SOIL pH Samples 4, 5, 6 which are the soil from the farm, soilfrom mines and the black soil from the mines respectively, are acidic as theyhave pH less than 7.it is important to note that sample 6 is the most acidic,while sample 4 is the least acidic among the 3 samples.Possiblecauses of the soil acidificationSample 4-sincethis is from the farm we expect the possible cause of soil acidification to befertilizers and acid forming organic materials. The application of chemicalfertilizers such as ammonium sulfate, urea etc. results in strong inorganicacids being produced when these fertilizers are oxidized in the soil by microbes.It is important to note that not all the H+ ions will be consumed bythe bicarbonate released when plants take up anions, as such the remainder isthe primary cause of the soil acidification. Similarly organic compounds suchleaf litter, sewage sludge or animal manure decrease the soil pH, throughoxidation of ammonium nitrogen or by organic and inorganic acids being formedduring decomposition.
Sample 5 and 6-thesesoil samples are from the mines as such, we expected the likely cause of the soilacidification to be exposure of potential acid sulfate material. Thesematerials are exposed in situations where pyrite- containing materials areexcavated and as a result they came into contact with water and air thus thereis production of large quantities of sulfuric acid .these potential acidsulfate material may also be exposed when sulfur bearing normally anaerobicsoils are exposed to oxygen because of mining activities and as such there isoxidation of sulfur. Acid mine drainage is another cause of soil acidificationwhen it comes into contact with soil as it is an extremely acid (0.5-2.
0 pHrange) and toxic brew formed when water percolates oxidized sulfuric materials.Effects ofsoil acidity Aluminum toxicity-when the soil pH drops below 4.8,there is an increase in Al+3 concentrationand also other species of aluminum gain increased solubility.
The presence oflarge concentration of aluminum results in stunted root system in plants as itdamages membranes and restricts cell wal7expansion so roots cannot growproperly. In order to solve for soil acidity one may consider adding lime,gypsum, organic matter to the soil to increase the pH .Limes include Calciticlimestone, dolomitic limestone, wood ashes etc.
Samples 1, 2, 3 are alkaline soils as they have a pHgreater than 7, however they are weak alkaline soils as they are close to theneutral point 7.As it is expected that these soils have nutrient deficienciesas such lack the micronutrients zinc, copper, iron and manganese as a resultthey are generally not suited for plant growth, as the optimum pH range formost plants is between 5.5 to 7.0.One can solve soil alkalinity by simplyadding fertilizers to the soil such as urea.
SOIL ECSamples from the mine (black) and those containing thehydrocarbons oil, and petrol have the highest EC readings. This may be due tothe fact that the high concentration of charged ions in the oil, petrolimpacted areas. Sample 5 had a very low EC value this may be caused byextensive leeching of the soil thus losing its soil content .
It is important tonote that EC less salt would mean less electricity conducted thus low ECreading.Effects ofsalinity on plant growthSoluble salts lower the osmotic potential of the soilwater thus making it more difficult for roots to remove water from the soil. Itis important to note that younger plants are more susceptible to salinity thanolder ones. Soil solution high in salts often delay, or prevent germination andcan also cause plants to lose water to their surrounding(more concentratedsolution) through osmosis.IT is important to note that as salt content in thesoil increases microbial activity decreases.
Soil pH vs Soil ECAs observed from the results when the soil pHincreases the soil EC decreases thus it can be said that they have an inverserelationship.