EFFECT OF AGE, CUTTING INTERVAL, NITROGEN AND FARMYARD MANURE ON ROOT-GROWTH PARAMETERS OF FORAGE GRASSES IN AN ACID INCEPTISOL

AR experiment was conducted during 1988-92 to study the effect of age, cutting interval. fertilizer nitrogen and farmyard manure on root-gro wth parameters of forage grasses grown in an acid Inceptisol soil of S ikkim. Root biomass (tonnes/ha) of forage grasses decreased in the fou rth year compared with second year. A 60-day-cutting interval resulted in higher amount of below-ground biomass than 20-day-cutting interval . Application of nitrogen increased the total root biomass, specific r oot length and specific roots length density of forage grasses, but fa rmyard manure decreased the total root biomass in golden timothy grass (Setaria anceps Stapf ex Massey). An increase in soil depth increased the specific root length of forage grasses. The total root biomass pr oduced by forage grasses was in decreasing order of 'BN 82048' hybrid of pearl millet [Pennisetum glaucum (L.) R Br. emend. Stuntz] x napier grass (P.purpureum Schum.) > broom-grass [Thysanolaena maxima (Roxb.) Kuna] > guatemala grass (Tripsacum laxum Nash) > golden timothy grass > palm-grass [Setaria palmifolia (Koenig) Stapf] > thin napier grass [Pennisetum polystachyon (L.) Schult.] > 'Makuem' guinea grass (Panicu m maximum Jacq.) > para grass [Brachiaria mutica (Forsskal) Stapf] > d allis grass (Paspalum dilatum Poiret) > 'NB 21' napier x pearl millet grass > 'PGG 1' guinea grass > 'Hamil' guinea grass.