Agroforesty/Includes pig production ideas

Some interesting math…

The yield of mulberries from references seems to be quite variable with an average of 9 tons per acre. Seems impressive, but it’s wet food. The calorie content is 43 Kcal per 100 grams, which comes out to be 3520 megacalories per acre. 2136 lbs of corn would yield the same number of calories. The mulberries have 1.44% protein, which doesn’t seem impressive until you take into account the amount of feed that is consumed to satisfy caloric needs. It would come out to the equivalent of corn with 12% protein. Figuring about 1000 lbs of corn to raise a hog, the stocking rate would likely be something like 2 hogs per acre.

The yield of walnuts from commercial farms is easier to find, they target 5 tons per acre. Quite impressive, but about half is shell and commercial farms would likely push harder than small organic people would, so I’ll figure 2 tons walnuts per acre is a reasonable goal. The calorie content of walnuts is 654 Kcal per 100 grams, which comes out to be 11890 megacalories per acre. It would take 7220 lbs of corn would yield the same number of calories (IE 130 bushel per acre corn!!!). Walnuts also have 15% protein, but are more concentrated than corn, and comes out to the equivalent of corn with 8% protein. Figuring about 1000 lbs of corn feed to raise a hog, the stocking rate would likely be something like 7 hogs per acre.

The advantage of mulberries (as J Russel Smith puts it) is that they yield over a longer period of time. Either source of feed would require a little (and just a little) extra protein that could be foraged for or fed from other small fields, such as a field of clover that was rotationally grazed. The seasonality of when these tree crops become avaliable and when spring born hogs need these foods matches quite well, but should we be suprized? Not really, as pigs likely evolved to subsist on food from trees with some extra foraging to supplement. Obviously, this stocking rate is rather low, which is one disadvantage. Or is it? The low stocking rate and the presence of “real” food couples with rotational grazing would likley be much less desctructive to the trees. Another disadvantage is that as the tree crops are seasonal, it is hard to image how hogs could be raised throughout the year. Likely there would be one “batch” per year, which is fine with me.

By the seasonality of the tree crops, I was refering to a mix of both nut and fruit crops. Specifically a mix of mulberry and walnut trees. The mulberry produces over a long period in the summer from June into August. Sweet, soft, small fruits seem like they would be perfectly picked up by hungry little mouths born in March. March, incedently, is the most common birth month in european wild boars. There wouldn’t be alot of fruit right way, but the piglets would be small and might still be with the sow. Because the sow doesn’t need bred back right away, high protein milk would be avaliable for a longer time and could help get them started. Mulberrys produce fruit until about August. In August, the walnuts start falling, producing massive amounts of food when there are big enough mouths to eat it. After a month or two of eating walnuts, it’s mid october, which is a good time for slaughter. I think what we have here is an animal perfectly designed by nature to eat tree fruits and nuts, especially if the farrowing time is right. That’s what I meant by the seasonality matching quite well.

It is interesting that the ecology of this type of system is a concern. I agree that is is unlikely that these planted forests/orchards would be very similar to native forests. Ecology is such a subjective word to me in general, but that another topic entirely. Either way, I think it would be more fair to compare the ecological impact of this system to the more standard corn/soybean hog raising system rather than to native forest. In other words, is it more ecologically sound to raise hogs in planted trees at a low stocking density or is it more ecologically sound to use the ground as cropland and keep the hogs in confinement. Based on rough math, the carrying capacity of tree crops is at least the same, if not more, than the carrying capacity of cropland. Also entering into this would be the power required to till, plant, harvest, and store crops each and every year. This power could be produced from animals, of course, but feeding and housing these animals would require even more land and further reduce the efficiency of the cropland-confinement system.

PS. Personally, I have only ever raised pigs in confinement. I found it suprising that this system seems so possible. Maybe it shouldn’t be, as forests are where pigs came from, but it was to me. I am trying to recheck as much math as possible because I think J Russell Smith overstates his case a bit. He said in one part of the book that hogs could be stocked at 2 per mulberry tree, which would end up with 80 per acre. Maybe for a short time, but the math doesn’t support that this stocking rate is sustainable. Still, the system looks competative with corn for total calories per acre and produces a crop every year (unlike ground for corn, which is often cycled).