Question:  query regarding leech  control in  water logged grassland 
Answer:  told him to keep some bloodstained piece of meat in a large basket & place the basket on the water, so that the  upper rim of the basket is just 1/2 inch below the surface of water -- after some time the leech will accumulate there , -- then remove the basket & kill or destroy the with the help of lime[ sodi-bi-carb] or sodium chloride [ common salt ] to cut the grass in such place one can use mustard oil on their leg, but action of mustard oil is just for 15 -30 munites -