Towards ecologically-based fertilizer recommendations that improve soil quality in high-density apple orchards

Project Overview

Project Type: Research and Education
Funds awarded in 2013: $140,000.00
Projected End Date: 09/30/2017
Region: Southern
State: Virginia
Principal Investigator:
Dr. Gregory Peck
Cornell University

Annual Reports

Information Products


  • Fruits: apples, general tree fruits


  • Crop Production: fertigation, nutrient cycling, organic fertilizers, application rate management, tissue analysis
  • Education and Training: on-farm/ranch research, participatory research
  • Farm Business Management: agricultural finance
  • Natural Resources/Environment: carbon sequestration
  • Production Systems: agroecosystems, holistic management
  • Soil Management: soil analysis, nutrient mineralization, soil microbiology, soil chemistry, organic matter, soil quality/health

    Proposal abstract:

    As more and more Mid-Atlantic apple growers plant high-density apple (Malus domestica) orchards, there is a great need to provide growers with environmentally-friendly fertilizer recommendations for these young, closely planted trees. Profitability for high-density orchards is largely dependent on obtaining sufficient vegetative growth and high fruit yields during the first three years after planting, a goal typically achieved through applying high rates of synthetically derived nitrogen fertilizer. However, there is little scientific evidence to support a specific fertilizer formulation, timing, or rate in these newly planted commercial apple orchards. Developing management practices and recommendations for the most sustainable management practices will support growers economically through more efficient fertilizer and ecologically by developing healthier soils, with increased microbial abundance and diversity. Additionally, by optimizing nitrogen fertilizer applications, external costs to society at large will be reduced.

    Growers traditionally use ground-applied synthetic fertilizers, such as calcium nitrate, urea, and/or ammonium nitrate, and in a few limited cases, carbon-based amendments, such as compost. Over the past two decades, there has been scant fertilizer research conducted for apple orchards in the Mid-Atlantic region, thus resulting in fertilizer application practices that are quite variable.  Recommendations from other regions alleviate some of the variability and subjectivity, but there is simply not enough information available to growers to support decisions that are both ecologically- and horticulturally-sound.

    Gaining a better understanding of soil quality and soil fertility is of great interest to commercial tree-fruit growers in the Mid-Atlantic region. In a 2011 research-needs survey of commercial apple growers in Virginia, 90% of the 74 respondents considered “improving management of nutrients requirements in Virginia orchards” to be either an “important” or “very important” area for future research. Similarly, 88% of the respondents considered “improving soil quality in the orchard” to be an “important” or “very important” area of research; and, 78% of respondents considered the “evaluation of potential environmental impacts from the orchard operation (including nutrient leaching)” to be “important” or “very important”.

    We have requested SSARE support to test the hypothesis that integrating organic, carbon-based fertilizers with inorganic fertilizers will increase soil organic matter and create microbial communities that are more supportive of sustainable and productive orchard systems than when either fertilizer source is used alone. More broadly, this is a test of the conceptual model that an integrated fertilizer program support sustainable apple orchard systems across a variety of landscapes and soil types in the Southeastern US. We believe that this conceptual model for sustainable nutrient management will be applicable to other perennial fruit cropping systems, such as peaches, grapes, and brambles. Our project team includes a fruit crops scientist, a soil microbial ecologist, commercial growers, and a private orchard consultant. This diversified expertise supports the systems-level approach that is needed to develop the most sustainable apple orchards possible. By examining the orchard ecosystems from the soil microbiome through tree growth, productivity, and considering the economic costs of different fertility management decisions, our project will advance sustainable agriculture throughout the Southern SARE region.

    Project objectives from proposal:

    Objective 1: Survey commercial apple growers in the Mid-Atlantic region to identify the fertilizer formulations, quantities, and application frequencies most commonly employed.

    The goal of the survey is to better understand current fertilizer practices in order to better effect change in grower behavior.

    Objective 2: Use an interdisciplinary approach to examine the benefits of utilizing carbon-based soil amendments in commercial apple orchard systems so that we can investigate the interaction between soil nutrient source and orchard productivity. Our project will investigate microbial community composition, biomass, and soil biological activity in the soil, particularly in the rhizosphere (the soil-root interface). The research will occur on replicated plots located in three separate regional apple orchards.

    Our research will utilize a research farm trial comparing synthetic fertilizers (calcium nitrate), chicken litter compost, municipal yard waste compost, and treatments that integrate synthetic fertilizers with composts when applied to newly planted high-density apple trees.

    We will also develop additional replicated on-farm trials with two cooperating growers. Between the three farm sites outlined in this objective, this research project will span over 200 miles and put growers throughout the Mid-Atlantic in close proximity to the test sites, which will encourage faster adoption of the most effective treatments.

    Objective 3: Educate stakeholders in orchard nutrition management. Develop printed and web-based outreach materials to support educational activities.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.