Application of high copper and zinc compost and its effects on soil properties and growth of barley

A compost of high copper (Cu) and zinc (Zn) content was added to soil, and the growth of barley (Hordeum vulgare L.) was evaluated. Four treatments were established, based on the addition of increasing quantities of compost (0, 2, 5, and 10% w/w). Germination, plant growth, biomass production, and element [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sodium (Na), magnesium (Mg), iron (Fe), Cu, manganese (Mn), and Zn] contents of soil and barley were determined following a 16-week growing period. Following harvesting of the barley, analysis of the different mixtures of soil and compost was performed. Micronutrient contents in soils as affected by compost additions were determined with diethylene-triamine-pentaacetic acid (DTPA) (Cu, Mn, Fe, and Zn) or ammonium acetate [Ca, Na, Mg, K, cation exchange capacity (CEC)] extractions, and soils levels were compared to plant uptake where appropriate. Increasing rates of compost had no affect on Ca, Mg, or K concentration in barley. Levels of Cu, Zn, Mn, and Na, however, increased with compost application. High correlations were found for DTPA-extractable Cu and Zn with barley head and shoot content and for Mn-DTPA and shoot Mn content. Ammonium acetate-extractable Na was highly correlated with Na content in the shoot. High levels of electrical conductivity (EC), Cu, Zn, and Na may limit utilization of the compost.