Overview/theory

Evaluating the water quality impacts of biomass production systems will allow us to assess the potential differences in dissolved nutrient loss and associated environmental impacts among the cropping systems.  Systems with lower fertilizer input requirements and or longer periods of plant growth are expected to have lower concentrations of dissolved nutrients.  Measuring the soil moisture associated with the systems will give us the information needed to determine the potential differences in the soil water dynamics and hydrologic impact of each production system.  Systems with lower soil moisture during high rainfall periods are expected to have greater water storage, less surface runoff, and have less nutrient loss through subsurface water flow. 

Approach

Two suction lysimeters (PVC tube w/ porous cup on end at a depth of 60cm) are installed per plot.  Vacuum is applied and water samples are extracted 1-2 weeks later (depending on precipitation).  These are analyzed for NO3-N, dissolved reactive phosphorus, and DOC.  Overall, samples are taken once per month.  Two access tubes (2” PVC) are installed per plot.  Volumetric water content is measured at 20cm intervals to a depth of 1.2m once per month.  Decagon devices have been installed this year that will give us soil moisture and temperature readings at a 5 minute interval for selected treatments and landscape positions (cont. corn, switchgrass, sorghum/triticale and summit, backslope, and toeslope).