Temporal effects of compost and fertilizer applications on nitrogen fertility of golf course turfgrass

Little information is available regarding the effects of compost topdressin gs on the fertility of low-cut fairway turfgrass. The objectives of this re search were to assess: (i) the effects of compost and inorganic fertilizer applications on turfgrass color and growth, (ii) the duration and magnitude of compost topdressings on foliar N concentrations, and (iii) the interact ion of compost and fertilizer applications on foliar N concentrations. Nitr ogen was applied as inorganic fertilizer at rates of 96, 192, and 384 kg N ha(-1) in 1997 and at 18, 96, and 192 kg N ha(-1) in 1998 and 1999. Compost topdressings were applied every May and September from 1997 to 1999. Compo st treatments consisted of: (i) 100% composted biosolids, (ii) a blend of c omposted biosolids and yard waste, and (iii) a nontopdressed control. Compo st topdressings significantly increased turfgrass color, growth, and foliar N concentrations. Color enhancement lasted for up to 8 wk for plots receiv ing composted biosolids and for up to 5 wb for plots receiving the blend of composts. Composted biosolids increased foliar N concentrations for approx imately 50 d following the May topdressings and for 26 d following the Sept ember topdressings. Foliar N concentrations following the May topdressings a ere increased by approximately 50% by the composted biosolids and by appr oximately 30% by the compost blend compared with the nontopdressed control. Differences in the duration of color enhancement brought about by the comp osts mast likely can be explained by differences in N content of the compos ts used.