Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/2/2003
Publication Date: 9/2/2003
Citation: Torbert III, H.A., R.D. Harmel, and K.N. Potter. 2003. Rainfall Simulation Evaluation of some P Index Criteria. 17th Annual Alabama Water Resources Conference, Orange Beach, AL, September 3-5, 2003. Interpretive Summary:
Technical Abstract: There are growing concerns regarding the fate of nutrient from land application of animal waste. In recent years, P indexes have been developed to provide information regarding nutrient loss potentials from animal wasted application methods and topography. However, in many cases, these P indexes have not been fully tested, especially in cultivated agriculture. Three factors commonly utilized in soil P indexes (including Alabama) for manure management are manure rate, manure incorporation, and soil slope. Rainfall simulations were conducted to examine the impact of these three factors on runoff losses of P on heavy clay soils under cultivated agriculture. Four manure application rates (0, 4.5, 9, and 13.5 Mg ha-1) was applied to two different soil slopes (5% and 8%) on a Heiden clay (fine, montmorillonitic, thermic Udic Chromusterts). The four application rates were also applied permanent to Bermuda grass (Cynodon dactylon (L.) Pers.) pasture on a 5% slope. The manure was surface applied to a corn production area, with or without incorporation. A rainfall simulator was used to generate water runoff for 30 minutes from a 1.5 X 2.0 m plot. Runoff samples were analyzed for runoff volume, sediment, sediment N and P, soluble NH4, NO3 and PO4. The results were analyzed using regression analysis techniques. Increased losses of NH4 and PO4 were observed with increasing manure application rate, with a significant reduction in losses observed when manure was incorporated. However, increased soil slope did not significantly impact the level of runoff losses of NH4 and PO4.