Effects of tomato-based rotations with diversified pre-planting on soil health in the Mediterranean soils of Western Turkey

Abstract

Turkey ranks fourth among the tomato (Lycopersicon lycopersicum L.) producers in the world and the tomato varieties extend to 40 % of the total vegetable yield of the country. Farmers have continued to cultivate tomato due to the economic potential of this crop in the main vegetable growing regions of Turkey. Intensive agriculture without employing crop rotations and the inclusion of the excessive and the same type of chemical fertilizers continuously regardless of the soil properties reduces the productive capacity of the soil and adversely affects its ecosystem functions. A three-year (2016−18) diversified cropping system combined with field experiments and employing reduced tillage was conducted in İzmir, a semiarid region in Western Turkey, adopting the randomized complete block design with three replications. Six different tomato-based rotations with diversified pre-planting comprising two, three and four different plant species [CR1 (tomato / corn / mustard); CR2 (tomato / bean / mustard); CR3 (tomato/corn/wheat/mustard); CR4 (tomato / bean / wheat / mustard); CR5 (tomato / corn / fallow); CR6 (tomato / bean / fallow)] were employed to evaluate the impact on the parameters of soil health such as basal soil respiration, nitrogen mineralization, and the activities of the enzymes dehydrogenase and β-glucosidase. In the tomato phases, soil samples were drawn on the 16th day after planting of the seedlings at 0−20 cm depth in April 2016 and April 2018. The multivariate analysis of variance revealed that different crop rotations (Treatment: CRs), and their interaction (TreatmentxYear) on the soil microbial characteristics were significantly different in terms of the dependent variables (P < 0.01). On analysis, the microbial parameters in the experimental soils soared by 36 % with the CR2, followed by a 29 % increase with the CR6 compared to the initial levels in both treatments. The average results at the completion of the experiment revealed that design CR4, which included legumes and experienced the greatest variety of plants in the rotation, encouraged 18–30 % more microbial activity than did the other treatments. Our results suggest that two diverse cropping systems CR4 and CR2 managed with reduced tillage could benefit soil health by improving soil respiration, N-mineralization, and the actions of the dehydrogenase and β-glucosidase enzymes. As both the fertilizer and irrigation inputs in CR4 were lower than in the other rotations, it could be recommended as a sustainable ecological and feasible crop rotation model for processing the tomato production under the Mediterranean climatic conditions.