In Son La province only, the use of plant protection products including herbicides has increasingly grown in the recent years, from 58,907 kg (litter) in 2010 to up to 287,247 kg in 2016. It means that each hectare of agricultural land consumes one to two litters of this toxic substance, or even hundreds of times more if calculated in terms of dissolution rate. According to the Diep Du sales agent in Chieng Pan commune, Yen Chau district, Son La province, one hectare of corn field needs 18 kg of seed (equal to two million VND), one tone of various fertilizers (five to six million VND) and about one million VND of herbicide. Despite of the precautions, farmers often overuse this toxic substance. For instance, they use up to 15 bottles (900 ml each) of either quick or slow effect herbicide instead of seven, or two kilos of powdered herbicide instead of one kilo, making the total use of both types up to 50 – 60 bottles (18 litter each).