Vegetation in Runoff Ditches Reduce Contaminates

Many growers view weeds in their irrigation ditches as a problem to be solved.  Mowing or spraying the weeds to keep ditches clean and obstruction free is the general practice.  You obviously want water to clear out of an area or the ditches wouldn't be there in the first place.  Here is an article that just might change your mind and possibly even save you some money in ditch vegetation management and create a cleaner environment. 

In an article by the Agriculture Research Service from the USDA,  entitled "Drainage Ditch Research Reveals Opportunities for Cleaning Up Runoff" (published in the January 2013 issue of Agricultural Research magazine), research was conducted by Matt Moore on contaminates of atrazine, lambda-cyhalothrin and their movement in irrigation ditches.  In one study he found that after one hour, ditch vegetation in a 160 foot section of ditch had removed 61% of the atrazine and 87% of the lambda-cyhalothrin to non-toxic levels at the end of the ditch.  In another study of lambda-cyhalothrin and bifenthrin, (both pyrethroid pesticides).  In only 3 hours 96 percent of the lambda-cyhalothrin and 99 percent of the bifenthrin were captured by the ditch vegetation.

This has also been proven for nutrients such as phosphorous and nitrogen.  Ditch shape and the vegetation that grows there will make a difference in what gets absorbed.  The amount of time in the ditch and the length of the ditch will be factors to consider as well. 

To read more about some of the findings on this and other studies about pesticides and nutrients moving from fields into ditches you can click on the full article here.    http://www.ars.usda.gov/is/AR/archive/jan13/ditch0113.htm