Evaluation of soilless media sensors for managing winter-time greenhouse strawberry production using a CapMat system

Abstract

It is important for a greenhouse strawberry grower to know that their capillary mat (CapMat™) fertigation system is working correctly and that plants are receiving the correct amounts of water and fertilizer. Pots with soilless mix are not expected to hold more than 70% water on a volumetric basis. Pots with less than 40% water content continuously are not supplied enough water and nutrients to the plants. Typically, pots located near the manifold distribution system get a little more water than those at the other locations, but water use will really vary according to the factors listed above as well as environmental parameters, but should not vary more than 20%. Fertigation is based on the drip tape distribution system, the media density of individual pots, and the spatial energy distribution within the greenhouse. To understand how these factors interact, pot moisture, media temperature, and electrical conductivity were spot checked with a relatively new commercial sensor and also monitored continuously along with greenhouse temperature, humidity, and photosynthetically active radiation (PAR) using a data logger system. We found that the variance in pot medium moisture and fertilizer was as expected as were fluctuations in air and mix temperatures. Calibrated commercial electrical conductivity and soil moisture sensors for measuring pot moisture and/or electric conductivity were reliable. Having this data may be a key to determining why plants in the UNL greenhouse produced more marketable fruit than plants in the commercial house.