Impact of Phosphorus Fertilizer Forms on Nutrition of Wheat, Pea and Canola, Soil Fate and Losses in Run-Off Water
Term: 4 years, ending March 2025
Status: Completed
Researcher(s): Jeff Schoenau, Blake Weiseth, University of Saskatchewan
SaskCanola Investment: $50,232
Total Project Cost: $339,892
Funding Partners: 4R Fund of Agronomic Research Foundation, Sask Wheat, Western Grains Research Foundation, SPG
Project Description
This activity will generate information on how P fertilizer source (form) and its interaction with placement and rate influences yield, fertilizer P recovery and use efficiency in a cereal- pulse-oilseed rotation, and the potential loss of soluble reactive phosphate off-site in spring snowmelt runoff in contrasting soils, and its relationship to the forms of P that accumulate in the soil and water. Fertilizer P management is currently relevant and of interest to prairie producers. Both producers and society are interested in improving the agronomic efficacy of P fertilizers by identifying the most effective sources and placement methods that can improve efficiency, return on investment and reduce losses to the environment. Importantly, losses of environmental concern include export to surface and subsurface water bodies. It is noteworthy that across the prairies, many producers are already using advanced practices including application at recommended rates using in-soil placement in bands at the time of seeding.
Part of the outcome related to the proposed research is to provide solid data that will encourage producers to continue to utilize advanced practices rather than revert to methods such as broadcasting forms of P that are susceptible to loss for the sake of operational efficiency. The work will support and promote the general fertilizer management practices used by prairie growers to progress from basic to advanced 4R nutrient stewardship practices promoted by industry and government and help increase overall adoption of 4R fertilizer P management practices by prairie growers. Producers will benefit from identification of the most efficient phosphorus sources, and effective placement and rates to maximize crop recovery of P in cereal-pulse-oilseed rotation and achieve maximum economic benefit from fertilizer applied.
Objective
To assess how fertilizer phosphorus forms, placement, and rate affect crop responses, fate in the soil, and run-off losses in Saskatchewan soil.
Grower Benefits
In this study, both the agronomic (yield, phosphorus (P) uptake and recovery of P fertilizer) and environmental (P concentration and P load in snowmelt runoff) performance of P fertilization practices employed over a three-year wheat-pea-canola rotation at three contrasting sites in Saskatchewan was most greatly influenced by P fertilizer source and placement. The observed effects were impacted by differing soil, crop and landscape factors. In general, lower solubility P fertilizer forms demonstrated lower plant availability as revealed in measured crop P uptake and recovery but also showed lower losses in snowmelt runoff water compared to more soluble sources. The P fertilizer forms of lower solubility like struvite may be suitable forms for site-specific application to field landscape locations with high risk of P transport off-site and near sensitive water bodies. Upslope regions of the landscape and soils with inherent limitations to crop growth and P utilization, such as saline areas, resulted in greater export of P in snowmelt. This study demonstrated that relative to rate of P fertilizer application, reduced crop uptake and removal of applied P fertilizer leads to accumulation of soil residual P that is a significant driver of increased P transport in snowmelt runoff water. Banded placement was slightly advantageous over spring surface broadcast and incorporation in promoting greater crop P uptake and apparent P recovery and reducing total P load in runoff water, but the benefits observed in this study may have been muted from immediate incorporation of the broadcast fertilizer by the seeding operation following application. As agronomic and environmental performance differed across sites, an accounting of localized landscape and soil characteristics is needed to improve our ability to prescribe the “right” combination of 4R Nutrient Stewardship practices to promote crop uptake of applied fertilizer P and prevent the accumulation of residual P in the surface soil, which is prone to losses in snowmelt runoff.