Browsing by Subject "Potassium"

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Assessing long term effects of compost fertilization on soil fertility and nitrogen mineralization rate
(2023) Reimer, Marie; Kopp, Clara; Hartmann, Tobias; Zimmermann, Heidi; Ruser, Reiner; Schulz, Rudolf; Müller, Torsten; Möller, Kurt
Fertilization with organic waste compost can close the nutrient cycles between urban and rural environments. However, its effect on yield and soil fertility must be investigated. This study investigated the long-term effect of compost on soil nutrient and potentially toxic elements (PTEs) concentration, nutrient budgets, and nitrogen (N) mineralization and efficiency. After 21 years of annual compost application (100/400 kg N ha–1 year–1 [100BC/400BC]) alone and combined with mineral fertilization, soil was analyzed for pH, organic carbon (SOC), nutrient (total N and P, Nmin, extractable CAL-P, CAL-K, and Mg), and PTE (Cu, Ni, Zn) concentrations. Yields were recorded and nutrient/PTE budgets and apparent net mineralization (ANM, only 2019) were calculated. N efficiency was the highest in maize and for mineral fertilization. Compost application led to lower N efficiencies, but increased ANM, SOC, pH, and soil N, and surpluses of N, P, and all PTEs. Higher PTE concentrations were only found in 400BC for Cu. Nutrient budgets correlated with soil nutrient concentration. A surplus of 16.1 kg P ha–1 year–1 and 19.5 kg K ha–1 year–1 resulted in 1 mg kg–1 increase in CAL-P and CAL-K over 21 years. Compost application supplies nutrients to crops with a minor risk of soil-accumulation of PTEs. However, the nutrient stoichiometry provided by compost does not match crop offtakes causing imbalances. Synchronization of compost N mineralization and plant N demand does not match and limits the yield effect. In winter wheat only 65–70% of N mineralization occurred during the growth period.
Nutritional and climatic effects on berry shrivel of grapevines in Southern Germany
(2012) Bachteler, Kristina; Wünsche, Jens Norbert
Berry shrivel (BS) is one of the economically most important physiological disorders in grapevine, but it is also one of the least studied ones. At the beginning of the ripening process, berries stop accumulating sugars and lose their turgescence. The must weight remains low, the berries taste sour and bitter. During the last ten years, several studies were conducted to narrow eliciting factors. As a result, an unbalanced ratio of K and Mg in the soil was considered likely to induce BS. To verify this hypothesis, two fertilization trials with two different varieties each, one via the soil and one foliar fertilization trial, were initiated. Within two years, no effect on the incidence of BS was evident. In the foliar fertilization trials, Mg, K and Ca fertilizers were tested with their effect on BS. For the first year, no significant differences could be observed. In the second year, more berries were affected by BS in the plots treated with Ca fertilizer. The plots with Mg fertilizer showed significantly less berries affected by BS than the untreated control in one variety. Extensive analysis of concentrations of Ca, Mg and K in berries illustrate that berries affected by BS show significantly higher concentrations of Ca compared to healthy berries. The loss of quality of wines made of berries affected by BS was demonstrated by must and wine analysis as well as by a consumer preference analysis. Phenolic compounds (in particular resveratrol) that are often used as indicators of abiotic stress were analysed as well. It was supposed that BS is caused or increased by abiotic stress so that the concentration of resveratrol in berries affected by BS is increased as well. However, in all varieties analysed, the concentration of resveratrol was higher in healthy berries than in affected ones. A direct connection between weather condition at bloom and especially at ripening was examined. Observations at monitoring sites and reports from other countries seem to show that cool and wet weather at these phenological stages might increase the risk of BS. It was only possible to statistically prove a connection between the precipitation at bloom and the incidence of BS.