Agricultural Water Quality in Cold Climates: Processes, Drivers, Management Options, and Research Needs

Abstract

Cold agricultural regions are important sites of global food production. This has contributed to widespread water quality degradation influenced by processes and hydrologic pathways that differ from warm region analogues. In cold regions, snowmelt is often a dominant period of nutrient loss. Freeze-thaw processes contribute to nutrient mobilization. Frozen ground can limit infiltration and interaction with soils, and minimal nutrient uptake during the nongrowing season may govern nutrient export from agricultural catchments. This paper reviews agronomic, biogeochemical, and hydrological characteristics of cold agricultural regions and synthesizes findings of 23 studies that are published in this special section, which provide new insights into nutrient cycling and hydrochemical processes, model developments, and the efficacy of different potentially beneficial management practices (BMPs) across varied cold regions. Growing evidence suggests the need to redefine optimum soil phosphorus levels and input regimes in cold regions to allow achievement of water quality targets while still supporting strong agricultural productivity. Practices should be considered through a regional and site-specific lens, due to potential interactions between climate, hydrology, vegetation, and soils, which influence the efficacy of nutrient, crop, water, and riparian buffer management. This leads to differing suitability of BMPs across varied cold agricultural regions. We propose a systematic approach ("CUPCAKE"), to achieve water quality objectives in variable and changing climates, which combines nutrient transport process Conceptualization, Understanding BMP functions, Predicting effects of variability and change, Consideration of producer input and agronomic and environmental tradeoffs, practice Adaptation, Knowledge mobilization, and Evaluation of water quality improvement.

Grand Challenges to Support the Freshwater Biodiversity Emergency Recovery Plan

“…It proposes strategic integration of patterns and processes that connect human and natural systems, as well as within-scale and cross-scale interactions and feedbacks between human and natural components of such systems (Liu et al, 2021). Interesting applications to freshwater systems include evaluation of water availability, use, quality, management and governance in Canadian agricultural watersheds (Liu et al, 2019) and fisheries management (Lynch and Liu, 2014).…”

Combining Tools from Edge-of-Field to In-Stream to Attenuate Reactive Nitrogen along Small Agricultural Waterways

“…Dynamic patterns in N export and attenuation that change with farming practices and waterway connectivity are insidious obstacles to management [33,34]. N attenuation in small, agricultural waterways can be very dynamic, driven by fluctuations in prevailing catchment hydrology [33,35], as well as interactions with climate, vegetation, and soils [36]. Nutrient retention and processing may be higher at low discharges and warmer temperatures, while at high discharges, retention and processing can be negligible relative to the increased N flux from the land and upstream [33].…”

“…Moreover, changes in the hydrology, water chemistry, and temperature of these inputs can together influence the microbially mediated processing rates and therefore the performance of attenuation tools [52,55,56]. For example, the efficacy of N management tools is limited by cooler water temperatures or high runoff volumes from snowmelt, particularly in cold climates [36]. The attenuation performance of a single tool can have different impacts in the receiving environment (i.e., changes in concentration or load), depending on what proportion of N is attenuated, and whether this primarily reduces mean N load or critical peaks in N concentration or N flux [57].…”

Nitrogen dynamics and nitrogen‐to‐phosphorus stoichiometry in cold region agricultural streams

“…The northern Great Plains is a cold region with widespread agriculture, low relief topography, short growing seasons, and a semi-arid to sub-humid climate (Baulch et al, 2019;Liu et al, 2019a). In this region, agricultural productivity and Annual maximum temperatures in a proximal Canadian Prairie basin have increased by 1.2˚C from 1942 to 2014 (Dumanski et al, 2015), and annual mean temperatures in this region are expected to increase 2˚C by 2050 (Töyrä et al, 2005).…”

“…The northern Great Plains is a cold region with widespread agriculture, low relief topography, short growing seasons, and a semi‐arid to sub‐humid climate (Baulch et al., 2019; Liu et al., 2019a). In this region, agricultural productivity and nutrient export tend to be limited by moisture and hydrological connectivity (Baulch et al., 2019).…”