THE ROTATION OF CROPS AND THE PROPERTIES OF ALMOND SHELL AS SUBSTRATE

Abstract

The almond (Prunus dulcis L.) shell is an organic residue of the dry fruit industry, which is underutilized in Mediterranean countries. With the purpose of utilizing this material as a substrate for cultivation, a study of its changes over time, regarding its physical and physical-chemical properties, as well as its granulometric distribution, was performed. Experiments were conducted in a greenhouse setting. The period of experimentation lasted for three growing cycles of tomato plants (Lycopersicon esculentum Mill.) and two cycles of melon plants (Cucumis melo L.) which are 165 and 100 d respectively, both cultivated in 25 L sacks. In order to analyze the substrate, samples were taken from three sacks utilized for each growing cycle. During the first 165 d of use the percent of weight of medium particulates (from 0.125 to 2 mm) decreased, while the thicket particulates (of 4 to 8 mm) increased. Over time, all the physical properties varied significantly. The apparent density was reduced by 0.28 cm^-3, while the total porous space was increased by 27 %. The humidity and compaction increased over 100 % at its optimal level. The air to water ratio was also modified, and when 430 d of use had been reached, the majority of its values were functioning at an optimal level. The values of the physical and chemical properties improved over time to their optimal level, so that this substrate can be used up to 695 d.