17. After harvesting a crop of cereals (other than maize), oil seeds or grain legumes (such as peas or beans) the controller shall ensure that from harvest until 1 March in the following year, one of the following conditions is met on the land at any time:
(a)the stubble of the harvested crop remains in the land; or
(b)the land is sown with a crop which will take up nitrogen from the soil; or
(c)the land is left with a rough surface, ploughed or disced, to encourage the infiltration of rain.