raindrop impact, reduce sheet flow and thus reduce the need for check dams. The hollow grass stems of the straw collect and bind a surprising amount of fine sediment. Also, mulch will create a better bed for vegetation to establish. In contrast, the rock surfaces of check dams don’ t support grass and tend to provide ideal habitat for rubbervine( Cryptostegia grandiflora). Mulching requires considerable manual labour or, alternatively a round bale unroller could be used. Some unrollers are simple implements that can be pulled by a 4x4 farm utility vehicle. The application of mulch may need to be refined for sites, climates and soil types; experimenting with types of hay, thicknesses, distance between mulch berms and light soil covers. Figure 29 describes experimental mulching on Site 22 in September 2024.
• Mulch straw could also be used to make berms and may reduce the number of rock check dams required.
Pre October 2024 October 2022
January 2025
January 2025
Site 22 underwent maintenance work in October 2024. After lowering the height of the bund and addressing the rill erosion in the reshaped bowl, mulch was placed in berms on the contour. Large square bales were used. The mulch was placed as biscuits(~ 10 cm thick). As an experiment, the mulch lines in the leading third of the gully( right side in Figure 29) was partially covered with some local soil( topsoil and subsoil mix). A tropical pasture seed mix was hand sown over all disturbed areas. In January 2025, 16 weeks after the maintenance work pioneering forbs, particularly Tar vine( Boerhavia erecta), was covering a significant part of the treated area where soil had been placed on the mulch. Unfortunately, Bellyache bush had also germinated rapidly. The sown seed had not germinated yet. The yellow dot in the bottom left photo indicates position where the bottom right photo was taken, facing towards the gully head.
Figure 29. Maintenance at Site 22 in September 2024 included mulch strips on the contour to cover as much bare area as possible.
NQ DRY TROPICS 43