Agronomy and Horticulture Department


Date of this Version



Great Plains Soil Fertility Conference, Denver, Colorado, March 5-6, 2002, pp. 260-71


In 1999, a field experiment was established to (I) quantify and understand the yield potential of corn and soybean under irrigated conditions, (2) identify efficient crop management practices to achieve yields that approach potential levels, and (3) determine the energy use efficiency, global warming and soil C-sequestration potential of intensively managed corn systems. The experiment compares systems that represent different levels of management intensity expressed as combinations of crop rotation (continuous corn, corn-soybean), plant density (low. medium. high) and nutrient management (recommended best management vs. intensive management). Detailed measurements include soil nutrient dynamics and C balance, crop growth and development, nutrient uptake and components of yield of corn and soybean, radiation use efficiency, soil surface fluxes of greenhouse gases, root biomass, C inputs through crop residues, translocation of non-structural carbohydrates, and amount, composition and activity of the microbial biomass. Data collected from 1999 to 2001 suggest that 0) current fertilizer recommendations do not allow expression of full attainable yield, (ii) high corn yields require higher plant density (37,000 to 44,000 plants/acre) and greater N and K uptake per unit yield, (iii) existing corn growth simulation models underestimate the actual dry matter production and yield measured at near-optimum growth conditions in the field, and (iv) the potential to increase C sequestration is greatest in continuous corn systems with intensive management