Temporal Effects of Compost and Fertilizer Applications on Nitrogen Fertility of Golf Course Turfgrass

Little information is available regarding the effects of compost topdressings on the fertility of low‐cut fairway turfgrass. The objectives of this research 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 interaction of compost and fertilizer applications on foliar N concentrations. Nitrogen was applied as inorganic fertilizer at rates of 96, 192, and 384 kg N ha−1 in 1997 and at 48, 96, and 192 kg N ha−1 in 1998 and 1999. Compost topdressings were applied every May and September from 1997 to 1999. Compost treatments consisted of: (i) 100% composted biosolids, (ii) a blend of composted biosolids and yard waste, and (iii) a nontopdressed control. Compost topdressings significantly increased turfgrass color, growth, and foliar N concentrations. Color enhancement lasted for up to 8 wk for plots receiving composted biosolids and for up to 5 wk for plots receiving the blend of composts. Composted biosolids increased foliar N concentrations for approximately 50 d following the May topdressings and for 26 d following the September topdressings. Foliar N concentrations following the May topdressings were increased by approximately 50% by the composted biosolids and by approximately 30% by the compost blend compared with the nontopdressed control. Differences in the duration of color enhancement brought about by the composts most likely can be explained by differences in N content of the composts used.