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Distribution of Available Nitrogen in Undisturbed Forest Soil Cores Following Fertilization with Urea and Ammonium Nitrate
Author(s) -
Pang Patrick C. K.
Publication year - 1982
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/sssaj1982.03615995004600030036x
Subject(s) - human fertilization , forest floor , ammonium , nitrate , nitrogen , chemistry , soil horizon , agronomy , zoology , urea , precipitation , environmental chemistry , environmental science , soil water , soil science , biology , geography , organic chemistry , meteorology
Undisturbed soil cores collected from a 31‐year‐old Douglas‐fir ( Pseudotsuga menziesii Mirb. Franco) plantation near Shawnigan Lake, B.C., were fertilized with (NH 2 ) 2 CO (200 and 400 kg N ha −1 ) and NH 4 NO 3 (200 kg N ha −1 ) and incubated for up to 5 months at 20°C/12°C (14‐hour day/10‐hour night) with air humidity of 80 to 85%. Cores with the 200 kg N ha −1 rate of fertilization were also given three monthly 24‐hour simulating precipitation treatments followed by incubation, starting 1 month after fertilization. Under conditions with or without precipitation, (NH 2 ) 2 CO and/or NO ‐ 2 were never detected in soil (forest floor plus mineral horizons) or leachates, and movement of ammonium (NH + 4 ) beyond the forest floor was limited. In the absence of precipitation, a small amount of NO ‐ 3 (9 to 18 µg N g −1 of dry soil) was detected in soil with (NH 2 ) 2 CO fertilization, whereas up to 124 µg N g −1 of dry soil was detected with NH 4 NO 3 fertilization. Redistribution of nitrate (NO ‐ 3 ) was limited and approximately 90% of it remained in the forest floor. With precipitation, a NO ‐ 3 concentration of 1 µg N g −1 was detected in soil over the study period after (NH 2 ) 2 CO fertilization. With NH 4 NO 3 fertilization, a maximum quantity of 32 µg N g −1 of NO ‐ 3 was detected in the forest floor after the first precipitation treatment and only a trace (2 µg N g −1 ) was detected after the third precipitation treatment. Leaching of NO ‐ 3 , though small (10 mg N liter −1 ), was restricted to NH 4 NO 3 fertilization. The recovery of nitrogenous fertilizers, (NH 2 ) 2 CO or NH 4 NO 3 , as NH + 4 plus NO ‐ 3 never exceeded 53% of the amount applied. The incomplete recovery of the fertilizers as inorganic‐N could be due to biological immobilization of N, or interactions of organic matter with unhydrolyzed (NH 2 ) 2 CO, NH + 4 (from urea hydrolysis and NH 4 NO 3 ionization), or NO ‐ 2 (from NH + 4 oxidation and NO ‐ 3 reduction).