Influences of Preceding Crops and Nitrogen Fertilization on Weed Population in Pasture Grasses

(1) Three cases were found by increasing of the nitrogen fertilization on forage grasses as follows: (a) Orchardgrass seeded in autumn predominated over the weeds, (b) both spring seeded orchardgrass and weeds increased, and (c) in the case of radino-clover seeded in autumn or spring weeds increased more than the forage crop, by the increase of nitrogen fertilizer. (2) The effects of preceding crops on weed population were also surveyed.