COMPORTEMENTS PHYSIQUE ET HYDRIQUE DES SUBSTRATS DE CULTURE DESTINÉS AUX PÉPINIÈRES FORESTIÈRES MODERNES (SAHEL TUNISIEN)

Abstract

In Tunisia, the composted forestry waste is extensively used in containers, to manage the optimal conditions for plants growth aboveground in nurseries, in order to produce quality plants regularly and in sufficient quantity. This study aims to assess the physical and hydraulic characteristics of a number of cultivation substrates based on forestry compost derived from Acacia braking, considered as the current substrate for the production of forestry plants in containers. In this respect, a series of simple mechanical vibrating and rotating screening under various meshes was undertaken in two modern forest nurseries in the Tunisian Sahel; one is in Chott Mariem and the other in Bembla II. The physical analysis of untreated and screened composts has concerned the dry bulk density and the porosities (total, aeration and retention). The hydraulic analysis has involved the pF curve and the time of rewetting of each substrate. The main obtained results showed that the tested substrates are particularly aerated, but with low water availability. For the substrates with coarse particles, the water penetration is relatively short compared to the fine-textured substrates. The Substrates derived from the rotating sieving have shown a rewetting time lower than that of the substrates derived from the vibrating sieving. Furthermore, greater the sieve mesh is, lower is the rewetting time. The forestry compost produced in Chott Mariem is undeniable, regarding the total porosity and aeration under the experimental conditions, and has satisfied the standard water retention in the raw and screened states (regardless of the nature and the mesh screening), however the compost of Bembla II was not consistent and its screening is entirely justified. In addition, its rotating screening, whatever the used mesh, did not much improve the porosity retention. For the dry bulk density, the latter has no handicap for the use of tested substrates in containers.