Without fertiliser application or weeding, but alternatively rotating with vetch and fallow, together with returning the straw to the soil after the harvest, the profitability of this ecological system can be multiplied by four when an ecological market exists.
This is what Gabriel Pardo Sanclemente from the Public University of Navarre in Spain states in his PhD thesis, Comparative study of fertilisation and weeding of the ecological cultivation of cereals on semiarid land.
Ecological systems of production of cereals are based on the rotation of crops, the use of natural organic additives and the mechanical control of weeds, in order to maintain the fertility of the soil and weeds in the long term and at reasonable levels.
In his PhD, Sanclemente specifically investigated the viability of ecological systems of production of cereals in semi-arid land, a viability which depends on the yield of quality crops free from agrochemical waste products and for which a higher price can be paid. This in turn means the gross profit margin of the crop yields is increased and, moreover, an agriculture practice which is more respectful of the environment can be achieved.
For the study experiments were carried out comparing chemical methods of fertilisation and weeding recognised by the Regulations on Ecological Agriculture. The thesis centred on the results from 26 tests carried out in various semiarid land zones in Spain and on which barley, using vetch as green fertiliser, was rotated with wheat and fallow.
According to the study results, it was determined that the greatest profitability was obtained from the 'ecological system' - organic fertilisation and the mechanical control of weeds. Behind this was the 'minimum system', which did not use fertilisation methods or the mechanical control of weeds. But trailing behind both of these systems and presenting the worst results in terms of profitability was the 'conventional system'.
Analysing the data, Sanclemente proposes the use of the 'minimum system' for crop growing, given that this system does not significantly diminish production while reducing costs, which in turn means profitability is increased.
The thesis results demonstrate that, in the wheat tests, the average production rates from fertilised and unfertilised plots are practically the same.
Likewise, it was found that the high levels of organic material and initial phosphorous for the organic crops were maintained after six years of testing, with the level of potassium dropping slightly. This data suggests that the crop rotation, combined with the regeneration of crop remains, was sufficient to maintain the initial contents of the nutrients.
With regards weeding methods, the study found that both the use of the hoe and of herbicides were found to be unsuitable for increasing crop yields in the test conditions. Thus, the density was, in general, poor in respect for the cereal plots after being left to lye fallow.
Finally the results showed that the lowest density of weeds after any weeding treatment - mechanical or chemical - did not give rise to any significant increase in grain production with respect to the control experiment.