Utilising dual-purpose crops in an Australian high-rainfall livestock production system to increase meat and wool production. 1. Forage production and crop yields

Abstract

Context Growing of dual-purpose crops for grazing by livestock has increased in popularity in the high-rainfall zone of southern Australia, a livestock production zone traditionally based on permanent perennial grass species. Aims A systems experiment examined the impact on pasture forage availability, sheep grazing days and crop yields when one-third of a farmlet was sown to dual-purpose wheat (Triticum aestivum L.) and canola (Brassica napus L.) crops. Methods The experiment comprised nine experimental units (farmlets) divided into three treatments with three replicate farmlets per treatment: control farmlets sown to phalaris (Phalaris aquatica L.)-based pastures; and two treatments with grazing of crops prioritised for either ewes or their progeny. Control farmlets comprised four sub-paddocks (0.231 ha each) in 2013 and six sub-paddocks in 2014–2016. Farmlets in treatments that included dual-purpose crops comprised six sub-paddocks (0.231 ha), with two sub-paddocks sown to permanent pasture and the other four sub-paddocks supporting a pasture–pasture–canola–wheat rotation. Key results Crops were sown in February or early March and grazing commenced by mid-May in all years. Canola was grazed first in the sequence in 3 of 4 years. Treatments had similar total sheep grazing days per year, except for the progeny-prioritised treatment in 2014 when agistment wethers were introduced to utilise excess crop forage. Grazing did not affect wheat yields (3.9 vs 3.7 t/ha, P > 0.05) but did reduce canola yields (3.6 vs 3.0 t/ha, P = 0.007). Pasture availability (dry matter per ha in the pasture paddock at entry by sheep) was higher in the control during late summer and autumn when the crops were being established; however, resting of pastures during late autumn and winter while crops were grazed resulted in no difference in pasture availability among treatments during spring. Conclusion and implications The key feed-gap is in late summer and autumn when dual-purpose crops are included in the system. Early and timely sowing of crops increases the grazing opportunity from dual-purpose crops before lock-up. Growing wheat plus canola provided some hedge against poor establishment and/or slow growth rates in one of the crops.