In January 2013 there was a Manure Management Update Conference in Lethbridge. I did not attend, but with the wonders of modern technology have reviewed PowerPoint presentations of the talks. It’s not as good as being there, but much better than reading the proceedings.
The value of manure
First, let’s go back more than 100 years.
In 1910, A. D. Hall, second director of the famous Rothamsted Agricultural Research Farm in jolly old England wrote: “The provisions of the “Agricultural Holdings Act” of 1900 award the tenant compensation for any unexhausted fertility he has brought to and leaves behind on the holding.” They derived a table of values for compensation based on the feedstuffs used.
Research from Rothamsted had already shown that barley yields were still double the control 30 years after manure application stopped. They had shown this with “exhaustion” experiments. They cropped the land with no further manure to see the rate at which the soil was depleted of nutrients and observe the consequent yield decline.
Early work at AAFC research stations on the Prairies showed farmyard manure to be a slow starter, but to provide long lasting effects if applied for years.
Now fast forward to the AAFC research station in Lethbridge in 1973. Theron Sommerfeldt set up long term manure experiments using modern feedlot manure with little bedding — good stuff from a nutrient standpoint. They started by applying manure at wet weight rates of 12, 24 and 36 tonnes/acre on an annual basis, double that for irrigated land. After only 12 years it was obvious that those rates were too high. Recommended rates were reduced.
Fast forward again to Lethbridge — this time to 2013, to see current data on manure management and soil fertility after long term feedlot manure application. In southern Alberta there are fields that test 300 parts per million of soil test phosphorus in the top 6 inches.
And now for some math
- 300 ppm P = 300 x 2.29 = 687 pounds of P2O5 (see sidebar)
- 687 pounds P2O5 = 1,321 lb./ac. of 11-52-0 fertilizer.
- With a fertilizer price of $725/tonne, that equals $434/acre.
That is a lot of unexpended manure.
In the future we must find ways to make better use of that valuable resource.
When the numbers get that high the soil is indeed very fertile but the potential environmental liabilities can be real and significant.
Now, 300 ppm is on the high end and I’m not sure how many fields test that high. But even if you divide that measurement by three, it’s still a big number.
Livestock folks getting short end of the stick
For decades we have thought of manure as a waste product to be disposed of. Dirt farmers think we are giving the cowboys a break by letting them dispose of their waste on our land. This old dirt farmer thinks it is time for change.
When pollution and environmental concerns were first talked about in the 1970s a buzz phrase was “the solution to pollution is dilution.”
When it comes to manure that is true in spades — not only for the reduced environmental risk but also for the enhanced agronomic and economic benefit.
Frank Larney has done years of work on manure composting at Lethbridge AAFC. Composting feedlot manure about doubles the concentration of nitrogen and phosphorus. In theory, that would double the distance manure could be hauled. But it will take more than that to make it work.
Monster trucks may help, that will but still fall short of the real need and roads may be a problem.
On the Prairies about one third to one half of farmers use manure, but that manure is only applied to about five per cent of acres.
The economics of the nutrient value of manure must be based on a longer term analyses of the benefits. There has been lots of manure research in Western Canada in the past 20 years — both the agronomic benefits and environmental challenges have been examined. But, as far as I know the “exhaustion” experiments that were conducted in the U.K. 100 years ago have not been done here. And, we cannot wait 30 years for the results.
So, the manure research folks need to take a look at all available data and interpret it in terms of decades not years. In the case of phosphorus it should be possible. This old scribe has said for years “phosphorus fertilizer is an investment in the land.” Phosphorus from manure is the same.
The University of Saskatchewan has a small research feedlot hanging over the South Saskatchewan River north of campus. It has been there for 40 years and has left a very small environmental footprint but many want to see it moved.
If and when a move does happen it is my opinion that the major research thrust should be what comes out the back of the animal. The focus should be how the manure can be treated or handled to allow the good news (nutrients) to be spread around to more of our large land base. About 80 per cent of Saskatchewan farmland is deficient in phosphorus. We have dribbled on a one year supply — or less — every year for the past 50 years. Even in livestock rich Alberta and Manitoba over half the land is also deficient in phosphorus.
We need some new and innovative thinking. We need a way to do what the Brits did 100 years ago and devise a schedule of payments for “unexpended manure.”