Sunday, 19 July 2009

The Nutrient Cycle

Cleaning the sheep stable once a year

When we harvest vegetables or fruit, either for ourselves or for our guests, we are removing nutrients from the vegetable garden. So how do we replace those nutrients and keep the garden fertile and healthy, so it can go on producing lots of delicious food for everybody? The answer is, as always, lots of hard work!

Traditionally, there was always a cyclical flow of nutrients within each farm. But when farming became industrial agriculture, the nutrient cycle became a linear system of nutrient flow. Artificial fertilisers were brought in bulk onto the farm, agricultural products were taken in bulk off the farm, and somewhere in the middle of this high-input high-output production system, what was once a prized commodity became a polluting waste. We’re talking manure, and lots of it.

Two piles of sheep manure; this years on the left, and last years(more rotted) on the right.

On our farm, we have ditched artificial fertilisers and gone back to a cyclical flow of nutrients. Which means that someone has to get very dirty once a year and spend a week mucking out the stable. In local parlance this muck is called “cucho”, and a year or so later, after it’s sat in a pile outside the stable being acted upon by natural processes, it’s known as “cutrina”. Cucho is a nutrient-rich but rough mixture of hay, straw and sheep-droppings, which is too strong to use on plants; whereas cutrina is a nutrient-rich and ready-to-use mountain of lovely goodness. We hoe it lightly into the soil of the vegetable garden, or lay it on the surface as a mulch and let the living things in the soil do the hard work for us (earthworms mainly, who drag organic matter from the soil surface down into the soil, making it more readily available to the roots of plants). The fruit and vegetable plants think it’s all their birthdays and Christmases rolled into one. So a big thank-you to our sheep, who not only keep the grass short in the orchards and provide lamb for the hotel restaurant, but keep us well-supplied with nutrients for the vegetable garden too.

Kitchen waste ready for composting

Then there’s the compost, which is another way of converting “waste” into a valuable input. Our compost has many ingredients – kitchen scraps, grass cuttings, prunings, muckings-out from the chicken shed, weeds, old hay and straw, nettles, to name a few. And once it’s all composted down we get another rich source of nutrients to go onto the vegetable garden. For more information on our composting techniques please see the blog entry from 8th May 2009.

A Cape Gooseberry plant well mulched with compost.

But doesn’t all this mean a net inflow of nutrients to the vegetable garden? Aren’t we simply taking nutrients from the meadows and pastures, and, by means of the sheep, transferring those nutrients to the vegetables and fruit? This is not a cycle, but a linear flow! Well, what we are aiming for are nutrient-poor meadows and pastures (because less nutrients in those areas makes for greater biodiversity – please see the blog entry of 7th August 2008), coupled with a lot of nutrients in the vegetable garden, as that is the most productive area of the farm. Also, we must view the farm and hotel as a single system, in which case we can see that most nutrients are indeed cycled within the system. For example, weeds are taken from the vegetable garden and composted, and that compost is put back onto the vegetable garden. As another example, vegetables are taken from the garden down to the hotel kitchen, from where the peelings and scraps are returned to the garden via the compost heaps.

Sheep grazing in the "Cuevona" meadow

A linear flow, unlike a cycle, must have both input and output. The only input of nutrients into this system is the food that we can’t grow ourselves (we grow about one third of all food eaten in the hotel), and the only output is what gets flushed down the toilet. If anyone has any safe sane suggestions of how not to lose that from the nutrient cycle, let us know!

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Hotel Posada del Valle is a small hotel in Asturias Northern Spain surrounded by its own organic farm and where we are passionate about organic farming, food, and sustainable livelihoods. In this Blog those of us who live and work at Hotel Posada del Valle open a door to share with all of you who are interested in what we are doing.