UTILIZATION OF THE SOLID FRACTION OF DIGESTATE FROM ANAEROBIC DIGESTION AS CONTAINER MEDIA SUBSTRATE

The solid fraction of two digestates (D1 and D2) pure and diluted with Sphagnum peat (25%, 50% vol. digestate) was investigated in order to replace totally or partially peat in growing media. They were analyzed for pH, EC, water soluble Ca, Mg, K, NH₄-N, NO₃-N, physical properties and submitted to germination (cress), root elongation (barley), plant growth (lettuce) tests for phytotoxicity and quality evaluation. Both digestates showed high pH and electrical conductivity and induced negative effects on cress germination; D1 had scarce amount of easy available water, high shrinkage rate and induced a decrease of barley root elongation. Mixing of digestates and peat strongly ameliorated chemical characteristics, and balanced bioavailable plant nutrients; consequently plant tests gave positive results. On the basis of our results it can be concluded that digestate can partially substitute peat, decreasing the high cost of peat based growing media.