Utilization of Community Leaves for Improving Orchard Soil Quality

Utilization of Community Leaves for Improving Orchard Soil Quality

Summary

Peach culture in the Northeast is detrimental to sustained orchard production, but application of leaf organic matter (OM) to orchards improves soil quality and recycles plant nutrients benefiting communities, farmers and the environment. Leaves with or without supplemental nitrogen were applied to plots of new and existing peach trees. Soil quality, including OM, tree growth, tree nutrient analysis, and fruit quality were assayed since inception. Data is being presented to growers and community leaders at a field tour set for May 8, 2002. Results are to be used for basing education and recommendations for the proper use of leaves for improving orchard soils.

Objectives/Performance Targets

This project addresses how to best apply leaf organic matter to the soils of tree fruit orchards in the Northeast. This project also examines the results of nutrient release from leaf organic matter in a commercial fruit production setting. Specifically, what is the effect of late season nitrogen release on the winter hardiness of fruit flower buds? Finally, this project investigates the contribution of the large amounts of calcium, available from decaying leaf matter, and its effect on fruit quality.

Accomplishments/Milestones

Approximately 1000 cubic yards of community collected leaves were distributed to 60 of the 100 plots. Each plot consists of six peach trees. Annual soil, leaf tissue and fruit samples have been collected; additionally, tree growth and mortality has been determined annually. Periodic soil moisture sampling was accomplished, although the frequent rains in 2000 prevented some sampling. A weather station positioned in the plots successfully monitored rain events and orchard temperature.

In the inception year of 2000, weekly rainfall in combination with leaf mulch applications increased soil moisture holding capacity. In some cases, soil moisture may have been a detriment to increased root growth, as observed in previous work by Ian Merwin. More moderate rainfall was observed in 2001, and growth in this year favored mulched plots. A grower field day has been set for the spring of 2002.

Impacts and Contributions/Outcomes

Soil test analysis confirmed previous work, countering the myth that composting OM decreases pH of the soil. Soil pH did not change; however, in some mulched treatments, pH increased slightly. Soil OM rose 2% to 6% in some plots by the end of the first growing season. Soil nutrient analysis revealed that both calcium and potassium rose significantly due to the application of leaves. Plant tissue analysis is a better gauge of crop response to plant fertility than soil tests. Fears of excess nitrogen in the plants from decomposition were unfounded. Leaf nitrogen was unchanged due to the application of leaves, along with Ca, Mn, Fe, Al, Zn, and Na. Increases in leaf tissue levels of P, K, and B showed distinct nutritional benefits of leaf mulch applications. Tissue levels showed a slight decrease of leaf Mg levels, although all samples were still in the optimum range.

Soil moisture gave mixed results, probably due to the unusually wet summer of 2000. Plots responded to leaf mulch by having 15% to 27% more soil water available when tested at least 14 days after a precipitation event. ‘Jersey Queen’ trees with established root systems responded to leaf mulch with 16% gains in trunk diameters, compared to only 11% for unmulched plots. However, high soil moisture content of the newly planted ‘Sugar Giant’ tree plots reduced trunk diameter increases. Unmulched plots increased 97% compared to only 91% increase for mulched trees during the year of planting.

Growers have displayed increased interest in OM promotion and orchard soil improvement. Incorporation of leaf OM in orchards did exist before this study, but increased awareness of the benefits has resulted in greater adoption of the practice.

Collaborators: