Water stress is one of the most significant challenges currently facing the world. An already changing climate means that many dry areas are becoming even drier, with increasingly unpredictable rainfall patterns. In recent years severe droughts in California, Brazil and South Africa have made the news: in 2018 Cape Town was just 90 days away from completely running out of water. Invisible to headline-readers, farmers are probably the group worst affected by water unpredictability. Last March I volunteered on a farm in India where there had been no rain since the previous October: many of the local farms had already lost their annual crops and were on the brink of losing some of their coffee trees. Of course, many drought-prone areas have established irrigation systems which draw on groundwater supplies to provide water for crops all year around. However, this system will only work in the long term if the groundwater is being restored by rainfall. If aquifers become too dry they can permanently lose capacity, as has happened with California’s Central Valley aquifer from the 2012-2015 drought (source). 

If you are reading this from the grey and wet autumn in the UK, you may think this doesn’t affect you. Well, the bad news is: it does. Our food system is now completely global. In 2015 the UK imported 48% of its unprocessed food (source). However, when you consider all the ingredients in our processed foods, that figure rises dramatically, to possibly as much as 80% (source). Moreover, the UK itself isn’t immune from rainfall unpredictability – the droughts of summer 2018 led to yields down 20% on the previous year, and heavy rain has caused flooding in many areas this year. This TED talk gives an excellent overview of how our extractive farming techniques and other human activities have degraded the global water system, leading to both droughts and floods.

Managing water well, therefore, should be a high priority for all farmers and landowners across the world. What ‘good’ looks like will vary from place to place, although some principles of avoiding run-off (when water doesn’t sink into the land and runs straight down the valleys, taking some of the vital top soil with it) apply everywhere. I am writing this from a farm in central Portugal, which enjoys a Mediterranean climate. Portugal is currently experiencing a drought – it hasn’t rained any meaningful amount since the beginning of summer. There is little life on any unirrigated land: the dominant colours of the landscape are browns, yellows and greys. We are expecting the first autumn rains any time. I’m told that this wetter season normally takes the form of heavy rain for a small number of days, with most days remaining dry. Therefore the priority for farmers here is to retain water on their land, so as to maximise its benefit for the plants and all the life in the soil, as well as to prevent erosion during the rainfall itself.

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Keyline design

One of the most important tools farmers have to manage water is the way they design their land. In Europe its very common to see a grid layout of orchard trees and long, straight rows of crops since this is perceived to be the simplest for the farmer and their tractor, as well as maximising growing area. However, this design just encourages run-off and erosion as it provides the water with an easy route down the valley. In the long term it creates more work and expense for the farmer who will have to provide the soil with the nutrients it has lost through erosion. So what’s the alternative? Enter: keyline design.

Developed by P.A. Yeomans in Australia in the 1950s, the keyline system is designed to slow, sink and spread rainwater by relieving compaction, opening up pore space in compacted soil and distributing excess water towards drier parts of the landscape. It is also purported to enhance soil fertility by opening up the soil to give the micro and macro organisms space to do their things. I am currently staying with the wonderful Carlos and Catarina, whose 1000+ tree fruit orchard, Dias nas Arbores, has been designed using keyline. This is a design system which can easily be done on a large scale. 

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How it works

Keyline design uses a specific cultivation technique with a chisel or specially designed keyline plow. In contrast to the majority of plows used in farming, this plow does not turn the soil. Rather it cuts deep, thin lines into the soil, leaving the vast majority of it undisturbed (which is beneficial for soil life and helps prevent erosion in heavy rains). These lines are slightly off-contour to promote the distribution of water away from the valleys and towards the drier ridges using gravity. Effectively this system creates an alternative easy route for the water to run down. This slows the movement of water and spreads it more uniformly, infiltrating it across the broadest possible area. It is, therefore, both a flood and a drought mitigation strategy.

By cutting deeply into the soil, the keyline system speeds the decomposition of organic matter by providing additional air and moisture. This helps build healthy soil, which ultimately will mean healthier plants and less need for inputs (e.g. fertilisers). It is best to plant close to the plowed lines, as they will provide natural irrigation and the roots of the plant will enhance soil structure and promote soil life. There is a positive feedback loop at play here – the first plants help improve the soil, and as the soil improves, more plants will grow. Therefore the keyline approach is an excellent one for restoring degraded land. 

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Expanding keyline design

If keyline is so good, why isn’t everyone doing it? Well, it has been fairly widely adopted across Australia, where it was invented (and where the water problems have been acute for quite some time). This website gives details of a number of keyline designed farms in the south of the country. In Europe, however, awareness and adoption has been slower. Its likely farmers are discouraged by the upfront costs involved in plotting and designing the land, as well as renting the plow. Farmers normally run their farms on incredibly tight margins, so not only would they struggle with a capital expense such as this, but they are unlikely to be able to afford the temporary loss of production associated with a completely new design. They need financial assistance. 

There is consensus that the already difficult water problems are only going to get worse on a business-as-normal trajectory. Changing how we manage and cultivate our land is vital. Through its focus on water distribution and infiltration, the keyline system helps climate change adaptation, as well as contributing to the restoration of nature’s water cycles which could help reverse some of the damage we have already done. For policymakers, keyline design is cheap and simple. It is one of the tools which should be a funding priority for governments and businesses in their efforts to mitigate human-induced climate and ecosystem decline.

Note: there is a lot more to keyline design than I’ve outlined here. If you’re interested in knowing more about, for example mapping the land, placing dams and improving soil fertility, this document is an excellent resource.