Irrigation Timing and Emitter Selection Affects Irrigation Efficiency and Plant Growth

Container nursery production requires large inputs of water and nutrients but often irrigation inputs exceed plant demand and lack application precision.  As a result of excess irrigation, excessive leaching of nutrients, such as nitrogen and phosphorus from container growing systems, occurs.  During a 3 year test, plant response and irrigation efficiency with micro-spray stakes combined with time of day of cyclic irrigation for production of container grown trees were evaluated. Irrigation efficiency was improved by 35% if applications were made in mid day or late afternoon with micro-spray stakes.  Container leachate volume was greater with early morning and evening irrigation than mid day or afternoon irrigation.  Nitrate-N and ortho-phosphate effluent was 67and 64% less, respectively, in container leachate from mid day and late afternoon irrigation compared to early morning irrigation. Micro spray-stake design affected irrigation efficiency.  Double sided stakes or rings had less overspray in #15 nursery containers than traditional fan style stakes. Height growth of Acer rubrum ‘Sun Valley’ maples was similar when trees were irrigated in early morning, in late afternoon or a combination of both. Trunk diameter growth was 10% larger with plants irrigated in mid day or late afternoon compared to plants that received only early morning irrigation.