Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/17/2006
Publication Date: 6/1/2007
Citation: Banuelos, G.S., Pasakdee, S., Benes, S., Ledbetter, C.A. 2007. The effect of biosolids on apricot production after 7 years of application. Communications in Soil Science and Plant Analysis, Volume 38, Issue 11 & 12, June 2007, pages 1533-1549.
Interpretive Summary: Nutrient input from utilizing sewage sludge or biosolids is under consideration in agriculture because more than 5 million metric tons of dry municipal sewage sludge are generated annually in the U.S. In a 7-year study we investigated the effect of long-term application of biosolids on apricot fruit quality and on the accumulation of essential elements and heavy metals in the fruit and in the soil. The results showed that the essential macro- and micronutrients were greater in fruits from trees grown with applied biosolids as compared to control (no biosolids applied). For all biosolid treatments, fruit maturation was delayed and fruit were firmer as compared to control. Other typical fruit quality parameters (i.e., juice pH, total acidity, organic acids, fruit skin color) were not affected by the applications of biosolids. Using non-industrial biosolids of this quality in apricot production may be advantageous for growers who need to transport firm fruit over long distances and for growers who wish to have a staggered fruit maturity.
Technical Abstract: We evaluated the effect of 7 years of application of biosolids on apricot quality and trace element accumulation in the soil and in the fruit. Biosolids were applied annually at rates of 0, 1.9, 5.8, and 11.7 Mg/ha. These rates provided 0 (control), 57, 170, and 340 Kg N/ha. These application were compared to an untreated control. Compared to the control, the applications of biosolids increased water extractable concentrations of Ca, Mg, S, P, Zn, and Cu from 0-90 cm; however, heavy metal concentrations (Cd, Cr, Co, Ni, and Ph) were not increased. Concentrations of Ca, K, S, Fe, and Zn increased in the fruit, whereas heavy metals were not significantly detected. For all biosolid treatments; fruit maturation was delayed, more green fruits were counted, and fruits were firmer as compared to the control at harvest. Juice pH, total acidity, organic acids, and fruit skin color, were not affected by biosolids application. Our results suggest that non-industrial biosolids can be safely applied at a rate of 11.7 Mg/ha to apricots in a sandy loam soil. Delayed fruit maturity and increased firmness of the fruit may result from the application of these biosolids.