Novel Organic Amendments To Improve Soil Fertility and Plant Nutrition
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There is worldwide demand for organic materials that would be suitable for addition to soils to improve fertility and thereby enhance the production of annual crops and forages. The expansion of biofuel production worldwide has resulted in co-products from fermentation such as distillers’ grain that, when fed to cattle, enable the nutrients used in ethanol production to be recycled by land application of the manures. Other organic co-products from bioenergy production include chars that are left behind from combustion. Leguminous crop residues have a high nitrogen content compared to many other residues and could act as useful “green manures” when added to soil. Such materials have potential as soil amendments but have not been extensively evaluated. The overall objective of the work described in this thesis was to determine the fertility benefits that may be realized by adding these amendments to soil. In this thesis work, three types of novel organic amendments (dried distillers’ grains and solubles (DDGS)-fed cattle manure, alfalfa pellets, and biochar) were evaluated for their effect on plant growth and nutrition and soil fertility in specific, promising applications. Three studies were implemented: 1) a study on the effect of adding different types of DDGS-fed cattle manure on canola growth and nutrition in the growth chamber, 2) a field reclamation study with alfalfa pellets and biochar added to disturbed soils near a potash mine, and 3) a growth-chamber study on use of biochar to improve canola growth and the use efficiency of added fertilizer nutrients on two contrasting Saskatchewan soils. In the manure study, the effect of wheat and corn DDGS-fed cattle manure (fresh and composted) on canola biomass yield, canola N, P, K, and S concentration, soil available N, P, K, S, Cu, Zn, and the recovery of added manure N was determined. Four rates of manure (60, 120, 180, and 240 t ha-1) were applied to two contrasting Saskatchewan soils (Brown and Black Chernozems) in controlled environment conditions, and canola was grown over a five week period. The reclamation study examined the effect of the addition of oat hull-based biochar and alfalfa pellets on biomass of tall wheatgrass and the concentration of N, P, K, and S as well as on soil concentrations of available N, P, K, S, and cation exchange capacity. Two plot areas adjacent to the PCS Cory Potash Mine (near Saskatoon) were utilized, including one on a degraded level area and one on a tailings pond containment berm. The amendments were applied in the fall of 2009 and the site was seeded with tall wheatgrass (Thinopyrum elongatum) in the spring of 2010. Plants were harvested from one m2 areas in each plot in the fall of 2010 and the soil in each plot was sampled in the spring and fall of 2010. The evaluation of biochar to improve plant growth and recovery of fertilizer nutrient was conducted in the growth chamber using biochar derived from willow feedstock. The willow biochar was added at 5, 10, and 20 t ha-1 rates alone, and also a treatment with biochar at 10 t ha-1 with urea and superphosphate fertilizer. The plant N, P, K, and S concentration, soil N, P, K, and S, and N recovery by canola were analyzed following a five-week growth period of canola on Brown and Black Chernozem soils. In the DDGS-fed manure study, the wheat-based DDGS-fed composted cattle manure added the most nutrient per unit weight of added manure of the different manure sources evaluated. Distillers grain fed cattle manure is higher in nutrient content than regular grain ration manure. The composting process further increases the concentration of nutrient ions in the manure and toxicity effects were observed at high rates of application (180 and 240 t ha-1). In the reclamation field trial, there was increased biomass of tall wheatgrass on soil amended with alfalfa pellets that is attributed to increased soil N availability, as also shown in increased soil nitrate contents. The biochar treatment on the berm resulted in increased soil organic carbon (SOC) contents. Biochar added to two Saskatchewan agricultural soils under controlled environment conditions revealed no significant effect of biochar, without or with fertilizer, on the canola yield, nutrient concentration, or fertilizer N recovery by canola grown on the two soils. All three types of organic amendments studied have different characteristics and potential for enhancing soil fertility, plant growth, and nutrition. Manure feed-source (such as wheat or corn DDGS) and processing (composting) all must be considered when determining rates of application for maximizing plant growth and nutrition in the first year following application. Including DDGS in the ration followed by composting will increase the nutrient concentration in the manure per unit weight, necessitating lower application rates of manure product. Alfalfa pellets provide a slow release fertilizer that can be beneficial in increasing plant growth in reclamation of disturbed soils. Biochar appears to have relatively little impact on plant growth and nutrient recovery in the year of application. Further field-scale research on the application of these amendments is required to determine the long-term effects on plant growth and nutrition.
DegreeMaster of Science (M.Sc.)
SupervisorSchoenau, Jeff; Farrell, Richard
CommitteeKnight, Diane; Peak, Derek
Copyright DateMay 2012
Manure, organic amendments, dried distillers' grains and solubles, biochar, alfalfa pellets, compost.