CULTIVATION AND TECHNOLOGY Soil improvement requires an integral approach als and organic matter was reduced. At a certain point, potato growers only applied nitrogen, potassium and sulphate. The third example De Haan is raising is the decrease in the number of crops in the cropping plan, and the use of fewer rotations. ‘More of the same crops gives plant and soil-specific attackers more opportunity to develop stronger populations. As a result, problems with nematodes, fungal and bacterial diseases have increased in the past thirty years. And, due to more frequent land rentals, particularly in potato cultivation, care for the soil has deteriorated as well.’ A solution for every problem Of course, over the years, solutions have also been sought for the problems that arose, De Haan says. Wider tyres have been developed for the heavy machinery, so that their lower pressure could limit soil compaction. Concurrently, several trials have been held with tractor paths systems, bed cultivation and non-turning soil cultivation, which aim to curb some of the disadvantages of mechanisation. Fertilisation can be improved by better analysis of animal manure and by applying dry and liquid fertilisers that are more in conformity with crop-specific nutrients. Solutions have also been found for rotation problems by applying green manure crops, soil decontamination and other methods that tackle pests and diseases occurring in the soil. Combining solutions ‘The most important shortcoming in all this is the lack of an integrated approach’, De Haan explains. All these measures are somehow interlinked and, Leo Hanse in fact, require the development of a system that supports soil optimisation. In his view, the Nemadecide program that is used for combating nematodes is an excellent example. ‘This computer program combines all the necessary measures. It’s not only the use of nemadecides that is at stake here, but also the effect of a wider rotation scheme and the use of resistant varieties. The final outcome determines the choices. This type of a program is not yet available for soil improvement. Only when we’ve solved this can we start thinking again about yields of 100 tons of potatoes per hectare.’ ● As a result of more frequent land rentals, particularly in potato cultivation, care for the soil has deteriorated as well. The size, weight and capacity of the machinery have rapidly increased, leaving inescapable traces in the soil. Potato World 2012 • number 3 19 Pagina 18
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