Agroforestry: An opportunity for more sustainability
The climate change brings many challenges to our conventional ways of farming, as you, dear readers, will undoubtedly know.
That we face an enormous disappearance of insects is also not exactly news any more, and we do not wish to bore you.
What is perhaps somewhat less well-known is that there is a novel approach in tackling the problems caused by global warming, and that is agroforestry.
What is agroforestry?
In general (and as the name implies), it is the concurrent use of both agriculture and forestry.
Large, monocultural farming certainly has short-term economic benefits.
Planting harvestable plants (tomatoes, grapes, potatoes etc.) in precisely defined lines on a field allows for machines to do all the harvesting.
However, it comes at the price of disappearing biodiversity.
Whereas in a wild field every pest has got its natural enemy (the birds eat the beetles and so on), pests can ruin entire harvests in a monoculture.
To prevent this from happening, farmers spray their fields with pesticides.
In these times of climate change, precipitation decreases, which causes groundwater levels to drop.
Plants, however, need regular precipitation in order to thrive.
As a consequence, farmers have to install irrigation systems. If these irrigation systems draw on the groundwater, the groundwater levels will sink even further. Alternatively, the feed may come from nearby rivers, however, that requires larger investments (pipelines, pumps, etc.).
It has been found that rows of trees plant alongside as well as in the fields can have beneficial effects on both the water management and the biodiversity of fields.
The economic drawback is immediately obvious: If a fraction X of a field is taken up by trees instead of whatever harvestable plant is planted on this field, the yield per unit area is lower.
In addition, farming machines may be more difficult to operate in a field partially occupied by trees.
The benefits such as improved water management and increased biodiversity, however, should be taken into account as well.
An important economic factor is also that the wood of the trees may be sold once the trees have reached a certain size and age. In addition, the leaves shed by the trees in autumn provide nutrients to the ground and while the contribution of a few trees around and in some fields might seem negligible those trees still contribute to carbon sequestration.
Practical examples
Viticulture in Southern France [1]
Most grapevines can withstand a little drought, they require between 640 and 890 mm of rain per year (preferably in the growing season, i.e. spring and summer). The grape varieties grown in southern France can withstand the usual summer conditions quite well, after all, otherwise they wouldn't be grown.
In recent times, however, summers have become significantly hotter, prolonged periods where temperatures reach 45 °C or more are not uncommon any more that can cause grapevines to wither.
Rows of trees provide shadow for the grapevines, which reduces the risk of withering.
Remediation of barren soils in Honduras
The region of Lempira in Honduras has seen a lot of slash-and-burn, which is to say that forests were cut down and burned to make place for farming land.
However, without the root-work of the trees, the soil lost its hold on the underlying rock and was washed away by seasonal floods.
As a result, farmers had to give up these newly created fields and moved on to slash-and-burn the next bit of forest. In time, plants re-occupied the barren land and so-called secondary forests established themselves.
By thinning and pruning these trees, the area has been turned into agriculturally useable land again. This land is now used to grow crops in a cycle that has been shown to be beneficial and sustainable.
Pork-farming in Germany
In the first two examples, trees were used as beneficial add-ons to agricultural activities. In this example, farming activities are shown to be beneficial to forests. This is known as silvopasture (from lat. silva forest).
Here, livestock is made to graze or forage in forests. An old practice that is being rediscovered, it is particularly suitable for pork farming in mixed forest with a reasonably high content of oaks, as the pigs feed of the acorns.
Is agroforestry therefore the solution to our agricultural problems?
Probably not.
Especially in Europe, the practice is only just beginning to be investigated.
The potential benefits are substantial, however, many practical questions still need to be addressed, such as: Which trees are most suitable for which problem while still getting the maximum effect?
Or: How do you plant the trees so that they don't interfere with farming equipment?
Given the time trees take to grow, how can we make sure that they will still be seen as a solution 20 or 30 years down the line, especially since the meteorological conditions we and our world is facing are changing fast?
As with questions regarding sustainability there is no magic bullet, no one-solves-all but seeing the combination of positive effects it provides agroforestry appears to be an arrow in our quiver we should not overlook.
[1] https://news.mongabay.com/2020/06/better-wines-among-the-pines-agroforestry-can-climate-proof-grapes-french-researchers-show/