Forage shrubs for the South Island dry hill country: 2. salt/lime amendments have potential to improve the versatility of saltbush (Atriplex halimus L.)

Abstract

Mediterranean saltbush (Atriplex halimus L.) seedlings were transplanted into a low-nutrient potting mixture amended with nine treatments of salt and/ or lime, and magnesium sulphate. Plant growth parameters were measured at regular intervals and the experiment was terminated at week 20, after which the rootshoot ratio was determined. A low rate of salt/lime (0.25% w/w) produced significantly greater stem elongation than other treatments, most of this occurring during the first 13 weeks of the trial. On termination of the trial, shoot/plant dry weight from this treatment was also greater. Field trials have recently been established on Omarama YGE soils in the Mackenzie Basin and Blackstone YGE soils near the Upper Manorburn Dam, Central Otago to investigate the effectiveness and longevity of this response, and the likely level of maintenance applications necessary to retain good survival and productivity in soils previously considered poorly suited to saltbush. Investigation of environmental limitations for saltbush over a wider geographic range and integration of this data with a GIS database is planned. An ability to plant saltbush as a forage shrub into soil types not previously thought suitable using readily available, economical soil amendments may provide sustainable agricultural benefits for a wider dryland farming market than originally anticipated. Keywords Atriplex halimus L., Mediterranean saltbush, soil fertility amendments, lime/salt, forage shrubs, sustainable dryland farming