1. Please state project objectives and what work was done this quarter to address them: Objective. To determine the influence of compost during the first three years of tree establishment on growth, productivity, and root and soil health of citrus trees on rootstocks with different vigor-inducing capacity. Another round of compost was applied at the usual rate. Flush ratings and soil moisture measurements continued. The soil moisture in the compost treated plots continues to be significantly higher than in the control plots and we are seeing significantly more (two to three-fold more) weed pressure in the compost treated plots. Soil and leaf samples were collected for macro- and micronutrient analysis. Many of the soil nutrients continue to be present in higher concentrations in the compost treated plots than in the control plots except for copper which was reduced by the compost. However, higher nutrient concentrations in the soil did not always translate to higher concentrations in the leaves. The cation exchange capacity and the soil pH were also significantly higher in compost plots than control plots.The fibrous root respiration was measured and roots from the compost plots have a higher respiration rate than roots from the control plots. Significant differences were also found among rootstocks with the citrandarins having higher rates than US-802. This was also reflected in the specific root length which was lowest for US-802 and highest for US-897. The specific root length appears to be moderately correlated with pounds soluble solids. A manuscript for publication was submitted and is under review. A Citrus Industry magazine article on this study was published in the June 2022 issue. 2. Please state what work is anticipated for next quarter:Flush ratings and soil moisture measurements will continue. Root respiration and specific root length will be measured. We will conduct tree ratings and tree size measurements. Leaves will be collected for CLas determination. The weed biomass will be determined.Data analyses will continue. 3. Please state budget status (underspend or overspend, and why): Most of the funds have been spent.