Legume establishment in challenging environments of northwest Queensland

Abstract

Establishing legumes on Mitchell Grass Downs country in northwest Queensland has the potential to reduce seasonal nutritional deficiencies, and subsequently increase animal performance within beef production systems. Legumes present an opportunity to increase crude protein (14 to18%) and metabolizable energy (8 to10 MJ/ME/kg DM) in the diet, as the nutritional quality of grass dominant native pastures declines markedly during the dry season (May to October).

Recent research initiated by the Queensland Government, with support from the Australian Government and Meat and Livestock Australia (MLA), has trialled establishment of deep-rooted and productive legumes (Desmanthus, Stylosanthes) on a property 80 km northeast of Julia Creek, Queensland.

This site is characterised by naturally treeless cracking clay soils, highly variable summer-dominant rainfall, (550 mm average annual rainfall, CV=0.43) and is highly susceptible to drought. The soil contains adequate Colwell phosphorus levels for legume growth (12mg/kg), however, sulphur (MCP) is low (4.6mg/kg). Rainfall variability, highly competitive adapted annual grass species and high summer temperatures (average maximum of 38oC) make establishment of legumes difficult.

In January 2024, following 350mm of rain, uncoated Stylosanthes seabrana (Caatinga stylo, Primar) and scarified Desmanthus (Ray and Progardes) was broadcast onto cultivated strips (10 m wide) prior to further anticipated rainfall. No herbicide or fertiliser was applied. Assessment in March 2024 showed good seedling populations of desmanthus (~20/m2) with fewer Caatinga stylo (~5/ m2). In May 2024, the survival of seedling populations under a dense monoculture of Flinders grass (Iseilema spp.) was observed. Further measurements will be completed following the 2024/2025 wet season to confirm successful establishment of mature Desmanthus and Stylosanthes on this site. This research was initiated due to regional producer interest and will be utilised in extension efforts under the north Queensland Pasture Resilience Program (https://futurebeef.com.au/resources/qprp/).