I am doing a hands-on experiment at the Los Altos Heritage Orchard, where I am looking at the impact earthworm castings has on soil properties and on plant growth consequently. I am comparing the 12 tree earthworm castings applied group to the 12 tree non earthworm castings applied control group. I am measuring soil nutrient differences between the 2 groups in pH, Nitrogen, Phosphorus, and Potassium, and seeing how that is reflected by plant growth over time, seen in budding count, stem length, and chlorophyll content. This experiment should give me great insight into earthworm castings and how they may benefit apricot trees over traditional compost or other soil additives.