A crop sown early to provide winter grazing plus a good grain yield, to be reliable, requires the highest agronomy standards.
Yet many of these crops ae sown almost as an afterthought with far less attention to issues like variety choice, stored soil water and high soil fertility.
Perhaps the biggest challenge for reliable dual purpose crops is getting them established early, and in a period typically low in rainfall of any consequence.
Being able to establish a crop on small rain events greatly improves reliability of timely establishment.
For example according to the app CliMate, based on 120 years of rainfall data, we can establish a winter crop in our favoured sowing window, around mid-February to the end of April, 95 percent of years on a 10mm or more rain event.
If we needed a 30mm rainfall event our probability drops back to 68 percent.
To establish successfully on lower rainfall amounts improves if one is able to choose lighter soil paddocks, have retained stubble cover, and have effectively conserved fallow rainfall since the harvest or graze-off of the previous crop.
How early to sow is a difficult decision and will vary from district to district with elevation (affects temperatures) important as well as year to year variation.
Seasonal variation in temperatures requires careful watching. A late heatwave would rule out sowing too early but being too conservative reduces the possible desirable sowing window and this reduces the probability of being able to sow early successfully.
Storing as much fallow water as possible, makes all the difference to being able to sow on time and to provide good winter feed, as well as the possibility of having stored soil moisture for grain recovery.
Research has shown, for most cropping areas of NSW, indeed Australia, good conservation of fallow moisture is worth on average 1.0 t/ha or more grain in grain only crops.
The benefit for dual purpose or grazing only crops is likely to be even greater. Often the difference between good winter feed and next to no winter feed.
One of my friends tells me he needs fallows for grazing over summer. I argue if you have pastures that grow well in summer, for example lucerne or tropical grasses, and if they are well managed, that fallow feed is not required and adds to winter feed when it is likely to be more required. Also allowing weeds to get away in the fallow, in addition to using stored soil water, commonly reduces nitrogen availability to the winter crop. Research suggests this is equivalent to around 50 kg/ha nitrogen.
Early sown dual purpose or grazing only crops mainly perform more reliably with more prolonged quality feed if varieties with "winter habit" are chosen.
"Winter habit" means varieties do not prematurely run to head, a problem if sowing "spring habit" varieties early, even slow maturing ones.
There are good "winter habit" varieties in most species used for dual purpose or grazing only, including oats, triticale, brassica, wheat and barley.
Commonly a major part of dual purpose crops is as part of a rotation prior to sowing pastures. If good fallow weed control is achieved, as well as in-crop, a new pasture has a higher probability of being established weed free.
Pastures starting off weed free have a greater establishment success as well as less in-pasture weed problems. These advantages generally last indefinitely, especially in long lasting pastures.
Weeds developing resistance to herbicides is an issue with dual purpose crops as it is with grain only ones.
Like many farmers we have added "double knock" to our strategy to get around fleabane and windmill grass developing resistance to glyphosate.
"Double knock" describes when a second herbicide treatment, for example gramoxone, follow seven to 10 days after the glyphosate 2-4,D treatment.
Timeliness of the first treatment, when weeds are young and fresh also is important.
High soil fertility is important for productive dual purpose or grazing only crops.
Nitrogen is commonly the critical issue. Its efficient use requires other elements, such as phosphorus, not to be limited.
Next week: Timeliness, planning, important for good fallow weed control management.
- Bob Freebairn is an agricultural consultant based at Coonabarabran. Email robert.freebairn@bigpond.com or contact (0428) 752 149.
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