A method of providing a plant nutrient composition, the method comprising: (a) contacting a cellulosic material with a composition comprising an amino compound; (b) contacting the cellulosic material with a composition comprising carbon dioxide, sulfur dioxide and mixtures thereof; (c) optionally, contacting the cellulosic material with a composition comprising a source of one or more elements selected from nitrogen, phosphorous, potassium, calcium, magnesium, sulphur, boron, cobalt, chlorine, copper, iron, manganese, molybdenum, zinc and sodium; (d) optionally, contacting the resultant material with a plant and/or a base growing medium.