Browsing by Subject "kalkitus"

Tiivistelmä - Referat – Abstract Acid sulfate soils are formed from sediment deposits containing sulfides, in which sulfur is present in the form of iron sulfides. In contact with air, the sulfur layer initiates a long-chain of biochemical and chemical reactions that increase the acidity of the soil and the amount of sulfate. Excessive acidity restricts plant development and growth. In acid soil, the aluminum solubility reaches a high level of toxicity for roots and slows down the microbiological degradation of organic matters, resulting in a reduction of nitrogen mineralization. Previous research results have shown that important liming has the potential to raise the pH of sulphate soils, and thereby reduce its acidity. With a high pH, the concentrations of ammonium and nitrate in the soil increase, facilitating nitrogen uptake and thereby also improving the efficiency of nitrogen uptake by plants. It has been speculated that, by increasing the nitrogen uptake efficiency and nitrogen utilization in plants, it will improve nitrogen use efficiency and so will reduce denitrification in sulphate soils and the resulting N2O emissions. However, to date, the studies on the effect of liming on plant nitrogen uptake (UPE) and utilization efficiency (UTE) and, consequently, on plant nitrogen utilization efficiency (NUE) have been minimal. The purpose of this study is to investigate how liming affects the yield formation and nitrogen uptake efficiency for barley (Hordeum vulgare L.) in unfertilized and fertilized acid sulfate soils. The field trial was established in Viikki, Helsinki, in the spring 2018. It followed split-plot design, in which the main plots were combinations of plant and nitrogen fertilization treatments (0 or 100 kg of nitrogen per hectare of fertilized barley (Kaarle) or unfertilized fallow) and lime treatments (0; 7,7; 15,3 t/ha) in four replicates. Liming raised the soil pH as expected and also increased nitrogen mineralization during the growing season, which is reflected in the nitrogen uptake. The effect of liming and fertilization on crop formation was small for barley biomass, yield component and grain yield. On the other hand, the liming effect reduced the nitrogen absorption efficiency and the nitrogen utilization efficiency and thereby the efficiency of nitrogen use. Fertilization also increased nitrogen uptake, but also decreased nitrogen utilization efficiency and nitrogen harvest index. The combined effect of liming and fertilization increased nitrogen mineralization. Liming treatment clearly increased nitrogen mineralization more in unfertilized soils than fertilized (there was no difference between liming levels). The drought in June and the low moisture limited the mobilization of nitrogen released from fertilizer in the soil, which would explain the effect of the nitrogen fertilizer treatment remaining relatively small. The drought also limited the development of the roots and thus the uptake of nitrogen and other nutrients. Lime treatment did not change NUE, UPE and UTE, but increased nitrogen mineralization and nitrogen uptake during the growing season, suggesting that under more favorable conditions the liming treatment could improve the efficiency and therefore improve the profitability and ecology of the barley crop. Further studies are needed as the results of studies performed elsewhere may not be valid under boreal conditions.