Organic amendment and minimum tillage in winter wheat grown in Mediterranean conditions: Effects on yield performance, soil fertility and environmental impact

The experiment was conducted to evaluate the agronomic benefit of the application of organic fertilizers combined with different soil tillage on quantitative and qualitative components of winter wheat (Triticum durum Desf., cv. 'Simeto') and on chemical soil fertility parameters. The environmental impact, due to heavy metals introduced in soil-plant system, was further investigated. Soil tillage treatments consisted of conventional (CT) and minimum tillage (MT). Fertilization treatments were: mineral at 100 kgN ha(-1) (N-min); municipal solid waste compost at 100 kgN ha(-1) (N-comp); 50 kgN ha(-1) of both compost and mineral fertilizers (N-mix); sewage sludge at 100 kgN ha(-1) (N-ss). These treatments were compared with an unfertilized control (N-0). No significant difference was observed between the two soil tillage treatments for quantitative yield production, while among the fertilization treatments N-ss did not show any significant difference compared to N-min. At the end of the research, the fertility of the soil (oxidable carbon, total nitrogen, available phosphorus) was on average higher in N-comp and N-ss treatments compared to the N-0 and N-min ones. The overall distribution of heavy metals in soil-plant system respect to the different fertilizer treatments has not allowed to grouped their effects with Principal Components Analysis. This result showed that the amount of potential pollutants applied by organic amendments did not modified the dynamic equilibrium of the soil-plant system. The MT, as well as the fertilization with the application of sewage sludge (N-ss), allowed to reach productive performance similar to conventional management (CT with N-min). Here we demonstrate that, in the short term period, sustainable agronomical techniques can replace the conventional one with environmental benefit. (C) 2015 Elsevier B.V. All rights reserved.