Walgett's jolly good fallow
From the November 2008 edition of Agriculture Today.
It has been a one in 20 year perfect spring at Walgett, with regular rain and cool temperatures, allowing for good grain filling.
Ten years ago it would have taken David and Peter Ricardo three weeks to cultivate their 5000 hectare farm, "Morvenvale", 25 kilometres south of Collarenebri.
The Ricardos’ farm has changed over the decade, since they introduced zero till tramline farming.
One of the main impacts of their new system has been more stable returns and reduced risk.
"We no longer rely on in-crop rainfall as much and only sow when the soil profile contains enough moisture," said David (pictured).
They store that moisture through preserving the soil ground cover and timely spraying of herbicide, and work hard at getting the spraying right for when there is moisture.
With current technology, the Ricardos can now cover the area in four days.
At Walgett, the season has again highlighted that those who carefully managed their summer fallow to retain stored moisture as close to the surface as possible are in a good position for the 2008 harvest.
North west NSW received excellent summer rain from November 2007 through to February, setting up large tracts of fallow for the 2008 winter crop, then the rain ceased for more than three months.
Walgett’s greatest agricultural resource is the fertile self mulching soil that can store up to 200 millimetres of valuable plant available moisture for cropping.
This stored moisture gave growers a tremendous buffer, now more valuable than ever, against the risk of receiving minimal in crop rainfall.
How the fallows were managed played an important role in how crops that received minimal in crop rain, except for the excellent early spring falls, have performed.
Fallows that were kept clean of weeds through timely fallow spraying generally kept their moisture reasonably close to the soil surface.
This gave farmers the opportunity to sow into the stored moisture when the sowing window opened, using moisture seeking narrow points and press wheels.
Users of tyned implements or chains to control weeds lost valuable surface moisture, so did anyone who was late to spray summer weeds.
They lost the opportunity to start sowing before June, whereas those who had good fallows were well into sowing when the June rain fell.
Good fallows enabled an efficient finish to sowing, then gave the opportunity to sow early crops like faba beans and canola.
June is not late to sow by any means, but producers with large areas to sow will have many crops sown at the tail end of the main season.
These later crops will be flowering and trying to fill grain when it is hot and will have less time to get their roots deep into the profile to use all the moisture stored over summer.
This season also saw crops that never satisfactorily established their secondary roots, and so were surviving on their primary roots and did not thrived until rain fell in early September.
Crops already up when rain fell in June shot off with strong root systems that would go deep into that summer stored moisture.
As the climate becomes more unreliable, careful herbicide management of fallows and the retention of soil ground cover becomes an even more important issue.
Growers and agronomists in this district are well aware of this and are already seeing substantial investment into new technologies to manage this year’s summer fallow with the purchase of WeedSeeker spray rigs.
As each season goes by the same lesson is learnt - a profile of stored moisture is the best start to the season.
Contact Myles Parker, Walgett, (02) 6828 0126, myles.parker@dpi.nsw.gov.au
