Stinging Nettle (Urtica dioica L.) as an Aqueous Plant-Based Extract Fertilizer in Green Bean (Phaseolus vulgaris L.) Sustainable Agriculture

Branka Maričić,Nikola Major,Igor Palčić,Marija Romić,Zoran Zorić,Dean Ban,Smiljana Goreta Ban,Branimir Urlić,Sanja Radman,Josipa Perković

doi:10.3390/su13074042

Abstract

Plant-based fertilizers, such as liquid plant extracts, contribute to the cultivation of vegetables, particularly in organic production. The objective of this study was to determine if aqueous nettle extract could be successfully used as a fertilizer, applied on the soil and foliarly, in green bean production under field conditions. The hypothesis was that it could successfully replace mineral fertilizers and be integrated into sustainable and organic agriculture. The experiment was conducted at two climatically and pedologically different locations (Zadar and Poreč) throughout two growing seasons (spring and autumn). Two types of aqueous nettle extracts were used: a short-term extract (SE) was prepared by the extraction of wild stinging nettle (183 g 10 L−1 of water) in water for 24 h, while a long-term extract (LE) was prepared at the same ratio with water extraction for 14 days. Both extracts were diluted with water at a ratio of 1:3 (extract:water) before use. The SE was applied foliarly, and LE, by pouring it onto the soil. The abovementioned treatments were compared with mineral fertilization with urea (U) and control (no fertilization (C)). Foliar fertilization with SE proved to be almost as efficient as fertilization with LE, poured onto soil, showing a positive effect on green bean vegetative parameters. Furthermore, aqueous nettle extracts showed a positive effect on the iron accumulation in the leaves.

Highlights

The successes of modern agricultural production have, for a long time, been associated with the frequent use of mineral fertilizers and pesticides [1]
Two different aqueous extracts of stinging nettle and their influence as fertilizers on green bean cultivation were studied with respect to the yield, vegetative parameters and chemical parameters in leaves
Foliar fertilization with the short-term nettle extract (SE) extract was found to be almost equivalent to fertilization with the long-term nettle extract (LE) extract poured onto the soil regarding the yield and vegetative parameters such as plant height and diameter

Summary

Introduction

The successes of modern agricultural production have, for a long time, been associated with the frequent use of mineral fertilizers and pesticides [1]. Consumer attention has focused on food quality and control, leading to increased demand for organically produced foods. Vegetables are an important part of everyday meals, so it is advisable to understand their nutritional and chemical properties [2]. Recent studies suggest that the mineral content in vegetables has been declining [3]. Green beans (Phaseolus vulgaris L.) are a polyphenol-rich food and have a positive effect on human health in controlling obesity, diabetes and inflammatory processes in the body [4]. They are rich in vitamin C, fiber, carbohydrates, minerals and proteins [5]

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