How Much Land to Feed a Person?

I've just been reading this post on Naked Capitalism, which raised the question of how much land you need to feed a person. In the past I've seen numbers in the range of 1 - 2 acres per person, but do you really need that much?

I think working out the answer is a bit complicated, but I thought I'd start with something simple. What yield would a 1 acre apple orchard give in the UK? Apple trees on MM106 are supposed to yield 30 - 60 kg a year on average when fully grown, and be about 4m wide. That means that one tree covers 12.57 m2.

Now, an orchard doesn't have a closed canopy, so lets say that the canopy area is 50% of the ground area. That means that in an acre you can fit 159 trees, with a yield between 4.8 and 9.5 metric tonnes. That is 13 - 26 kg of apples a day, and each kg contains about 10 apples. Of course, you can't eat the apples evenly through the year without some method of preservation, but let's pretend that you can.

Next, an apple contains about 50 calories. 13 kg of apples is therefore 13 * 10 * 50 = 6500 calories. The average intake for a man should be around 2500, so this is far more than required. If we only care about energy, and ignore all the other nutrients people need, then our hypothetical man in fact needs at most 0.4 acres, and perhaps as little as 0.2 acres.

Of course, this is a massive simplification, for a few reasons. These are:

1. No-one would try to survive by eating 5 kg of apples a day
2. This assumes that the yield can be consumed evenly throughout the year
3. It assumes that there is no spoilage in storage
4. It assumes that there is no need to worry about variations in yield due to weather etc.
5. It assumes that all that matters is energy, and not other nutrients
6. It assumes that there is no need for additional land to grow fertility / mulch materials

But allowing for some pessimism, land to grow a bit of food for chickens (meat/eggs) etc., 1 acre per person for a good diet does seem like it might be about the right answer for the UK.

Another way to approach the problem is to divide the total amount of agricultural land in the world by the number of people (it doesn't work for individual countries due to food imports, but luckily the world as a whole doesn't import any food) . This gives an answer of 1.8 acres per person, based on numbers from Wikipedia. But again, this answer is imperfect for any particular place because of wide variations in climate across the globe, and because the world's land isn't used to produce a healthy, sustainable diet in the most efficient way possible. This is obvious since on the one hand we have overconsumption of luxury foods like meat in much of the world, and hunger in much of the rest. In addition, the current agricultural system relies on massive injections of mined / artificial nutrients, so a sustainable system could actually require more than 1.8 acres per person at a global level.

So what's the right number? A minimum is probably at least 0.5 acres per person. A realistic number with a bit of meat/eggs is probably more than 1 acre per person. How much more I'm not sure.

Sweet Cicely

Sweet Cicely growing through plastic mulch

My favourite herb is now showing serious signs of growth! It has been slowly sending up a couple of tentative shoots for weeks, which have been viciously attached by slugs, but it finally has a couple of leaves on it. The picture above shows the most advanced, but the other ones I have in the ground and/or pots also seem to be making a move.

I first bought a sweet cicely plant from the a market stall of the Herb Nursery, about 2 and a half years ago. I'd previously read about it in various gardening books, and I have to say that despite its relative lack of availability in garden centres it does live up to its good reputation. The leaves, young seeds and roots are all edible with a delicious sweet anise flavour. And when I say sweet, I mean sweet - the young seeds taste like crunchy Black Jacks, which were one of my favourite sweets as a child.

It's quite a pretty herb, pollinators love the flowers, and it will quite happily live in shady damp corners. In fact, when I tried growing it in full sun it looked seriously unhappy by summer, so it's definitely a plant for the shade. But doesn't everyone have some shade? And since most other herbs have 'full sun' on the label, having such a good one for those awkward places is really nice.

So why can't you buy it everywhere? The only possible issue I've seen is that it's supposedly difficult to get the seeds to germinate, as they need a period of cold. But I've not had any issues growing sweet cicely from seed as long as that need is met - in 2012 I stratified the seeds in the fridge, but last year I just planted them in autumn and left them in the garage all winter.

Song of the Day - Come Undone

Medlar leaves

Of all the fruit trees that I planted, the one I've been keeping the closest eye on is the medlar. The leaf buds have been getting gradually bigger over the last few weeks, but over the last day or two they've finally started to open! You can see the tree in the picture below:

My Iranian medlar from Keepers Nursery

And here's a close-up of the leaves unfurling: 

The medlar is leafing out!

Why the medlar specifically? Well, fruit trees take up quite a lot of room (12.5 m2 if the diameter is 4m), so the rest of fruit tree varieties were carefully selected according to a variety of more practical criteria:

1. picking time
2. disease resistance
3. yield
4. reliability
5. storage duration for the fruit
6. ability to fertilise other trees I ordered

Of course, each one was a compromise, but the main emphasis was on usefulness and reliability.

The medlar was a bit different. I know that I like jelly made from the fruit, although I've not tried it raw. In fact, I love the jelly - I would say it is much better than quince jelly, which seems to have the better reputation in general. But in most of the world it is not grown much any more for its fruit, so finding reliable numbers for yield is quite hard. Does it provide more than an apple tree in its place would, or a pear tree? Does the fruit store as well as a late-keeping apple? Doubtful on both counts. But I don't really care too much, because out of the trees the medlar was my 'something slightly different and interesting'.

So what does the medlar offer? In addition to the unusual and not widely available fruit (unless you're from Iran or Europe a few centuries ago), it is quite a pretty tree with zigzagging branches and a lot of colour in autumn. Despite its origin around the Middle East, it also has a history in this country, so it's something to talk about when people ask what it is.

The 'Iranian' variety which I've planted is from Keepers Nursery. The family who run the nursery are Iranian themselves, where the fruit is still quite popular, and have a relatively large range of different varieties. Their 7 varieties beats the usual 1 - 3 of other fruit tree nurseries. Here's what they say about the Iranian medlar, which they introduced themselves:

Iranian Medlar is a dessert variety introduced by Keepers Nursery. It originates from the wild medlars which grow in the Alborz Mountains in northern Iran. It is widely grown in Iran where it is a traditional and popular late autumn and early winter fruit.

The fruit is slightly smaller than most other varieties of medlar and rather more conical in shape. It is the one of the best flavoured medlars. In common with other medlars the fruit has a brown russet skin. The flesh is quite hard and green until it is fully ripe when it turns brown in colour and becomes soft. It is quite sweet with a texture and flavour similar to a thick apple puree. It ripens earlier than other varieties. It can be left on the tree to ripen in November or picked prior to ripening and allowed to ripen in storage. The ripe fruit can be frozen and eaten fresh after defrosting.

The tree is compact with a bushy growth habit. It crops very well and does not have any major disease or pest problems. It has attractive large white blossom in May. Unlike most fruit trees medlar blossom opens after the leaves.

I chose this variety because I do want to try eating the fruit raw, so good flavour is attractive, because they say it is compact (Medlars tend to be spreading trees), and because well, again it's something different. As far as I know, no other nursery has taken up selling the Iranian medlar variety yet, preferring to stick to the more well known Nottingham and/or Royal varieties. Of course, the Iranian variety might not live up to the description,  but I guess I'll find out in a few years.