Grains Research and Development

Date: 01.06.2002

Windrowing beans not a good delaying tactic

1.Seeds have not yet reached physiological maturity and windowing at this time will cause small defective grain. 2. The hylum is darkening but is not yet a distinctive black line, so it is still too early to mindow. 3.The distinctive black hylum indicates physiological maturity, so it is time to windrow if all seeds are at least at this stage.

WINDROWING IS no longer Andrew Weidemann's choice of harvesting methods for Aquadulce broad beans now that he has seen the results of Birchip Cropping Group trials.

Like many other growers in the Wimme ra, Mr Weidemann had been windrowing beans to help manage his time during the harvest. He also wanted to reduce seed losses on the ground that result from shattering when direct heading without windrowing.

Trials at Mr Weidemann 's property 'Sunnydale' ,50 km east of Horsham in Victoria, returned yields of 2.2 t/ha for direct heading. This was significantly higher than yields from early-windrowing (1 .7 t/ha) and mid-windrowing ( 1.8 t/ha) treatments.

" It is clear that the yield penalty from windrowing was more than the yield loss from direct heading," says Mr Weidemann. He says that most of the loss in yield was from a decline in seed weight during windrowing.

"If I had weeds like prickly lettuce or wild radish at harvest time, then I would consider windrowing for up to a week because this would dry out the green matter enough to improve harvesting conditions. But I wouldn ' t leave it for more than a week because of the decline in seed quality," he says.

According to Liam Lenaghan, Research and Extension Manager of the Birchip Cropping Group, the time of windrowing also affected grain quality (see table). " It appears also that the re was less seed discolouration in plants that were windrowed later."

Mr Lenaghan says discolouration was greatest on top of the windrow (exposed to weather) and the bottom of the windrow (subjected to moisture from being in contact with the soil ).

Grain quality for windrowed versus direct-headed Aquadulce beans. The numbers in the columns reflect the percentage of the treatment sample that fits within each discolouration percentage category.

Horses for courses

The implications are that windrowing is not a good way of delaying harvest of Aquadulce broad beans. Mr Weidemann attributes the relative success of direct harvesting partly to the height of Aquadulce, and also to the fact
that they tend to lodge. He also gives his new header, with retractable fingers across the front, some of the credit for the good results with the direct-headed treatments.

Howcver, pointing to the results of a nearhy non-replicated demonstration, Mr Weidemann says he would be interested in trying windrowing with Fiesta VPPBR logo raba
beans. " Fiesta VPPBR logo raba beans are wil taller and they tend to bounce off the rods at the header front.

"Although this might make Fiesta VF'" more suited to windrowing than Aquadulce, we would still need to be careful of the potential loss in seed weight and quality during windrowing," he suggests.

Mr Lenaghan says the message for growers is clear. "Windrowing beans is not a management technique that allows harvest to be delayed. Yield penalties and grain quality issues may also result from windrowing beans."

The treatments were:

  • eontrol - direct-head crop at maturity
  • early windrow - seeds in middle pods have distinct black line on hylum (no black line visible on seed in top pods)
  • mid-windrow - seeds in top pods have distinct black line on hylum (seed in bottom and middle pods fully formed)
  • late window - seeds in top pods have complete black hylum (bottom and middles pods are now very ripe and can shatter).

Program 4 Contact: Mr Liam lenaghan 03 5492 2787 email liam@bcg.org.au