Soil phosphorus management for food and water security in cold agricultural regions
Abstract
Phosphorus (P) is a critical element for both food and water security. There is a "paradox" in agricultural use of P: while too little P limits crop production, too much P can lead to degradation of water quality. It is a grand challenge to manage soil P to achieve both food and water security across the world. In cold agricultural regions, there are additional challenges in managing soil P. Phosphorus uptake by plants is impeded by cool temperatures in spring, which requires farmers to maintain a sufficiently high level of P availability (from soil and/or fertilizer) to ensure early plant growth. However, as much of the P loss from soil to water occurs during snowmelt period and there are few options to mitigate this loss, hence maintaining soil P at low runoff risk levels becomes especially important to achieve P load reduction goals. Therefore, there is an urgent need to assess best P management practices in cold agricultural regions. Here, we present research related to soil P management in Canada. We found that different nutrient and tillage management practices in the past have resulted in high variability of soil P content and varying extents of P stratification in Canadian watersheds. Likewise, the response of crop yields to addition of P fertilizers also varies. In long-term field experiments, we found strong association between soil Olsen-P and P balance (R2 = 0.7 to 0.95, p = <0.0001 to 0.02). Moreover, flow-weighted mean concentrations of total dissolved P in snowmelt runoff were significantly correlated with Olsen-P in the top 5 cm of soil (R2 = 0.45, p < 0.01). Implementing a soil P drawdown approach by decreasing P fertilizer application rates reduced total dissolved P concentrations in snowmelt and rainfall runoff by >50% from soils with high P contents, without negatively impacting crop yields. Results demonstrate the potential to maintain soil P contents at optimal levels by balancing long-term soil P budgets to achieve both food and water security in cold agricultural regions.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGC54D..11L
- Keywords:
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- 0402 Agricultural systems;
- BIOGEOSCIENCES;
- 0470 Nutrients and nutrient cycling;
- BIOGEOSCIENCES;
- 1615 Biogeochemical cycles;
- processes;
- and modeling;
- GLOBAL CHANGE;
- 1630 Impacts of global change;
- GLOBAL CHANGE