Novel Organic Amendments to Enhance Nutrient Cycling and Organic Matter in Problem Soils

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The proposed research evaluates the impact of adding novel organic amendments, including biochar, humic material (leonardite) and composted manure, to chemically, physically and biologically challenged salt affected soils in Saskatchewan. Planned studies will address basic questions surrounding behaviour and interactions of organic matter in saline soils, as well as assessing and developing practical means (amendments, rotations) that will make the soils more productive. Two field research sites with salt affected soils (saline, solonetzic) in the Brown and Dark Brown soil zones of Saskatchewan will be established. Understanding the effect of the amendments on soil and plant productivity, nature of salt minerals and their interaction with organic matter, carbon and nitrogen turnover and sequestration is emphasized. Previous work by the applicant has examined impacts of novel organic amendments made to non-saline soils, which has led to a better understanding of their effects on soil quality and plant growth. A continuation of this work to include saline soils is justifiable as there are over 6 million acres of salt affected lands in Western Canada. Furthermore, increased precipitation and higher temperatures in recent years has led to higher water tables and increased evaporation in many regions that has contributed to the spread of salinity. Climatic variability can contribute to salinization, but the salt affected soils also offer promise for carbon sequestration through amendment and improvement in productivity. However, there has been very little scientific attention given to organic matter dynamics and nutrient cycling in saline soils. Low plant productivity caused by salinity present before and during cultivation contributes to low organic matter content in these soils as well as large amounts of inorganic nutrients that have accumulated from past fertilizer applications. Amendment with organic materials that can sorb cations and anions, improve water relations and encourage microbial activity will potentially promote better nutrient utilization and growth of salt tolerant forages and annual crops like hybrid canola and barley grown in rotation. A contribution to improved water quality is also anticipated if nutrients and salts are effectively sequestered by organic matter. Field and controlled environment studies will use a combination of traditional chemical, physical and novel synchrotron based techniques to better understand how the amendments influence soil salinity, water and air relations, carbon and nitrogen forms and turn over, nature of organo-mineral complexes, and their ability to promote germination and growth of salt tolerant forage grasses and annual crops. This research will contribute to grower adaptation and mitigation of climate change along with economic prosperity.