Yield and quality of irrigated summer fodder crops in northern Victoria

Abstract

Dry matter (DM) yield, in vitro digestibility (DMD%), and nitrogen (N) concentration were determined for 28 cultivars of millet (Echinochloa utilis), hybrid forage sorghum (Sorghum spp.) and maize (Zea mays), under irrigation at Kyabram, Victoria. These summer fodder crops produced large amounts of digestible dry matter (DDM) under intensive irrigated management in northern Victoria, indicating their potential importance for animal production in irrigated warm temperate regions, where pasture dominates the present land use. Single harvest cultivars produced more DM and DDM than did multiple-cut types but with a lower N concentration and generally lower digestibility. Comparing the highest 3-year mean yields for each species, sweet sorghum cv. Honey drip produced more dry matter (273 t/ha) than did maize cv. XL77 (21.6 t/ha) but yields of DDM were similar (14.4 v. 14.0 t/ha). Both yielded more DM and DDM than grain sorghum cv. Pacific 303 (20.1 t DM/ha and 12.4 t DDM/ha). Maize had higher digestibility (65.0%) than grain sorghum (61.5%) or sweet sorghum (53.0% DMD) and higher N concentration (1.1%) than sweet sorghum (0.9%). All maize cultivars had similar dry matter yields but differed in grain yield. Echinochloa millet cv. Shirohie produced a similar amount of DM (16.3 t/ha) and DDM (10.8 t DM/ha) to sorghum x sudan grass hybrid cv. Sudax (17.1 t DM/ha and 10.7 t DDM/ha). This contrasts with their comparative performance at lower latitudes where sorghum hybrids have the higher yield. There was no difference in mean yield between cultivars of sorghum x sudan grass hybrid. Millet had a higher digestibility (65.9%) and nitrogen concentration (1.9%) than sorghum x sudan hybrids (63.3% DMD, 1.5% N). In this environment, maize and Echinochloa millet had similar DDM yield capacities to sorghum cultivars oftheir equivalent type but superior forage quality.