The effects of clipping height and frequency on net primary production ofAndropogon gerardii(C4grass) andBromus inermis(C3grass) in greenhouse experiments

Abstract

AbstractThere are potential agronomic and environmental benefits from incorporating warm‐season (C4) grasses into temperate pasture systems, usually dominated by cool‐season (C3) grasses, but there is a lack of information on how frequency and height of defoliation affects C4grasses. Three greenhouse experiments were conducted under (i) spring, (ii) summer and (iii) spring + summer clipping regimes. In each experiment, the effects of clipping frequency (weekly and monthly) and clipping height (clipped to 5 and 10 cm) were determined on above‐ and below‐ground net primary production (ANPP and BNPP) and total and seasonal dry matter (DM) yield forAndropogon gerardiiVitman (big bluestem, C4grass) andBromus inermisLeyss (smooth brome, C3grass). Six replicates per treatment were used. In all experiments, ANPP and BNPP of smooth brome was greater than that of big bluestem although during late summer months big bluestem had higher DM yields of herbage than smooth brome. There were different effects of frequency and height of clipping for both species on two similar measurements: total annual DM yield and ANPP, indicating that the ability to generalize about the effects of defoliation from ecological and agronomic grassland standpoints is questionable. Clipping effects on ANPP and BNPP were different for summer‐clipped pots than for spring, and spring + summer‐clipped pots, indicating that management could be tailored to meet specific agronomic or conservation goals.