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Sustainable Agricultural Practices for Improving Soil Carbon and Nitrogen Content in Relation to Water Availability – An Adapted Approach to Mediterranean Olive Groves

Koubouris, G. C, Kourgialas, N. N, Kavvadias, V, Digalaki, N, Psarras, G
Communications in soil science and plant analysis 2017 v.48 no.22 pp. 2687-2700
Olea europaea, agroecosystems, ammonium, canopy, composts, electrical conductivity, experimental design, field experimentation, herbicides, irrigation, microbial biomass, nitrates, nitrogen, nitrogen content, olives, orchards, soil depth, soil microorganisms, soil organic carbon, sustainable agriculture, tillage, trees, vegetation, weeds
A field experiment was conducted in an irrigated olive orchard to determine the effects of an orchard management system consisting of increased carbon input management on spatial distribution (tree inter-row/in-row, soil depth 0–10/10–20 cm) of nitrogen and carbon in the soil as well as on some microbial properties in relation to water availability. The experiment consisted of 12 blocks (each with 4 trees covering 200 m² of land), uniform olive tree canopy size and natural vegetation, used as replications (three per treatment) in a split plot design for the following four treatments: a) spreading of olive mill compost on the soil without soil tillage, b) spreading of chopped pruning residue on the soil without soil tillage, c) combination of b + c, and d) control which received no organic materials and soil was kept free of weeds with frequent tillage and herbicide sprays. Increased soil organic matter content (SOM) (up to +80%), NO₃ N (up to +194%), and NH₄ N (up to +37%) by carbon inputs were observed in soil layer 0–10 cm. Irrigation enhanced SOM, NH₄ N, and electrical conductivity (EC) while it favored NO₃ N increase by carbon inputs. All microbial properties (Soil Basal Microbial Respiration, Soil Microbial Biomass Carbon, and Metabolic quotient) were significantly higher at 0–10 cm in comparison to 10–20 cm depth. This study suggests good agricultural management practices for optimized soil organic carbon (SOC) storage adapted to the typical Mediterranean agroecosystems.