Maximising cropping yields involves the adoption and continued use of a combination of latest research data and agronomic tools with almost timeless commonsense information, sometimes centuries old.
Europe, for example, was promoting the value of crop rotations more than 400 years ago and in a general sense such knowledge remains critical today.
We do know more about all sorts of specific issues relevant to the advantages of rotations, but the general gist such as disease control and the value of legumes for soil fertility restoration remain much the same.
More specifically, we better now appreciate the need for non-cereal crops in the rotation to help address diseases like common root rot, take-all and crown rot.
Cereal nematodes are more recent crop pests and we have an ever-expanding knowledge of different crop and variety tolerance and resistance and can better design rotations to minimise these pests.
We certainly have a more refined knowledge of the need for efficient weed control during fallows to store soil moisture than was the case in the past.
Sixty years ago, when farming was expanding in northern and western areas of NSW (as well as other low or erratic rainfall areas of Australia), there was a general appreciation that stored sub soil moisture would generally help improve crop yields and seasonal reliability.
More recent research has shown that for almost all cropping areas of Australia, efficient storage of fallow moisture (for example via stubble retention and timely killing of weeds), on average increases cereal crop yield by one tonne a hectare or more.
Equally critical is that recent research shows weeds allowed to get away in the fallow not only use soil moisture likely to be vital for crop growth and grain production, but commonly use nitrogen that then becomes less available to the following crop.
While this nitrogen may breakdown and be released back to the soil, commonly, availability is not in time for the coming crop.
Soil tests and trials show available soil nitrogen when weeds have not been timely controlled can be lower by 40 kilograms a hectare or more, compared to timely fallow control.
That can result in either big yield losses or much greater costs to correct the deficiency.
Timely weed control, mainly via appropriate herbicide use, commonly means an extra spray or two over the fallow period.
Weeds are best controlled when young and sappy and kills on difficult to control weeds also are far better from an early, timely treatment.
In summer, a day or two, not a week or two, can be the difference between good weed control conditions and poor ones.
Wet or dry years, generally speaking, tend to support early sowing with varieties of appropriate maturity rather than so called “main season” or late sowing.
Risks of frost damage can be greater, but advantages include crops heading and filling in milder conditions more conducive to high crop yields.
In years gone by, our fathers or grandfathers tended to begin sowing early partly because sowing took such a long time.
But even then, many farmers appreciated the merit of early sowing with a variety of appropriate maturity.
Part of good farming today also includes a good knowledge of crop variety features other than just maturity, quality and yield ability. Resistance levels against a multitude of diseases like the three rusts, yellow leaf spot and septoria (especially for the south), and two crop damaging species of root lesion nematodes is also important.
Next week. Attacking invasive weeds.
- Bob Freebairn is an agricultural consultant based at Coonabarabran. Email robert.freebairn@bigpond.com or contact (0428) 752 149.
