Ground Cover Supplement : GC Supplement - Soil constraints
5 Non-wetting soils WAX-DEGRADING BACTERIA Many bacteria present in soil produce bio-surfactants capable of releasing the non-wetting coatings from sand surfaces in water-repellent soils. Inoculation of water-repellent soils with these bacteria under laboratory conditions significantly reduced repellence compared with the non- inoculated control (Figure 4). However, inoculation of non-wetting soils under field conditions with the bacteria was less successful, most likely due to competition from other microorganisms. Enhancing populations of natural wax-degrading bacteria (for example, through liming) is likely to be the best way to lift their activity in repellent soils (pages 18 and 19). SOURCE: CSIRO FIGURE 4 Water repellence over time of a non-wetting soil sample either inoculated with a wax-degrading bacterial population or left uninoculated. 0 100 200 300 Time (days) Water repellency (MED) 3.0 2.5 2.0 1.5 1.0 0.5 With inoculant (73ww) No inoculant Bacteria (spirals and fine thread-like hyphae) and fungi (larger hypha, top left corner) living between sand particles. Many of the bacteria are capable of degrading the water-repellent waxy coating on sand particles provided sufficient moisture is present. SOURCE: DR GUPTA VADAKATTU, CSIRO Disturbing dry non-wetting soils can increase water repellence by as much as twofold. PHOTO: EVAN COLLIS SOURCE: CSIRO FIGURE 3 Canola emergence from non-wetting sand seeded dry (right) and following 25mm of rainfall (left).
GC Supplement - Foliar fungal diseases of pulses
GC Supplement - Grain storage 2015