Conservation tillage in a semiarid Mediterranean environment: results of 20 years of research

Conservation tillage techniques are becoming increasingly popular\udworldwide as they have the potential to generate environmental, agronomic,\udand economic benefits. In Mediterranean areas, studies performed\udon the effects of conservation tillage [in comparison with the\udconventional tillage technique (CT)] on grain yield of cereal crops\udhave reported contradictory results as well as considerable year-to-year\udvariation, demonstrating how the impact of different soil tillage techniques\udon crop productivity is strongly site-specific. The present paper\udsummarises the main results from a set of experiments carried out in\udSicily during the last 20 years in which we compared no tillage (NT) to\udCT in terms of their respective effects on the productivity and quality\udof durum wheat, while at the same time varying some other crop management\udpractices (e.g. crop sequence, N fertilisation, wheat genotype,\udsowing time). On average, no differences were observed between the\udtwo tillage techniques; yields were 3.84 and 3.87 Mg ha–1 for CT and\udNT, respectively. However, NT guaranteed superior yield when water\udstress during the crop cycle was high, whereas CT led to higher yields\udwhen water availability was adequate. Moreover, the results suggest\udthat the use of NT needs to be accompanied by a rational crop sequence. In fact, a cumulative detrimental effect of NT over time was\udfound for continuous wheat. Finally, grain quality in terms of protein\udcontent was slightly higher for CT (15.1%) than NT (14.4%). Thus,\udwhen using NT, the rate of nitrogen fertiliser application should be\udincreased to offset this difference