Bioindicators and nutrient availability through whole soil profile under orange groves after long-term different organic fertilizations

We investigated long-term (18 years) effects of three organic (cow manure (CM), poultry manure (PM), compost from agro-industry orange wastes (OW)) and one inorganic fertilization (IF) on various soil biological indicators (microbial biomass C, soil respiration, total phospholipid fatty acids (PLFAs), total bacteria, Gram-positive and Gram-negative bacteria and fungi) and nutrient contents (total and extractable organic C, total and mineral N, available P and K) along the profile of a Typic Haplustept under orange Mediterranean orchards. All fertilizers were added on the same N content basis (190 kg N ha−1 per year). Variables related to carbon cycling gradually worsened with depth, regardl…