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Nitrogen Fertilization and Cropping System Impacts on Soil Quality in Midwestern Mollisols
Author(s) -
Russell A. E.,
Laird D. A.,
Mallarino A. P.
Publication year - 2006
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/sssaj2005.0058
Subject(s) - agronomy , environmental science , fertilizer , cropping system , tillage , soil fertility , soil quality , soil water , crop , biology , soil science
High grain production of corn ( Zea mays L.) can be maintained by adding inorganic N fertilizer, and also by using crop rotations that include alfalfa ( Medicago sativa L.), but the relative impact of these management practices on soil quality is uncertain. We examined the effects on soil of N fertilization rate (0, 90, 180, 270 kg ha −1 , corn phase only) in four cropping systems: CC, continuous corn; CS, corn–soybean [ Glycine max (L.) Merr.]; CCOA, corn–corn–oat ( Avena sativa L.)–alfalfa; and corn–oat–alfalfa–alfalfa (COAA). The 23‐ and 48‐yr‐old experimental sites, situated in northeast (Nashua) and north central (Kanawha) Iowa, were in a replicated split‐plot design and managed with conventional tillage. At Nashua, we measured available N, potential net N mineralization and microbial biomass C (MBC) throughout the growing season; all were significantly higher in the CCOA system. At both sites, post‐harvest N stocks, and soil organic C (SOC) concentrations were significantly higher in systems containing alfalfa. Grain yield was most strongly correlated with soil N properties. At Nashua, N fertilizer additions resulted in significantly lower soil pH (0‐ to 15‐cm depth) and lower exchangeable Ca, Mg, and K and cation exchange capacity (CEC) in the CC and CCOA systems. In an undisturbed prairie reference site for Nashua, low available N, low pH, and high CEC suggested a strong influence of the vegetation on nutrient cycling. In terms of management of soil fertility, inclusion of alfalfa in the rotation differed fundamentally from addition of N fertilizer because high yield was maintained with fewer adverse effects on soil quality.