This work was carried out under the supervision of Dr. Asher Bar-Tal and Dr. Moshe Shenker
The application of organic residues and composts in agriculture is increasing as a strategy for enhancing soil fertility, organic C sequestration in the soil organic carbonfraction and for organic waste recycling. Organic residue application is also
recommended to compensate for the decline in soil organic matter (SOM) as result of theconversion of native soil to agricultural soil. The beneficial effects of increased levels ofSOM on chemical, physical and biological properties of soil have been widely demonstrated. However, the effects of the mineralization of the applied organic residues combined with SOM mineralization on soil chemistry have been overlooked; especially the fate of soil carbonates in semi-arid and arid soils due to the production of CO2 and release and/or consumption of protons.
The pure CO2-H2O-calcite reaction system is well known in the literature; increasing the partial pressure of CO2 in air leads to its dissolution in water as carbonic acid. In neutral or basic water environments the carbonic acid dissociates, releasing protons which can cause the dissolution of calcite and/or other solid carbonates. On the other hand, decreasing CO2 partial pressure in the air of such pure systems leads to carbonate precipitation due to increased pH. However, unlike pure CO2-H2O-calcite system, in the soil medium, the effects of increasing CO2 partial pressure due to application of organic residues and SOM mineralization on calcite dissolution/precipitation is unclear, especially in arid and semi-arid regions.
This work was carried out under the supervision of Dr. Asher Bar-Tal and Dr. Moshe Shenker
The application of organic residues and composts in agriculture is increasing as a strategy for enhancing soil fertility, organic C sequestration in the soil organic carbonfraction and for organic waste recycling. Organic residue application is also
recommended to compensate for the decline in soil organic matter (SOM) as result of theconversion of native soil to agricultural soil. The beneficial effects of increased levels ofSOM on chemical, physical and biological properties of soil have been widely demonstrated. However, the effects of the mineralization of the applied organic residues combined with SOM mineralization on soil chemistry have been overlooked; especially the fate of soil carbonates in semi-arid and arid soils due to the production of CO2 and release and/or consumption of protons.
The pure CO2-H2O-calcite reaction system is well known in the literature; increasing the partial pressure of CO2 in air leads to its dissolution in water as carbonic acid. In neutral or basic water environments the carbonic acid dissociates, releasing protons which can cause the dissolution of calcite and/or other solid carbonates. On the other hand, decreasing CO2 partial pressure in the air of such pure systems leads to carbonate precipitation due to increased pH. However, unlike pure CO2-H2O-calcite system, in the soil medium, the effects of increasing CO2 partial pressure due to application of organic residues and SOM mineralization on calcite dissolution/precipitation is unclear, especially in arid and semi-arid regions.