Hi Darren, I'm one of your old students (Greece 2010) and very happy I took this PDC with you.
My question is about keyline, a technique you said that works well to increase water infiltration on broad acre. A friend of yours in Latin America, Eugenio Grass, is giving keyline courses to poor farmers, and I'm wondering how relevant it is for a poor farmer to learn something as tricky to implement as a keyline system with a Yeomans' plough. Unfortunately, I have to bring swales in the discussion to make my point ("unfortunately", because I know there are kind of opposing schools).
1) Intellectual understanding. Let's face it: it is much easier to teach how to define contour lines, rather than keylines. With contour lines, you just need an A-Frame. With keyline, you need to teach topography (how to find the keypoint), then A-Frame to define the keyline, then a way to define the lines downside and upside of the keyline, parallel to it.
2) Hardware. Did you try to make keylines without a tractor? I do not think that's possible. While this is not a problem in rich countries, poor and small farmers in many regions of the world would NEVER be able to even rent a tractor to do the keyline plowing. But then, why does Grass teach in regions like rural Nicaragua (where I've been the past year)? A swale, at least small ones, can be done by hand, and if the farmer has some money, it's cheaper to hire people than a tractor.
3) Cost. I don't remember exactly the numbers, but during the PDC you said the cost for 1 m of keyline is something like 0.5 cents while 1 m of swale is 2-5 cents, meaning it's way cheaper to do keyline. What is missing, is that you build the swale once, but you have to use the yeoman's plough once a year during at least 2 years, most probably during 3 - 4, so at the end the costs are similar.
4) Ecological biodiversity. When I see images of broad acres with keyline, I miss the trees! Yes, you may increase water infiltration, yes, you may get better pasture, but at the end of the day, it's still a huge piece of land without trees... By the way I have the same issue with holistic management: huge and fertile pieces of land, but no trees on sight. The only notable exception is when you plant trees using a keyline geometry: that looks wonderful! The nice part of swales is that they are a tree growing system.
So, for all those reasons, I would not recommend keyline plowing to people who don't have money, or who have difficulties understanding abstract stuff, like how to identifiy a keypoint (and during my teacher's training, I've seen a LOT of people with a PDC but no idea about how to identify a keypoint). But maybe I'm wrong, and I'm looking forward to hearing your comments
all the best,
greg