For those of you who may not be familiar with the term, "bro science," is when a dude (it's always a dude) makes a few casual observations about a phenomenon and then launches into sweeping generalizations he proclaims loudly, widely, and authoritatively. When Garth and I run experiments on the farm we generally refer to them as "cowbro science" because we're both well aware that with our work lives centered on taking care of animals and running a marketing/distribution business we have neither the time nor attention to develop powerful hypotheses and test them rigorously. The fact that we actually are brothers and cow handlers makes it all that much better. Gently mocking ourselves helps us keep our "findings" in perspective.
With that disclaimer in place, our longest running agricultural experiment actually shows some promise. If you're new to the blog or just skipped the boring screeds I wrote about my bamboo patch you can find the back story here, and here. The rest of this post will make more sense if you read those two old pieces first. The short version is we're trying to develop a way to save money on our grass-fed beef and grass-fed lamb operation. Cows eat a lot and feeding them is one of our big expenses. Reducing the cost of winter feeding will allow us to keep our prices as low as possible.
Last week I completely defoliated 100 square feet of bamboo. The leaves and twigs came in at 33 lbs green weight. Multiply that by 432 (the number of 100 ft sections in an acre) and the total wet yield for an acre of bamboo forage near the end of the growing season is 14,256 lbs, or about 7 tons. Of course we farmers want to compare apples to apples and the only way to do that is on a dry matter (DM) basis. I sent a sample of leaves to DairyOne for analysis right after defoliating the plants and the DM composed 47.5% of the weight I picked. So... 14,256 lbs x 0.475 = 6,771.6 lbs, or a little less than 3.5 tons/acre of actual yield.
For comparison's sake I asked my neighbor how many tons of hay he takes off his field since the soil is identical to the bamboo patch. He gets about 2.5 tons/acre of high quality hay per year.
Hay and standing bamboo forage are not precisely equivalent, but for my purposes they're close enough to draw meaningful conclusions. Both will keep my animals well fed through the winter. If I can get a roughly equivalent yield/acre/year I'll be many dollars ahead. Making hay requires diesel fuel, expensive machinery, and a lot of labor. Feeding standing forage requires an order of magnitude less capital investment (fences and water vs tractors and fuel). Strip grazing livestock requires time to set up and take down portable fences, but feeding hay does too (staging bales, cutting off the twine, giving the animals access to the bales, hauling manure if the bales are all fed in the same spot for a whole winter, etc). Between making hay and then feeding it out again the labor demand for strip grazing is many hours less than for an equivalent mass of hay. The hay my neighbor puts up has more feed value than bamboo leaves, so it has an advantage there, but because of all the other points in its favor I expect bamboo to save us a substantial amount of money over the long haul once I get a big enough stand going to support my cattle into the winter.
Over the course of this growing season I observed the bamboo stand more closely than in past years. The growth pattern of bamboo is distinctly different from the 'normal' cool season pasture grasses such as orchard, fescue, timothy, and brome growing on my farm. A typical cool season grass growth curve starts slowly in April, gradually ramping up until sometime in June, and then tapers back off. As the total mass of plant matter accumulates into summer the quality of the forage declines precipitously.
By either grazing or cutting hay a few times the growth curve can be reset and quality will remain fairly good across the entire growing season. If the field is not mowed, trampled, or bitten, mass continues to accumulate but at a slow rate and quality of feed drops to a very low point. The goal of a competent grazier (one who manages grazing animals) is to rotate his animals in such as way that they're usually eating pasture somewhere near the intersection of these two trend lines.
If I were to fallow a field for an entire growing season and then use it as stockpile it would look like this.
This field is out to the right of the end point on the lines in the schematic above. It is past the "Seed Ripe" stage of grasses. Note all the brown leaves and stems. There is plenty of biomass standing in a field like this, but there is not much worth eating even for an easy fleshing cow. The standard prescription for winter stockpiling of good quality pasture therefore is to try to graze two or three times by the middle of August and then rest as much of the farm as possible, allowing the pasture to "stockpile" for winter. Cold weather and lack of sun shut down most plant growth by mid-October in central New York, so working back about sixty days (a good middle-of-the-road amount of time to strike a balance between quality and yield) puts us around August 15th for the start of pasture stockpiling. Describing the timing of things and making it happen in anything but a perfect year are two entirely different beasts though. Rain, temperatures through the season, number of cattle, stocking rate in pounds per acre, fertilization or lack thereof, number of grazing taken during the season, and grass/legume/forb composition are all variables at play. It can be quite a challenge to get everything to line up just right, and here is where I am optimistic bamboo will make for good winter forage. Rather than flushing suddenly in the spring and then senescening into brown straw-like feed bamboo grows slowly and steadily all season long. It pushes new leaves from its twigs continuously through the growing season, building leaf mass in a nearly linear manner through the summer and fall. The newest October leaves and the oldest leaves pushed in June all go into winter looking green and nutritious. If it works it will make for a very simple management plan - graze once with sheep in the spring to stunt competing grasses and then stay off the bamboo stand all summer and fall. Once winter hits I'll simply strip graze the bamboo stand a single time. The timing is fortuitous since we run our cattle and sheep together most of the year, but separate them during lambing, which will coincide with "weeding" the bamboo stand in the spring.
Potential yield was the final large stumbling block that could have derailed this particular cowbro experiment. Now our next step is to get bamboo growing on a full acre of ground so we can figure out best management practices for how to utilize it in on our farm. Stay tuned for future updates!
-Edmund