Using nitrogen (N) to grow feeds is a very practical option especially during the colder months. After an extremely dry summer leading to low soil N levels, strategic use of N can grow cost effective feed.
Key points to consider are:
- Focus N applications to paddocks that have a good grassy composition. These paddocks are usually coming off a long cropping rotation and are being spelled due to weed issues. Look for areas that have a high ryegrass residual stubble.
- Good Rates of N are required to maximise growth. 80-100L of Flexi-N is recommended. You are better off applying higher rates to a smaller area than lower rates to a bigger area. Work done in Esperance last season showed that we grew 14kg DM/kg N using 50L/ha of Flexi-N but by increasing rates to 100L/ha growth rates doubled to 29kg DM/ kg N.
Nil – Top Left 880 kg/DM/ha
50L/ha Flexi-N - Top Right = $30/ha: 1180 kg/DM/ha or 300kg more or 14kg DM/kg N
100L/ha Flexi-N – Bottom Left = $60/ha : 2130 kg/DM/ha or 1250kg more or 29kg DM/kg N
200L Flexi-N – Bottom Right = $120/ha : 4060 kg/DM/ha or 3180kg more or 37kg dm/kg N
- Defer grazing for at least 10 -12 days if possible, this allows pasture to give the best response.
- Timing of N applications can be difficult. Nitrogen needs to be applied prior to the rain and in dry years this can be hard to predict. Using Flexi-N rather than urea can lower the risk of losses through volatilisation. Rather than waiting for rain and germination it may make sense to apply the N earlier than later.
- Insect control especially as the months become colder. Insect numbers of 12 000 mites/m2 is the equivalent to 1 DSE. Consider a residual insecticide pre-rain. Flexi-N can be used as a carrier and do both jobs at once.