The ph value of soil is largely a function of carbon dioxide present A healthy soil may have enough carbon dioxide as a product released from to give a pH value of 4-7 Hydronium ions are able to displace nutrient ions held to mineral particles and humus ②CO2 Reacts with H2O forming H2CO3 ③H2CO3 reacts with H2O, forming HCO3 and H3O+ ① Root releases CO2 ④H3O+ displaces nutrient Soil then available to root particle root Fig15 11 by releasing carbon dioxide, a plant guarantees a steady flow of nutrients from the soil to its roots• The pH value of soil is largely a function of carbon dioxide present. A healthy soil may have enough carbon dioxide as a product released from to give a pH value of 4-7. • Hydronium ions are able to displace nutrient ions held to mineral particles and humus. Fig15.11 by releasing carbon dioxide, a plant guarantees a steady flow of nutrients from the soil to its roots ① Root releases CO2 ② CO2 Reacts with H2O, forming H2CO3 ③ H2CO3 reacts with H2O, forming HCO3 - and H3O+ ④ H3O+ displaces nutrient ion (K+ shown), which is then available to root Soil particle root