Recently, a visitor asked us a question many people have asked us: How do we plan to grow different crops in between rows of trees in our farm that create shade? I stumbled on a metaphor that seems to answer the question and also provides a way of understanding farm design. 

Farm design could be linkened to photography. One of the first (and probably only good) lessons I learned in photography is that you have to become "light sensitive" just as the film or cmos cesor chip that records the image is light sensitive. By observing and remembring repeatedly the light condition at the time of shooting a picture, you can internalize a sense of how much light is good for a particular picture in a particular spot which is at a particular degree of brightness. Aperture, Shutter Speed and ISO, when I first discovered them, felt like nothing short of genius. No matter what the external brightness is, high or low, you can still manage to allow the right amount of light to fall on your film/chip.

Aperture in the size of the opening behind the lens that determines the Amount of light getting in through the lens. Shutter Speed is Duration of time for which light is let throught the lens. Amount and Duration, either individually or combined can be used to decide how much light is allowed to fall on the surface of the material (film or chip) that makes the image. ISO is the light sensitivity of the film/chip.

Similarly, if you have a lot of trees in your farm, it acts like a semi-transparent lens cap. The shade created by the tree allows different degrees of light to reach the ground (depending on the type of canopy of the tree). In some places there is more shade and some places more light. Now, depending on the type of crop you want to plant, knowing how much light is required by that crop and for how long, you can prune the trees. Pruning acts like the Aperture - it decides the amount of light falling on the ground. Which branches you prune acts like the Shutter Speed - as the Sun travels east to west, the light falls for more time on some branches than others (which depends on the angle at which the Sun's rays fall on a tree). By pruning the branches that block sun light for a longer duration, you can create a longer shutter speed. The leaves of the crop you select to plant has its own ISO.

In general, in spite of shade created by the trees, unless it is a very thick canopy of large trees with widely spread of branches, some sun light does reach the ground. That much light is enough to keep many plants alive though the growth rate would be affected. By knowing how much sun light is required by a crop and its ISO, one can decide it's location between the rows of trees. And additionally prune the trees if needed.

One of my friends, Mohan in Palakkad, Kerala has created a thick forest in his 2 acre land. You cannot even walk stright for three steps without hitting on a tree. Yet, he said he keeps planting trees in his farm. I asked him the secret. He smiled and said, "I walk around the farm at noon and look for spots on the ground that receive some sun light, and plant my new saplings in those spots! He said that those spots will continue receiving direct light for at least a hour and that is enough for the saplings to grow beyond the critical survival period.

In a forest, trees, plants and all kinds of brushes grow together and they don't bother about optimal growth. A forest is more interested in diversity and co-existance and the combined synergistic good it can create by being a "forest" than in the optimal growth of individual species. In an Agroforest, we try to strike a balance between the optimal growth of an individual species and the combined synergy of many different species.

A forest is like a camera on auto-mode: it can create good-enough, average pictures and emphasis is on variety and their combined synergy: capturing a variety of life moments and enjoying their combined memories require only good-enough pictures.

An Agro-Forest is like a camera on manual-mode: we can control the aperture and shutter speed (besides choosing the right framing), and create outstanding and better than average crops, though not in as many numbers as a forest, in resonably good numbers to resemble a forest.

Seems like there are a lot of lessons here for the social life of human beings as well.