Effect of pH Levels of VFS Soil on Reducing Transport of Soluble Nutrients from Manure Borne Runoff

Abstract

Low efficacy of vegetative filter strips (VFS) in reducing soluble nutrients has been reported in many research articles. It is known that solubility of phosphorus and nitrogen compounds is largely affected by pH of soil. Changing in soil pH thereby changing nutrients solubility may result in decrease in their transportation through VFSs. A study was conducted to evaluate the effect of pH levels of VFS soil on soluble nutrients transport reduction from manure borne runoff. Soil was treated with calcium carbonate to change the pH at different levels. Soil with different pH levels was packed into galvanized metal boxes that were 2.44 m long, 0.50 m wide, and 0.25 m deep. Tall fescue grasses were established in the boxes to simulate the vegetative filter strips. Boxes were placed in an open environment and tilted to a 3% slope. Simulated runoff solution was prepared by diluting fresh manure to tap water. Runoff simulation was conducted by flowing simulated runoff solution through the VFS by a peristaltic pump at 1.45 liter per minute. Water samples were collected at the inlet and outlet as well as from the leachate. Collected samples were analyzed for total Phosphorus, ortho-phosphorus, ammonium nitrogen, nitrate+nitrite nitrogen, and total Kjeldahl nitrogen. Results and discussion on the filter strips performance will be presented in this paper.