Effect of controlling the leaching fraction on the fertigation and production of a tomato crop under soilless culture

• Predetermined leaching fraction as parameter of fertigation.
• A new method of fertigation.
• Easy and efficient fertigation way.

In recent decades, the improvement of automated fertigation systems has gained great importance for the efficient use of water and fertilizers and for environmental sustainability. The objective of this study was to evaluate the performance of a new fertigation system compared to the fertigation-control tray system, which has been widely used in soilless cultures. A tomato crop (cv. Ramyle) was cultivated in coir crop units at the University of Almeria from November 2012 to May 2013. The fertigation-control tray method was used as a control (T0) and was compared to a new proportional integral derivative (PID) controlled method (T1), which was designed to maintain a constant leaching fraction. A plot design subdivided into three blocks was used, in which the drainage volume was automatically measured. The crop yield and some parameters related to fruit quality and size distribution were estimated. The results show a better distribution of the desired drainage fraction in T1. T1 had lower drainage electric conductivity (EC) values and significantly higher fertigation absorption. There were no improvements in the total crop yield or in most of the measured quality parameters. However, a significant improvement in the largest fruit size was recorded under the T1 treatment.