More than 80 percent of sampled Saskatchewan fields could benefit from additional phosphorus and so could more than 65 percent of fields sampled in Alberta and Manitoba.
Farmers in Alberta and Manitoba tend to use manure more often than those in Saskatchewan, but they all could benefit from better phosphorus management, says Tom Jensen of the International Plant Nutrition Institute, a non-profit research organization largely funded by fertilizer companies.
He told those at a Jan. 16 agronomic update that the IPNI studies soil tests every five years and has found similar results in 2005 and 2010 regarding prairie phosphorus levels.
Read Also
Ag in Motion speaker highlights need for biosecurity on cattle operations
Ag in Motion highlights need for biosecurity on cattle farms. Government of Saskatchewan provides checklist on what you can do to make your cattle operation more biosecure.
He said prairie soil has good levels of phosphorus despite those results, but it is in forms not readily accessible to plants.
“Less than a tenth of a pound of phosphate per acre in any one time can be sucked out of soil solution right away,” he said.
However, that doesn’t mean phosphate fertilizer is inefficient, he added.
“I get upset when I’m at meetings and people will say phosphorus fertilizers are inefficient. That’s a lie,” he said.
“We need to realize that phosphorus, it reacts so quickly with other compounds in the soil that we can’t get much higher (than 25 percent) uptake in the crop during the year of application. The good news is, it’s darned hard to lose phosphorus from the soil. In the long term, phosphorus efficiency is actually 90 percent.”
The agriculture industry was rife with rumours last year about a pending shortage of phosphorus, with some predicting supplies would run out in as few as 60 years.
Jensen rejects those predictions, although he agreed readily available phosphorus supplies are dwindling.
“It doesn’t matter how many (years) it is, it just means that there’s not a lot of easily available phosphate rock to mine. In my opinion, we’re not going to run out of phosphorus but we’re going to pay more for it.”
Existing reserves are primarily in North Africa, China, the Middle East and the United States, though environmental concerns about open pit mining in the U.S. will likely preclude much recovery there, Jensen said.
“Chances are, here in Western Canada, over the next 20, 30, 40 years, most of the phosphorus that we’re going to be using is going to originate primarily from Morocco.”
Jensen said phosphorus can be managed and preserved by bringing soil levels to optimum and then taking steps to replace losses from cropping.
He said most farmers are “mining” their soil of adequate supplies by not replacing phosphorus that is lost from harvest.
The nutrient is best managed over the long term, he added.
“The phosphorus that will be used by crops in the year 2013 is phosphorus that’s been put on that land for the last 10 or 20 years.”
