Agriculture

In Ontario, farmers commonly use a MZ (Maize (Zea mays L.))-SB (Soybean (Glycine max))/WW (Winter wheat (Triticum aestivum)) – CC (mixed cover crop) rotation to maximize economic benefits. This study aimed to investigate the short-term impacts of the crop rotation phases and their associated management practices in this diversified cash crop rotation on soil health and the abundance of nitrogen (N)-cycling soil microbial communities (SMCs). Additionally, the abundance of N-cycling SMCs and plant-available N in both surface (0-5 cm) and rooting zone (5-15 cm) depths were characterized in tile-drained (TD) and non-TD fields. In the present study, soils collected under the CC phase had the highest labile carbon levels (10-17% higher) and water-stable aggregates (35-50% higher) compared to the other two crop phases. Lower nitrifying (amoA) gene abundances and soil NO3--N levels were observed in the CC phase compared to the MZ and SB-WW phases, suggesting a potential for decreased nitrification in the CC phase. The presence of SB potentially influenced the soil N concentration in the subsequent WW phase likely due to the release of symbiotically fixed N in the SB-WW phase. Further, higher amoA abundances and NO3--N in the SB-WW phase imply a potential for increased nitrification in the SB-WW phase. Additionally, higher amoA/nosZI and nirS+nirK/nosZI ratios were observed in the MZ phase than in SB-WW and CC phases, suggesting a potential capacity for increased N2O emissions from the reactions mediated by N-cycling SMCs in soils planted to MZ during fall sampling days. In the TD and NTD field study, higher NO3--N levels were observed in TD-SB-WW fields at 5-15 cm vs. 0-5 cm depths, which was possibly facilitated by tile drainage. The TD-CC fields displayed higher nosZI gene abundances and lower nirS+nirK/nosZI abundance ratios, suggesting a greater potential capacity for decreased N2O emissions in soils planted to CCs during the spring sampling days. When examining changes in plant available N by soil depth, reduced downward movement of NO3- through shallow soil depths (0-15 cm depth) was observed in the CC phase compared to cash crops. This short-term study highlights the potential contribution of the CC phase, particularly within TD agricultural fields, for improving soil health and reducing potential N2O emissions. Together, these results suggest that management-associated differences in crop rotation phases have temporary effects on soil health and the abundance of SMCs. Future studies linking N-cycling SMC's potential activity and field-scale N2O fluxes will provide a better insight into the longer-term sustainability of Ontario's cash crop management systems.

Author Keywords: denitrification, maize-soybean-winter wheat- cover crop rotation, nitrification, soil depth, Sustainable agriculture, tile-drainage

Eutrophication is an ongoing global problem and agriculture is an important non-point source of nutrient loading. Specifically, nitrogen (N) and phosphorus (P) losses from agricultural landscapes continue to drive water quality issues. In southern Ontario, agriculture has intensified in recent decades, with major expansions of cash crop production and extensive tile drainage (TD). Through intensive monitoring of 12 tile outlets draining operational fields under the conventional corn-soybean-wheat rotation, this study examined differences in measured and volume-weighted total P, total N, and nitrate-N concentrations and loads over 28 months (October 2020- April 2023) amongst crop covers and between growing (GS; May – September) and non-growing seasons (NGS; October – April). Nitrogen concentrations (i.e., TN and NO3-N) in TD eluent were consistently high both between seasons and were found to be significantly highest from winter wheat (WW) fields in the NGS, and corn fields in the GS. Volume-weighted TP concentrations were not significantly different either amongst crop covers or between seasons, although TP losses tended to be highest from the cover crop (CC) fields in the NGS. Differences in N and P losses between years and amongst crop covers were attributed to differences in legacy soil nutrients, the establishment and decomposition of over-winter cover crops, and physical soil properties. The results of this study can inform agricultural management by addressing the urgent need for improved information around the relationship between agricultural practices and nutrient losses, especially in the NGS.

Author Keywords: Best management practices, Crop rotation, Over-winter cover crops, Seasonality, Tile drainage, Water quality

Small scale farming at the homestead or hobby farm scale provides opportunities for members of the public to visit farms, see livestock, and engage directly with how their food is produced. This scale is often dismissed as or minor importance, yet the biosecurity of larger farms makes these small farms often the only ones that the public can visit. My research explores whether communities want these direct connections with agriculture, and if this provides understanding of the interconnection of farming ecosystems. As a small scale egg producer, I first provide a personal autoethnography of my own operation. I then examine my customers attitudes toward my produce and farm, and analyse interview of other local producers and community members.

Author Keywords: Connectivity, Diversity, Family farming, Homesteading, Small-scale agriculture, Sustainable agriculture

Diversified agroecosystems supporting greater genetic, structural, and functional diversity improve soil health and ecosystem function. However, there is limited understanding of how multiple forms of diversification, such as mixing cover crop species and adding arbuscular mycorrhizal fungi (AMF), alter belowground carbon supply to soil. In a controlled environment experiment using rhizoboxes, I investigated the belowgound response of cover crops – red clover (Trifolium pratense) and barley (Hordeum vulgare) – grown in monoculture or mixture, with and without AMF inoculation. Root morphological and mycorrhizal traits that characterize the hypothesized root economics spectrum (RES) were integrated with novel sampling of dissoved organic carbon fluxes and easily extractable glomlin in rhizosphere soil. Results revealed species-specific shifts on the RES suggesting that diversification through species mixing and AMF additions can alter belowground carbon allocation pathways, with potential implacations for plant performance and soil carbon stabilization in agroecosystems.

Author Keywords: Arbuscular mycorrhizal fungi, carbon sequestration, cover crops

This thesis introduces a weather-driven bio-economic optimization model for agricultural planning and decision-making. The model integrates weather simulations—including precipitation, temperature, relative humidity, and reference evapotranspiration (ETo)—to estimate crop yields using the AquaCrop simulator. These yield estimates are then incorporated into a multi-objective optimization (MOO) model that aims to maximize gross profit and economic water productivity (ET), while minimizing land use. The MOO model's results provide insights into key agricultural planning questions, such as what, where, when, and how much to plant.The findings demonstrate the model's potential to enhance agricultural decision-making by offering optimized crop combinations that improve both economic returns and land use efficiency. This research contributes to the development of a dynamic agricultural planning model by integrating weather forecasting, crop simulation, and multi-objective optimization.

Author Keywords: AquaCrop, Artificial neural network, Markov chains, Multi-objective optimization, Reference evapotranspiration, Stochastic differential equation

On many farms, stone and wooden field borders define field sizes. These are commonly perceived as land lost to production and refuges for pests and disease, causing such fences and hedges to be removed to create larger fields for increased productivity; this process has eliminated trees and shrubs that provide habitat along these fencerows. This research explores the alignment of agricultural productivity and wildlife conservation, proposing that species such as feral apples may serve as direct economic resources for producers and act to protect such remaining fences and hedges. This study focused on farms in the Dummer Moraine, which have small fields, adventive hedges on rock piles and rail fences. Using field size analysis, apple frequencies and apple jelly tasting, the research demonstrates that feral apples could provide economic incentive for keeping these hedges intact, offering a practical mechanism for their conservation, benefiting both biodiversity and farm productivity.

KEYWORDS: biodiversity conservation, farm gate sales, fencerows, feral apples, hedges, linear forests

Author Keywords: biodiversity conservation, farm gate sales, fencerows, feral apples, hedges, linear forests

This study used literature from the social and ecological sciences to look at the practice of seed saving in the Global North for adaptation in the face of climate change. The hypothesis is that small-scale gardeners and farmers are adapting seeds to the changing climate as they grow them, which is not the case for growers who grow only food. However seed savers face obstacles and are dwindling in number – even though the practice is thousands of years old. Using survey and interviews of seed savers in two communities in Ontario Canada (one Indigenous and one settler), this mixed methods Participatory Action Research project explores the challenges and opportunities for seed saving in the context of climate change. The results indicate that both seed savers and their crops are adapting to climate change, but that the challenges and implications diverge for Indigenous vs settler communities. A framework of recommendations to advance seed saving in a beneficial, decolonizing way is proposed.

Author Keywords: climate change, Food security, food sovereignty, Seed Keeping, Seed Saving, Sustainable Food Systems

In Ontario, farmers commonly use a MZ (Maize (Zea mays L.))-SB (Soybean (Glycine max))/WW (Winter wheat (Triticum aestivum)) – CC (mixed cover crop) rotation to maximize economic benefits. This study aimed to investigate the short-term impacts of the crop rotation phases and their associated management practices in this diversified cash crop rotation on soil health and the abundance of nitrogen (N)-cycling soil microbial communities (SMCs). Additionally, the abundance of N-cycling SMCs and plant-available N in both surface (0-5 cm) and rooting zone (5-15 cm) depths were characterized in tile-drained (TD) and non-TD fields. In the present study, soils collected under the CC phase had the highest labile carbon levels (10-17% higher) and water-stable aggregates (35-50% higher) compared to the other two crop phases. Lower nitrifying (amoA) gene abundances and soil NO3--N levels were observed in the CC phase compared to the MZ and SB-WW phases, suggesting a potential for decreased nitrification in the CC phase. The presence of SB potentially influenced the soil N concentration in the subsequent WW phase likely due to the release of symbiotically fixed N in the SB-WW phase. Further, higher amoA abundances and NO3--N in the SB-WW phase imply a potential for increased nitrification in the SB-WW phase. Additionally, higher amoA/nosZI and nirS+nirK/nosZI ratios were observed in the MZ phase than in SB-WW and CC phases, suggesting a potential capacity for increased N2O emissions from the reactions mediated by N-cycling SMCs in soils planted to MZ during fall sampling days. In the TD and NTD field study, higher NO3--N levels were observed in TD-SB-WW fields at 5-15 cm vs. 0-5 cm depths, which was possibly facilitated by tile drainage. The TD-CC fields displayed higher nosZI gene abundances and lower nirS+nirK/nosZI abundance ratios, suggesting a greater potential capacity for decreased N2O emissions in soils planted to CCs during the spring sampling days. When examining changes in plant available N by soil depth, reduced downward movement of NO3- through shallow soil depths (0-15 cm depth) was observed in the CC phase compared to cash crops. This short-term study highlights the potential contribution of the CC phase, particularly within TD agricultural fields, for improving soil health and reducing potential N2O emissions. Together, these results suggest that management-associated differences in crop rotation phases have temporary effects on soil health and the abundance of SMCs. Future studies linking N-cycling SMC's potential activity and field-scale N2O fluxes will provide a better insight into the longer-term sustainability of Ontario's cash crop management systems.

Author Keywords: denitrification, maize-soybean-winter wheat- cover crop rotation, nitrification, soil depth, Sustainable agriculture, tile-drainage

Eutrophication is an ongoing global problem and agriculture is an important non-point source of nutrient loading. Specifically, nitrogen (N) and phosphorus (P) losses from agricultural landscapes continue to drive water quality issues. In southern Ontario, agriculture has intensified in recent decades, with major expansions of cash crop production and extensive tile drainage (TD). Through intensive monitoring of 12 tile outlets draining operational fields under the conventional corn-soybean-wheat rotation, this study examined differences in measured and volume-weighted total P, total N, and nitrate-N concentrations and loads over 28 months (October 2020- April 2023) amongst crop covers and between growing (GS; May – September) and non-growing seasons (NGS; October – April). Nitrogen concentrations (i.e., TN and NO3-N) in TD eluent were consistently high both between seasons and were found to be significantly highest from winter wheat (WW) fields in the NGS, and corn fields in the GS. Volume-weighted TP concentrations were not significantly different either amongst crop covers or between seasons, although TP losses tended to be highest from the cover crop (CC) fields in the NGS. Differences in N and P losses between years and amongst crop covers were attributed to differences in legacy soil nutrients, the establishment and decomposition of over-winter cover crops, and physical soil properties. The results of this study can inform agricultural management by addressing the urgent need for improved information around the relationship between agricultural practices and nutrient losses, especially in the NGS.

Author Keywords: Best management practices, Crop rotation, Over-winter cover crops, Seasonality, Tile drainage, Water quality

Ontario grain corn is highly valuable, accounting for 60% of Canada's total corn output. Grain producers are increasingly interested in including cover crops (CCs) in their cropping systems, but they have concerns regarding successful CC establishment and potential adverse competitive effects on corn yield and nutrient status. One option to improve the success of CC establishment is the interseeding in corn at the V4 -V6 stages. Interseeding improves the chances of good CC establishment, with potential benefits for soil health, weed control, and plant productivity. This thesis research was conducted to evaluate the short-term effectiveness of interseeding annual ryegrass (AR), red clover (RC), and their mixture (MIX) in grain corn at three locations in central and southwestern Ontario. Cover crop and corn yields, and their nitrogen (N) uptake, residual soil N, soil biological parameters, weed biomass, and residue decomposition rates were measured. CC biomass was highly variable (range: 0 - 1.6 Mg ha-1), influenced by climatic conditions, location, and CC type. Total carbon (C) and N contributions from CCs were similarly influenced by site-year and CC type. Regression analyses showed significant influence of corn biomass on CC establishment. Red clover had a significantly lower C/N ratio (11.8) than AR (18.2) and MIX (15.6). Strikingly, the amount of CC biomass accumulated in early spring reduced weeds by 50%. Moreover, CCs did not reduce corn grain or stover yield, nor N uptake, and soil mineral N in either fall or spring. Soil metabolic activity measured by BIOLOG Ecoplates was significantly greater in plots with AR than RC, MIX or NOCC. Soil biological parameters showed no CC effect. Results of residue decomposition i.e., C and N mineralization showed negligible CC residue effects on corn stover decomposition or N immobilization. The findings from this research suggest the need for assessing a more diverse range of CCs over longer durations to establish more specific CC niches for improving soil health in Ontario corn systems.

Author Keywords: CLPP, cover crops, grain corn, nitrogen uptake, residue decomposition, soil health