Fertilizer use in paddy cultivation [Sri Lanka]

agricultural chemicals agronomic characters arroz asia asie cereales cereals costos costs crops cultivos cultivos de grano economic plants economic sectors engrais extension extension activities fertilizers grain crops plantas plante plante de culture plants precios prices prix productividad productivity produit agrochimique professional services profitability rentabilidad rice riz secteur tertiaire sector terciario service service professionnel services servicios servicios profesionales tertiary sector vulgarisation agricole