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Soil‐Test Biological Activity with the Flush of CO 2 : II. Greenhouse Growth Bioassay from Soils in Corn Production
Author(s) -
Franzluebbers Alan J.,
Pershing Mary R.
Publication year - 2018
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/sssaj2018.01.0024
Subject(s) - mineralization (soil science) , soil water , agronomy , dry matter , sorghum , nitrogen cycle , nitrogen , organic matter , fertilizer , cycling , environmental science , chemistry , soil science , biology , forestry , organic chemistry , geography
Core Ideas Grass growth in the greenhouse was dependent on soil nitrogen mineralization. Soil‐test biological activity was a valuable indicator of nitrogen mineralization. Biological activity, residual inorganic nitrogen, and total nitrogen were most important. Soil nitrogen (N) mineralization is variably affected by management and edaphic conditions. A routine soil test that reflects both soil biological activity and N mineralization could improve predictions for N fertilizer recommendations to cereal grains on different soil types and landscape settings. We collected soils from 47 corn production fields in North Carolina and Virginia at depths of 0 to 10, 10 to 20, and 20 to 30 cm and evaluated soil C and N characteristics in association with sorghum‐sudangrass [ Sorghum bicolor (L.) Moench ssp. Drummondii] dry matter production and N uptake during 6 to 8 wk of growth in the greenhouse. Plant dry matter and N uptake were strongly associated, as expected. Plant available N (sum of net N mineralization during 24 d of aerobic incubation + residual inorganic N) had the strongest association with plant dry matter production ( r 2 = 0.76) and N uptake ( r 2 = 0.85). However, the flush of CO 2 during a 0‐ to 3‐d period following rewetting of dried soil was nearly equally effective at r 2 = 0.74 and r 2 = 0.76, respectively. Multiple regression models with 4 ± 2 additional variables led to r 2 = 0.88 ± 0.10 among different separations of data based on depth, region, and soil textural class. We suggest the optimum combination of variables to predict soil N availability would be the flush of CO 2 , residual inorganic N, and total soil N concentration, as they balance relevant scientific information with limited soil‐testing resources (time and labor). We demonstrated that the flush of CO 2 was a rapid and reliable indicator of soil N availability.