1) The document summarizes a study of sediment and nutrient loss from paddocks used for rotational grazing and winter housing of dairy cattle at Breneman Farms in Wisconsin over two years. 2) Most sediment, phosphorus, and nitrogen loss occurred during snowmelt events on frozen ground in winter and spring, primarily from one major runoff event each year. 3) Despite housing cows at higher densities in winter, losses from the farm were extremely low and well below tolerable limits, likely due to the farm's soil characteristics, gentle slopes, and perennial sod cover that aid infiltration.

1. Understanding Nutrient and Sediment Loss at Breneman Farms- 5 Sediment and Nutrient Loss From an Out-winter Paddock Area on a Grass-based Dairy Kevan Klingberg, Dennis Frame and Fred Madison UW Extension/Discovery Farms Anita Thompson, Amanda Crowe and Tim Radatz UW Madison Biological Systems Engineering

2. Breneman Farms On-farm research was conducted on the Breneman farm to investigate environmental challenges and opportunities for grass-based dairies on the Wisconsin landscape, 2002-2007. Surface water quality monitoring was conducted to measure sediment and nutrient loads in runoff water from paddocks that were used for regular rotational grazing, then again used to seasonally out-winter the dairy herd.

3. Breneman Farms Grazing-based dairy. 42 paddocks. 80 crossbred dairy cows + young stock. (1.6 acres / AU) Coarse textured soil Out-winter cows and older heifers Columbia County, WI

4. Breneman Farms Total watershed = 142.7 acres Area east of road as well as western wooded area were determined to contribute negligible runoff towards watershed outlet. Monitored acreage adjusted to 28.5 acres. Monitored area: small watershed where cattle are grazed through the season as well as out-wintered. (middle area)

5. Data The data presented in this presentation were provided by the UW – Madison Biological Systems Engineering Department, as part of a cooperative project with the UW-Discovery Farms Program.

6. Data Breneman Farms, Rio, WI: Monitored surface water runoff from October 2005 – September 2007. Field year = 12-months (Oct 1 – Sept 30) Always represents the year in which it ends. Field year coincides with the crop year.

7. 2006 Precipitation The first year October 2005 – September 2006 = overall average year. Precipitation (ice, sleet and snow) was 33.0 inches, compared to the 30-year average of 34.5 inches for Portage, Wisconsin.

9. 2007 Precipitation Second year monitoring on the Breneman farm was another average year for precipitation. Precipitation (ice, sleet and snow) was 32.4 inches, compared to the 30-year average of 34.5 inches for Portage, Wisconsin. Although the annual precipitation was average, 9 months were below average and 3 months were above average precipitation. Winter 2007 was dry again, concluding with slightly more than one half the normal precipitation. August 2007 precipitation was 4.6 inches above normal.

11. Sediment Loss Runoff and sediment loss from runoff events, 2006-2007

12. Sediment Loss, 2006 2006 had very little runoff, which means there should be very little sediment delivery: sediment loss on the out-wintering paddocks = 1.83 lbs / acre. A comparison of the runoff (either volume or depth) shows the affect of frozen and non-frozen soil conditions: The runoff on March 7 was larger than the March 9 event The total suspended sediment loss was greater in the later storm. This is most likely due to thawing of the upper soil profile. The amount of soil loss from this 28.5 acre area was extremely low and poses no threat to water quality.

13. Sediment Loss, 2007 2007 sediment loss was 58.08 lbs per acre, significantly more than in 2006. Tolerable soil loss on this farm is 4 or 5 tons / acre 8,000 – 10,000 lbs / acre Compared to 2 yr average of 30 lbs / acre for this project The majority of sediment moved during the March 10 snowmelt event (99 percent). The amount of sediment lost in the other five storms was less than 0.5 lbs per acre.

14. Sediment Loss During both years of the study, this farm had one significant runoff event that accounted for 88 percent and 99 percent of the total annual sediment loss. Both of these events corresponded with temperature-induced snowmelt on frozen ground as winter transitioned to spring. Based on several years of on-farm monitoring, the Discovery Farms Program has seen large sediment losses from a single runoff event on several farms, under a wide variety of farming systems (no-till, minimum tillage, grazing, etc.) and in all regions of the state. Soil loss produced by a single runoff event can contribute the majority of the sediment loss for the entire year.

15. Sediment Loss A comparison of the estimated soil loss (RUSLE2) to the actual soil loss: The RUSLE2 estimated soil loss for this farm was 0.04 tons per acre or about 80 lbs per acre. Actual soil loss on this farm was 1.83 lbs per acre in 2006 and 58.08 lbs per acre in 2007. (30 lbs / acre average). Based on two years of data, it is impressive how close the RUSLE2 soil loss estimate was, compared to actual soil loss.

16. Phosphorus Loss Types of phosphorus loss from runoff events 2006-2007

17. Phosphorus Loss, 2006 During the 2006 field year (October 1 – September 30), the total phosphorus (total P) loss was extremely low, amounting to 0.017 lbs per acre, as measured through field edge monitoring. About 50 percent of that phosphorus was in the particulate fraction and 50 percent was dissolved.

18. Phosphorus Loss, 2006 Percent of P loss during frozen and non-frozen ground periods, 2006, Breneman Farm Almost 90 percent of 2006 phosphorus loss ran off during the frozen ground period.

19. Phosphorus Loss, 2007 During the 2007 field year (October 1 – September 30), the total phosphorus loss was 1.25 lbs per acre. The majorityof the phosphorus ran off during the frozen ground period. About 99 percent of the total phosphorus load occurred as a result of the March 10 runoff event.

20. Phosphorus Loss, 2007 In 2007 about 90 percent of the phosphorus was in the dissolved fraction (compared to 50 percent in 2006), while the remaining 10 percent was bound to soil particles. The increase in measured dissolved P in 2007 coincides with the fact that almost all of the total phosphorus lost was during the frozen ground period when sediment losses are minimal.

21. Phosphorus Loss, 2007 Phosphorus lost in the dissolved and particulate form, 2007, Breneman farm 1.25 lbs per acre lost. 90% dissolved - 10% bound to soil particles. 99% of annual loss is result of 1 runoff event, March 10.

22. Phosphorus Loss The 2-year P loss for this project was extremely low: 0.017 lbs per acre (2006) and 1.25 lbs per acre (2007) The overall mean average loss on other Discovery Farms is about 2 lbs per acre per year (84 site years, 2003 – 2008 data ranging from 0.03 – 7.0 lbs per acre per year).

23. Nitrogen Loss Types of nitrogen loss from runoff events 2006-2007

24. Nitrogen Loss, 2006 For the 2006 field year the losses to surface waters of total nitrogen were determined to be 0.05 lbs per acre, which is an extremely low number. All of 2006 N loss was total Kjeldahl N (TKN); early March runoff. Total N is the sum of the total Kjeldahl N plus nitrite and nitrate Total Kjeldahl N is the sum of organic N sources plus ammonium

25. Nitrogen Loss, 2007 In field year 2007, total nitrogen losses reached 5.64 lbs per acre. 3 lbs per acre was in the organic form 0.26 lbs per acre was in the nitrite/nitrate form 2.36 lbs per acre ran off as ammonium. In field year 2007, nearly all of nitrogen losses occurred during the frozen-ground period.

26. Nitrogen Loss The 2-year N loss for this project was low: 0.05 lbs per acre (2006) and 5.64 lbs per acre (2007) The overall mean average loss on other Discovery Farms is about 7.2 lbs per acre per year, (84 site years, 2003 – 2008 data ranging from 0.03 – 16.0 lbs per acre per year).

27. Conclusions The majority of all runoff happened on frozen ground due to temperature-induced snow melt. The majority of sediment, P and N loss was also during the frozen ground period of February and March, and primarily a result of one single day or multi-day event.

28. Conclusions In 2006, when the winter runoff was a very small volume, and there were two growing season runoff events: annual P constituents were split evenly between sediment and dissolved P; and the majority of N constituents were Total Kjeldahl N (ammonium N + organic N). In 2007, when the winter runoff was larger and growing season runoff events were minimal: annual P constituents were 90 percent dissolved P; and N constituents were split between Total Kjeldahl N (95 percent) and nitrite / nitrate N (5 percent).

29. Conclusions Gently sloping – perennial sod cover - sandy soil characteristics of this south central Wisconsin MIG dairy enhance precipitation infiltration and minimize surface water runoff through times of non-frozen soil conditions.

30. Conclusions Soils on this MIG farm have NRCS defined tolerable soil loss values of four or five tons per acre per year. A RUSLE 2 soil loss estimate for the farm was determined to be 0.04 tons per acre per year. That soil loss estimate of 80 lbs per acre is slightly larger than the two year average monitored sediment loss of 30 lbs per acre per year. The combination of weather conditions, physical landscape characteristics and the Breneman MIG farming system led to soil loss on this farm being less than 1 percent of T.

31. Conclusions The Brenemans congregate 80 dairy cows and 40 replacement heifers (128 mixed animal units) into 2 acre out-winter paddock lots for 7-10 days, after which the animals are moved to different out-wintering sites through the winter season. The stocking rate practiced by the Brenemans (1.6 and ~ 0.5 acres per mixed animal unit for the grazing and winter seasons respectively), for their farming system, looses significantly less sediment than tolerated (T), as well as minimal amounts of phosphorus and nitrogen.

32. Information Available This presentation is the fifth in a series of seven developed to provide the data and information collected at Breneman Farms. All of the presentations, factsheets and briefs are available on the UW - Discovery Farms website. http://www.uwdiscoveryfarms.org

34. There are eight briefs available for Breneman Farms (2 page summaries of the factsheets).