Update: Thesis and presentation posted for download June 2nd, 2008, adding extension articles as I find them.

A little different than the regular travel stuff on my website, this page covers what I have been studying for the last few years.

This project compares the conventional Canadian method of winter feeding of cattle in pens and then scraping up and spreading manure by machine, to feeding cattle hay directly on the pasture and letting them spread their manure themselves.

What was found was large gains in soil and forage nutrient capture by the feeding on pasture method.

A hundred and four lbs/acre (117 kg/ha) of inorganic soil nitrogen was gained on the winterfeeding sites compared to the check, with areas ranging as high as 550 lbs/acre.
Nothing was gained where manure or compost was spread.

Forage was then harvested for the next year and a half on the pasture, and the nutrients extracted by the grass were measured.
In a year and a half the grass extracted approximately 177 lbs/acre (200 kg/ha) of extra nitrogen from the winterfeeding site, approximately doubling what was found in the soil test. Only 25 lbs/acre extra was extracted by the grass where compost was spread, and 19 from the raw manure treatment.

The efficiency of nutrient capture after a year and a half of harvesting was calculated as 34% of the nitrogen hauled onto the winterfeeding sites in feed and bedding, or 38% of that excreted by the animals. Phosphorus was 22 and 26%. These figures approach or exceed that found in forage trials with the application of commercial fertilizer.

Efficiency of recovery of the spread manure nutrients was calculated as 1% of the nitrogen hauled to the drylot animals in feed and bedding. Phosphorus recovery was calculated as 3%.

These findings boil down to large potential gains in nutrient efficiency (free fertilizer) and better pasture growth for cattle producers by winterfeeding their cattle directly on pasture, with the added benefit of not having to haul manure and much reduced fuel use/machinery time.

Various articles on this project are up on the net already, but the whole thesis and Powerpoint presentation are now posted here.

How does the rate of manure spread by the cattle compare to that spread by machinery?

A: The cattle were calculated to spread about half the weight of manure and bedding that was spread on the raw manure strips, or approx 15 tons/acre at equivalent moisture. I had calculated originally for the cattle to spread the same 30 tons/acre as was spread by machine, but had neglected to adjust for the much lower dry matter content of manure direct from the cow.
 

Why is feeding cattle in a corral/drylot appear to be such an inefficient way to cycle nutrients?

A: There is a number of reasons for this:

1) There are a lot of nutrients in cattle feed. Each round bale of hay (1384 lbs or 628 kg) we fed contained approx. 27 lbs (12 kg) of nitrogen, 3 lbs (1 kg) of phosphorus, and 25 lbs (11 kg) of potassium.

2) Cattle don't retain a lot of nutrients in their feed. Figures vary somewhat, but seem to be in the 10% range for nitrogen, 15% for potassium, and 20% for phosphorus.

3) Nitrogen is expelled by the animal mostly in the urine, not in the dung. And the urine form is 90% urea. This urea is the same stuff sold in commercial fertilizer dealers as 46-0-0. The nitrogen component of synthetic urine used in testing is made by mixing laboratory grade 46-0-0 in a bucket of water. Cattle can therefore be looked at as liquid nitrogen fertilizer factories.

4) Drylots (corrals, pens) concentrate cattle and therefore, nutrients. The animals in the drylot pens used were kept at 21 X the density of the animals fed on the pasture.

All these factors result in huge amounts of nutrients expelled by the cattle in the small area of the drylot, for example 6003 lbs/acre (6728 kg/ha) of nitrogen in the form of liquid urea fertilizer. That's a lot of fertilizer nitrogen to simply pour on the ground.

Other research has shown that this high concentration of urea nitrogen simply gases off into the atmosphere. In effect a drylot is a big evaporation pan for nitrogen, and what is left to be hauled off is the 'hard' nitrogen that is left over, and unfortunately not much good for plant growth.

Will feeding on pasture automatically make give me lots of extra forage?

A: No, while it supplies lots of immediately available fertilizer nutrients (from the urine), slow release fertilizer nutrients (from the feed residue and manure), and thatch for moisture conservation and grazing animal urine nitrogen capture, the response of the forage still depends on good pasture management such as rotational grazing, not letting the cattle 'punch out' the field in the spring thaw, etc. And of course without rainfall nothing will grow.

How was the overall recovery of nutrients in the drylot system calculated?

While the nutrient recovery on the winter feeding sites was easy to work out (nutrient amount in feed and bedding minus amount measured in the grass additional to the check), working out the cycle for the drylot system was more difficult, as the losses in the pens were not measured, so the efficiency loss measured out in the pasture on the spread manure and compost treatments only told part of the total nutrient loss story from the drylot systems.

Therefore literature figures for pen losses (and in the case of composting, additional losses from the composting process) were combined with the recovery percentages measured from the spread manure and compost.

For nitrogen I used a literature figure of 13% removal of excreted nitrogen from cattle pens ( Bierman et al. 1999) multiplied by the recovery rate of 5 to 9% of N found in the pasture in this trial. Compost had an additional literature loss of 33% of N (Larney et al. 2006).

For phosphorus I used a literature figure of 90% removal of excreted P (Kissinger et al. 2005) multiplied by a 3 to 5% capture rate in the pasture. Compost had an additional literature loss of 18% (Larney et al. 2006).

Overwintering of cows is a major cost in a cow-calf production system on the prairies. Winter feeding hay and straw directly on pasture is a potentially more efficient and economical system compared to conventional drylot feeding in a yard. The objectives of the research described in this thesis were to compare winter feeding cattle directly on pasture to traditional drylot over-wintering of cattle and the associated mechanized spreading of manure on pasture. This trial compared the effects of winter feeding systems on pasture nutrient distribution, nutrient recovery in soil and forage, pasture forage response, cattle performance, and economics.

The experiment was conducted at Lanigan, SK, on an old russian wildrye grass pasture. Pasture nutrient levels and distribution were measured before and after winter feeding, as well as forage yield, and cattle weight and condition. Nutrient capture and cycling was assessed along with the economics of the different systems. In the pasture fed systems, cattle were fed by either bale processing or bale grazing methods over the winter of 2003-2004. Cattle concentration was 2080 cow-days ha-1, with the cattle in the field for 130 d. In the intensive system used for comparison, cattle were fed in a drylot and 67 tonnes ha-1 of raw manure or 22 tonnes ha-1 of compost was mechanically spread on the pasture in the fall of 2003.

Soil inorganic nitrogen (N) levels (0-15 cm) measured in the spring where the cattle were winter fed on pasture were 3 to 4 times the unfertilized, unmanured control treatment, with a mean gain of 117 kg N ha-1. Soil inorganic N was not significantly elevated where manure or compost had been spread by machine. Soil extractable potassium (K) was doubled on the winter feeding sites, with a mean gain of 1209 kg K ha-1. Soil extractable K did not increase where manure or compost had been spread mechanically. Soil distribution patterns of both nutrients were highly uneven following pasture feeding, with levels of inorganic soil N ranging from 12 to 626 kg ha-1 and extractable soil K ranging from 718 to 6326 kg ha-1. Additional nutrients in surface residue from uneaten feed, bedding, and manure were also heavy and variable following pasture feeding. Greater retention of N and K from urine added directly to the soil in the field in the bale grazing and bale processing systems compared to the drylot system is believed to be responsible for high soil available N and K levels compared to manure hauled from the drylot into the field.

Soil extractable phosphorus (P) levels (0-15 cm) were measured in the fall of 2005. The compost treatment had the largest increase at 2.6 times the control, an additional 46 kg ha-1. Mean soil P levels did not increase significantly where the cattle were wintered.

Over 18 months and 3 harvests, forage dry matter yields where the cattle were fed on pasture were 3 to 5 times the control where the cattle were fed on the pasture, and 1.4 to 1.7 times the control where raw manure or compost was mechanically spread. Also, protein content of the forage was increased to a greater extent in the in-field feeding compared to hauled raw manure or compost, reflecting a greater conservation of N.

The gain of N in the forage over 18 months on the winter feeding sites was 200 kg ha-1 of N, almost double what was measured in soil inorganic forms. Fourteen kg ha-1 of P was also recovered. This represented 34% of original feed N and 22% of original feed P that was imported into the field. Recovery of nutrients applied in the raw manure and compost sites was much lower, with only 7% recovery of N and 4% recovery of P in the forage. This was calculated to be 1% of original feed N and 3% of original feed P.

The system by which the cattle were overwintered had little influence on cattle weight and condition. All systems performed favorably in maintaining body weight and condition over the winter. Some slight advantages in cattle weight gain and condition were found on the winter feeding systems compared to the in-yard drylot that appeared to be related to slightly increased feed intake.

Economic calculations favored winter feeding directly on the pasture by 25% over the drylot systems when the feed value of additional pasture growth over 18 months was included and by 56% when the value of additional soil nutrients was factored in. Feed costs were similar between the systems but pasture feeding had savings in machinery use, fuel consumption and manure handling costs, and gains in pasture productivity.

My defense was carried out on May 2nd, 2008, and went well. Revisions were minor and the completed thesis was converted to pdf and posted as a download on the university website here: Thesis 1.5 MB pdf . For those who prefer pictures I converted the defense powerpoint to pdf as well and have it as a 7mb download here:  Defense presentation 7 MB pdf . If the presentation pictures are sideways in your viewer 'View - Rotate View' will turn them correctly in Acrobat or Foxit.

Note, for those from North America accustomed to standard measurements, this thesis and presentation was done entirely in metric, as per the scientific standard. Luckily kg/ha is very close to lbs/acre, only slightly higher. To convert from kg/ha to lbs/ac multiply by .8922.

Powell, J.M., F.N. Ikpe, Z.C. Somdas, and S. Fernandez-Rivera. 1998. Urine effects on soil chemical properties and the impact of urine and dung on pearl millet yield. Exp. Agric. 34:259-276.
Excellent trial from Africa, the only other one I know of that directly compares feeding cattle directly on pasture with feeding in a drylot and spreading manure with machinery.

Griffin, G. 1997. Effect on water quality, soil fertility, and subsequent forage yield as a result of wintering cows on a forage stand. [Online]. Available at http://h1.ripway.com/Paul%20Jungnitsch/Griffin1997Bale-grazingsoilnutrientsforagegrowth.pdf  (accessed 12 Sept 2003; verified 02 June 2008). North Peace Forage Association, Fairview, AB. Farming for the Future Report No. 1997a; 7pp. Download here:  Griffin Bale Grazing 0.8 MB pdf

Lenehan, N.A., J.M. DeRouchey, T.T. Marston, and G.L. Marchin. 2005. Concentrations of fecal bacteria and nutrients in soil surrounding round bale feeding sites. J. Anim. Sci. 83:1673-9.

Owens, L.B., R.W. Van Keuren, and W.M. Edwards. 1982a. Environmental effects  of a medium-fertility 12-month pasture program: I. hydrology and soil loss. J. Environ. Qual. 11:236-240.

Owens, L.B., R.W. Van Keuren, and W.M. Edwards. 1982b. Environmental effects  of a medium-fertility 12-month pasture program: II nitrogen. J. Environ. Qual. 11:241-246.

Owens, L.B., R.W. Van Keuren, and W.M. Edwards. 2003. Non-nitrogen nutrient inputs and outputs for fertilized pastures in silt loam soils in four small Ohio watersheds. Agric. Ecosyst. Environ. 97:117-130.

Dixon, J.E., G.R. Stephenson, A.J. Lingg, D.V. Naylor, and D.D. Hinman. 1981. Stocking rate influence upon pollutant losses from land wintering rangeland cattle: a preliminary study. p. 261-264. In Livestock Waste, a Renewable Resource. Proc. 4th Int. Symposium on Livestock Wastes, 15-17 Apr. 1980. Am. Soc. Ag. Eng. St Joseph, MI.

Saskatchewan Ministry of Agriculture. 2008. Bale Grazing and the Bale Grazing Calculator. Download here:  Bale Grazing and the Bale Grazing Calculator 1.5 MB pdf . View as a web page  here , download the Excel calculator from here . In-depth article, lots of info and pictures.

Manitoba Agriculture, Food, and Rural Initiatives, Agriculture and Agrifood Canada, and Manitoba Forage Council. 2008. The Basics and Benefits of Bale Grazing. Download here:  Bale Grazing Basics and Benefits 0.2 MB pdf
Well thought out recommendations using the latest knowledge of bale grazing practices.

Angus Beef Bulletin. 2007. Bale-grazing: less work, better return. Download here:   Bale-Grazing: Less Work, Better Return 1.5 MB pdf . Article on Neil and Barbara Dennis's operation in Wawota, SK, bale grazing 800 animals on 1843 acres.

Livestock and Forage Group of the Agricultural Research and Extension Council of Alberta (ARECA). 2006. Year Round Grazing Handbook. Download here:  Year Round Grazing 0.9 MB pdf .
Excellent workbook that looks at all aspects of winter feeding cattle in the field, including details from the operations of 5 farmers in Alberta.