Management Effects on Biomass and Foliar Nutritive Value of Robinia pseudoacacia and Gleditsia triacanthos f. inermis in Arkansas, USA

Abstract

The browse potential of black locust (Robinia pseudoacacia L.) and thornless honey locust [Gleditsia triacanthos f. inermis (L.) Zabel] has not been adequately tested. Our objective was to determine effects of fertilization and pollarding on biomass and foliar nutritive value in separate studies of black locust and thornless honey locust in Arkansas, USA. Shoots were sampled monthly for two consecutive growing seasons in 2002 and 2003 to determine foliar, shoot, and total aboveground biomass, shoot basal diameter, and foliar nutritive value (crude protein and in vitro digestibility). Black locust yielded more foliar biomass when pollarded at 50 or 100 cm and fertilized with 600 kg P ha 1 , than at 5 cm with or without P, averaging 3.5 Mg dry matter ha 1 . Black locust foliar crude protein and in vitro dry matter digestibility ( £170 and 534 g kg 1 , respectively) decreased as leaves aged, but still met maintenance needs for beef cattle (Bos taurus L.). Thornless honey locust had little agronomic potential because of slow establishment, low foliar yield (330 kg ha 1 ), and a 2% reversion to undesirable thorny phenotype. Black locust should be