oilseed rape harvesting© Tim Scrivener

A new online tool aims to help farmers calculate the cost of lodging in oilseed rape, which can cause significant crop losses, even with low angle leaning.

The crop losses are the result of lodging reducing the amount of light getting into the canopy, thereby restricting essential assimilate supply and so reducing seed fill.

See also: Oilseed rape canopy management Academy

“But oilseed rape growers have not been as aware of the financial impact of lodging as, say, cereal growers have been,” says BASF business development manager Clare Tucker.

For the first time growers are able to quantify the detrimental effects of lodging in rape thanks to a new web-based tool based on detailed ADAS research.

“The extent of yield loss in oilseed rape depends upon the growth stage when lodging occurs, the severity of lodging and how much of the crop is involved,” she explains.

Farmers need to input their expected oilseed rape price and then the percentage of the crop that is lodged, the growth stage of the crop and the approximate lodging angle. It then calculates the yield loss, financial losses and Thousand Seed Weight (TSW) changes due to lodging.

Mrs Tucker says it is quite worrying how much yield can be lost from just a small amount of lodging. 

“The tool shows quite clearly the significant losses resulting from even low angle leanings (of around 22.5 deg), often regarded as insignificant to yield.”

For example, a crop leaning 22.5deg at early seed fill and affecting 30% of the field will result in losses of nearly 0.2t/ha.

“Also rape growers could easily be unaware of how extensive lodging is in their crop, as it can go unnoticed in the middle of fields until harvest.

“Two aerial surveys, undertaken by ADAS in 2012 and again in 2014, give the real picture. In 2012 35% of the area of rape surveyed was lodged at 45deg or more and in 2014 this was 27%.”

Eight out of every 10 fields in 2012 and nine out of every 10 fields in 2014 had at least 10% of the total area lodged at 45deg or more.

ADAS also looked at the yield losses from lodging at different growth stages. Early lodging (mid-flowering) theoretically is the worst time for lodging, but there is potential for the plant to partly recover and light can reach the developing pods again.

There is no time for plant recovery when lodging occurs at seed-fill – the pods still need light at this time and if cut-off by lodging, pod abortion occurs and yield is lost.

The Oilseed Rape Lodging Yield Calculator can be found on the AgriCentre website.