b Department of Plant Physiology, Govind Ballabh Pant University of Agriculture & Technology, Pantnagar, India-263145 *Corresponding author email address: nainpooja6@gmail.com Annals of Plant and Soil Research 25 (2): 211-220 (2023) https://doi.org/10.47815/apsr.2023.10259 Characterization of pine needle and pine needle biochar: a potential soil amendment for sustainable forest waste management POOJA NAIN, K.P. RAVERKAR, RAMESH CHANDRA, NAVNEET PAREEK, S.K. GURU, GEETANJALI BHANDARI a Department of Soil Science, Govind Ballabh Pant University of Agriculture & Technology, Pantnagar, India-263145 Received, January, 2023; Revised accepted, May, 2023 ABSTRACT Pine needles are the residue of pine (Pinus roxburghii), a problematic forest waste and is highly flammable which is the one of major causes of forest fire in the North Western hills of India. High lignin and resin content with low moisture is the reason behind it being one. To find an appropriate management of this residue the pine needle was characterised and further converted to biochar (500 º C), a carbon-rich solid material produced through a process called pyrolysis by heating biomass, in the absence of oxygen. This process breaks down the organic matter into volatile gases, leaving behind a residue known as biochar. Pine needles are suitable for generating biochar due to their high carbon content, low moisture content, high lignin content, abundance and availability. The pine needles aromatic compounds contribute to biochar stability and potential applications. Physical, Physico-chemical, and spectral characterisation of biochar was performed to analyse its further applicability and the biochar, was found suitable as soil amendment and as a mean of enhancing soil organic carbon. Keywords: Pine needle residue, pine needle biochar, characterisation, soil amendments INTRODUCTION Pine needles, which are the result of the regular shedding of leaves from the fast-growing Chir pine (Pinus roxburghii) in the North Western Himalaya region (encompassing India, Nepal, and Bhutan), cover a vast forest area of approximately 7.62 million hectares (Mha). Every year a large amount of flora and fauna get affected due to fire in the pine forest. The reserve pine forest in Uttarakhand includes an area of about 0.343 Mha. In Uttarakhand alone, about 2.058 million metric tonnes (MMT) of needle wastes are available annually and in the Indian Himalayas region, it accounts for about 15.9 MMT per annum. Studies conducted in the hills of Uttarakhand, India, have revealed that pine needle productivity is estimated to be 6.3 tons per hectare per year (Singh et al., 2016, Singh et al., 2021). However, the natural decomposition process of pine needles is slow (Kainulainen et al., 2002), leading to their accumulation on the forest floor. This thick layer of dry needles poses two significant issues: it acts as a fire hazard and inhibits the growth of grass, which is a food source for cattle (Dwivedi et al., 2016). The occurrence of large-scale forest fires, often caused by the presence of this dense layer of pine needles, contributes to severe air pollution and has devastating environmental consequences (Tzamtzis et al., 2006). Consequently, it is crucial to find alternative uses for pine needles to mitigate the risk of forest fires. The kinetic studies suggest that pine needles can be a good source for conversion to bio-oil and biochar through pyrolysis. In light of the fire hazard posed by pine needles and their abundant availability in India, especially in hilly regions of Uttarakhand, the objective of this research was to study the properties pine needle biochar for its use as soil amendments/conditioner. MATERIAL AND METHODS Characterization of Pine needle residue Pine needle were first air-dried and then dried in an oven at 60±5ºC for 72 h and 6 h respectively. Proximate analysis was carried out to determine the volatile matter, fixed carbon and ash content of the pine needle (Table 1). According to the standardized test method for moisture analysis, 1 g of the sample was retained in a hot-air-oven at 105°C for 1 h. Next, the oven-dried sample was weighed. Moisture