And without that energy input, there's no way that get 6+t/h. Either you intercrop with a nitrogen fixing legume, and then you are growing the maize in hills rather than flat rows, and the productivity per plant can be good, but the spacing kills the 6+t/h. Or you deplete the nitrogen, and the yield per plant plummets.
Meanwhile, intercropping potatoes in hilled rows with truck gardening crops you can get more than 10 t/h with a rotation.
Certainly, competing in oil-fed agriculture, potatoes are at a disadvantage to maize, but that may be a temporary state of affairs that will pass. I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.
In petro-farming, maize does call for more nitrogen fertiliser than potatoes. (On the order of, roughly, 300-400 kg/ha N for maize with yields above 10t/ha, while 200 kg/ha N is "enough" for potatoes). While tilling/harvesting will call for more energy in potato culture than maize, particularly with the advent of low- or no-till methods for sowing maize.
In petro-farming, maize does call for more nitrogen fertiliser than potatoes. (On the order of, roughly, 300-400 kg/ha N for maize with yields above 10t/ha, while 200 kg/ha N is "enough" for potatoes)
And then translate that to energy yield per hectare over energy cost of nitrogen fertiliser per hectare ... on the above:
22.5 t/ha compared to 6.8 t/ha grain maize!
that is: 44 kg N-fertilizer / ton maize yield for maize 9 kg N-fertilizer / ton maize-equivalent yield for potatoes I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.
The numbers were the industrial farming ones above, not the kind of hand-worked fields that lie behind in the latest Arc of the Sun diary ... for discussion of targets in the medium term time-frame in the EU or US, industrial farming has to be assumed, though possibly with marginal movement in the direction of sustainability. I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.
