Standard Procedures Proposal of Laboratory Experimental Tests Assessment for Water Permeability of Anti-Rain Agricultural Nets

Climate change threatens the agricultural field by affecting production yields and crop quality. Yield protection is an increasingly pressing priority to preserve the ability of agriculture to meet food demand with more sustainable production of appropriate quality and quantity and with less demand for plant protection products. For this reason, nowadays the use of agricultural nets is becoming increasingly widespread to counteract possible risks from abiotic stresses. Among all agricultural nets, the anti-rain ones have the predominant purpose of protecting crops from damage caused by severe weather events. The present study aims to verify whether anti-rain nets could be used as greenhouse covering material, starting from the evaluation of the rainwater permeability index Φrw. For this purpose, a laboratory rain simulator was designed and several tests were performed on the chosen anti-rain net, varying its inclination and the duration and intensity of the simulated rainfall, returning different normalized permeability indices NPI, of which the standard deviation (SD) was calculated. The optimal rainfall duration of the artificial rain test was determined at the minimum value of the sum of the SDs, identified as about 25%, at a duration of 10 min. Subsequently, tests were carried out to define the Φrw index for a rainfall lasting 10 min, by varying the other parameters, returning the lowest Φrw index of approximately 45% at a 20◦ net inclination and with the weave perpendicular to the slope. The results highlight the possibility to use anti-rain nets for greenhouse covering, replacing or supplementing commonly used nets, facilitating oxygen exchange and maximizing light capture capacity, essential for vegetative–productive balance. A proposal for standardizing the procedures to test nets, based on experimental tests, has never been proposed in the scientific literature. Regarding fruit and vegetable crops, there are several issues to be evaluated; this study only considers rain protection, through nets can be used for different fruit and vegetable varieties.