Investigating the effect of using diatomite on the capacity to absorb and retain water in the soil

The agricultural sector is the main consumer of water resources in our country. To increase irrigation efficiency and optimal use of water resources in arid and semi-arid areas, it is considered to use super absorbent materials with very high water absorption ability. Diatomite is a material with super-absorbing properties that is receiving attention today, and it is a mineral that is abundantly found in South Khorasan. This mineral, which is the sedimented remains of a marine fossil, has many microscopic holes and therefore has the necessary potential to solve water shortages and deal with drought stress. Considering these interesting features of this material and considering the location of South Khorasan province in a dry region with a lack of moisture and the worsening of this problem due to the continuous drought of recent years, the main purpose of this research is to investigate the use of diatomaceous in Esfazar Birjand region to improve agricultural soils with big texture it is.

In order to investigate the effect of diatomite on the water absorption and storage capacity in the soil, the soil sample with sandy texture was first prepared from Bidokht village of Birjand. Different amounts (0, 10, 20, 40, 60, and 80 grams) of small diatomaceous earth with different particle sizes (0 to 2, 2.36 to 4.75, 4.75 to 12.5, and 12.5 to 19 mm) were added to one kilogram pots of soil. The experiments were conducted in a completely randomized design with three replications. The number of investigated treatments is 24 and in 3 replications. For the size of diatomite particles larger than 2 mm, only the treatment of 40 g/kg soil with two replications was used. In this research, besides raw diatomite, calcined diatomite was also used in the treatment of 20 g/kg soil. The process of calcining raw diatomite without pyrolysis agent was carried out at 900 degrees celsius for four hours in the mineral processing laboratory of Birjand University. In all treatments, diatomite particles were completely mixed with one kilogram of dry soil, and then the soil moisture was brought to the agricultural capacity (18%). Weighing the pots once every ten days and the amount of moisture reduction for different treatments. It was measured and based on the available moisture, irrigation was done until the moisture reached the agricultural capacity. For some time, the pots were saturated with water based on the percentage of saturated moisture, and the gravity moisture content of each treatment (amount of water removed) was measured. After 4 months, the effect of adding raw diatomite and calcine on soil water absorption capacity and water retention capacity was measured.

Based on the results of this research, adding diatomaceous to the soil had a significant effect on increasing the saturated moisture content of the soil. So that the highest moisture content of the soil by adding 80 grams of diatomite. For every 10 grams of raw diatomite added to one kilogram of soil under investigation, 1.25% was added to the saturated moisture content of the soil. Also, it was obtained it was found that the use of calcined diatomite increased the water absorption capacity of the soil by about 20% more than raw diatomite. It was also found that by adding diatomite particles larger than 4.75 mm, the water absorption capacity of the soil increases significantly. These results determined that crushing diatomite actually causes the loss of a major part of its internal empty space that has the capacity to absorb water. This happens with the further crushing of diatomaceous. Therefore, it is recommended to use coarse diatomite particles with an approximate size of 5 to 12 mm or 12 to 20 mm to improve agricultural soils with low water absorption capacity. In relation to the water holding capacity, the results showed that for every 10 g/kg of diatomaceous earth added to the examined soil, 0.6% is added to the 48-hour moisture level of the soil. The use of calcined diatomite did not show any effect on the water holding capacity, but the use of coarser raw diatomite particles increased the water holding capacity of the soil. In total, the results of this research showed that the use of raw diatomite particles with a size of 4.75-19 mm has the most effective for increasing the water absorption and retention capacity of agricultural soils.