1. Ron Fleming and Malcolm MacAlpine University of Guelph Ridgetown Campus, Ridgetown, ON, N0P 2C0 Paper No. CSBE08-142

2. Background NMA sets limits on spreading rates based on: Land slope Hydrologic Soil Group Application method (e.g. incorporated) Distance to surface water

3. Factors influencing runoff risk: Soil texture Soil structure Land slope Soil management Vegetative cover Soil moisture level Risk of rainfall after spreading Frost in soil Manure DM Rate of application Application method

4. Objectives Develop maximum land application rates for liquid manure. Assess the impact of post application rainfall events on runoff on different field slopes Propose maximum land application rates on pre-tilled and untilled land surfaces

5. Setup Small plots – 1 m x 1 m Different land slopes Different manure types Surface-applied manure HSG: C or D Simulated rainfall on some plots

8. Setup FactorsNumberDetails Liquid applied3Swine, dairy, water Land slope33 to 5%, 6 to 8%, > 9% Application rate346.7, 93.5 and 140.2 m 3 /ha Tillage2Un-tilled vs tilled Replications3 Total plots162

9. Site 1, un-tilled section, 2.9% slope

10. Site 1, tilled section, 2.7% slope

11. Rainfall simulation 1 in 5 year storm (25.5 mm in 30 minutes) 24 hours after manure applied On 2/3 of plots

13. Site 2, tilled section, 4.7% slope

15. Results Spreading after wheat harvest in August & September Soil: silt loam HSG: mostly C Dairy manure: 7.4% DM Swine manure: 2.5% DM

16. Site 1 - 2.8% slope Site 2 – 5.0% slope Site 3 – 15.1% slope

17. Results (cont.)

18. Average volume of runoff was highest at steepest slope (Site 3) – other 2 sites not significantly different Average volume of runoff higher for swine manure than for dairy manure

19. Runoff volume – all plots – median & 95% confidence intervals

20. Results (cont.) 140 m 3 /ha resulted in significantly more runoff than lower two rates (97 & 47 m 3 /ha) Applic. rate 140 m 3 /ha; runoff = 963 mL Applic. rate 94 m 3 /ha; runoff = 253 mL Applic. rate 47 m 3 /ha; runoff = 97 mL

21. Results (cont.) Pre-tillage did not lead to a “significant” reduction in the volume of liquid runoff Mean runoff - tilled sites was 309 mL Mean runoff - un-tilled sites was 523 mL Similar for individual sites, for individual liquids and for each application rate Impact of vegetative cover?

24. Results (cont.) After simulated rainfall, Runoff Volume: Influenced by site (more at Site 2), but not by slope Influenced by liquid application rate – the higher the initial rate, the more rainfall runoff Not influenced by initial liquid applied

25. Conclusions Lowest application rate met NMA standards in all cases and highest rate exceeded in all cases Lots of variability in runoff No runoff on 25% of plots Runoff highest for steepest slope (15.1%)

26. Conclusions More runoff for Swine manure (DM=2.5%) than Dairy manure (DM=7.4%) Nutrients in runoff similar to applied liquid Following simulated rainfall, nutrients in runoff much lower than initial liquids

27. This year Slope Plots 1 m wide by 4 m long – manure on 3 m length

28. Funding Ontario Ministry of Agriculture, Food & Rural Affairs – Nutrient Management Research Program

29. Questions