Experimental stylo accessions produce higher yields than commercial pasture legume varieties on light textured soils in southern Queensland.

Pasture legumes are the best long-term option to increase productivity of grass pastures for large areas of Australia, however there are no commercially available, summer-growing legume varieties that are well adapted to sandy and loamy textured soils in the frost prone sub-tropics. A recently completed eight-year project collected 40 accessions of legumes from old pasture evaluation trial sites that were sown more than 20 years ago, as well as two roadside locations. These accessions were compared to 10 commercial varieties and three previously shortlisted accessions across six trial sites (three districts and two soil types) in southern Queensland between 2016 – 2019, during drought years. The five highest yielding accessions of stylos were from two species (Stylosanthes scabra and S. seabrana) and had 39 – 67% higher yields than the best performing commercial variety when averaged across all trials. These accessions also had good disease tolerance and formed effective nodules with commercial rhizobia. The five highest yielding accessions have been shortlisted for release as new varieties due to their potential to significantly improve productivity for the grazing industries in the sub-tropics of Australia

Improving the reliability of establishing legumes into grass pastures in the sub-tropics

Poor establishment is the most common reason for failure of pasture legumes sown into existing grass pastures on commercial farms in the sub-tropics. Although good establishment is recognised as critical to the long term productivity and persistence of legumes, most producers use low-cost and low-reliability establishment techniques such as broadcasting out of planes after either no or minimal pasture disturbance (e.g. fire); one-pass cultivation with seed spread at the same time; or severe soil disturbance and a rough seed bed behind a blade plough used primarily for controlling woody regrowth. This paper reports the results of a trial designed to test the impact of different fallow periods (medium – 4 months; short – 2 months; disturb at plant and no disturbance); seed-bed preparation (cultivation or zero tillage); drilling or broadcasting seed and post emergence herbicides when establishing legumes into existing grass pastures. The most common, commercially used establishment techniques of sowing legume seed into grass pastures with no disturbance or single pass cultivation treatments at plant all resulted in establishment failure. Spraying at plant resulted in adequate numbers of legumes. Short or medium fallows resulted in similar densities of legume plants with between all treatments, however treatments with greater control of the grass and post emergence weed control grew better which resulted in more seedling recruitment in the subsequent year. At 25months after sowing only fallowed treatments with Spinnaker post-emergence weed control achieved legume numbers above benchmark figures for establishment success. The trial demonstrates that agronomic practices commonly used for grain cropping (such as fallowing to store soil moisture) can improve the reliability of establishing legumes into existing grass pastures