of soil N and P. Treatment with N, K, or N + K reduced soil pH, possibly because of microbial nitrification of NH 4 + associated with uptake by aspen of NH 4 + and K + with replacement of H + in the soil.