Adapting soybean for profitable rotations in sugarcane farming systems : SRDC Final report

Abstract

Cropping of soybean has been shown by the yield decline joint venture to increase the yield of the following sugar crop by 15 to 30 percent. One impediment to the increase of soybean in sugarcane production systems is that the financial benefit of inclusion of a fallow crop like soybean into a sugarcane production system is delayed until sugar crops harvested in the following years. However, by inclusion of a grain soybean option, growers are more likely to manage the crop better and can gain the financial return from harvest of grain in addition to benefits to the following cane crop delivered by improved soil health. This project sought to complete varietal evaluation of experimental varieties with improved potential for harvest of grain through to the point of commercialisation to industry. Varietal evaluation trials were conducted at sites in the Burdekin, and on the Atherton Tablelands at early, mid season and late summer planting dates and in the south at Bundaberg and Nambour also at late summer planting dates and in the Burdekin during the dry season. In addition farmer participation in varietal evaluation was encouraged via strip trials. Ultimately eleven strip trials were conducted in the second year of the project and five in the third. In addition large scale seed increase of the new variety was conducted at Nambour and at Walkamin and a second round of seed increase sown in June 2005 in northern Australia. Soybean is unique among grains in having a very high content of protein of a type which is highly digestible and finds ready acceptance in stock feed milling. Grain of light hilum varieties is also readily accepted into higher-value human consumption markets. During the last year of this project, members of the Northern Australian Soybean Industry Association (NASIA) were involved in commercial evaluation and release of the new variety named Stuart. In particular North Queensland Tropical Seeds and Bettacrop conducted pre-release evaluation and also participated in the next round of evaluations along with Mt Tyson seeds Queensland Cotton, Beangrowers Australia and Philp Brodie Grains. The new variety has been licenced to NASIA for commercial production. The new soybean variety ‘Stuart’ was named after Mt Stuart south of Townsville, following the theme of local mountains. Stuart is adapted to coastal production from Nambour to Mossman. It has a very light grey hilum and is suitable for some human consumption uses. It has high levels of nematode and rust resistance, maturity a week or more earlier than Leichhardt and is adapted to both wet and dry season planting in north Qld and has generally higher grain yields. Stuart is taller than Leichhardt and adapted to row widths from 50 to 130 cm. It has a more erect and open canopy than Leichhardt, making control of insects by insecticide application slightly easier. Lodging may however occur with plant populations over 35 plants per square metre or in early-season sowing. Good quality grain possessing light hilum and apparent suitability for food grade uses was produced from strip trials in several farmers fields. Relative to existing varieties Leichhardt and YY, Stuart offers higher grain yield and higher value grain through access to food grade uses rather than feed or oilseed crushing. Release of a new soybean variety and an ongoing varietal improvement program will help to underpin sustainability in tropical cropping systems and provide a basis for new industry development.