Effect of Fodder Crops on Weeds in Summer Rice Fallow

In the summer rice fallow of double cropped low land rice filed, four different fodder crops were raised under varying nitrogen regimes with the objective of evaluating its effect on weeds, during 2017-18. The experiment was laid out in Randomized Block Design. The fodder crops were fodder cowpea (CO- 9), rice bean (Bidhan- 2), fodder maize (African tall), fodder sorghum (CO (FS) 31). The varying nitrogen regimes were 100, 75 and 50 per cent recommended dose of nitrogen (RDN). The weed composition in the experimental field included grasses, sedges and broadleaved weeds. Both at 20 and 40 days after sowing (DAS), the weed population was more in fallow treatment. The weed dry matter production was significantly more in the fallow plot. At 40 DAS, weed dry matter production was relatively less in fodder cowpea. Weed smothering efficiency (WSE) was relatively greater in all the fodder crops except fodder cowpea at 20 DAS. However, at 40 DAS the WSE in rice bean, fodder maize and fodder sorghum declined, while in fodder cowpea it increased. Nitrogen removal at 20 and 40 DAS was significantly more in fallow plot. At 40 DAS, both N and P removal by weeds was significantly less in fodder cowpea. At 40 DAS, K removal was significantly less in fodder cowpea especially at 100 and 75 per cent RDN.