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United States Department of Agriculture

Agricultural Research Service

Title: Utilization of Biosolids As a Fertilizer for Growing Canola.

item Banuelos, Gary
item Sharmasarkar, Shankar -
item Pasakdee, Sajeemas -

Submitted to: Compost Science and Utilization
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 17, 2002
Publication Date: January 5, 2004

Interpretive Summary: More than 5 million metric tons of dry municipal sewage sludge are generated in the US annually. Biosolids is a by-product of the municipal wastewater treatment process. Depending on the source of biosolids (industrial vs non-industrial) the greatest potential commercial use for this material is agricultural fertilizer for growing crops. In our field study we evaluated growing canola in soils amended annually with composted biosolids originating from a non-industrial source. Generally biosolid applications increased concentrations of plant available nutrients in the soil. As a result, biosolids of this quality increased both total dry matter yields and concentrations of all nutrients in the leaves. Among the non-essential trace elements to cause concern, only cadmium was detected at slightly elevated levels. Our results show that a composted biosolids of non-industrial origin can be successfully used for growing canola after seven years of application.

Technical Abstract: Growing canola in biosolid amended soils could be an inexpensive fertilizer as well as an inexpensive form of biosolid disposal. A 2-year study was conducted to determine the yield and nutrient distribution in canola and in soils amended with composted biosolid treatments (in kg N ha-1): 0(control), 57 (low), 170 (medium), and 340 (high). Among the essential elements analyzed (Ca, Mg, K, P, S, B, Mn, An, Cu) and the non-essential trace elements (Cd, Cr, Co, Pb, Ni), there were significant differences in the total macro- and micronutrient concentrations between biosolid treatments and the control at 0-15 cm soil depth. Concentrations of total S, P and Zn were significantly higher at surface than the subsurface (15-45cm). At 0-15 cm depth, soils accumulated higher levels of extractable Ca, Mg, S, P and B with all biosolid treatments compared to 15-45 cm depth. There was a significant increase in soil salinity and soil organic matter content with biosolids treatments at 0-15 cm depth. Biosolid treatments increased the total dry matter yields 1.5 to 3.8 times more than the control and increased concentrations of most essential elements in canola leaves, except for Mg and K. Cadmium was detected in leaves of plants (<3 mg/kg) grown in medium and high biosolid amended soils. For all treatments, the order of elemental accumulation in the leaves was: N>K>Ca>S>P>Mg>Mn>Zn>Cu. The overall results indicate that amending a sandy loam soil with composted biosolids of a non-industrial origin for 7 years can increase yield and nutritional quality of canola with negligible increases in non-essential trace element concentrations in soils and in canola leaves.

Last Modified: 4/22/2015
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