AGRONOMIC PRACTICES AT LOW ENVIRONMENTAL IMPACT FOR DURUM WHEAT IN MEDITERRANEAN CONDITIONS

摘要

The application of conservative agricultural practices such as crop rotation, shallow tillage, and organic fertilizer could usefully sustain crop yield and increase soil fertility, thus playing an important role in the sustainable agriculture. This study was conducted to determine the effects of conservative agronomic practices on yield and quality of wheat. The effects of these practices on soil fertility were further investigated in this four-year study (2005-2008). Two cropping systems, durum wheat in continuous cropping, and in two-year rotation with leguminous crops, were investigated at Foggia (Southern Italy) in rain-fed conditions. Within each cropping system, two levels of crop management were compared: i) conventional, characterized by a higher soil tillage management and mineral fertilizers application; ii) conservative, with a lower soil tillage management and organic-mineral fertilizers. The seasonal weather greatly affected the wheat yield and quality, inducing lower production in years that were characterized by unfavorable climatic conditions. This trend was found when the conventional treatment was applied, both in continuous cropping and rotations. The effects of cropping systems and crop management pointed out the positive role played by the leguminous crops (common vetch and chickpea) in crop rotation. This introduction improved wheat yield in rotation (6.47% compared to the continuous cropping), improved grain protein content (5.88%), and reduced the productive gap between conventional and conservative treatments (9.24 and 14.14% of the wheat in rotation and continuous cropping, respectively). Conversely, the effects of cropping systems and crop management on soil fertility were not very high, since the differences found at the end of the study in total nitrogen values were poor. However, total organic carbon (16.04 and 17.58% for cropping system and crop management, respectively) and available phosphorus values (11.30 and 7.43%) depend on root organic matter contribution, plant biomass residues, and fertilizations. The suitable crop rotation and the sustainable crop management appear important agronomical practices to improve yield and quality of wheat, and may reduce the environmental risks resulting from conventional intensive cropping systems.