Mr Glenn Mcdonald1, Mr Grey Poulish1
1Department of Primary Industries and Regional Development, Albany, Australia
Biography:
Glenn is a research scientist with the Department of Primary Industries and Regional Development. He has more than 25 years’ experience in crop agronomy and physiology research including soil amelioration, waterlogging, drought and oats as well as a stint as a grower group facilitator. Glenn and his family live in Albany and he works throughout the South Coast and Great Southern as part of DPIRD’s “Soil Reengineering” project
Abstract:
Duplex soils cover a large proportion of the WA Wheatbelt and are difficult to ameliorate due to rapid changes in soil characteristics such as chemistry, depth to clay and soil texture. The effects of subsoil amelioration on these soils are poorly understood.
This research aimed to improve crop performance by increasing root exploration and improve the longevity of this effect through root growth enhancement.
One-off amelioration treatments were implemented at three sites during spring to optimise soil moisture conditions. Two different machine designs were used with one being used to inject liquid ameliorants at 10-40cm depth. The sites were bulk sown with the crop management by the host grower.
Both machines resulted in increased yield at all sites. The response to added ameliorants was less consistent but tended to enhance the positive yield effect of decompaction. The deeper the duplex clay layer, the less responsive to decompaction the sites were. It is logical that where the dense clay layer is closer to the surface, fracturing this clay to encourage deeper root exploration would result in greater yield responses.
While decompaction increased root abundance, the addition of banded subsoil ameliorants at 10-40 cm depth only increased root abundance where the clay layer was shallower. For the site with the shallowest clay layer, the surface application of extra phosphorous fertiliser at treatment implementation increased grain size and yield without change in crop biomass. This indicates that the extra yield resulted from improved root growth providing additional soil water access during grain fill.