Response of wheat crop during transition to organic system under Mediterranean conditions

Organic agriculture is an ecological production management system aimed at sustainableproduction of safe food, environmental protection and maintenance of soil health. The objectiveof this study was to evaluate, in a period of organic transition, the effects of different organicfertilizers on wheat yield, grain quality and soil characteristics. The research was performedin an experimental farm of Southern Italy (Foggia), over a three year period. An organiccommercial fertilizer and compost, obtained from municipal wastes, with and without acommercial bioactivator, were compared in a randomized block design. Grain yield and qualityand soil total organic carbon content (TOC) were measured. The Henin-Dupuis model was alsotested to simulate soil organic C dynamics after organic fertilizer application. Among the years,significant differences were observed in grain yield and quality, indicating that wheat cropresponse was influenced by the weather conditions. The grain and straw yield was notsignificantly affected by the organic fertilizer used, though the compost resulted in significantlylower grain quality compared with the organic commercial fertilizer. In any case, at the end ofthe experimentation, the compost resulted in significantly higher TOC (+4%) compared to theorganic commercial fertilizer. The results showed that the compost may be used as analternative to sustain wheat productivity, feasible also from an economic point of view and toconserve soil fertility. Finally, under the local Mediterranean conditions, the soil organic Cdynamics could be defined by the Henin-Dupuis model, also considering the C supply of annualroot residues.