Premium
Chemical Transformations of Urea‐Nitrogen and Movement of Nitrogen in a Shortgrass Prairie Soil
Author(s) -
Stillwell M. A.,
Woodmansee R. G.
Publication year - 1981
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/sssaj1981.03615995004500050015x
Subject(s) - urea , nitrification , chemistry , nitrate , ammonia volatilization from urea , nitrogen , ammonium , leaching (pedology) , zoology , urine , urease , environmental chemistry , soil water , biochemistry , soil science , environmental science , biology , organic chemistry
This study, conducted on the Central Plains Experimental Range during the summer of 1979, was to (i) quantify the temporal dynamics of the transformations of nitrogen (N) in a simulated urine spot, (ii) determine the effect of urea hydrolysis on pH, and (iii) determine the depth of movement of nitrate by leaching. Miniplots of blue grama were established, and open‐ended aluminum cylinders 10 cm in diameter and 40 cm in length were embedded in each plot. Simulated urine was applied to two‐thirds of the plots at a rate of up to 45 g N m −2 . The remaining plots were controls. After the simulated urine application, only 6% of the added N remained as urea at 2 days; no urea‐N remained at 4 days. Maximum accumulation of ammonium‐N (39.9 g N m −2 ) was simultaneous with the disappearance of urea. Elevated levels of nitrate were first detected at day 12 when 6.7 g N m −2 had accumulated. No measurable nitrite accumulated during the experiment. Through the first 4 days, 83% of the (urea + ammonium)‐N in the profile was in the top 15cm of the soil. With the rains near the end of the study, nitrification proceeded, and nitrate was leached through the profile to below the depth of the cores. Simulated urine significantly affected soil pH to 15 cm. From an initial pH near 6.0, urea hydrolysis increased soil pH from 0.6 to 1.3 units. As nitrification prodeeded after day 40, the pH decreased to below control levels.