Ferguson J.C.,Lincoln University at Christchurch |
Hewitt A.J.,Lincoln Agritech |
Eastin J.A.,Kamterter Products LLC |
Connell R.J.,Lincoln Agritech |
And 2 more authors.
Journal of Plant Protection Research | Year: 2014
Drift Reduction Technologies (DRTs) are becoming increasingly important for improving spray applications in many countries including New Zealand (NZ). Although there is a growing database on the performance of DRTs, there is no rating system showing the effectiveness of the DRT's performance. In Europe, DRTs are classified relative to current reference technologies as part of the rating systems used to establish spray drift risk reduction. We have recommended some key elements of such a comprehensive exposure risk reduction scheme for any country, based on prior and on-going research into the performance of specific DRTs in row, tree, and vine crops. Our intention was to create a rating system to determine the effectiveness of a given technology. This rating system would improve spray application practices and environmental stewardship for a wide range of crops and application scenarios.
Barkle G.F.,Aqualinc Research Ltd |
Stenger R.,Lincoln Agritech |
Wohling T.H.,Lincoln Agritech |
Wohling T.H.,University of Tübingen
Soil Research | Year: 2014
To investigate the fate of nitrogen (N) from urine, dairy cow urine was amended with bromide (Br) and chloride (Cl), and applied onto a loamy sand soil with an underlying vadose zone of gritty coarse sands and pumice fragments with groundwater at ∼5.5m depth. Textural changes and hydrophobicity resulted in heterogeneous flow and high variability in the Cl, Br and N masses captured. Three forms of N derived from the urine, organic-N (org-N), ammonium-N (NH4-N) and nitrate-N (NO3-N), were measured at 0.4m depth. At 1.0m depth, effectively all measured N was NO3-N. At 4.2m, the mass of recovered N (average 33% of applied N, s.d. 21%), although solely speciated as NO3-N, was not significantly different from that at 0.4m (average 24.5% of applied N, s.d. 0.1%), suggesting that no substantial assimilation of NO3-N had occurred in this vadose zone. Below the interface of the Taupo Ignimbrite and the Palaeosol at 4.2m depth, recoveries of the Cl and Br tracers were negligible. In addition, the isotopic signatures (δ18O and δ15N) of the nitrate were different and the NO3-N concentrations were higher than in the upper vadose zone. These results all suggest that the Palaeosol was acting as a hydraulically limiting layer resulting in lateral unsaturated flow occurring at this interface. The fact that no nitrate assimilation was observed in this field study, despite previous laboratory studies showing substantial assimilative capacity, underlines that that the nitrate assimilative capacity in the vadose zone is a function of both hydrological and biogeochemical factors. © CSIRO 2014.