Marktillstånd och borbrist på åkermark planterad med gran i Västerbottens län

Sammanfattning: This study was made on former agricultural areas that had been planted with spruce or pine, in the county of Västerbotten. The goal of the project was to investigate suspected deficiency of boron in these areas. Several objects have been reported for possible deficiency and some of these have the characteristic symptoms of boron-deficiency. The hypotheses are that 1) Boron deficiency is present at several of the investigated objects. 2) Planting of forest on cultivated postglacial sediments leads to a successive podzolisation with a decreasing content of organic matter in the mineral soil, due to decomposition, and a decreasing pH in the soil, even on locations that have been added lime. To be able to confirm or reject the hypotheses a number of tests were performed. Loss of ignition to obtain organic matter content on the objects, ICP/MS-DRC was used to obtain content of boron in spruce and pine needles, pH was determined and density on the objects were determined by fixed volume cylinder sampling. 13 objects were investigated in this study and two of these were control objects where no former agriculture had occurred and no visible deficiency of boron had been observed. Most of the objects suffered from boron deficiency and the content of soil organic matter on the objects were lower than in cultivated areas on similar soils. All objects, also those previously limed three to four decades ago, or ash fertilized as late as three to four years ago, were developing mohr layers and had top soil pH in the order of magnitude of natural spruce forest on same soil type.