Determination of Effects of Various Plastic Covers and Biofumigation on Soil Temperature and Soil Nitrogen Form in Greenhouse Solarization: New Solarization Cover Material

This research was carried out to determine the effects of traditional solarization cover material by testing new covering material and biofumigation treatments on changing temperatures and soil nitrogen forms (ammonium, nitrate and nitrite). The study was carried out for 2 years (2011-2012) in a plastic covered greenhouse in Isparta, Turkey. The solarization process lasted 40 days in the summer, on a parcel of 2 x 2 m, and was repeated 3 times. Hourly temperature changes at 5, 10, 20 and 30 cm soil depths were recorded during the study. At the end of the experiment, in soil samples taken from 0 to 15 cm and 15-30 cm soil profiles, nitrate (NO3-), nitrite (NO2-) and ammonium (NH4+) analyses were performed. During the solarization process, the upper surface of the soil yielded a higher temperature rise, while the increase declined towards lower layers. Bubble solarization and bubble water solarization led to a higher temperature rise in lower layers of the soil, as well as higher heat protection, compared to other applications. In both years of the study, NO3- levels significantly increased, especially in the second year at each depth, by over 100 %. The tested new covering material provided higher heating effects compared to conventional ones; moreover, the new material did not yield a higher nitrate accumulation as biofumigation caused.