![Sample our Environment & Agriculture journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5934/TOC-Subject-Sample-2021-Environment-Agriculture.jpg"})
Summary
The effects and interaction of gibberellic acid and nitrogen on pasture production, composition, and nitrogen levels were studied on a 2-year-old sward of ryegrass and white clover following mid-April application when the natural growth rate was slow.
The application of gibberellic acid caused a rapid stimulation of growth, reaching a maximum within four weeks. Fertiliser nitrogen was slower acting, but its production equalled that obtained from gibberellic acid six weeks after application. Over the subsequent six months gibberellic acid depressed yields significantly, while slight nitrogen responses continued. No significant interactions were recorded.
Gibberellic acid caused yellowing of the herbage and stem elongation up to the first mowing, six weeks after application.
Yield responses and depressions of individual species resulting from treatment with gibberellic acid are presented. There was evidence of an increase in sward density within six weeks of application.
Gibberellic acid caused increased yields of nitrogen (oven-dry material) up to six weeks after application. Samples taken fourteen weeks after application showed a lowering of nitrogen yields from the acid treatment.