The above table demonstrates the importance of early sowing to maximise returns per hectare on forage brassicas.
This trial was run in a very dry spring year with rainfall well below average from September to February and higher than average temperatures. This highlights the importance of sowing early with available moisture for both forage yield, carrying capacity and subsequently gross returns.
*Stocking rate – based on 50 days grazing; lambs turned off average 40kg lwt, with feed on offer of 2.5kg/head/day and averaged 270g/head/day growth rates.
**Total value – assumption dressing out 46%. The early sowing produced an additional $621/ha over the later sowing.
Note: Market price example of 650c/kg cwt the early sowing would produce an additional $807/ha.
Brassicas do best in a rotation following grass but may be sown after any crop. If sowing after a crop, consideration should be given to herbicides applied during the cropping phase.
As forage brassicas are small seeded, sow into a fine, firm seedbed and ensure good seed to soil contact. Ensure maximum germination by sowing at a depth of 10-15mm (approximately). For best results, sow when soil temperature is 10°C and rising, and moisture levels are adequate for germination. Seed should be drilled or broadcast and rolled into a cultivated seedbed. Avoid broadcasting seed if the soil is dry.
Seed on a dry surface will not germinate until substantial rain (at least 20mm) has fallen. Depending on farm practices, direct drilling/drilling (whether the paddock is cultivated or uncultivated) can also be successful for sowing a brassica crop.
Brassicas are sensitive to water deficiency, especially at establishment. Shallow-rooted crops (leafy turnips, turnips and swedes) are more sensitive, while deep-rooted crops (kale, rape and raphanobrassica) tolerate drought conditions better. Forage brassicas can produce between 20-40kgDM/mm of water used. Ensure adequate time is given when applying knockdown herbicides to allow complete weed kill while conserving soil moisture before sowing a forage brassica.