CULTIVATION AND TECHNOLOGY Soil improvement requires an integral approach In early March, the partners of Wageningen Potato Centre (WPC) in Emmeloord came together for a brainstorming session on the topic of soil. The meeting was introduced by research expert Janjo de Haan of PPO-AGV (Applied Plant Research for Arable Farming) in Lelystad. He sketched an alarming scenario: every aspect of knowledge about cultivation is still increasing, but the hectare yield is stagnating and the quality of the soil is decreasing. W ith this message, researcher Janjo de Haan brings the potato sector back to earth. Back in 1978, the PPO researchers already predicted that the potato yield would rise by an average of 100 tons per hectare within the foreseeable future. They based their future perspective on the significant progress in cultivation from after WW II until that moment. The mechanisation boom, plant protection chemicals, fertilisers, the construction of drainage systems, knowledge of pests and diseases, the improvement of varieties, all these measures were conducive to this boost in potato yields. Unfortunately, the forecast of thirty years ago proved to be too optimistic. The average yield per hectare of consumption potatoes barely reaches 60 tons at the moment. What went wrong? Soil scientist Janjo de Haan points to the soil as a possible important explanation. The biggest problem is that the sector is failing to find integral solutions for a wide range of problem areas. And the list is long. De Haan mentions a considerable number, each with its specific consequences for the limited growth in yields. Problem areas highlighted De Haan highlights three examples of growing problems. Number one is mechanisation. ‘A blessing, many farmers thought in the seventies, which it was. They got more done with less labour and that can be called progress. But the size, weight and capacity of the machinery rapidly increased, which left inescapable traces in the soil. The result? Damage to soil structure with the obvious consequences. Less water storage, poor root development, bad mineral absorption and stagnation of organic soil formation’, De Haan summarises. Number two is fertilisation. ‘Until the introduction of the artificial fertiliser, many farmers were still using animal manure in combination with straw. This had double advantages: the soil got the main minerals and trace elements, and organic matter. With the introduction of artificial fertiliser, the broader application of minerIt would be a good thing to develop a soil optimisation support system, says researcher Janjo de Haan. 18 Potato World 2012 • number 3 Pagina 17
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