Effect of preceding crop on the agronomic and economic performance of durum wheat in the transition from conventional to reduced tillage

Preceding crop greatly affects the agronomic and economic performance of durum wheat, but its interac-tion with tillage intensity was scarcely investigated at the early transition from conventional to reducedtillage. This work was aimed at studying how preceding crop determines the performance of durumwheat during the early transition from conventional to reduced tillage. To this end, the effect of four pre-ceding crops (sunflower, durum wheat, alfalfa and maize) in interaction with two tillage systems withoutinversion (RT1 – chisel ploughing, disking twice, and harrowing and RT2 – disking twice and harrowing)and a conventional tillage (CT – mouldboard ploughing, disking twice, and harrowing) was studied ondurum wheat in two years of cultivation. The effect of preceding crop on grain yield and yield componentsof durum wheat was different depending on tillage intensity, and this effect varied depending on the yearof cultivation. Grain yield increased by 1.1–4.2 t ha−1with the increase of the intensity of tillage in bothyears and all preceding crops, with the only exception of wheat crop following sunflower in 2009–2010and following maize in 2010–2011. RT2 decreased wheat grain yield when compared with RT1 only withalfalfa as preceding crop. Differences in grain yield among tillage systems and crops preceding wheat inboth years were mainly due to variations of mean kernel weight and number of spikes per unit area. Theprofitability of durum wheat varied according to the year of cultivation, the preceding crop and the tillagesystem. Overall, in both years profitability was lowest and negative following wheat under reduced tillagesystem, while it was highest and positive following alfalfa under CT. Reduced growth of durum wheatwith reduced tillage systems was mainly consequence of weeds and volunteers plants development andnitrogen availability in soil resulting from nutrient immobilization. It can be concluded that potentialyield penalties in durum wheat in the transition from conventional to reduced tillage can be alleviatedby an appropriate selection of preceding crops.