Submitted to: Humic Science and Technology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 3/14/2012
Publication Date: N/A
Technical Abstract: The benefit to corn production of a humic product derived from lignite was evaluated for three years under otherwise conventional crop management in Iowa farmers’ fields. Humic material was applied as a liquid extract at a rate of 3 pints acre-1 (0.57 L ha-1), generally as a foliar spray along with routine pesticide applications during early growth stages of corn. In all three years, hand-sampled corn plants collected at physiological maturity in 30 to 35 farmers’ fields across Iowa showed a significant increase in grain weight with product application in 70 to 80% of the fields, covering a range of soil types and grain yield levels. Mean increases were 10-15 bushels acre-1 (630-940 kg ha-1), and these were inflated, as expected, compared to a limited number of yield increases estimated by mechanical combine, typically 5-10 bushels acre-1 (310-630 kg ha-1), or about 5% of normal yield levels. Grain weight increases were associated with slightly larger stover biomass and larger cobs. Plant nutrient concentrations were not affected at harvest. In-season measurements in a few intensively monitored farmers’ fields associated product application with slightly taller plants, increased leaf area, earlier onset of pollination, extended grain filling, and delayed senescence, i.e. extended duration of photosynthesis and decayed rotting of stems. Limited visual observations indicated great proliferation of roots, especially lateral roots. Initial studies of alfalfa (Medicago sativa L.) found biomass increases with product application of 7-29%. In general the humic product increased economic yield in a large majority of cases by amounts that were agronomically marginal but economically significant.