The Effect of Compost Application and Plowing on Phosphorus Runoff Charles S. Wortmann Department of Agronomy and Horticulture Nutrient Management for Soil Productivity and Water Quality Protection

Phosphorus in fresh surface waters  P is often most limiting nutrient to the growth of aquatic vegetation  Agricultural land is a major source of P ♦Greater losses with high soil test P, e.g. where much manure has been applied ♦Manure P excretion is increasing as diet P increases due to feeding by-products

 Several field factors affect P loss ♦Site factors, e.g. soil test P and P application ♦Transport factors, e.g., erosion and runoff  Relative importance of total P vs. dissolved P entering waters ♦Aquatic vegetation uses dissolved P ♦Much runoff P is not dissolved P, but may become available with time ♦Need to be concerned about total P loss Phosphorus in fresh surface waters

Research at the UNL – ARDC

Objectives Determine the effects on management practices on runoff, sediment loss, and P loss  During the years of application,  The residual effects during 2001 to 2004  Residual effects during 2004 to 05 and effect of plowing extremely high P soil  Residual effects of and effects of vegetative barriers

Effects during the years of application  Composted feedlot manure was applied annually for 3 years to meet the N need of irrigated corn  Two compost types were used ♦Low P compost: 670 lb/A P applied ♦High P compost: 1025 lb/A P applied  The plots were disked

Compost effect on soil test P (Bray-P1) Depth, inches Hi-P compost Lo-P compost No compost

Results: Runoff and erosion, Runoff volume and sediment loss were greatly reduced by compost application during the years of application.

Runoff and erosion: The residual effect of compost applied 1-3 yr previously was reduced runoff and sediment loss.

Runoff and erosion:  The residual effect of compost at 4 – 5 yr after application ♦Slightly reduced runoff ♦Greatly reduced erosion  The effect of plowing ♦Reduced runoff ♦Slight increase in sediment loss

P loss during years of application: ‘99-01 Compost application 1.P concentration in runoff much higher. 2.P loss was increased.

Runoff P concentrations were very high 1-3 yr following compost application.

Runoff P loss was greater with compost applied, but not so much given the difference in soil test P.

 Soil P levels remained very high where compost had been applied 4 years before  Plowing greatly reduced P at the soil surface.

P loss  The residual effect of compost at 4 – 5 yr after application ♦Much more dissolved P loss ♦About 100% more total P loss  The effect of plowing ♦Greatly reduced dissolved and total P loss

Phase IV,  Continued study of residual effects  Vegetative filter strips occupying 1 or 4% of the plot area

Summary  Effects of composted manure application persisted during, and for 5 years after, application ♦Greatly increased soil test P ♦Increased runoff P concentration ♦Reduced volume of runoff and erosion ♦Increased runoff P loss

Summary  Runoff P loss was more affected by change in erosion and runoff rates compared to soil test P  Excessive amounts of P can be applied with little loss if there is little erosion and runoff.

Summary  Plowing soil with excessively high surface P reduced ♦runoff with no increase in erosion ♦P concentration in runoff, and ♦P loss. ♦However, erosion needs to be prevented.  Well-placed vegetative filter strips occupying 1% of the land area are reducing runoff and P loss

P index development  A comparison of 5 PIs from the Midwest.  Differences evaluated considering research results  J. Soil Water Conserv.  Developed P index for Nebraska together with NRCS

Site/management factors  Soil P levels  P application practices: time, rate and method of application  Management practices such as tillage, cover crops, conservation practices, etc. Transport factors  Runoff  Erosion: rainfall, snowmelt and irrigation  Distance from center of ‘field’ to a stream, water body, etc. Erosion > runoff >> soil test P > Erosion > runoff >> soil test P > distance to water body if within 300 ft > P application practice

Results from Nebraska P Index: scores and ratings Erosion rate, t/A Soil Bray-1 P, ppm , L1.2, L2.1, M3.7, M

Results from Nebraska P Index: scores and ratings Erosion rate, t/A Soil Bray-1 P, ppm , L1.2, L2.1, M3.7, M 82.4, M3.7, M6.0, H10.1, H

Results from Nebraska P Index: scores and ratings Erosion rate, t/A Soil Bray-1 P, ppm , L1.2, L2.1, M3.7, M 82.4, M3.7, M6.0, H10.1, H 164.7, M7.0, H11.3, H18.4, VH

Erosion calculator Erosion (t/ac) = 12.5* LU * CP * ((K– 0.32)* )/.32 * SF * R/135 * T * I LU = Land use CP = Conservation practice K = Soil erodibility SF = Intermediate slope factor R = County rainfall factor T = Tillage factor I = Irrigation

Reducing Risk of Phosphorus Pollution of Surface Waters in Crop-Ethanol- Livestock Ecosystems of the Midwest C. Wortmann C. Shapiro, D. Tarkalson, Dept. Agronomy & Horticulture H. Nourdenni, Chemical Engineering G. Erickson, Animal Science T. Franti, D. Schulte, Bio-systems Engineering D. Jose, Agricultural Economics K. Brunkhorst, Nebr. Corn Board USDA-CSRESS Managed Ecosystems/Nebraska Corn Board

P reduction project: feeding beef a ration of 40% bi-products results in 100% more P excretion (and >75% more NH3 volatilization)

P removal from ethanol stream Steep water, 84% water, 2.7% P Dry germ, 5% water, 0.3% P Corn fiber, 11% water, <0.1 % P Glute n- starch mix, 73% water, 0.2% P SEP, 10% wate r, 0.7% P

Composting vs. stock-piling feedlot manure  Development of decision guide  Research on bulk reduction and N loss with composting

Effect of vegetative buffers on P runoff

Setback distance ….  Effect of non-application (setback) distance to concentrated water flow.

Watersheds: GIS and stakeholders  Linking GIS, watershed model, and index tools with local knowledge ♦Develop BMP targeting criteria for producers/ advisors for pollutants ♦GIS linked with simple tools (e.g. RUSLE1, modified P index) for use at field level with producers/stakeholders

Heartland Regional Water  Use

Our Heartland approach  Focus areas ♦2004 P management ♦2005: N management ♦2006: Pesticide management ♦2007: Targeting the application of BMPs in landscapes  Activities ♦Regional research roundtable ♦Regional training workshop ♦Develop or enhance extension resources  Extension circulars  Web site  On-line lessons  In-state training activities

Heartland ….

2007 Heartland NPM Workshop  Targeting the application of BMPs in landscapes  June 5-7 in Nebraska City

nrcs.usda.gov