Energy balance of crop rotations
1988
Krejcir, J. (Vysoka Skola Zemedelska, Brno (CSFR). Fakulta Agronomicka)
The amount of supplementary energy in the experimental rotations of crops in our country using the traditional method of tillage is estimated to attain 20,0 GJ per ha per annum on the average. In the total amount of this energy introduced in the rotations of crops the highest percentage, 33 approximately, falls to commercial fertilizers and approximately the same percentage, 27 - 28, falls to the fuel and farm machinery used for the purpose. With the use of minimum tillage, in comparison with the traditional method of topsoil treatment, the amount of energy input tends to decrease, the difference being 8 - 10 per cent. As a rule, the energy saving of fuel and oil varies about 15 per cent when the cultivation of soil is minimized. The smallest amount of energy input has been estimated for the crop rotation II (rotation of the Norfolk type) in which the highest efficiency of energy utilization is obtained at the same time . With an increased proportion of cereals in the rotation, the energy gain when converted to energy unit in general tends to decrease more markedly. As a rule, the energy gain is 5 - 10 per cent higher with the minimum tillage applied. In the input : recovered balance of energy the ratio of 1 : 6.5 - 7.3 is obtained most often under the traditional cultivation of soil, while with the minimum tillage the energy gain is 0.4 - 0.8 parts higher as a rule (relatively (5 - 10 per cent)). Farmyard manure and postharvest crop remains occupy an important position in a total energy balance. Their energy brought in the soil can be distinctly higher than the direct expended energy and thus the balance of total energy input to economic biomass may prove to be a losing one.
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