Agroecosystems Lab

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Development and Implementation of Ricefield Management Practices to Improve Water Quality

Background and Methods: Rice production in the Sacramento Valley has led to some concerns in water and air quality. Field management changes include the incorporation of straw residue, over winter flooding of rice fields, and new crop establishment methods. The impact of these practices on water quality is not known. Nitrogen, phosphorus, and organic carbon losses to surface waters can lead to degradation of surface water quality, alteration of surface water ecosystems, and negative interactions with water treatment practices for public consumption. Both plot level and field level experimental sties will be used in this study. Plot studies will be set up at the Rice Experiment Station to evaluate the effects of alternative crop establishment methods (to control herbicide resistant weeds) on water quality. On-farm research will be conducted throughout the Sacramento Valley to evaluate the effects of straw incorporation (burn vs. incorporation) on water quality.

Objectives: The primary objective will be to determine the concentration and load of various solutes in drain waters coming from rice fields throughout the year as impacted by various crop establishment methods and straw management practices. Among these management practices we will determine, from plot and field level outflows: (1) the concentration and amount of total carbon (organic and inorganic), dissolved carbon (organic and inorganic), nitrogen (nitrate and ammonium), orthophosphate (total and dissolved), potassium, and copper; (2) water chemical, physical, and biological properties such as dissolved oxygen levels, total dissolved solids, electrical conductivity, turbidity, and ecoli concentrations; and (3) pesticide concentrations and loads (plot level only). Solute concentrations and water properties will also be determined on the peripheral drains upstream and downstream of the ricefield water.

Outcomes: Based on these studies, best management practices (BMP) will be developed for California rice growers which will reduce the outflow of soil nutrients and environmental contaminants from rice fields while controlling weeds and invertebrate populations.