Does soil resource spatial heterogeneity influence plantgrowth?

Loecke, T. and G.P. Robertson

Presented at the All Scientist Meeting (2004-10-08 )

Agronomic soil nutrient management typically supplies plants with a spatially homogeneous distribution of soil nutrients at both the field scale and the individual plant scale.  Recent advances in spatially explicit nutrient management practices, e.g. fertilizer banding and precision application have led to increased nutrient use efficiencies.  Are there potential benefits from managing plant residues in a spatial explicit manner?  This would have particular significance in organic based cropping systems. To address this question we have initiated two greenhouse experiments: 1) to determine if the spatial distribution of decomposing plant residues at the scale of an individual plant influences plant growth and nutrient acquisition, and 2) to evaluate whether roots differentially proliferate in patches of residues of varying quality.  Root proliferation, the selective growth of roots into areas of high resource availability, is thought to be important for plants in heterogeneous soil environments, where proliferation may provide a competitive advantage. In experiment 2, we are testing the hypothesis that root proliferation will be proportional to the benefit from each residue type.  Primarily data suggest the distribution of plant residues influences corn and annual sunflower growth to a greater extent than that of smooth brome, giant foxtail, or little bluestem. 

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