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Subsurface Application of Manures Slurries for Conservation Tillage and Pasture Soils and Their Impact on the Nitrogen Balance
Author(s) -
Dell Curtis J.,
Meisinger John J.,
Beegle Douglas B.
Publication year - 2011
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2010.0069
Subject(s) - denitrification , manure , nitrous oxide , leaching (pedology) , environmental science , slurry , tillage , liquid manure , greenhouse gas , agronomy , volatilisation , soil water , nitrogen , environmental engineering , chemistry , soil science , ecology , organic chemistry , biology
Injection of cattle and swine slurries can provide soil incorporation in no‐till and perennial forage production. Injection is expected to substantially reduce N loss due to ammonia (NH 3 ) volatilization, but a portion of that N conservation may be offset by greater denitrification and leaching losses. This paper reviews our current knowledge of the impacts of subsurface application of cattle and swine slurries on the N balance and outlines areas where a greater understanding is needed. Several publications have shown that liquid manure injection using disk openers, chisels, or tines can be expected to reduce NH 3 emissions by at least 40%, and often by 90% or more, relative to broadcast application. However, the limited number of studies that have also measured denitrification losses have shown that increased denitrification with subsurface application can offset as much as half of the N conserved by reducing NH 3 emissions. Because the greenhouse gas nitrous oxide (N 2 O) is one product of denitrification, the possible increases in N 2 O emission with injection require further consideration. Subsurface manure application generally does not appear to increase leaching potential when manure is applied at recommended rates. Plant utilization of conserved N was shown in only a portion of the published studies, indicating that further work is needed to better synchronize manure N availability and crop uptake. At this time in the United States, the economic and environmental benefits from reducing losses of N as NH 3 are expected to outweigh potential liability from increases in denitrification with subsurface manure application. To fully evaluate the trade‐offs among manure application methods, a detailed environmental and agricultural economic assessment is needed to estimate the true costs of potential increases in N 2 O emissions with manure injection.