Silver platter messages
From the October 2007 edition of Agriculture Today.
Correctly blaming lack of rain on poor crop performance does not explain why some patches are still green and producing grain but as little as five metres away, the crop is dead.
As yet another season fails to deliver even close to average rain in many regions, there are "great lessons of hope that we will do better with limited moisture", according to district agronomist, Barry Haskins.
Mr Haskins says some answers on soil quality and moisture management are universal, ramming home the importance of stubble retention.
"Analysis now is handing us some very important messages on a silver platter, even though it is dismal to wander around observing what the crops are telling us," Mr Haskins said.
Mr Haskins is based with NSW Department of Primary Industries at Hillston in the dryland Riverina wheat belt, where less than 150 millimetres have fallen in 2007.
Many paddocks across the region, especially those which have concentrated strips of stubble from the header rows, have shown superior crop performance within the stubble row, whilst away from the stubble cover the crops are dead.
"On many occasions ‘good’ areas have had no more access to moisture than the dead ones, but they are obviously able to use rain more efficiently, or conserve it when it does fall," Mr Haskins said.
"This highlights how much extra moisture can be conserved when stubble is retained and what a difference it can make in a tight finish.
"In addition, the microbial activity beneath this stubble is amazing early in the season, which could also offer many benefits in both the long and short term.
"This trend highlights to me the need for retaining all of our stubble, and that in this environment, insufficient biomass is produced to support healthy crops and hungry stock.
"Another thing I have observed is the patchiness in wilting crops, and the difference in crop potential between the patches.
"In many crops in the region, patches will yield more than two tonnes per hectare, whilst metres away another patch is dead - both had the same rainfall.
"I’m assuming these patches very regularly coincide with old tree stump burns, where soil carbon is higher, old rabbit holes with nutritional variation, or areas which have laid water following summer storms," he said.
In the latter case, stored moisture is simply enabling the crop to finish, but whatever is found in the soil down rabbit holes or following tree burns is worth its weight in gold, as it allows crops to produce huge amounts of grain on very little moisture.
Then there is the importance of stored moisture.
"Cultivated or chemical fallows this season haven’t performed very well compared to stubble cropped paddocks, simply because they stored minimal moisture last year," Mr Haskins said.
However, there are some sections of crops on a two year fallow, where the soil has stored moisture from both 2005 and 2006.
These sections are holding on well, showing the importance of stored moisture and the ability of soils to hold moisture over long periods.
"It takes a tough season to observe these important lessons; crop variations in better seasons tend not to raise complaint," Mr Haskins said.
Mr Haskins’ colleague, Wagga Wagga based district agronomist Nigel Phillips says unfortunately, the market rarely rewards producers for environmental gains.
"So changes to on-farm practices will need to have proven economic advantages and be based on sound evidence," Mr Phillips said.
"Small changes in soil structure and moisture retention characteristics can potentially influence farm productivity in dry years and may be critical if we are moving into a period of lower rainfall."
"Stubble retention and controlled traffic are two examples of improved soil management practices that will have a positive benefit."
Many of these same practices also provide productivity gains in wetter years through improved drainage and nutrient holding ability.
Contact Barry Haskins, district agronomist, Hillston, (02) 6960 1320, barry.haskins@dpi.nsw.gov.au
