Micronutrients in cereal crops

摘要

Seven elements essential for plants are defined as micronutrients: boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni) and zinc (Zn). Deficiency of these nutrients can cause yield losses in crops and impaired crop quality. The overall aim of this thesis work was to increase the knowledge how micronutrients in Swedish cereal crops are affected by nutrient management and soil properties in order to improve crop status and avoid yield losses. Data from long term and short term Swedish field trials and a Swedish monitoring programme were evaluated to examine impacts of nutrient management and soil properties on crop accumulation. In addition, soil depletion was quantified and methods for prediction of micronutrient availability in soil were assessed.ud udAlthough crop production solely with mineral fertilizers may result in depletion of micronutrients in arable soil, results showed that depletion rate is slow and difficult to detect, even over decades. Repeated applications of organic fertilizers caused micronutrient accumulation in soil, but generally did not result in increased micronutrient concentrations in cereal crops. Instead, soil properties affecting micronutrient availability were of greater importance for crop accumulation.ududHigh nitrogen (N) fertilization rates resulted in increased concentrations of most micronutrients in winter wheat, whereas the micronutrient to N ratio generally decreased. Accumulation of micronutrients during crop growth differed from N uptake patterns, possibly due to differing availability in soil. Nitrogen fertilization rate had no or minor effects on the accumulation dynamics or translocation from shoot to grain of micronutrients, except for Fe.ud udEasily accessible data such as total micronutrient concentration in soil in combination with pH or analysis of grain concentrations can be useful tools for estimation of micronutrient availability in soils. New methods of soil analysis, such as diffusive gradient in thin films (DGT) also showed promising results in predicting Cu uptake in wheat.ududThe results presented in this thesis can be useful in identification of fields with an elevated risk of micronutrient deficiency in cereal crops.