Monitoring the effects of pH and EC regulated drip fertigation on microbial dynamics of calcareous soil in tomato (Solanum lycopersicum L.) cultivation under greenhouse conditions in a Mediterranean climate

• Published in: Scientia horticulturae 2022-12, Vol.306, p.111448, Article 111448
• Main Authors: MALTAS, Ahmet Safak, TAVALI, Ismail Emrah, UZ, Ilker, KAPLAN, Mustafa
• Format: Article
• Language: English
• Subjects: Fertigation, Lime; Number of bacteria; Soil enzymes; Soil fertility
• ISSN: 0304-4238; 1879-1018
• DOI: 10.1016/j.scienta.2022.111448

•The soil was significantly affected by pH and EC regulated drip fertigation both in terms of enzyme activities and the presence of bacteria during the tomato cultivation.•pH and EC regulated drip fertigation was observed to stimulate urease enzyme activity in the second growth season compared to the first season.•Accumulation of salts and its negative effect on number of bacteria, alkaline phosphatase and dehydrogenase activities become more apparent in the second growth season.•The pH of the water to be dripped by fertigation to tomato plant rhizosphere in the range of 6.5-7.2 and EC in the level of 2.0 dS m−1 would be ideal for microorganisms and microbial activity in calcareous soils under the Mediterranean climate. The microbial dynamics of the soil, together with the available nutrient content of the soil, is seen as a very important indicator of soil fertility. In this study, the effects of drip fertigation with different pH and EC applications in the cultivation of tomato under greenhouse conditions on microbial dynamics of calcareous soil were investigated using number of bacteria (heterotrophic aerobic mesophilic) and enzyme activities (urease, alkaline phosphatase, β-glucosidase, dehydrogenase). pH and EC regulated fertigation applications on soil are as follows: a) pH 7.2 EC 2.0 dS m−1 (NA+CF-1), b) pH 7.2 EC 3.5 dS m−1 (NA+CF-2), c) pH 6.5 EC 2.0 dS m−1 (NA+CF-3), d) pH 6.5 EC 3.5 dS m−1 (NA+CF-4), e) pH 5.0 EC 2.0 dS m−1 (NA+CF-5); and f) pH 5.0 EC 3.5 dS m−1 (NA+CF-6). Results indicated significant effects of both pH and EC regulated fertigation on soil in terms of enzyme activities (except urease and dehydrogenase) and the presence of bacteria. The measured parameters showed greater values in the first growth season compared to the second (except urease) and the differences between the treatments in the first growth season were statistically significant. In addition, in both growth season, positive relations occurred between number of soil bacteria and total N, available P, urease and alkaline phosphatase activities. On the other hand, due to increasing salinity (in the second growth season) number of soil bacteria, alkaline phosphatase, β-glucosidase and dehydrogenase activities are negatively affected. It would be ideal to have the pH of the water to be dripped to rhizosphere in the range of 6.5-7.2 and the EC in the level of 2.0 dS m−1 in order to provide more efficient and safer protection of the soil fertility in terms of soil microbia