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NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.

2021

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Sammendrag

Predicting N mineralization from green manure in different soil types during the cold season is instrumental for improving crop management with higher N use efficiency and reduced risks of N losses in a cool and humid climate. The objective of our work was to study the effects of low temperatures and soil type on the net nitrogen (N) mineralization and the relationship between N and carbon (C) mineralization from N-rich plant material. A silty clay loam and a sandy loam were incubated with or without clover leaves for 80 days at 0, 4, 8.5 or 15 ◦C. The results showed a substantial mineralization of N in clover leaves (7% of N added), unaffected by temperature, already on 3rd day. This was followed by net N immobilization for about 4 weeks in the clay soil, with similar tendencies in the sandy soil, and more severely at the higher than the lower temperatures. After 80 days of incubation, net N mineralization was only 13–22% of total N in clover leaves. The ratio of net mineralized N to C was higher at lower temperatures, and higher in the sandy than in the clay soil. After the immobilization period, the N mineralization increased, positively related to temperature, and the ratio of net mineralized N to C became constant. In conclusion, low temperature during the initial phase of mineralization altered the ratio between net N and C mineralization from easily decomposable plant material, and the net N mineralization occurred more rapidly in the sandy soil. The change in stoichiometry at low temperatures, as well as the modifying effect of soil type, should be considered when predicting N mineralization of N-rich plant material.

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Persian walnut (or English walnut) growing dates back to 7000 BC in Persia, a gene center of Juglans regia L. The top leading countries in walnut production are China, the USA, and Iran accounting for ~75% of world production. Nuts are an essential component in human nutrition because their consumption provides the required amount of energy (720 kcal per 100 g of fruits), unsaturated fatty acids, carbohydrates, proteins, fibers, sterols, tocopherols, minerals (K, P, Ca, Mg, and Na), volatiles, and other bioactive constituents. In addition, walnut kernels are rich in oil (50–70%) and protein, depending on the cultivar, location, and irrigation rate. Although mostly consumed raw, walnut kernels are increasingly processed by cold pressing into light yellow edible oil used in foods as flavoring, like salad dressings or cooking. Walnut oil is especially valued for its high content of essential fatty acids (linoleic and linolenic acids) and micronutrients such as phytosterols, squalene, and other tree nut oils polyphenols, and tocopherols. As by-products, both shell and cold-pressed cake from walnut that remains after the cold pressing process of oil can be used in various ways (food, cosmetics, pharmaceutical products, or textile industry). Especially residual walnut press cake is practical when used in food and in pharmacy, mostly integrated into other products. The reason for treating residual cake as a value-added product lies in the fact that defatted cake is generally rich in polar phenolic compounds and, as a source of natural antioxidants, is expected to show significant antioxidant activity. The most abundant polyphenols found in walnut oil cake are hydrolyzable tannins. In addition, press cake is rich in dietary fiber, protein, residual oil, polyunsaturated fatty acids, and tocopherol, all considered health-enhancing components. Therefore, by using walnut oil cake as a low-cost product, many aspects connected with the valorization of food wastes are covered, such as consumers' dietary habits, economy, and environmental protection.