CN4238134

NGN Stubble management to improve seeding efficiency and crop establishment

Stubble management is a significant issue in Western Australia particularly in the high rainfall zone, where it is not uncommon for cereal yields to reach over 7 t/ha with the resulting stubble loads being up to 10 t/ha. This is a high amount of stubble residue left post harvest and is an increasing concern for local growers due to poor establishment of following crops, nitrogen (N) tie-up, disease carryover issues and seeding operation inefficiencies such as, blockages, hair pinning, poor soil throw and bulldozing. As a result, plant establishment has become increasingly difficult, particularly Canola establishment.  Traditionally, high stubble loads in the region have been removed by burning, however, there has been a move away from burning due to a combination of social license issues, as well as farming system concerns. Burning increases the risk of erosion and nutrient loss and decreases soil moisture. Growers are also concerned with Nitrogen (N) tie-up from retained crop stubble. Although cereal stubbles contribute very little N to the following crop, stubbles are a source of carbon and N is required from the soil to breakdown this high carbon material. Previous GRDC research has been conducted to understand the additional N requirements needed to overcome early N immobilisation by stubble, this research suggests that an additional 5-6 kg N/t of cereal residue can help overcome the issues of stubble N immobilisation. (https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2018/02/the-effect-of-stubble-on-nitrogen-tie-up-and-supply). Investigation into whether the addition of nutrients, in addition to an enzyme ‘digester’ to stubble in conjunction with mechanical stubble treatments, during the summer fallow period, can increase the rate of stubble breakdown to allow for improved winter crop establishment (especially canola) and reduction in early season nitrogen tie-up. Reduced carryover of stubble-borne diseases could also be explored via observations

Locally relevant spring and/or summer sown cropping opportunities for grain growers following excessive winter waterlogging – South-Western Australia

Locally relevant spring and/or summer sown cropping opportunities for grain growers following excessive winter waterlogging - South-Western Australia

Since January 2021, the price of urea has increased from $256/t to $1,026 (Australian Trade and Investment Commission, 2022). This has been driven by rising global energy prices and by Russia and China imposing fertiliser export restrictions in 2021 and constraining global supply. It has been predicted that continued conflict between Russia and Ukraine will further increase global energy and fertiliser prices. This is currently a considerable concern for growers in Western Australia. Growers in the highly productive (and high-risk) Albany Port zone are looking towards management measures that will de-risk their nitrogen strategies. An opportunity lies in utilising often plentiful residual soil moisture at harvest to seed a legume cover crop such as cowpea, lab lab, soybeans, vetch or other small seeded legumes that can be brown-manured and incorporated prior to seeding. This is in place of the traditional summer chemical fallow.