Crop Productivity and Soil Resilience Observed On Short-Term Corn Stover or Cob Harvest On Several Northern Soils.

Highly productive soils are found throughout the US Corn Belt in part due to their inherently high soil organic matter. Their productivity contributes to the high corn grain and stover yields; hence, this crop residue is predicted to be a significant bioenergy feedstock within this region. The objective of this study is to assess short-term impact of harvesting corn stover or corn cobs. It contributes to on-going research, which is seeking to answer the question “How much biomass can be sustainably harvested from a given field and still maintain soil productivity?” Three plot-scale on-farm trials in corn-based rotations (corn-soybean on clay loam; corn-soybean-wheat on clay loam and corn-edible bean sandy loam soils) were established in west central MN to augment existing plots located at the Swan Lake Research Farm. Baseline soil C, pH, N, P, and K were determined at the beginning of the experiments. Crop yield was monitored annually following one-pass cob or stover harvest operation. Aggregate size distribution was measured by rotary sieve as an indicator of resilience to erosion. One cycle of stover or cob harvest had little or no impact on corn, soybean, edible bean or wheat yield in on-farm trials.  Likewise, three cycles of harvesting corn stover at the experimental site with a corn-soybean rotation did not substantially impact yield.  However, after three-harvest cycles, aggregate size distribution shifted toward smaller aggregates that are less resilient to erosion at the expense of larger aggregates. Results suggest short-term resilience of productivity does not predict long-term sustainability.

REAP publication