Perennial crop growth in oil-contaminated soil in a boreal climate
2015
Yan, Lijuan | Penttinen, Petri | Simojoki, Asko | Stoddard, Fred | Lindström, Kristina
Soil contamination by petroleum hydrocarbons is a global problem. Phytoremediation by plants and their associated microorganisms is a cost-effective strategy to degrade soil contaminants. In boreal regions the cool climate limits the efficiency of phytoremediation. The planting of oil-tolerant perennial crops, especially legumes, in oil-contaminated soil holds promise for great economic benefits for bioenergy and bio-fertilizer production while accelerating the oil degradation process. We established a multi-year field experiment to study the ecological and agronomic feasibility of phytoremediation by a legume (fodder galega) and a grass (smooth brome) in a boreal climate. In 40months, soil oil content decreased by 73%–92%, depending on the crop type. The oil degradation followed first-order kinetics with the reduction rates decreasing as follows: bare fallow>galega–brome grass mixture>brome grass>galega. Surprisingly, the presence of oil enhanced crop dry matter and nitrogen yield, particularly in the fourth year. The unfertilized galega–brome grass mixture out-yielded the N-fertilized pure grass swards over years by an average of 33%. Thus, a perennial legume–grass mixture is both ecologically and agronomically sustainable as a cropping system to alleviate soil contamination in the boreal zone, with considerable potential for bioenergy and bio-fertilizer production.
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