SOIL AMENDMENT HISTORY EFFECTS ON N AVAILABILITY FROM FERTILIZER AND MANURES

Authors: Mallory, Ellen; Griffin, Timothy

Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 8/2/2004
Publication Date: 10/31/2004
Citation: Mallory, E.B., Griffin, T.S. 2004. Soil amendment history effects on n availability from fertilizer and manures. American Society of Agronomy Meetings.

Interpretive Summary:

Technical Abstract: Repeated applications of organic materials can substantially increase soil carbon (C), nitrogen (N), and microbial activity. A 282-day incubation experiment investigated whether soil amendment history also affects N availability from different N sources. Soils were from the Maine Potato Ecosystem Project, Presque Isle, ME and had been under different soil management treatments since 1991. The 'amended' treatment included heavy additions of manure and compost, and a leguminous green manure. The 'unamended' soil treatment included inorganic fertilizer and red clover interseeding. Nitrogen source treatments were: control (no N), NH4 fertilizer (F), and two dairy manures that had previously been found to result in net mineralization (MM) and net immobilization (IM). The manures and fertilizer were applied at a rate of 50mg NH4 kg-1 soil. Soil inorganic N was initially 2.5 times greater and accumulated 1.75 times faster in the amended vs. the unamended soil. When N sources were added, ammonia consumption occurred 1.5 to 2 times faster in the amended soil. Nitrate accumulated more rapidly in the amended soil under F and MM treatments. In contrast, under the IM treatment there was no difference in NO3 concentration between the soils after day 14. Amendment history did affect N availability, but this difference was eliminated with the addition of a C-rich manure. These results indicate that both soil and manure characteristics should be considered when predicting manure N availability.