Do we need deep banding of phosphorus in no-till systems in the Canadian Prairies?
Term: 5 years, beginning in 2023
Status: Ongoing
Researcher(s): Maryse Bourgault, University of Saskatchewan
SaskCanola Investment: $96,890
Total Project Cost: $514,448
Funding Partners: TBC
Objectives
To determine if deep banding of P fertilizer is necessary in no-till cropping systems in Saskatchewan.
Our research questions include:
Does deep banding P fertilizer improve yields compared with P applied at 5 cm depth at the same rate?
Does the deep banding operation by itself impact yields?
Does splitting P applications between depths help? In other words, will P placement at both depths produce maximum yields?
How long might the benefit of P at depth be noticeable on crops in a grain-oilseed-pulse rotation?
Project Description
Maximizing crop yields given the weather variability that is commonly experienced in the Canadian Prairie is an important component of improving economic potential of grain cropping. Fertilizer costs are important and nutrients that may be placed where they are not available at the right time would provide a poor return on investment, reducing economic margins. More stable yields, if achieved with this practice, would also help with reducing risks from year to year. In addition, more efficient fertilizer use has obvious benefits for environmental sustainability. This practice may reduce P loss by distributing the P within the soil profile rather than be concentrated in the top 5 cm.
Long-term no-till technologies have led to important advances in soil health in Western Canada but have also led to the stratification of non-soluble nutrients in the topsoil. While nitrogen (N) is soluble and will move down the soil profile with water, applied phosphorus (P) fertilizer does not tend to move. The movement of P down the soil profile is generally through roots that later decompose. Current best practices (i.e., the 4R of Nutrient Stewardship) suggest placing P fertilizer in a sub-surface band about 5 cm below the seed, although broadcast and seed-placed fertilizer are also still commonly practiced. Unfortunately, once the topsoil dries out, roots are no longer able to access nutrients from this layer, and therefore depend on moisture and nutrients lower in the soil profile. Since the topsoil dries out on a regular basis in our environments in Western Canada, and often remains dry for long periods during the growing season, there are concerns that crops might suffer from undiagnosed P deficiency and show reduced crop yields. Symptoms of mild P deficiency in wheat at the vegetative stage include a stunted growth and leaves that appear slightly wilted, symptoms that are easily confused with water stress. Undiagnosed P deficiency is potentially a serious and widespread problem with yields limited by phosphorus in addition to, or rather than, water availability. Fertilizer inputs are increasingly expensive, and producers often tell us that they do not consistently get a return on investment with P fertilizer. Could this be because placing P fertilizer at the 5 cm depth is still too shallow? In addition, a major barrier to the application of P at depth is the financial and labor costs associated with an additional operation prior to planting. Could we then place enough product so that this operation may only be needed once every 5+ years? Comparisons of 9 treatments of P2O5 (MAP) at different rates at either 5cm, deep banded (20-30cm depth), or split between 5cm and deep band (up to 60kg/ha deep banded for multi-year supply of P2O5).