Researcher Looks For Way to Improve Efficiency of Starter Fertilizer

Source: Saskatchewan Agriculture and Food

How much is too much, or not enough?

That is just one of the questions Jeff Schoenau of the Department of Crop Science at the University of Saskatchewan will attempt to answer as part of a Saskatchewan Agriculture and Food (SAF) Agriculture Development Fund (ADF) project (#20050725) over the next few months.

“With the move toward low-disturbance seeding systems, there is a limit to how much phosphorous (P) and potassium (K) fertilizer can be safely put down in the seed row as a starter," he says. "If you want to disturb the soil less during the seeding operation, you have to use narrow openers, and that, coupled with the wide row spacing, means that the seed and fertilizer get crammed together, which increases the likelihood of fertilizer burn.”

Given the move to fertilizing in a single pass using low-disturbance openers, Schoenau says there is a need to re-evaluate safe rates of starter fertilizer, which are placed in or near the seed row so that the seedlings get easy access to nutrients like phosphorus and potassium that are immobile in the soil. Because phosphorous and potassium cannot move very far through the soil, they have to be placed very near the seeds for the seedlings to derive any nutrient benefits. This lack of mobility also increases the potential for damage from an over-application of fertilizer, because the nutrients cannot dissipate in the soil.

“So what we are doing," he says, "is to look at safe rates of combined, seed-placed phosphorus and potassium applications using these low-disturbance seeding-fertilizing configurations. We are also looking at the effectiveness of a new controlled-release phosphorus (CRP) fertilizer product, which has a special coating that controls the release of the nutrients into the soil water.”

One of the potential advantages of CRP, explains Schoenau, is that farmers might be able to safely place higher rates of fertilizer phosphorus in the seed row.

“If you have a recommendation for a high rate of phosphorus, and you have a sensitive crop and a seeding unit that has low seed-bed utilization, you may damage the crop if you try to place all the phosphorus with the seed in the seed row. CRP may overcome this limitation by allowing all the recommended P fertilizer to be safely placed in the seed row. As a secondary benefit, the slow release nature of CRP could improve the crop utilization and efficiency of uptake."

So far, research is showing that CRP allows higher rates of fertilizer application in the seed row. Further research is planned into the actual affect of CRP on crop uptake, as well as on P and K combinations.

This is a one-year project. Schoenau hopes that, by late-December, he will have a good idea of how the starter fertilizers affect the safety of crops when placed in the seed row, and also, how they affect the availability and crop utilization of phosphorus.

For more information, contact:

Jeff Schoenau, Ph.D
Department of Soil Science
University of Saskatchewan
(306) 966-6844