Abstract
Horticultural systems, specifically vegetable production systems, are considered intensive agricultural systems as they are characterized by high nitrogen (N) fertilizer application rate, frequent tillage, and irrigation operations. Accordingly, horticultural production in temperate climates is prone to N losses — mainly during post-harvest (during fall and winter) or pre-plant (spring) periods — such as N2O emissions and nitrate leaching. The risk for N losses is linked to low crop N use efficiency (NUE) combined with a narrow C:N and high N content of crop residues. Here we reviewed the studies conducted in Canada and similar climates to better understand the risk of N2O emission and potential agronomic management strategies to reduce N2O emissions from horticultural systems. Current knowledge on N2O emissions from horticultural systems indicate that increasing crop NUE, modifying the amount, type, time, and rate of N fertilizer inputs, and adopting cover crops in crop rotations are some of the effective approaches to decrease N2O emissions. However, there is uncertainty related to the efficiency of the existing N2O mitigation strategies due to the complex interactions between the factors (soil characteristics, type of plant species, climatic conditions, and soil microbial activity) responsible for N2O production from soil. Little research on N2O emissions from Canadian horticultural systems limits our ability to understand and manage the soil N2O production processes to mitigate the risk of N2O emissions. Thus, continuing to expand this line of research will help to advance the sustainability of Canadian horticultural cropping systems.
Highlights
Nitrous oxide, a potent greenhouse gas with 298 times greater warming potential than CO2 (IPCC 2007), is produced in the soil primarily through processes of nitrification and denitrification (Bremner et al 1997)
Due to high economic and nutritive value of vegetable and perennial fruit crops, certain cropping systems are subjected to large amount of N fertilizer inputs (Chen et al 2005; Thompson et al 2007) which poses an enhanced risk of N loss to the environment (Agneessens et al 2014; Di and Cameron 2002)
We reviewed the potential soil, crop, and climatic factors to analyze the risk of N2O production in some horticultural production systems in temperate climates
Summary
A potent greenhouse gas with 298 times greater warming potential than CO2 (IPCC 2007), is produced in the soil primarily through processes of nitrification and denitrification (Bremner et al 1997). In Canada, planted area of perennial fruit crops increased by 3.3% over 2011 to 2020 period (Statistics Canada 2021). Unlike perennial fruit crops, planted area of field vegetable crops decreased by 4.8% over the 2011 to 2020 period (Statistics Canada 2021). Due to high economic and nutritive value of vegetable and perennial fruit crops, certain cropping systems are subjected to large amount of N fertilizer inputs (Chen et al 2005; Thompson et al 2007) which poses an enhanced risk of N loss to the environment (Agneessens et al 2014; Di and Cameron 2002). Our objectives are to (a) evaluate the risk of N2O emission by way of analysing what is known about N cycling in horticultural systems, (b) synthesize management strategies which show promise in minimizing N2O emissions from these systems, and (c) highlight future research needs for better understanding of N2O dynamics in Canadian horticulture
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