How To Make Sure Cows Benefit Trees in Silvopasture?

I have been reading a lot about silvopasture over the course of the past couple years, because we are trying to reduce ongoing maintenance costs of our highly experimental farm (currently done with weedwackers). Our farm is ten hectares of former cattle pasture that we reforested, by planting about 11,000 trees five years ago. We have primarily tropical fruit trees, and support trees, as well as a handful of timber trees. Our site is located in the high jungle of northern Peru.

I was watching this conference with Ian Mitchell Innes: https://www.youtube.com/watch?v=27fUjjlwm7U

At about the 1 hour 6 minute mark he shows an image of a (mesquite?) tree in southern Texas and mentions how the high-density rotational grazing ended up contributing to the decline of the tree by changing the soil from a fungal dominated soil to a bacteria-dominated soil.

What do you think of that? Any hard science to back that up, or hard science to refute that? I’ve seen Ian present anecdotal pieces of evidence in some of his other presentations, showing that the management intensive ("mob") grazing favored grasses at the expense of other plant types.

So then, why is it that silvopasture works? Why do natural savannas work? Some of these grazing gurus even talk about the buffalo shoulder to shoulder grazing through savanna areas under trees. What makes a deliberately planted silvopasture tree any different from the Mesquite shown in the above example? If bacterial dominance of the soil created by the management intensive grazing were really a big concern, then what should be done to ensure the health of silvopasture trees in spite of the bacterial soils fostered by livestock grazing?

Ian specifically claims that the tree decline was due to augmenting the Fungal/Bacterial ratio of the soil in favor of Bacteria, and does not suggest that tree decline is a result of mechanical (hoof) damage such as compaction of root zones or direct damage to lateral roots. I know most people blame cows’ weight for killing trees, but such examples are usually where cows are given unrestricted frequent access to the same trees over and over again, not in contexts where a grouping of trees is exposed to cattle for one day and then given two months of rest/recovery.

i thought some folks may not know what silvopasture is so i thought I would share this:

Well-managed silvopastures employ agronomic principals, typically including introduced or native pasture grasses, fertilization and nitrogen-fixing legumes, and rotational grazing systems that employ short grazing periods that maximize vegetative plant growth and harvest.

https://www.fs.usda.gov/nac/practices/silvopasture.php

Maybe by bumping this thread some of your question might get an answer.

I have heard Greg Judy talk about it as well.  But if cattle kill mesquite by grazing near them, Ranchers all over Texas will be celebrating tonight!  

I think it is something to be aware of and manage for, but killing mesquite is a stretch.



To address your question, rotational grazing patterned after migrating herds, means the animals need to be kept moving.  Nutrient build up occurs if the stay in one spot and that upsets the soil biology balance.  

Jack Edmondson wrote:I have heard Greg Judy talk about it as well.  But if cattle kill mesquite by grazing near them, Ranchers all over Texas will be celebrating tonight!  

I think it is something to be aware of and manage for, but killing mesquite is a stretch.

My thought exactly!!!

Mesquite is really truly hard to kill.

And you can drive by plenty of mesquite filled cow pastures where I am.

Of course, the stretches of land are big as well but we have one mesquite in our small cow paddock and even with them eating it as far up as they can reach, it is alive and well.

Simply put, cows don't kill mesquite.

As for silvopasture, it's not a straightforward answer by any stretch. Trees need to be roughly at least 3 times the height that the livestock is able to graze. Livestock, in most if not all, are going to have a negative if not total detrimental effect on trees that have the majority of their foliage within reach.

Be careful with how you are applying mob type rotational grazing. The migrating herds only passed through an area once up to maybe passing through an area over a couple months period of time with very long periods of rest for the grasses over the entire year. I am going to guess that you want to graze your livestock for several months within the same pasture, on a rotation of course.  Not just a couple times a year. Where I am I prescribe rotational grazing with the following in mind, and it does not fit the mob grazing mentality, but this is highly effective.

Never graze the grass to a height of shorter than 3 inches.
Never allow seed heads to form on the grasses
Never graze a pasture for a period longer than 7 days
Never return to a pasture sooner than 28 days

I don't know the grasses where you are so these 'Never Fail' rules may not apply to the grasses you have. They do effectively apply to the sod forming grasses east of the Mississippi River in the United States. Not so much to the native bunchgrasses.  It works well in many other areas across the US and Canada as I'm told, but caution should be used.

I have my doubts about applying a mob grazing approach to an area with fruit trees as I suspect the precipitation pattern is such that a mob grazing system isn't going to work.  Also consider, there are/were a great number of the same species of animals that live/lived locally  that are/were in the migrating herds that did not/do not migrate. You need to consider the whole picture. When you don't, things often don't turn out quite as planned, although it doesn't necessarily mean what you intend to do will end up as a disaster either.

In the silvopasture systems I am familiar with, I don't consider the livestock to ever be a benefit to the trees. I'm not saying there isn't a way the trees can benefit from the livestock, as there might be and I'd like to know if there is. Silvopasture as I see it and the thought from areas where I have been is a way to increase the total production on an area by doing two things. In this case grow trees and graze.  The end result or target is to get  0.75 percent production from the grazing and 0.75 percent production from the trees such that total production is 1.50 percent (or 150%) which is more for that piece of ground if you were doing either activity by itself. I haven't ever encountered anyone that has suggested you are going to get 1.25 percent from the livestock grazing and 1,25 percent from the trees so that the total output is 2.50 percent (250%). The idea is to get more total production, not get an increase on the individual practices in addition.