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Title:Effect of rotation, organic inputs and tillage on crop performance and soil quality in conventional and low-input rotations in central Iowa
Author(s):Lazicki, Patricia A.
Advisor(s):Wander, Michelle M.
Department / Program:Natural Res & Env Sci
Discipline:Natural Res & Env Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
organic matter
low-input systems
diversified crop rotations
Abstract:Even though the benefits of low external input (LEI) cropping systems to crops and soils are well recognized the specific links between cropping practices and associated soil quality and crop responses are not yet clear. In the Marsden plots in central Iowa, crop yields and input use efficiency have been increased by the use of longer and more diversified rotations and reduced chemical inputs. In this work we sampled roots and soil parameters at multiple dates and two depths in all cropping phases, in order to quantify changes in physical, chemical and biological soil quality indicators and root responses associated with tillage and cropping factors in a conventional and two LEI rotations of different lengths and including different legume species. Improvements in soil quality indicators and plant productivity were expected to be driven by the amount and placement of organic residues and to fluctuate with tillage and cropping phase. On a system basis, particulate organic carbon (POM-C) and potentially mineralizable nitrogen (PMN) were increased in both LEI rotations relative to a two year (2-yr) corn (Zea mays L.) -soybean (Glycine max L.) rotation. Biologically labile organic matter fractions were highly stratified in the 2-yr rotation compared to the LEI rotations and the lower depth of the 2-yr rotation was consistently depleted. Corn roots followed a similar pattern, being concentrated in the top depth in the 2-yr rotation while more fully exploring the profile in the LEI rotations. Low C:N ratios in the soybean roots in the LEI rotations suggest greater N availability in the LEI soybean phase. Soil parameters did not differ between LEI rotations even though the 3-yrrotation included red clover (Trifolium pratense L.) instead of alfalfa (Medicago sativa L.), a shorter rotation length, and significantly greater mean annual organic inputs than did the 4-yr rotation. Corn yield in the 3-yr LEI rotation was significantly higher than that achieved in the 2-yr conventional rotation, and soybean yield in the 4-yr rotation was higher than that in the 2-yr rotation. Seasonal sampling showed that 1) soil parameters fluctuated during the growing season but did not increase in response to particular cropping phases and 2) that the stratification observed in the 2-yr rotation was consistent over time for both corn and soybean. The practice most responsible for increasing soil quality and plant performance in the LEI rotations appeared to be the deep incorporation of compost and green manures prior to corn production. This practice benefited both corn and soybean, primarily by increasing the amount and distribution of nutrients available to roots as evidenced by greater POM-C and PMN levels in the subsoil.
Issue Date:2011-08-25
Rights Information:Copyright 2011 Patricia A. Lazicki
Date Available in IDEALS:2011-08-25
Date Deposited:2011-08

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