Ground Cover Supplement : GC Supplement - Grain and Graze
yield was small and the heavy grazing produced 4t/ha of feed compared to 1.4t/ha when lightly grazed. "When deciding on stocking rate and grazing intensity, it will be a trade- off between the value of the feed over summer and autumn and final grain yield," explains Ms Paridaen. 2012-13 triAl Grazing management Canola resilience was well and truly tested in the 2012-13 trial, with three very heavy grazing periods between the end of January and the end of April. Ms Paridaen says plants were lost and for a while it seemed as if the crop would not recover. But the thick starchy stem and root system of the established canola enabled the plants to hang on and they started to grow back once the break finally came. "The recovery of the plants was just astounding," she says. "By winter 2013 it was impossible to distinguish the grazed and ungrazed plots." The 2012-13 trial demonstrated that canola can recover from the stress of complete defoliation and still go on to produce a reasonable grain yield (Table 2). The 2013 canola generated about one tonne less feed than the 2012 crop, but Ms Paridaen says the value of the green feed during the dry 2013 summer and autumn would most likely have outweighed the extra feed available in the more favourable 2012 season. "It is difficult to put a price on almost three tonnes of high-quality green feed when there is nothing else around," Ms Paridaen says. □ grdc research code sFs00020 more information: Annieka Paridaen, Southern Farming Systems, 03 5265 1666, firstname.lastname@example.org 19 Fodders and mixed farming "Monitoring feed levels during grazing is important, as it did not take long for the sheep to completely eat the paddock bare once they became accustomed to the canola. "In the 2012 trial, the third and final grazing was much heavier than planned due to the sheep eating it down very quickly." Grain yield Grazed canola yielded more than ungrazed canola in the 2011-12 trial, with nearby spring-sown ungrazed plots yielding 1.9t/ha compared to 2.7t/ha for grazed plots. Nearby canola (CBTM Taurus) sown at the conventional time (April) yielded 2.3t/ha. Grazed plants had more branches and a denser canopy than ungrazed plants. The number of times the crop was grazed had no significant impact on yield. Grazing twice yielded 0.1t/ha more than a single grazing and 0.2t/ha more than grazing three times (Table 1). "Although there was a yield penalty by grazing three times compared to two, the third grazing supplied an additional 1t/ha of high quality feed at the beginning of May," Ms Paridaen says. Heavy grazing reduced yield compared to light grazing, irrespective of grazing frequency. However, the reduction in Grazing spring-sown canola had no impact on final grain yield while delivering 3t/ha of high-quality sheep fodder during the extremely dry summer/autumn of 2013. The spring-sown canola compared very well to the commercial forage rape Winfred in terms of summer feed supply. TABLE 2 Dry matter production and grain yield for several winter canola varieties sown in spring 2012 and harvested in December 2013 at Inverleigh, Victoria. Variety Time of sowing Grazing Spring estab (pl/m2) Autumn survival (pl/m2) Reduction in plants (%) Summer DM (t/ha) Grain yield manual harvest (t/ha) Taurus Spring Grazed 47 26 --43 2.5 4.0 Ungrazed 42 30 --29 5.0 Autumn 8 3.6 Hyola 971 CL Spring Grazed 41 28 --28 2.4 4.6 Ungrazed 42 28 --28 5.2 Autumn 14 4.4 Hyola 930 Spring Grazed 42 26 --38 2.2 4.9 Ungrazed 39 36 --4 5.2 Autumn 11 4.1 CB 143 CL Spring Grazed 43 24 --44 2.3 4.2 Ungrazed 38 30 --18 4.5 Autumn 17 3.9 CB Sherpa Spring Grazed 38 24 --35 2.8 4.7 Ungrazed 43 27 --36 5.2 Autumn Not sown -- Winfred Spring Grazed 62 31 --49 2.8 -- LSD (P= 0.05) 12 7 NS NS 0.8 SOURCE: ANNIEKA PARIDAEN, SOUTHERN FARMING SYSTEMS PHOTO: ANNIEKA PARIDAEN grazing spring-sown canola had no impact on final grain yield while delivering 3t/ha of high-quality sheep fodder during the extremely dry summer/autumn of 2013.
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