Mitigation of nitrogen (N) and phosphorus (P) runoff has become a major goal of the nursery industry. Woody and herbaceous ornamental plant production is a significant source of surface water and groundwater pollution. Plant production in containers is extremely intensive; one acre of land can be occupied by numerous containers, and nursery cultural practices, such as the use of soilless mixes and frequent irrigation are highly conducive to nutrient leaching. A number of Best Management Practices have been proposed to maximize production and minimize groundwater contamination from runoff and leaching losses. These practices vary with particular nursery conditions but most encompass proper irrigation and fertilizer programs to optimize nutrient use efficiency. Inoculation with arbuscular mycorrhizal (AM) fungi can also be included as an important component of nurseries’ cultural programs to reduce nutrient runoff while maintaining plant quality and yield. AM fungi develop an extraradical mycelium that enhances the plant ability to acquire mineral nutrients and water.  We investigated the effects of mycorrhizal colonization in nutrient use efficiency and on N and P leaching in nursery conditions. Mycorrhizal and nonmycorrhizal plants of Rhus integrifolia were grown in a soilless mix with no fertilizer or with half or full rate of 18N-2.6P-9.9K osmocote^® controlled release fertilizer. Plant growth, mycorrhizal colonization and the content of N and P in leachates collected weekly were compared.

Results/Conclusions Mycorrhizal plants grown in half and full rate of osmocote^® were taller and larger than nonmycorrhizal plants. Mycorrhizal colonization increased nutrient use efficiency of R. integrifolia. Compared to the plants grown with half rate of osmocote^®, full rate of osmocote^® increased the growth of mycorrhizal plants but not of the nonmycorrhizal ones. The concentration of nitrate and orthophosphate was lower in leachates obtained from mycorrhizal plants grown with full rate of osmocote^®. Our results highlight additional uses and benefits of mycorrhizal fungi in horticultural practices.