Northward shift of agriculture; opportunities and challenges

Why Northern Agriculture?

• It is projected that the agriculture-feasible areas in the boreal zone might treble by the end of the 21^st-century.
• Latitudinal shifts, rather than altitudinal shifts, dominate the projected global expansion. The magnitude and progress of the projected northward shift is particularly great for higher latitudes (>50° N).
• Such a trend could be transformational to the local land use if this potential is acted upon.
• However, the temporal variation in the expansion may complicate short-term agricultural development and management planning and practices; inner-continental regions are more likely to undergo a non-linear change in the total area that will experience expansion of agriculturally-feasible temperatures, with regular cooling and warming cycles.
• Such patterns suggest the importance of both, short-term and long-term planning and thus the need for locally relevant approaches to any proposal for any expansion in agricultural land.

A critical risk is that boreal expansion of agriculture occurs in advance of a necessary understanding and thorough assessment of knowledge that is required to: 1) mitigate climate risks; 2) be environmentally sustainable; 3) identify and address best cropping options; 4) address key elements of food security; and 5) consider the concerns, desires, needs, and constraints of local communities.

Context

Climate change increases the growing degree days in boreal ecosystems  prompting considerations of land use conversion (LUC) for agricultural use. If climate change predictions are actualized the current breadbaskets might no longer be able to sustain the demands of the current and future populations. This increases the demand for arable lands in cold climates experiencing climate shifts accelerating northern land use conversion and intensification (LUC/LUI). The most common soils in the wet and cool circumboreal region are Podzols. In Canada the cultivation of Podzols is only common in eastern Canada and in some coastal areas of British Columbia with the majority being found in areas traditionally considered unsuitable for agriculture. In the province of Newfoundland and Labrador (NL), a region with agriculture fully based on converted boreal lands, 55% of soils are classified as Podzols, of which 44% are Ferro Humic Podzols. Nevertheless, converted Podzols have limited agronomic productivity due to their water holding capacity, relatively low organic matter (OM), coarse parent material, all contributing to fertility unknowns. When cultivated, the O or LFH, Ae and upper B horizon could be mixed often resulting in the loss of the upper layers. However, it is common for the organic surface horizons and the Ae horizon to be removed during conversion and thus lost to variable extents, depending on the land clearing protocol employed. The resulting converted Ap horizon may thus significantly reflect the chemical and physical properties of a podzolic B horizon. One option considered for expanding boreal region agriculture, notable in Eastern Canada, is to also re-purposing formerly abandoned lands. However, non-tilled soils under tree plantations or abandoned agricultural lands, may undergo a partial re-podzolization altering the parameters of the soil layers even before a full podzolic horizonation is eviden.

Climate change models suggest that precipitation will be altered in the future thus affecting runoff, drainage, soil moisture and nutrient kinetics. With LUC modification and changes in hydrogeological parameters, the major impact of agriculture will be the risk to watersheds especially due to soluble nutrients including N and even water-soluble P. Replacing a natural boreal forest with an agroecosystem will increase the demand for nutrients, as soil organic matter is depleted, altering biochemical cycles. LUC changes the input of plant material to soils, accelerates mineralization of remaining soil organic matter due to priming effects driven by tillage and application of organic or mineral fertilisers, affecting soil microbiological functions. Thus, LUC impacts soils capacity as a sink or source for both carbon and nutrients. Specific to Podzols LUC favours phosphorous (P) fixation as aluminium (Al) and iron (Fe) phosphates increasing the need for fertilization. All these changes modify the nutrient kinetics thus impacting potential agricultural productivity.

Challenges (https://doi.org/10.3389/fsufs.2021.663448)

(i) heterogeneity in socio-economic and environmental conditions between and within regions (e.g., between Finnoscandia, Canadian prairies or Russia, or between Canadian provinces and territories),

(ii) growing urban populations,

(iii) fragmented research support systems, development models and policies focusing on regional and local concerns and opportunities while neglecting global challenges.

Critical knowledge gaps exist concerning if and how northern regions can incorporate, adapt or develop practices as the acknowledged northward shift of the agricultural zone allows agricultural expansion, intensification and diversification.

The agricultural sector development must account for divergences between sustainable development goals addressing food security/self-sufficiency, mitigating CC and preserving biodiversity [effects of CC and LUC on carbon, nutrient and water cycles, while addressing negative (e.g., drought risk, diseases) and positive (e.g., crop diversification) impacts on agricultural production]

These require research capacities and site-specific, long-term agricultural experiments, currently scarce in the northern regions. Accounting for the multi-sectoral nature of the agri-food sector requires multi-disciplinary research and development along the entire agri-food value chains.

Development toward sustainable and resilient northern agri-food systems must avoid repeating the failures of agricultural practices in temperate and tropical regions that prioritize production over nature. Wherever northern agricultural expansion is considered necessary, development ought to guarantee the adoption of locally adapted plant varieties, sustainable agro-ecological and soil management practices.

An example is the possibility for conversion of marginal lands naturally low in organic matter to promote net carbon fixation while producing agricultural products. Contrastingly, protect organic carbon rich peatlands, while supporting adapted land use systems.