Effect of White Clover (Trifolium repens L.) Undersowing Cultivation and Nitrogen Fertilization on Weed Infestation, Biomass Yield and Its Component, Content and Uptake of Macroelements of Willow (Salix viminalis L.)

Abstract

Fertilization of willow with nitrogen is an important issue with economic and environmental implications. The study was aimed at determining the effect of nitrogen fertilization and white clover on weed infestation, morphology, biomass and chemical composition of willow. A field experiment was established at Wroclaw University of Environmental and Life Sciences (Poland) during the years 2013–2017 with the use of a randomized complete block design (RCBD). The results showed that the number and dry mass of weeds per m2, the number of willow shoots and the fresh weight yield of willow were smaller where the clover was sown. The plants were found to be higher after applying nitrogen fertilization. The dry mass yield and shoot diameter did not depend on the cultivation method. Nitrogen fertilization increased the ash content. Undersowing willow with white clover, higher nitrogen content was found. Nitrogen fertilization increased the content of ash, and in undersowing cultivation, the willow stems had higher nitrogen content than in monoculture. On average, the phloem had 5.6 times higher crude ash content and 4.6 times higher nitrogen content than wood. On the basis of the conducted research, it can be concluded that in the first years after planting, the undersowing growing of willow with white clover can be an alternative to plantations fertilized and non-fertilized with nitrogen.