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31
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Introduction
My research interests focus on assessing the agro-ecological benefits provided by forage and service crops (enhanced soil and water quality, nutrient cycling and nutrient use efficiencies, mitigating net greenhouse gas emissions, and improved biodiversity) and how targeted agroecosystem management can augment these benefits.
Publications
Publications (31)
Soil Phosphorus Forms from Organic and Conventional Forage Fields
Abstract
Recent studies exploring soil phosphorus (P) status of organic dairy farms in Canada report low concentrations of Olsen soil test P (STP), yet the impact on crop productivity is unclear. It is suggested that soil biological activity, including organic P mineralization, may s...
Low concentrations of Olsen soil test phosphorus (STP) on organic dairy farms in Canada have been reported, however, the resulting impact on crop productivity is unclear. This study evaluated mixed forage (alfalfa [Medicago sativa L.]/timothy [Phleum pratense L.]) productivity, nutrient uptake, and related soil biological and biochemical properties...
Snowmelt runoff often comprises the majority of annual runoff in the Canadian Prairies and a significant proportion of total nutrient loss from agricultural land to surface water. Our objective was to determine the effect of agroecosystem management on snowmelt runoff and nutrient losses from a long‐term field experiment at Swift Current, SK. Runof...
Soil phosphorus (P) cycling in agroecosystems is highly complex, with many chemical, physical, and biological processes affecting the availability of P to plants. Traditionally, P fertilizer recommendations have been made using an insurance‐based approach, which has resulted in the accumulation of P in many intensively managed agricultural soils wo...
Phosphorus (P) runoff from agriculture exacerbates eutrophication globally. Despite diverse mitigation options, the issue persists, necessitating the evaluation of slow-release fertilizers for crop production to minimize environmental P losses. Struvite, a P-rich, recycled product with low water solubility, holds promise for minimizing off-site env...
Information is required to understand how novel biodiversity strategies can improve cropping system resilience to climate change. A “business as usual” (BAU) rotation (wheat–canola–wheat–soybean) was compared with a “warm-season crop” (WS) rotation (corn–sunflower–dry bean–canola); a “biodiverse” (BD) rotation (fall rye with cover crop– corn/soybea...
Struvite (NH4MgPO4·6H2O) may be an appropriate fertilizer to address phosphorus (P) deficiencies in organic cropping systems, but field studies assessing crop response to struvite are lacking. Field experiments were conducted over 3 yr on a low‐P, alkaline soil in Manitoba to assess the effect of struvite application rate on the yield and P accumul...
Balancing the weighting of various components of phosphorus loss in models is a critical but often overlooked step in accurate estimation of risk of P loss under field conditions. This study compared the P loss coefficients used to predict dissolved P losses from desorption from accumulated P in the soil, and those incidental to applications of P a...
Soil phosphorus (P) deficiency is common in organic cropping systems in which access to manure or other suitable P sources is limited. Insufficient P supply may be particularly detrimental to crop yields in systems relying on biological nitrogen fixation by legumes. High-purity struvite (magnesium ammonium phosphate hexahydrate) recovered from wast...
Struvite (magnesium ammonium phosphate hexahydrate) is a sparingly soluble, phosphorus (P)-rich mineral that can be recovered from wastewater streams and is gaining attention as a slow-release fertilizer. Crop productivity response to struvite is often greater than expected based on the low solubility of struvite in water, indicating that processes...
Struvite is a phosphorus (P)-rich mineral that can be extracted from wastewater for use as a fertilizer, but its impact on the soil biological community is unknown. Many crop plants associate with arbuscular mycorrhizal fungi (AMF) to help access soil P and other resources, but addition of soluble P fertilizers typically reduces AMF colonization of...
Phosphorus (P) nutrition of field crops is challenging on organic farms without an adequate supply of manure or other P-rich amendments. High-purity struvite extracted from municipal wastewater has been proposed as a suitable P source for organic cropping systems. Greater understanding of crop agronomic response to struvite is needed to develop app...
Phosphorus (P) loss to freshwater is a key driver of eutrophication, and understanding the scale and spatial distribution of potential P sources is a key pre-requisite for implementing policies for P management to minimize environmental impacts. Soil test P (STP) is a useful indicator of the accumulation of P in soils, but these data are not readil...
Adequate phosphorus (P) is needed for crop production, but excessive P poses a potential risk to water quality. Results from the cumulative P balance calculations within the indicator of risk of water contamination by phosphorus (IROWC‐P) developed in Canada were assessed to determine the spatial and temporal trends in P accumulation at a regional...
This preliminary field study examined response of grain and forage crops under organic management to addition of struvite fertilizer in a low-phosphorus (P), high-pH soil in Manitoba, Canada. Struvite addition increased spring wheat grain yield in one of two years, but did not affect flax grain yield. Struvite addition increased alfalfa-grass forag...
Phosphorus (P) loss to surface freshwater is a key driver of environmental degradation, including blooms of both harmful (e.g., microcystis) and nuisance (e.g., cladophora) algae, along with the development of hypoxic zones that could significantly impact fish habitat. Mitigating P losses from agricultural land will require a detailed understanding...
Low concentrations of Olsen soil test phosphorus (STP) on organic dairy farms in Canada have been reported, however, the resulting impact on crop productivity is unclear. This study evaluated mixed forage [Medicago sativa L. (alfalfa) / Phleum pratense L. (timothy)] productivity, nutrient uptake, and related soil biological and biochemical properti...
Soil phosphorus (P) tests are designed to indicate plant-available inorganic orthophosphate (Pi), but fail to account for Pi that may become available through organic phosphorus (Po) mineralization. This P source may be especially important in soils with low concentrations of solution and labile Pi. We assessed gross Po mineralization and immobiliz...
Recent studies exploring soil phosphorus (P) fertility on dairy farms under organic management in Canada have reported low concentrations of Olsen soil test P (STP), yet the impact on crop productivity is not clear. In this thesis, soil biological and biochemical properties relating to plant P availability in perennial forage fields (Medicago sativ...
Under the rules of organic certification, phosphorus (P) deficiency in crops can be
an important limitation to production. Phosphorus is notoriously difficult to extract
from the soil; however, many plants have evolved to form a symbiotic association
with soil fungi to cope with this difficulty. This chapter considers the arbuscular
mycorrhizal (AM...
Phosphorus deficiencies are limiting crop production in agricultural soils worldwide. Locally available sources of raw phosphate rock (PR) are being recognized for their potential role in soil fertility improvement. Phosphorus bioavailability is essential for the efficiency of PRs and can be increased by acid treatments. The utilization of organic...
Plants colonized by arbuscular mycorrhizal (AM) fungi have been shown to respond positively to the application of insoluble forms of inorganic phosphorus (P) such as rock phosphates (RPs). The mechanism(s) underlying such responses remain(s) unknown and although it has been hypothesized, there is no experimental support for the production of chelat...
Phosphorus deficiencies are limiting crop production in agricultural soils worldwide. Locally available sources of phosphate rock (PR) are being recognized for their potential role in soil fertility improvement. For applications of PR to be effective, the phosphorus must be made plant-available. Modification with acid-producing microorganisms has t...
Deficiency in plant-available phosphorus is considered to be a major limiting factor to food production in many agricultural soils. Mineral resources are necessary to restore soil phosphorus content. In regions where conventional fertilizers are not used due to cost limitations or to mitigate adverse environmental effects, local sources of phosphat...
About 99% of soil microorganisms are unculturable. However, advances in molecular biology techniques allow for the analysis of living microorganisms. With the advent of new technologies and the optimization of previous methods, various approaches to studying gene expression are expanding the field of microbiology and molecular biology. Methods used...