Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2001
Publication Date: 4/1/2002
Citation: Liebig, M.A., Varvel, G.E., Doran, J.W., Wienhold, B.J. 2002. Crop sequence and n fertilization effects on soil properties in the western corn belt. Soil Science Society of America Journal. 66:596-601. Interpretive Summary: Understanding long-term management effects on soil properties is necessary to determine the sustainability of cropping systems. Soil physical, chemical, and biological properties were measured in a long-term cropping system study in eastern Nebraska. Properties were evaluated 16 years after initiation of the study in four crop sequences and three N fertilization treatments to a depth of 12 inches. Nitrogen fertilization had a greater influence on soil properties than crop sequence, with much of the influence concentrated in the surface 7.6 cm. Increased N-rate resulted in higher organic C, total N, and particulate organic matter (POM), but lower microbial biomass and soil pH. Among crop sequences, one 4-yr rotation (Corn-Soybean-Sorghum-Oat+Clover) possessed significantly lower soil bulk density, but higher potentially mineralizable nitrogen and POM present as soil organic matter as compared to other crop sequences. Among the treatments evaluated in the study, 4-yr crop sequences possessed a balance of soil attributes that should enhance biological productivity and nutrient cycling efficiency over time.
Technical Abstract: Understanding long-term management effects on soil properties is necessary to determine the relative sustainability of cropping systems. Soil physical, chemical, and biological properties were measured in a long-term cropping system study in the Western Corn Belt. Properties were evaluated after 16 years in four crop sequences [continuous corn (CC), corn-soybean (C-SB), corn-oat+clover-grain sorghum-soybean (C-OCL-SG-SB), and corn-soybean-grain sorghum-oat+clover (C-SB-SG-OCL)] each at three N fertilization rates (ZERO, LOW, and HIGH) to a soil depth of 30.5 cm on a Sharpsburg silty clay loam (fine, smectitic, mesic Typic Argiudoll). Nitrogen fertilization had a greater impact on soil properties than crop sequence, with management effects most pronounced at 0-7.6 cm. Increased N-rate resulted in higher organic C, total N, and particulate organic matter (POM). Organic C, in particular, was 1.4 Mg ha-1 higher in the HIGH HN-rate treatment as compared to the ZERO N-rate treatment. Increased N-rate, however, resulted in lower soil pH levels and reduced microbial biomass by about 20% between the HIGH and ZERO N-rate treatments. Four-year crop sequences had more potentially mineralizable N (55 kg ha-1 for four-year sequences vs. 46 kg ha-1 for average of CC and C-SB) and higher percentages of POM present as soil organic matter (17.1% for the C-SB-SG-OCL sequence vs. 13.9% for other sequences). Results from this evaluation indicate 4-yr crop sequences promoted a balance of soil characteristics that should enhance soil functions over time.