Effect of hydromulches on soil temperature in open field conditions in organic farming.

Abstract

<p>During the last decades, investigation is being focused for environmental reasons on the search of alternatives to herbicides and plastics of petrochemical origin to control weeds, both in herbaceous and woody crops and especially in organic farming. With this purpose, more environmentally-friendly materials are being used worldwide, including biopolymers and papers, mainly in annual herbaceous crops due to their shorter useful live. For this reason, various research groups are investigating on the manufacturing of hydromulches of different composition and characteristics as harmless mulch materials which exert properly their functions. In this framework, in the current study we evaluated the effect of three hydromulches on soil temperature in an intensive almond crop planted in the open field. The hydromulches were based on by-products derived from the agricultural sector (barley straw, rice husk, rests from mushroom production), mixed with gypsum as a binder and recycled paper paste and applied liquidly on the ground with subsequent solidification. Additionally, two unmulched treatments were considered as control (manual weeding and a no-weeding treatments). Soil temperature was measured at 5 cm depth, and the variables considered, expressed as ºC, were maximum (T<sub>max</sub>), minimum (T<sub>min</sub>) and mean temperature (T<sub>mean</sub>), cumulative soil heat (C<sub>heat</sub>) and soil temperature amplitude (TA). C<sub>heat</sub> was calculated as the sum of the daily T<sub>mean</sub> and TA as the average of (daily max – daily min soil temperature).</p> <p>As general results, T<sub>mean</sub> was higher in the unmulched controls than in the hydromulches mainly for increasing T<sub>max</sub>, resulting T<sub>min</sub> practically no affected by the cover. Consequently, TA and C<sub>heat</sub> were higher in the controls, which shows the damping effect of the hydromulches mainly for reducing the highest temperatures, which could be positive for the crops in the current global warming context.</p> <p><strong>Keywords</strong>: hydromulches, soil temperature, global warming, organic farming.</p> <p><strong>Acknowledgements</strong>: Project RTA2015-00047-C05-03 - INIA (Spanish Ministry of Economy and Competitiveness).</p>