Evaluation of rock fragments for use as mulching materials

الملخص EN

Four mixtures of rock fragments (<8-mm-old, <15-mm-old, <8-mm-new and <15-mm-new) and sandy soil were studied.

Porosity of the rocii materials ranged from 0.45 to 0.61 while it was 0.29 for the sandy soil.

Saturated hydraulic conductivity was 1.48x10'^ m/s for the sandy soil while it ranged from 55x10'^ to 64x10'^ m/s for the rock fragments.

EC values for the 8-mm-new and 15-mm-new were 0.24 and 0.34 dS/m, respectively.

The respective pH values were 8.17 and 8.41.

For measuring isothermal cumulative evaporation, the fragments and sandy soil were packed in a measuring cylinder (one-liter) then saturated with distilled water.

A similar cylinder was filled with distilled water as well.

The evaporation took place at the cylinder tops under laboratory conditions (21-22 °C) for 22 days.

Percentages of final cumulative evaporation of rocks or sandy soil to evaporation from the free-water surface were 96.2, 71.5, 71.5, 72.1 and 66.1% for the soil, 8-mm-new, 15-mm-new, 15-mm-old and 8-mm-old, respectively.

Depths of water table for minimum evaporation were 0.084, 0.065, 0.086, 0.086 m for the 8-mm-new, 15-mm-new, 8-mm-oldand 15-mm-old, respectively.

Therefore, it is recommended to place a layer (0,065 - 0.085 m) of these rocks on a soil surface for evaporation suppression in orchard or hydroponic culture