Timing and placement of sulfur on corn

Objectives:

• Determine the prevalence of corn, soybean and wheat sulfur (S) deficiency, magnitude of response, and economic impact of sulfur fertilization across Ontario. This is a continuation of Grain Farmers of Ontario (GFO)-sponsored surveillance trials initiated in 2018.
• Determine the effect of S fertilizer type, placement, and timing on corn production. Calculate the economic return for each treatment.
• Determine the effect of S type and application timing on hard red wheat yield and protein content. Calculate the economic return for each treatment.
• Evaluate the effect of elemental S particle size, soil moisture, and temperature on the timing and pattern of plant available S release from elemental S.
• Determine if the measure of available S with ICP analysis matches those from colorimetric analysis of sulfate, particularly after elemental S application.
• Calibration of the calcium chloride soil test for Ontario conditions for corn soybean and wheat.

Impacts:

• Surveillance of S response across Ontario in corn, soybeans, and wheat will allow ongoing monitoring of the prevalence of S deficiency and the economic impact of S fertilization across Ontario.
• Trials on timing, placement and type of fertilizer in corn will allow for determining S fertilization strategies for maximum economic return.
• Sulfur fertilizer type and application timing in hard red wheat will determine what practices will maximize yield and protein content and include analysis of the economic impact of each treatment.
• All trials will be used to continue to develop the S soil test for Ontario and help to identify other factors like soil texture that may influence the likelihood of response.
• A more predictable estimate of plant available S from the use of inexpensive elemental S as a fertilizer.

Scientific Summary:

Sulfur (S) fertilizer is commonly applied for grain production in Ontario. A project funded by Grain Farmers of Ontario (GFO) and the Ontario Agri-Food Innovation Alliance (a collaboration between the Government of Ontario and the University of Guelph) found a significant response to S on some corn and winter wheat trials, although most sites did not respond, and no soybean trials responded. As such, when all corn and wheat sites were evaluated together, there was no economic advantage to S fertilization. These results indicate that a means of determining which sites may be responsive, reducing the cost of S fertilization, and identifying more effective means of application are required. The current funded project is also attempting to develop a soil test for use in determining which sites may respond. Regardless, a less expensive S fertilizer and/or methods of application that have a greater chance of seeing a response will be beneficial. At the same time, S deposition data recorded by Environment Canada suggests a continued downward trend. This would suggest the likelihood of response to S may continue to increase.

Given the ongoing changes to S deposition and the challenges with accurate predictions of crop S responsiveness, we propose 4 areas of investigation:

1) Continue conducting surveillance trials for S response across Ontario initiated in 2018. These trials consist of 2 treatments, no S and added S fertilizer at 20 kg S Ha^-1. Continuing these surveillance trials in corn, soybeans, and wheat will provide insight into how the crop responsiveness changes through time and provides a basis for predicting the economic impact of S nutrition for Ontario as a whole. These trials will also be used to further calibrate the developing S soil test for Ontario. We propose continuing these trials for 4 years.

2) Timing, placement, and fertilizer type in corn. This part will occur over 3 years with one trial each year. This trial will compare two materials, elemental S to sulfate-based fertilizer, fall vs spring application of both fertilizers, and the comparison of broadcast vs side-band application.

3) Timing and type of S fertilizer application on hard red wheat. This part will include one trial in each of 3 years. This trial will compare elemental and sulfate-based fertilizer applied in the fall or spring, with or without added foliar S applied at heading time.

4) A laboratory incubation study will also be done to evaluate elemental S particle size, soil temperature and moisture level on sulfate release. This study will help to better predict the availability of elemental S applied to soil in order to better utilize this inexpensive material.

External Funding Partners:

The project was funded in part by the Ontario Agri-Food Innovation Alliance, a collaboration between the Government of Ontario and the University of Guelph.