A concern: food productivity

[kenneal - lagger]

All those things should be used in a warm climate as well Adam so we're still at a disadvantage.

[trimnut2]

The reliance on oil in order to achieve modern yields is certainly worrying, and without plentiful cheap oil I doubt present day yields could be maintained.
We should however be able to do better than farmers of 100/150 years ago, since knowledge and technology has improved, and does not all rely on oil.
1) - 7)

And contadino's ( 8 )
Perhaps I might add:
9) A much greater knowledge of potentially productive species for each environment.

Adam and contadino. I agree with your points raised here keeping in mind Adam's first sentence. Taking those advances into account I still cannot accept the thinking that many are implying: That these advances will allow us to be sustainable on greatly reduced production areas in comparison to "pre-oil" eras.

To take an example from the thread: The claims in the book are pretty ambitious though: 'Raise enough fresh, healthy, organic vegetables for a family of four on a parcel of land as small as 800 square feet'. Thanks to Ben for that quote.

Unfortunately many seem to equate statements like this to food self sufficiency. More unfortunately statements like that leave out the more difficult side of the food supply equation: Production and maintenance of areas for staples, fruit and possibly meat.

The best figures I have found for pre-oil agriculture are:

Japan: Zone 9b, volcanic soils, excellent rainfall, fully irrigated: 2.2 ht.
::Four grain crops a year. ie approximately 10 crop hectares a year.

France: Zone 8, excellent soil, fully irrigated : 12.5 ht. :: One grain crop a year.

Many more figures are available but those above are typical. It should be noted that both quoted production figures were in areas with excellent agricultural production characteristics. Not many areas can claim the same productive qualities.

I recently heard a figure of 400 square feet for self sufficiency mentioned at a local talk. When asked the speaker could not justify the figure. Dangerous behavior in my view.

[RenewableCandy]

I think you have to look at whatever is the "limiting factor". I would guess for the UK that's incoming energy (i.e. sunlight), followed by simply the number of people, as already implied by ll the discussions focusing on area. However in Oz I should imagine the limiting factors are first, water, and second, quantity of humus in the soil. In other words, you'd need more area, but otoh more area is available.

[kenneal - lagger]

I read somewhere that Terra Preta would work well in OZ by retaining the nutrients and moisture.

[trimnut2]

RenewableCandy I agree with the points you make. Certainly water and humus are big issues over here and certainly are limiting factors.

I still grapple with the underlying issue of possible/likely production figures and land/water availability and most peoples perceptions of this issue. At a big sustainability conference recently I spent an hour with some head planners pointing out that an excellent vegetable garden could not be food sustainability. "Where do you grow your breakfast cereal?" got my point across.

Kenneal, I have set up a number of trials using many diffferent soil ameliorants over many years. Bearing in mind that the results can be site specific I have not had a measurable advantage, above good site preparation, maintenance and fertilization, in any of the trials.

The reason would appear to be simple. In our soil types we have average or above CEC and, good for Australia, OM levels. Hence increasing nutrient and water retention is probably not going to be improved by the small amounts ameliorants can supply in these soil types. Doubtlessly different environmental conditions would produce different responses.

[Keela]

I still grapple with the underlying issue of possible/likely production figures and land/water availability and most peoples perceptions of this issue. At a big sustainability conference recently I spent an hour with some head planners pointing out that an excellent vegetable garden could not be food sustainability. "Where do you grow your breakfast cereal?" got my point across.

Good question trimnut2. I recently did a stocktake of our store. I wrote down the calorific value of everything I have put up. This year I did quite a bit of gardening and we ate our own veggies all summer along with other bought goods.

BUT the bulk of my food store calories does not come from my garden. It is in the form of grains, beans, flour, sugar, dried fruit etc that I did not grow. The stuff I put up form our own garden has only limited calories: indeed the calories come mostly from the sugar I added when making the jams and chutneys etc.

And as for the stored home-made tomato sauce (no sugar in this) - it is really flavouring and not food because the calories are so low!

I have yet to find a grain that I can grow easily in the garden.

Spuds are okay but I have so far only grown enough to last us from June to October. Same with onions.

I've a handful of other crops still to dig up: oca, jerusalam artichoke, parsnips and leeks. Then that's it until next June!

Self-sufficiency is a LONG way off. And I think I grow quite a bit!

[kenneal - lagger]

Have you tried adding minerals in the form of a volcanic rock dust, Trimnut?

http://www.remineralize.org/about.php
http://www.seercentre.org.uk/

Together with low temperature carbon and compost, would it rebuild your soil?

[DominicJ]

Regarding point 4.
Will they?
I just cant see a battery powered plough working.

I have a mains powered rotovater which is ok for a small veg garden, but acres and acres of fields miles from your homestead?, or even a field next to it, running an extention cord to the other end of a field isnt exactly wise, especialy if your then driving around ploughing up the soil.

Its possible, but is there a legal frame work in place to not make it illegal and a land owndership pattern in place to make it practical?

Some of us may have or be aiming for a 4 hectare plot with a house in the middle, but thats an oddity.
Not to mention the electricity required, a litre of diesel contains a lot of energy, close to 50MJ, 14kw/h. If the national grids up and electric tractors get priority, cool, if not, your going to need some serious solar panels to power a tractor.
Better numbers
Smallest tractor I could find after a quick google is 25hp
http://www.compactractors.co.uk/tractor ... actorID=43
That look really small.
1hp is about 700w, so thats 17.5kw, even if you assume two thirds of the power is wasted, your tractor is still going to want 5kw of power.
Thats just out of the question with solar and would require a serious water turbine.

Isnt that a jolly thought.

Once you accept the scale its quite easy to feed a small group of people quite easily, a full sized apple tree should produce 120kg of apples, takes 10 years to reach that size, but you can get 400 on a hectare, each with 25 square metres of space.
Thats 48,000 kg of apples
Assuming you have this 4 hectare plot, you still have 3 hectares for pigs, potatos, onions, garlic, carrots, ect, and some chickens.
Sod wheat.

The problem of course, there are 28million hectares in the UK, less than 1 per family, and a lot of it waste land, if only by virtue of being north facing, not the 100m plus my idea would need.

Assuming wood for fuel, you would need more space for woodland.

[trimnut2]

keela, thanks for your observation and example. I shall keep it in kind, do the same, and use the calorie count to illustrate my point.

Kenneal, Volcanic dust, compost and carbon all used here on my farming operation. Basically a good patch of dirt.

Most of the trialling referred to has been on tree planting re-generation projects - Lands that can be highly variable in condition, but most do have reasonable soil. Unfortunately soil improvements in the way I would do it for my veg production is out of the question on those lands.

DominicJ Thanks for an interesting post. The point you explore reminded me that some years ago we explored the possibility of building/using an "electric gantry tractor" - basically a "lateral move-(think irrigation)" tractor. Although we abandoned that idea it has several merits. It is easiest described as Diesel-Electric with the Diesel stationary running a moving electric gantry "tractor". Of course diesel need not be the power source. Perhaps that system may make more sense than adapting the conventional tractor to electricity.

Gantry tractors have automatic "GPS", 24/7 very quite operational possibilities but probably expensive relocation possibilities. Within the actual operations site gantry tractors can be more efficient than conventional tractors.

[DominicJ]

Trimnut2
Very interesting, sorry for the delay getting back to you I was doing a bit of research on what an electric gantry tractor may be.
I'm thinking two long supports running paralel and something is dragged between them, so either to plough or top or whatever, assuming one long field, that should work very well.

The main problem in my mind of was simply powering the thing, although it does solve the running wires after a moving vehicle that has lots of flailing bits, without some sort of hydro it just seems insurmountable

[JohnB]

There were steam ploughing engines, where a stationery engine or engines hauled a plough across a field on a cable

Using a fixed or portable electric (or other energy sourced) winch could achieve the same result, and has the benefit of not compacting the ground.

[DominicJ]

Thanks for the picture, thats kind of what I was thinking.
But, it doesnt solve my first problem.
If there is a national grid, 25hp electric ploughs could be possible, although you still have to get fields electrified, which would take a lot of land redistribution work.
If the national grid doesnt exist anymore, your still left with the problem of powering it.
If you have a ready supply of coal, a steam engine is fine.

[adam2]

Regarding point 4.Will they?I just cant see a battery powered plough working.I have a mains powered rotovater which is ok for a small veg garden, but acres and acres of fields miles from your homestead?, or even a field next to it, running an extention cord to the other end of a field isnt exactly wise, especialy if your then driving around ploughing up the soil.d.

I agree that a battery powered plough appears unlikely except perhaps in special cases for small areas.
Electric power from the grid or a fixed RE system is just about possible but somewhat of a challenge.

When I suggested that electric vehicles would partialy replace horses, I was thinking more of lightweight vehicles for running errands, checking on livestock, making local deliveries etc.

For ploughing any substantial area, heavy horses, steam power, or bio-diesel appear more likely prospects.

An electric rotavator with a long lead is certainly useful for small areas.