|Van Kempen, Stephen|
Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 10/1/2004
Publication Date: 10/1/2004
Citation: Jaradat, A.A., Archer, D.W., Johnson, J.M., Van Kempen, S.J., Wagner, S.W., Eklund, J.J. 2004. Pattern and factor analyses of diverse plant and yield attributes' responses to alternative crop rotations and management practices. In: Proceedings of the 4th International Crop Science Congress, September 26-October 1, 2004, Brisbane, Australia. 2004 CDROM.
Technical Abstract: Research is needed in the upper Midwestern USA to identify cropping systems that simultaneously improve the economic and social viability of farms and decrease reliance on external inputs while protecting the environment and improving the natural resource base. The objective of this research was to map initial soil and crop yield variability, quantify patterns of spatial yield variability in cropping systems in response to increased crop diversity and contrasting management practices and determine optimum levels of spatio-temporal sampling and sub-sampling of plant, crop, soil and environmental variables. All phases of a two-year (corn-soybean) and a four-year (corn-soybean-wheat/alfalfa-alfalfa) crop rotation were established in 2002 on 192 geo-referenced plots in a randomized complete block design. Two levels each of three management factors (organic and inorganic systems, conventional and strip tillage with or without the recommended nitrogen fertilizer rates for each crop) were randomized. Three factors (F1, F2 and F3) explained 49.2% of total variation in forty-two soil chemical, physical and biological variables estimated on soil samples from all 192 plots. Total yield in 2002 and 2003 were negatively correlated (r=-0.37, P<0.05) and yield variance in 2003 was 79% of its initial value in 2002. Variance components of all two- and three-way interactions were significant (P<0.05) in 2003; however, in 2002 significant interactions were limited to tillage x fertility and system x fertility. In 2003 system x tillage accounted for 52% (P<0.05) of total variance in corn yield, system x tillage x fertility accounted for 33% (P<0.05) of total variance in soybean yield and fertility accounted for 40% (P<0.05) of variance in wheat yield. Crop-specific two-factor structures were found among tillage, fertility, systems, F1, F2 and F3 and explained 36.0, 38.1 and 49.5% of total variation in corn, soybeans and wheat yield, respectively. Yield based on sub-samples was positively and significantly (P<0.05) correlated with whole plot yield in wheat (r=0.42), soybeans (r=0.51), alfalfa (r=0.57) and corn (r=0.87). Multiple regression analysis indicated that two to three sub-samplings and growth monitoring past the 200 Julian date and a final sub-sample at harvest generated adequate data (R**2=0.75-0.83) to create a detailed spatio-temporal map of the experimental site, plant development and crop yield in a single cropping season. Future sub-sampling and monitoring will be refined to account for the dynamic effects of major factors and their interactions on plant growth and development, and on crop yield and yield components.