Summer crops play a key role in dairy feed systems, especially as farmers work to produce as much home-grown feed as possible.
Summer crop options
Options for summer crops, which will depend on the region, soil moisture and access to irrigation water, include maize, millet, sorghum, chicory, brassicas and legumes. Annual or Italian ryegrasses are worth considering for quick spring feed.
Planning is important to get the best production from your summer crop investment and remember to purchase seed early to ensure supply.
Maize is a summer silage crop with the potential to produce a large amount of high-energy forage. It has a lower cool tolerance compared to sorghum and millet with higher yield potential and no prussic acid. Maize silage is highly valued because it typically contains around 30 per cent starch. Grain contained within the plant is the primary source of starch and one of the main factors driving silage energy density, along with fiber digestibility.
The key aims of maize silage production are yield and energy content. Growing maize for silage is expensive and therefore requires good management to achieve high yields of high-quality product to be economically viable. It requires specialist row-crop planting and harvesting equipment and is suitable only for chopped silage stored in a pit or bunker.
Millet and sorghum
Millet and sorghum are summer forage options for dairy farms due to their potential to rapidly accumulate dry matter in warm conditions. They perform better than most other annual summer crops when soil moisture is limited, making them a good option when water is scarce. Millet and sorghum have a high tolerance to water stress and low risk of insect attack and as a result produce more feed than most broad leaf summer crop options. However, yields can be affected by low temperatures in summer.
The nutritional value of millet and sorghum tends to be less than other summer crops. Both are lower in crude protein (6–9 per cent) than other summer crop options and higher in fibre concentration which will affect dry matter intake.
Chicory is a deep-rooted summer-active, short-term perennial herb with potential to provide good grazing for dairy herds in southern Australia. It has significant growth potential in late spring and summer, which can complement the seasonal production pattern of perennial ryegrass. It can provide reliable summer growth, even with low rainfall due to its deep taproot system and has high nutritive characteristics when grazed (+12 MJ ME/kg DM and up to 25 per cent DM crude protein).
Brassicas are grown on about 70 per cent of dryland dairy farms in southern Victoria and Tasmania. Ensuring you achieve a high conversion of crop into milk requires planning and good management. Turnips are a popular brassica crop because they grow well in summer and are very nutritious for dairy cows. Current turnip varieties are leafier and more upright than older varieties with two-thirds of the bulb above the ground. Bulb turnips are also used to help bridge a summer feed shortage.
Regrowth brassicas are forage crops of the brassica species that can regrow after most of the aerial part of the plant has been grazed. They include forage rape (Brassica napus), kale (Brassica oleracea), hybrids such as pasja (Brassica campestris x Brassica napus) and leafy turnips. Regrowth brassicas are gaining popularity among dairy farmers in southern Australia, mainly as an alternative to bulb turnips during summer and more recently as an autumn forage option.
Lablab is a high-protein summer legume crop that can be grown in northern Australia under irrigated or dryland conditions. It can be grazed or harvested for silage during summer and autumn. Lablab is a creeping vine that will grow to between one and two metres high, producing yields of between five to eight tonnes of dry matter per hectare if irrigated and grazed well. It can also produce crude protein levels as high as 35 per cent.
Soybeans are a summer legume grown as a high-protein and cost-effective silage option in northern Australia. Soybeans have the highest yield (up to 14 tonnes of dry matter per hectare) and forage quality (more than 22 per cent crude protein) potential of summer legume crops and can be grown under dryland conditions.