Land Application Opportunities/Issues in Agriculture.

Land application of a multitude of waters is becoming a more common practice as requirements to place the water in public waters becomes more cumbersome.  The cost of treatment whether secondary or tertiary also is a hindrance that makes agricultural land application more appealing since little treatment is needed, sometimes only a clarifier.  The soil becomes the biological system that treats the water and the crop becomes the destination for the nutrients applied.  Advantages to growers are free nutrients and free water for more crop production.  The nutrient value can easily be over $1,000,000 to a farm from a single food processing plant if the nutrients were purchased, so the economic benefit to the farm can be substantial.  Land application of wastewater  has a wide assortment of concerns.  First is the irrigation system. Will it hold up and can it withstand large particles such as potato solids without degrading or clogging the nozzles?  Second is regulatory. A state agency that knows little about farming or agronomics will set nutrient loading rates and expect monitoring schedules and specifics that may or may not be scientifically sound and necessarily protective of the environment.  Nutrients can be applied to meet crop nutrient needs, but some nutrients may either not be needed by the crop or may be in excess of crop need, although they may or may not be stored in the soil.  Third is unknowns. Will there be some component that will degrade the soil or crop?  There may be unknown issues at onset that take awhile to be discovered and worked out.  Last is fresh water irrigation considerations. Some wastewater land application discharge permits in Oregon and Washington are being written with a no leach clause at the five foot level. This means fresh irrigation water is not allowed to percolate below the five foot depth to carry salts out of the root zone so salt accumulation could be a problem where rainfall is insufficient to meet the salts leaching requirements.  The quality of both the fresh water and the wastewater becomes important to make this assessment.  Properly managed and correctly practiced, land application treatment of a wide assortment of waters can be a win-win for the grower and water generator.