Get reliable science

As a result of recent technological improvements, contour furrowing has become the accepted method of reclaiming scalds in semi -arid far western New South Wales. Landholders in the Broken Hill district now support a full time commercial rehabilitation scheme. The Broken Hill Land, Reclamation Demonstration Program commenced in 1986 as a four year investigation and demonstration program with the following objectives: develop contour furrowing technology; demonstrate the technology to landholders; make available the resources necessary for widespread implementation of the program. The significant developments of this program include the improvement of mouldboard design and ripper tyne configuration. These improvements have resulted in a longer furrow life, greater water holding capacity behind each furrow, and increased the volume of soil moisture storage. Erosion caused by excess runoff and wind is reduced, and runoff is harvested for plant growth and soil improvement. Survey of the furrows using a laser level system has enabled the survey /furrowing /reseeding process to become a one pass operation. This has not only reduced the cost per hectare but has also increased the accuracy compared with other survey techniques. Increased survey accuracy has maximised the volume and area of water ponding behind each furrow and also reduced the possibility of breaching. Results of contour furrowing trials at Broken Hill have indicated the importance of seedbed design and seed placement on the establishment of perennial saltbush species Atriplex vesicaria, A. nummularia and bluebush species Maireana astrotricha and M. pyramidata. Evaluation of twelve furrow zones indicated the most suitable sites for seed establishment. The sides of the furrow were found to be the most suitable sites for seed establishment. Poor establishment occurred from seed sown in the ponded zone above the furrow, the apex of the windrows and in the bottom of the furrow channel. Further trials investigated the suitability of three sowing methods: broadcasting; hand (precision) sowing at the preferred furrow zone; and a mechanical sowing method which incorporates low cost seedbed preparation and seed placement. These trials demonstrated the need for accurate seed placement in relation to the preferred furrow zone and control over sowing depth. Future trials will aim at improving the reliability of seed delivery and sowing depth, articulation of the mouldboard and pre- sowing seed treatment.