102 Schaffert and Percival: Influence of Biochar, Slow-Release Molasses, and an Organic N:P:K Fertilizer Arboriculture & Urban Forestry 2016. 42(2): 102–110 The Influence of Biochar, Slow-Release Molasses, and an Organic N:P:K Fertilizer on Transplant Survival of Pyrus communis ‘Williams’ Bon Chrétien’ Emma Schaffert and Glynn Percival Abstract. High mortality rates result from transplanting bare-rooted plants into urban landscapes where unsuitable soil conditions, such as low fertility and poor structure, oſten exist. Coupled with little aſtercare, these losses can cause high economic losses to the industry. Previous studies have shown lowered transplant stress and higher survival rates through the addition of soil amendments at the time of planting to improve soil conditions. The efficacy of three soil amendments applied singly and in combination—biochar, slow-release molasses, and an organic N:P:K fertilizer—were investigated for their potential to reduce transplant losses of Pyrus com- munis ‘Williams’ Bon Chrétien. Results of this investigation showed that use of these soil amendments in virtually all cases had sig- nificant positive effects on tree growth and vitality across two growing seasons. For example, all amendments reduced mortality of Pyrus communis ‘Williams’ Bon Chrétien’ by 20% compared to none in treated controls, while increases in fruit yield and crown canopy coverage per tree ranged from 19.3% to 46.7% and 14.4% to 31.1% over non-amended soils when averaged over two growing seasons. Amendments of biochar with an organic N:P:K fertilizer and an organic N:P:K fertilizer alone showed, on average, the high- est improvements in vitality and growth. Results indicate use of biochar, slow-release molasses, and organic N:P:K fertilizer amend- ments offer potential for increasing bare-root transplant survival and establishment of Pyrus communis ‘Williams’ Bon Chrétien. Key Words. Biochar; Fertilizer; Pyrus communis; Soil Amendments; Transplant Stress; Tree Mortality; Tree Planting; Urban Trees. Benefits of urban greening and urban forestry are increasingly recognized due to the wealth of sci- entific evidence showing how urban greenspace improves human physical and psychological well- being, as well as absorbing atmospheric pollutants and particulates, and reduces the urban heat island effect (Smardon 1988; Nowak et al. 2006; Susca et al. 2011). Research is now focusing on how to better plan, implement, and manage greenscape in urban environments, such as in towns and cities. For economic reasons, bare-rooted ornamental trees and shrubs are predominantly used in greenscape plantings. However, many of these plants are oſten unsuccessful in establishing aſter planting with mortality rates frequently ranging from 30% to 50% over the first growing season (Hirons and Percival 2012). Liſted bare-rooted tree stock are frequently subjected to large root losses (e.g., up to 98%) (Wat- ©2016 International Society of Arboriculture son and Himelick 1982) aſter becoming damaged or detached, resulting in a distorted root:shoot ra- tio and subsequent development of root defects, such as circling and promotion of irregular lateral root elongation (Hirons and Percival 2012). Addi- tional stressors post-liſting, including desiccation and rough handling, are viewed as the most com- mon cause of transplant mortality, although severity can be species specific, depending on their abil- ity to regenerate roots (McKay et al. 1999). These result in poor root to soil contact, poor root sys- tem permeability, and insufficient water uptake to meet the demands of canopy transpirational water losses, which causes internal water deficits (Kozlowski and Davies 1975; Grossnickle 2005). Stimulation of root growth following transplant- ing is advocated as a means of reducing transplant losses (Koch 1996; Rolland et al. 2002; Percival and
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