There have been some positive outcomes regarding oilseed rape crops, as Teagasc tillage specialist Shay Phelan points out that crops at Teagasc Oakpark have good ground cover. The leaves of rape crops are understood to store nitrogen, raising the concern on whether or not to use fertilisers.
But with the current state of affairs regarding high fertiliser prices, Phelan has questioned whether using the leaf cover area as a means of determining a chemical fertiliser recommendation for a specific crop. He says this is done by using what is called a Green Area Index (GAI) app.
Step one is to take a number of photographs across a field. He explains that this ensures that one gets a representative imagery of what the entire crop looks like. According to Phelan, a GAI of 1.0 equates to 1m2 of plant cover per square metre of ground. Crops with this value contain 50kg/ha of nitrogen.
The GAI app is downloadable and one would then upload the photographs taken into the app. Phelan says the app then calculates a GAI for every photo submitted. Teagasc is also recommending the application of a compound fertiliser that matches the nitrogen, potassium and phosphorous requirements of the crop at the first application.
LSL News.