Economics of agro-chemical use in paddy [rice] production: experience at Gal Oya [herbicides, insecticides, Sri Lanka]

agricultural chemicals analisis analyse analysis arroz asia asie cereales cereals cost benefit analysis crops cultivos cultivos de grano economic analysis economic plants grain crops herbicidas herbicide herbicides insecticidas insecticide insecticides methode methods pesticide pesticides plaguicidas plantas plante plante de culture plants produit agrochimique rice riz