Determining the impact of temperature and organic fertilizer type on the soil mineral nitrogen supply and the productivity of organic cranberry crops

Description

Organically grown cranberries command twice the price of conventionally produced fruit, and Québec, with 30% of the total growing area, is a world leader in this sector. However, through better control of nitrogen fertilization, it should be possible to boost organic production by reducing the 24% variability in yields observed with conventional crop management. One problem is that the nitrogen supply of organic fertilizers is modulated by temperature and this complicates efforts to monitor nitrogen availability (both quantity and synchronization).

Therefore, when there are nitrogen deficits in the spring, over-fertilization, or when nitrogen is released too late in the season; the result can be lower crop yields and/or quality, lower fruit-bearing potential the following year, or increased susceptibility of plants to disease. These problems will be exacerbated by the increased variability in temperature that climate change will bring. With the aim of providing growers with an optimal and flexible fertilization program, this project will characterize the nitrogen release from various organic fertilizers as a function of temperature and determine the nitrogen-intake dose response curves in the field.

Objective(s)

Obtain better crop quality and yields through the flexible management of nitrogen fertilization (fertilizer type and dose) as a function of temperature. For three organic fertilizers, we will:

1. Determine, in the lab, their biochemical characteristics, as well as their rates of mineralization and release of available nitrogen, as a function of temperature.
2. Determine their impact on the dynamics of available nitrogen in the field.
3. Assess biological activity and soil health.
4. Measure the crop’s utilisation of nitrogen as a nutrient.
5. Determine the nitrogen-intake dose response curve.
6. Calculate and compare the variable contribution margins.