SLU news

Food production and self-produced energy on a small farm – what is possible?

Published: 25 September 2013

It is theoretically possible for a small-scale Swedish farm to be self-sufficient in energy and at the same time supply “its share” of the world’s population with food. This by combining the use of horsepower with cultivation of rapeseed oil for tractor operations. But that would mean major social challenges to get enough manpower for such a diversified production, and to solve the distribution of food. This is evident in a study conducted by Sheshti Johansson at SLU.

The research farm Ekeby in eastern Sweden was used as a model for different scenarios. Ekeby has 11.5 hectares of arable land and pastures. The animals are reared solely on grazing and roughage. The research question was about how biomass based tractive power affects food production on a farm. The four investigated scenarios were i) diesel-powered tractor, ii) rapeseed oil for tractor operations combined with draught horse power, iii) the tractor running on ethanol from wheat (where ethanol was produced in large scale elsewhere), and iv) the tractor running on potato-ethanol produced at the farm.

Enough food in horse scenario
Globally, there are 0.2 hectares of arable land per person. This means that the studied farm would need to produce food for 58 persons. With the scenario where the rapeseed oil is combined with horsepower it is possible to produce this amount of food while being self-sufficient in energy. In contrast, ethanol takes too much acreage to produce enough food. Benefits of horses as draft animals compared with the cultivation of energy crops is also that ley to feed horses is easier to get into a crop rotation and causes less soil compaction. Furthermore, the total energy used at the farm is less in the horse scenario.

Potassium deficiency in all scenarios
The flows of plant nutrients were also calculated. All scenarios were balanced in terms of nitrogen. The rapeseed oil & horse scenario showed a small deficit of phosphorus that could be adjusted through return of bones from slaughtered animals. In all scenarios, there was a significant lack of potassium, which is not a problem on the sedimentary clay soils in Sweden, but elsewhere demands a solution for recirculation.

Efficient dairy cows
The study also shows that milk production, even with low-producing cows, is an efficient way to produce food from grasslands. With only sheep and no cows, only half as many people can be supplied on the same acreage.

When Sheshti Johansson presented her study at the NJF conference “Organic farming as a driver for change”, she brought up for discussion if it is possible to optimize this kind of small-scale systems for higher yields. She pointed out that higher yields are leading to faster turnover of nutrients. She also discussed the need for labour for food production in Sweden, based on similar small-scale systems. With today’s salaries, it is an equation that does not add up.

– But what is work and what is leisure in the future, Sheshti asked. For example, to take care of horses many do for free already today.