PESTS IN CHAFF
SURVEY OF VERTEBRATE AND INVERTERBATE PESTS AND BENEFICIALS HARBOURING IN HARVEST WEED-SEED CONTROL SYSTEMS
The aim of this project is to determine whether there is a difference in invertebrate and mouse populations across different HWSC systems over the WA grainbelt, specifically if there is a species change with accumulating chaff within paddocks and the impact on the following crop.
Project lead organisation
There are several techniques commonly employed in HWSC. The highest adoption of HWSC is in the GRDC western region with an estimated 67% of all farmers undertaking at least one HWSC strategy in 2014.
One of the most common HWSC is narrow windrow burning however there has been a recent shift against this method due to the requirement to concentrate and burn all harvest residue, both chaff and straw, reducing the amount of organic matter returning to the paddock. There are also associated problems with burning in autumn; burning permits, smoke haze complaints and the need for conducive weather conditions to get a good weed seed kill.
Chaff lining has recently become popular in the place of windrow burning. Chaff lining, originally known as 'windrow rotting', has been championed by WA grower Mic Fels. The concept involves funnelling only the chaff fraction of crop residue (containing weed seeds) into a confined row directly behind the harvester using a narrow chute an spreading the straw faction back onto the paddock. The chaff and weed seeds are then left to rot down over time. To promote rotting, the chaff lines need to be placed in the same location year after year by running the harvester on a controlled traffic system (CTF) system.
Chaff tramlining is a similar concept to chaff lining, but the chaff fraction is diverted through a chaff deck onto permanent wheel tracks in a CTF system. Wheel traffic creates a hostile environment that inhibits weed seed germination. The methodology is only available to those growers that have permanent tramlines in place.
Chaff dumping has been around for some years. It is the collection of the chaff fraction using a cart towed behind the harvester. The chaff in the cart is then dumped, usually in piles in the paddock. The chaff is then either burnt, grazed or left to decompose.
The practice of chaff lining is increasing. A survey of WeedSmart subscribers showed the percentage of growers using chaff lining increased from 6% in 2016 to 26% in 2017. This change in practice is likely to influence the diversity of invertebrates and vertebrate pests (mouse) found in paddocks. A better understanding of any changes to pests and beneficial species will enable growers to make a more informed decision regarding which HWSC system to use and direct future investment in control.
The aim of this project is to determine whether there is a difference in invertebrate and mouse populations across different HWSC systems over the WA grainbelt, specifically if there is a species change with accumulating chaff within paddocks and the impact on the following crop. This can only be achieved by undertaking a longitudinal survey.
Results and Reports