Fertiliser prices have doubled in the last twelve months to $1000 - $1100 a tonne on the back of global shortage, and a surge in demand due to high grain prices.  Grain growers are struggling to lock in supplies as US manufacturing reduces its output, and China winds down production to reduce emissions ahead of the Olympics.  Global demand for nitrogen, phosphorous and potassium is forecasted to increase by nine percent by 2011-12.

According to the GRDC variability in crop performance in 2007 means the carry over of nutrients from last season to this year needs to be critically examined.  If finances are restrictive phosphorous (P) fertiliser should be calculated to manage P supply for the 2008 crop only.  Do not fertilise for the following pasture crop or for a build-up of soil reserves.  Use a combination of paddock records and soil testing to determine the 2008 application.

Mineral nitrogen (N) availability is often under estimated following a low rainfall year, due to the extended period of mineralisation (the drought acts like a fallow).  This year there is likely to be some carryover fertiliser N from failed crops, and increased mineralisation if there is good early rain.  There will be less carry over from crops that grew well early, but failed to finish.     

AUTHOR: Michael O' Keefe, Waste Management Consultant, Rural Solutions SA
CONTACT: www.grdc.com.au or Michael O'Keefe, Rural Solutions SA Clare Office, Telephone: (08) 8842 3775