Project lead: Sylvia Nyamaizi
Project personnel: Shaobing Yu, Jessica Stoeckli, Dean Babuin, Carson Yuchen Li
Supervisors: Sean Smukler and Aimé Jean Messiga
Project partners and funding:
- Agriculture and Agri-Food Canada, A-Base funding
Phosphorus is the second essential nutrient for plant growth. In BC, mineral and manure phosphorus applications that are in excess of plant requirements have led to legacy phosphorus accumulation in the soil. This largely poses a great risk of pollution to water resources. A better match of phosphorus applications to different cropping systems is therefore required in order to maintain or draw-down excess soil phosphorus and reduce phosphorus losses to water resources. In this project, we considered silage corn and blueberries as major cropping systems in the Fraser Valley.
It is the main goal of this research to better understand the mechanisms controlling phosphorus cycling in high-phosphorus soils. This will enable us to reduce the risk of phosphorus losses to water sources and build resilient cropping systems in BC. The main research outputs will be: 1) refining mineral starter phosphorus recommendations to improve the efficiency of phosphorus fertilizer applications and 2) developing a simple agri-environmental phosphorus saturation index for reference.
Research questions:
The overarching objective of this work is to contribute to the development of strategies and tools that will improve phosphorus management and help to monitor environmental phosphorus risks related to agricultural soils with high phosphorus in the Fraser Valley.
- What is the appropriate starter fertilizer P rate that can effectively promote the growth of young silage corn plants?
- Does phosphate availability increase with starter fertilizer phosphorus rate and time from seeding?
- Is mineral starter phosphorus application associated with an increase in species abundance of soil microorganisms and enzyme activity in the rhizosphere of silage corn during the early growing season?
- What are the critical P risk indicator values for a wide range of soils?
- How do we classify environmental P risk for agricultural soils in the Fraser Valley?
- How does increasing soil pH affect phosphorus saturation indicators in high phosphorus soils of the Fraser Valley?
Project sites and design:
Study one and two: We conducted eight field trials in Agassiz, Chilliwack, and Rosedale in the Fraser Valley in south coastal British Columbia between 2020 and 2021. In each field trial, five starter phosphorus (mineral fertilizer) treatments (0, 5, 10, 15, and 20 kg P ha–1) were arranged in a randomized complete block design.
Study three: Soil (0-30 cm) was collected from a 13-year long-term blueberry experiment at Agassiz Research and Development Centre (Agassiz RDC), Agriculture and Agri-Food Canada. In this study, soils were selected based on their variable pH to fit into four acidic classes: extremely acidic (4.1), very strongly acidic (4.8), strongly acidic (5.5), and moderately acidic (5.8) as treatment groups.
Measurements and data collection:
We measured environmental factors in both field studies and growth chamber experiments, including climate data like precipitation and air temperature, as well as soil temperature. Various soil parameters were measured including soil test phosphorus concentrations, total phosphorus, organic phosphorus, aluminum, and iron concentrations, soil phosphorus pools, phosphorus sorption capacity, agri-environmental indicators (water extractable phosphorus, phosphorus saturation index (PSI), and degree of phosphorus saturation (DPS)).
As part of the established field experiments with silage corn, we measured the availability of phosphate in the soil, root growth, and dry matter yield in response to mineral starter phosphorus fertilization. We also measured enzyme activity (acid and alkaline phosphomonoestrases, Β-glucosidase and β-N-acetyl-glucosaminidase (NAGase) activity and microbial carbon in the rhizosphere. Microbiome composition and taxonomy will be compared using DNA sequences from rhizosphere collected at 3- and 6-leaf stages of young silage corn plants.
Reports and publications:
- Effects of increasing soil pH to near-neutral using lime on phosphorus saturation index and water-extractable phosphorus
- Mineral phosphorus fertilization for silage corn in manured soils in the Fraser Valley, Canada
- Environmental Phosphorus Risk Classes for Silage Corn in the Fraser Valley, Canada
- Improving agricultural phosphorus management to reduce environmental loss in high phosphorus soils in the Fraser Valley, British Columbia