Water, water

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Rivers are over-topping their banks

It’s been a bit wet in the UK recently. When we compared our rainfall data for 2014 with that for this year, we saw that we’ve had approximately 50% more in November and more than 60% more in December (and it’s not quite over yet).

We are lucky in that we live on a hill and, although water flows through our garden from the field behind, it doesn’t hang around for long. In addition, our raised beds and raised chicken area act like sponges, and then drain gradually once the rain stops. Others are not so fortunate. Those living in the bottom of valleys are on the receiving end of all the water that has drained off the land further up the catchment. And so in recent days there is news of flooding in such locations.

It seems that we have suffered much more severe floods in recent years than previously and the media is keen to apportion blame… councils allowing developers to build on floodplains for example or upland livestock farming. But it’s a complicated picture and there are lots of reasons behind the current situation. Which means there isn’t a magic bullet – we can’t do one single thing to solve the problem.

Perhaps the first thing to consider is that this is about changing climate. By putting a blanket of carbon dioxide (and other greenhouse gasses) around our planet, we are trapping energy in our atmosphere. The result is the increase in storms and severe weather events. You will see many claims in the media that our changing climate is not the result of human activity. These often come from such renowned “experts” as Nigel Lawson, with his degree in Philosophy, Politics, and Economics and James Delingpole, with his degree in English Literature. If you are interested to see the credentials of those in the public eye who are sceptical about climate change, check out the DeSmog disinformation database. In contrast, the people actually undertaking scientific research about climate change overwhelmingly agree that it’s happening and that it’s anthropogenic. Indeed, according to NASA:

Multiple studies published in peer-reviewed scientific journals show that 97 percent or more of actively publishing climate scientists agree: Climate-warming trends over the past century are very likely due to human activities. In addition, most of the leading scientific organizations worldwide have issued public statements endorsing this position.

So, that’s something to bear in mind.

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The local supermarket car park will soon be awash

But, back to the floods themselves… There are several things that we need to do. We need to remember that floodplains serve a particular purpose in a river catchment, and that is not providing flat land for housing! Apart from anything else, floodplains are where rivers should be able to overflow; where the water spreads out, slows down and deposits the soil particles that it’s carrying before it reaches the sea. Floodplains should be the place where we catch the fertility of the land before allowing it to be washed away, and where, as a result, we can farm productively in the drier months. Channelling water so that it moves rapidly through this part of the catchment means that the energy is not dissipated and any nutrients will disappear out to sea.

Further up river catchments we also need to slow down the movement of water. We need to develop a landscape that holds water – upland bogs and grazed diverse grasslands are good for this – and where water is intercepted by trees and shrubs. We don’t need a smooth landscape where water just flows off – we need diverse topography, with pools, banks along contours, a mixture of vegetation types and a well-developed soil. Upland woodlands slow the movement of water, from the moment it falls. Leaves, twigs and branches intercept rain and increase the time it takes for that water to reach the surface. Tree roots make the ground more permeable, and this increases infiltration. Plus, the organic nature of deciduous woodland soils means they act like a sponge and hold large amounts of water.

Anywhere in the catchment, we can make a difference to the water-holding capacity of soil. You are doing this if you add compost to the beds in your garden. In addition, any organic matter incorporated into the soil (whether in a tiny garden or on a large farm) is acting as a sink for carbon and thus reducing net greenhouse gas emissions. These are really good reasons to compost waste and to treat any organic matter as a resource not a problem to be disposed of… not to mention increasing soil fertility and therefore allowing you to grow better crops, which photosynthesise and thus also reduce carbon dioxide in the atmosphere. Another benefit, is that increasing the water-holding capacity of soils reduces the impact of droughts – something we have also encountered recently. Adding organic matter, therefore, is a win-win situation.

So, whilst we can’t stop the flooding right now, we can manage our land better to reduce problems in the future. And we can all do this – plant a tree, make compost, build a garden bed, collect rainwater to flush the toilet or water your house plants. Every action helps and together we can make a difference.

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Over the banks but not over the bridge

 

 

To dig or not to dig

I frequently hear about the value of using a no-dig system when growing vegetables, but a recent post by Deano on his Sustainable Smallholding blog has made me think quite a bit about this issue and about the entrenched ideas that can permeate specific approaches to gardening (or any other aspect of our lives).

If you have read much of this blog, you will know that I am interested in permaculture and using this approach for designing systems in my gardening and elsewhere. Often, in the permaculture world, one finds reference to no-dig systems. The idea is that, in nature, productive systems are able to establish and thrive without any turning of the soil like we use in traditional gardening and agriculture. In order to emulate natural systems, the principle is that organic matter applied to the surface of the soil becomes incorporated into the soil structure by the action of worms and other soil fauna; just like it would in a woodland.

Woodlands produce organic matter that is incorporated into the soil by the fauna

The theory is sound, but in practice it may not be the best option. Natural systems have no ‘agenda’ – the vegetation that develops on a soil is the one that can thrive there. When we garden, however, we have specific aims and a specific time frame: it’s no good having to wait for 30 years for a deep fertile soil to develop when we need to feed ourselves now. Usually the reason for digging is to loosen the soil and to incorporate organic matter. It is true that, in some soils, worms and other soil animals can do this quite quickly, but it is not the case for all soils, as Deano has demonstrated with his heavy clay soil. Clay is a valuable component of soils as it is mineral-rich, but it is also sticky, impedes drainage and dries rock hard, and when it is abundant in soil, it creates a difficult environment for worms. Its presence is to be valued but, like most things, in moderation. Other components of soil – sand, silt, organic matter, water and air – are also important. The addition of organic matter to a heavy clay soil can help to improve aeration, fertility (including the release of chemical elements from the clay) and drainage. Given enough time, worms will do the mixing for you, but if you need it to happen this year, then some mechanical incorporation is the answer.

One of the arguments against digging (or ploughing) is that it damages the soil structure and adversely affects the habitat of the soil fauna. This is, indeed, true. For example repeated ploughing can lead to the creation of a hard, impermeable ‘plough pan‘ at the depth that the plough reaches because it smears the soil at this level. In addition, digging or ploughing causes physical damage to soil fauna and flora – potentially killing worms and chopping up fungal mycelium, mixing up soil micro-organisms, exposing buried organisms to the surface and burying those from the top layers.

So, there are pros and cons… the essential issue is that you must know and understand your soil in order to select the right way to manage it. You must also understand what you need from your soil. It’s about making informed decisions. And this is, perhaps, the real issue: we should not allow sensible ideas to become dogma. There can never be a single solution that fits all situations, and by making rules and being prescriptive will inevitably lead to disillusionment when that answer doesn’t  work.

It’s not just humans who dig!

In fact, I don’t dig my vegetable beds much because, as I have mentioned before, there was very little soil in my garden when we moved in so we build raised beds. The imported soil was light and friable and supports large numbers of worms, which do mix organic matter in quite quickly. Having said that, however, I do dig. I particularly like in situ composting involving digging a hole and burying fresh organic matter – a mix of material high in nitrogen plus something like wood chip or shredded paper to provide carbon and improve structure – especially when I’m planting runner beans or members of the squash family. And sometimes I dig in compost for a quick addition and to stop the chickens chucking it around all over the place. Talking of which, the chickens do quite a lot of digging too!

But, perhaps I need to get to know my soil better in order to make more informed choices about how I manage it and, with this in mind, I’m going to be testing the pH of my beds soon and I will be thinking a bit more about the structure and texture of the soil.

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