Nutrient availability is an essential aspect of plant growth and development. Sandy soils have low nutrient-holding capacities. Huanglongbing (HLB) trees have lower fine root density and thus decreased capacity to uptake nutrients. Organic amendments have been known to increase nutrient-holding capacities in sandy soils and provide additional nutrients. The objectives of this study were to 1) determine the influences of organic amendments on citrus production on sandy soil, and 2) assess the potential of organic amendments to alleviate the negative impacts of HLB. The study was conducted over six months in a greenhouse setting at the Citrus Research and Education Center in Lake Alfred Florida using Valenica sweet orange on Swingle citrumelo rootstock grown on Candler fine sand. Treatments of compost (5% and 10% by volume) and peat moss (5 and 10% by volume) and a control composed of Candler fine sand without amendment were applied to a total of 50 trees, 25 of which were HLB-affected and the other 25 were healthy trees. The following variables were measured: tree diameter, tree height, leaf chlorophyll content, soil nutrient content, tissue nutrient content, soil organic matter content, and biomass and nutrient accumulation. Organic amendments improved soil organic matter content by 20 to 40%. Organic amendments also increased plant and root growth parameters and demonstrate an ability to alleviate the negative impacts of HLB. Our research will eventually be followed up by field studies to validate the greenhouse observations.
