| Popis: |
Lupins are frequently the preferred legume species used in dryland crop rotations on light sandy soil types. These soils are prone to erode and the probability of sandblasting is increased if sown to lupins because of their slow growth and low vegetative cover during establishment. In addition, lupins are vulnerable to sandblasting, having above-ground growing points in contrast to cereals where the meristem is below ground and sheltered from damage unless erosion is severe. Consequently, there is concern about sandblasting having an economic impact on farming returns by causing yield reduction in lupin crops. This study reports the impact on the development and yield of narrow-leaf lupins exposed to different durations of sandblasting at a constant wind speed. A portable wind tunnel was placed in the field generating a turbulent boundary layer with a constant free stream mean velocity of 13.7 m/s. Field-grown plants of narrow-leaf lupin (cv. Merrit) were exposed to this velocity field with a total transport mass of 0, 42, 78, 153, and 248 kg/m achieved by maintaining a constant rate of soil introduction and increasing the run time. Plants with an average leaf number of 3.4–9.7 showed macro-damage symptoms increasing in severity with increased transport mass. Yield reduction was not significant up to a total transport mass of 78 kg/m at which plants were showing damage symptoms of wilting and burning of immature leaves and with minor damage of mature leaves. As levels of total transport mass increased, yield reduction occurred, until at the maximum treatment level of 248 kg/m, there was an 18% grain yield loss. At this treatment level damage symptoms included loss of most of the leaf tissue and scoring of the stem. These results indicate that sandblasting can cause significant yield reductions in lupin and that measures to control soil erosion through minimum tillage practices or windbreaks should be considered. |
