The influence of construction parameters on radiometric performances of agricultural nets

Plastic netting is most commonly used in agriculture to protect greenhouses, fruit-trees and ornamental plants from solar radiation, insects, birds, hail, wind, snow or heavy rainfall. There are many net typologies on the market with different construction parameters. It appears that there are no shared criteria for choosing the net typology which best fulfils a specific requirement, but that the choice generally depends on empirical or economic criteria, not on scientifically relevant considerations. In order to investigate the influence of net construction parameters on their radiometric properties, a set of field tests were performed using a spectroradiometer (GER2600) with a wavelength range of 250-2500 nm. Transmittance was calculated in field tests in the following wavelengths: UV (300-380 nm); Visible (380-760 nm); PAR (Photosynthetically active radiation 400-700 nm); NIR (760-1500 nm). Tests were carried out on 25 different kinds of commercial nets. An experimental setup of 120 x 120 x 50 cm was used to evaluate the radiometric properties of the nets tested. In addition, trials were performed on a full scale shade-house (9.60 x 4.40 x 30.00 in) covered with 4 different kinds of shading nets. Experimental test results made it possible to define the influence of net colour, porosity, shading factor and solar angle on the evaluation of transmittance in the UV, PAR and visible light wavelengths.