Net covering in orchard has been spread to prevent hail, wind, bird and insect damages. But it changes the meteorological environment inside the orchard. This study was conducted to define how net covering changes the environment. Meteorological observations conducted in the pear orchard with shelf at Shiroi, Chiba Prefecture from May 13 to Nov. 6, 1987. The orchard (N-plot) was horizontally covered at 4m height and was surrounded all sides by blue, 10mm×10mm mesh, “hishimeori” net (YK-3815, 380denier). Another orchard (C-plot) with the same structures but without net was observed as the control. 1. The standardized wind speeds of both orchards were compared. The results showed that the net covering suppressed the wind speed by 36% at the upper side of shelf and by 12% at the lower side of shelf. 2. Transmissivity of solar radiation of the net was about 85% on average but it increased with the increase in solar altitude. 3. Evaporation by pan evaporimeter was suppressed in N-plot by 1mm/day in fine days. It was the distinct indication with the wind speed suppression. 4. Fluctuations of the observed temperature and humidity were large, so that mean values of 6 fine days were used. The results showed that net covering increased the mean temperature at the upper side of shelf by 0.5°C in the day time and decreased by a little during the night. The humidity increased both lower and upper sides of shelf by 4-5%. 5. Soil temperature in N-plot decreased by maximum 2.5°C at 1cm depth and by 0.3°C at 10cm depth in the daytime. On the other hand, it increased by a little during the night. Net covering evidently changes the meteorological environment inside the pear orchard. We should be careful of the influence on the crop development.
