Novel Approaches to Optimise Early Growth in Willow Crops

Isabella Donnelly,John Finnan,Kevin Mcdonnell

doi:10.3390/agriculture9060116

Isabella Donnelly, John Finnan + Show 1 more

Open Access

https://doi.org/10.3390/agriculture9060116

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Abstract

Willow is a fast growing, high yielding biomass crop that can help reduce reliance on fossil fuels. However, long establishment times to get to profitability and sustainable yield may deter interest in planting the crop. A number of different approaches were investigated to optimise and accelerate early growth. These approaches were water immersion, plastic application, altering stem orientation at planting, altering coppicing timings and applying growth hormone. Glasshouse and field trials were used to test the different approaches. In this work, planting material was soaked for a varying number of days and plastic was applied or not applied in field trials. In the planting orientation approach, stems were planted diagonally or vertically with half of the planting material above the ground level or horizontally below ground level. Additionally, willow crops were coppiced at different times throughout their first growing season and a growth hormone trial was also incorporated in this work. Water soaking, plastic application, coppicing during the growing season or hormone application did not improve early growth or yield. However, early growth and yield were increased by manipulating the planting orientation of willow stems. Planting orientation treatments in which part of the stem was left above the ground increased early growth and yield significantly compared to the control without requiring extra inputs at planting. The beneficial effects of coppicing can be achieved by manipulating the planting procedure so that the first year’s growth is not disregarded.

Highlights

Ireland imports 89% of fuel for energy which is mainly made up of fossil fuels [1]
The later in the growing season that coppicing is practised, the greater the detrimental effect on yield as displayed by treatment 4. These results demonstrate that coppicing willow crops, during the growing season, retards growth and substantially delays yield development
Pre-soaking of willow planting material has been shown to increase the water content of willow cuttings and promoted root initiation and development [37,38], but our work found that these benefits do not translate to higher yields in a field setting

Summary

Introduction

Ireland imports 89% of fuel for energy which is mainly made up of fossil fuels [1]. There is a concerted effort by policy makers to develop indigenous sources of energy, mainly driven by European Union Directive 2009/28/EC, which outlines the requirement for 16% of Irelands energy to come from renewable sources by 2020 [3]. Half of Irelands forests are less than 25 years old [7], and the time required to mobilise biomass resources from Ireland’s limited current and future forestry may be too long and unfeasible to yield significant biomass supply in the short term [8]. Biomass is used for renewable energy generation at present in Ireland but the huge potential offered by bioenergy is relatively untapped, with an over reliance on imported fossil fuels [9]. Cost efficient allocation of biomass should get more attention to allow the sector to prosper and become an economically profitable farming enterprise [10]

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