Educated guesses can now make way for sound advice in fertilising one of New Zealand’s most important crops.

 

The various types of forage brassicas add up to the largest area of crop under cultivation in the country – around 250,000 ha are grown annually.

 

Now, new fertiliser decision support systems developed by Crop & Food Research – supported by Ballance Agri-Nutrients and PGG Wrightson –  aim to help farmers get the best from their brassicas.

 

For each paddock of Pasja or kale the systems can determine the correct type and amount of fertiliser to apply, how much yield it can stimulate and whether the farmer will gain an economic return.

 

To do this the new Pasja (and Kale) Calculators use information on key factors affecting crop yield such as soil fertility (based on a soil sample), local climate information, sowing date and the anticipated grazing date.

 

Ballance fertiliser reps have just begun using the system with clients.

 

Crop & Food Research agronomist, Derek Wilson, who led the research project, says until now people have had to base fertiliser recommendations for brassicas on limited information and "sometimes this yielded good results, sometimes not".

 

“The Calculators take into account that soil fertility varies from paddock to paddock, and that there are different fertiliser requirements for maximum yield and economic return. The result is responsible use of fertiliser, with less risk of over- or under-fertilising. So the outcome is an economic and environmental win-win”.

 

“This fertiliser work is an important first step towards improving brassica performance but there’s more research to do on areas like crop establishment and weed, pest and disease control”.

 

“Despite the high potential of forage brassicas, their overall performance has not been particularly good,” he says. “Too many crops either fail completely or produce low yields – about 20% fail to get past the establishment stage successfully”. 

 

PGG Wrightson  agronomist Andrew Dumbleton says forage brassicas are mainly a New Zealand crop “so we have to do the work ourselves”. “But it’s a great opportunity to increase the overall productivity of our pastoral systems”.

 

A team of six Crop & Food researchers worked on the Pasja and Kale Calculators project over four years with on-farm trials throughout the country, from Waikato in the north down to Southland.