EVALUATING BIOCHAR APPLICATION FOR SALINITY MITIGATION AND NUTRIENT AVAILABILITY IN AGRICULTURAL SOILS OF THE CENTRAL VALLEY

Could the application of biochar be an essential component in mitigating salinity stresses and improving nutrient availability in agricultural soils? California’s Central Valley is one of the United States' major agricultural hubs, contributing a quarter of the nation’s food supply. A consequence of this production is the excessive application of agricultural chemicals and groundwater extraction rates exceeding replenishment rates. This leads to a number of issues including groundwater and soil salinization as condensing aquifers increase solute concentrations in groundwater, which is eventually used for irrigation. By applying biochar to soil, the movement of salts and nutrients in and out of the soil matrix is altered, decreasing the potential for salinity stresses to plants. This is due to the biochar’s porosity and surface charge, which absorbs the excess salts contributing to high salinity in the soil. By decreasing the salinity, the nutrient uptake for plants in the soil system is improved through changes in osmotic pressure and potassium availability. To evaluate biochar within the conditions of the Central Valley, biochar is applied to a farm field site on campus. Soil samples are then taken monthly, sealed, and preserved through freezing for further analysis. The samples are then used to determine the ion and macronutrient concentrations using a variety of techniques, including electrical conductivity probing and elemental analysis of soil-water-slurries. By looking at the samples over time, the samples are expected to decrease in salinity the longer the biochar is allowed to interact with the soil. A decrease in salinity is also expected to improve available macronutrients such as nitrogen, phosphorus, and potassium. The findings from this research could provide valuable insights into the applications of biochar as a strategy to mitigate salinity in soils and reduce the volume of fertilizers applied in agricultural zones.