Developing Organic and Reduced-Input Tree-Fruit Production Options

Project funded by the USDA Organic Research and Extension Initiative (OREI), the Utah Specialty Crop Block Grant Program, and Utah State University Experiment Station and Cooperative Extension

Jennifer Reeve, Brent Black, Diane Alston, Corey Ransom, Ruby Ward, Silvana Martini

Situation:

The Wasatch Front is a prime location for tree-fruit production in Utah.

Rapid urbanization, dwindling water resources, rising costs of inputs, and loss of export markets is making it increasingly difficult to continue farming in the area.

Organic and reduced-input production may help growers access growing local markets, benefiting a rural way of life and providing economic incentives for managed urban growth and farmland preservation.

Organic and reduced-input production may help reduce costs and benefit the environment through enhanced synergies between ecosystem services and production goals.

Objectives:

1. Characterize potential tradeoffs in water use efficiency and tree growth with living and non-living mulches and internal (N fixing legumes) and external fertility inputs

2. Characterize system responses to management practices through monitoring weeds, arthropod dynamics, and soil quality

3. Select orchard floor cover crops for early season N release in environments with cold winters, arid summers, and shallow alkaline soils

4. Select orchard floor management, fertility and pest management practices for:

   1. Increased fruit quality

   2. Maximum ecosystem services

   3. Maximum economic return

5. Increase adoption of new management practices through education and outreach

Actions:

Orchard Establishment

Two peach orchards were established at the USU Horticultural Research Station in Kaysville, Utah. One orchard (1.1 acres) is dedicated to organic management strategies and was certified organic in 2011. The second orchard (0.9 acres) is dedicated to testing a range of reduced-input approaches against organic and conventional standard practices.

Treatments

Organic Orchard: random complete block design with four replicates

Treatment	In Row	Alleyway
1	straw mulch + compost	grass
2	straw mulch + compost	legume*
3	alyssum living mulch + compost	grass
4	alyssum living mulch + compost	legume
5	woven fabric + compost	grass
6	tillage + compost	legume

*the legume used is Bird’s Foot Trefoil

 Integrated Orchard: random complete block design with four replicates

Treatment	In Row	Alleyway
1	conventional herbicide + NPK	grass
2	conventional transitioned to organic in 2011	grass
3	conventional herbicide + compost	grass
4	paper mulch + reduced herbicide + NPK	grass
5	paper mulch + organic herbicide + compost	grass

Orchard Floor Management

We are investigating alternative orchard floor management strategies in order to reduce inputs for shallow alkaline soils, short hot summers, and cold winters.

Soil Fertility and Soil Quality

Baseline soil nutrients (0-30 cm) and soil quality (0-10 cm) measurements were taken from each plot. Soil and tissue N will be sampled monthly from April to September. Compost is applied to meet soil test phosphorus needs and fertilizer (NatureSafe 13-0-0) adjusted at the plot level to meet tree need.

Water use Efficiency

Each plot is equipped with micro sprinklers on individually controlled irrigation systems.  This allows each of the treatments to be watered independently based on tree need, and allows water use for each treatment to be calculated separately. 

Mulch and Organic Herbicide Selection

In 2008 and 2009 we assessed newsprint, straw and woodchips alone and in combination with acetic acid (20%), Matran (clove oil), Greenmatch EX (lemongrass oil), a citric acid based experimental product and glyphosate for weed control.

Organic Pest and Disease Control

We are monitoring pest and disease dynamics and the efficacy of organic pest control strategies. Information is available on Utah's pests and diseases.

Educational Activities

Field days to showcase the project were held at the Kaysville Horticultural Research Station in August  2008, 2010 and 2012. A field day and workshop dedicated to organic treefruit and vegetable production is planned for June 2013.

Future Goals:

Create a long-term research site that can be used for cross-disciplinary whole systems research to develop integrated solutions

Potential Contributions:

                • Soil microbial ecology

                • Landscape ecology

                • Social sciences

                • Macro, meso and micro scale modeling

                • System sustainability

Potential Benefits:

This project and its outreach and educational activities will help growers:

                • Learn about new orchard management practices for Utah

                • Learn about the importance of ecosystem services

                • Learn about the need for integrated solutions

The replicated field trials will improve understanding of how trees, living and non-living mulches and nutrient sources interact with or alter pest dynamics, water use, soil quality, fruit quality and economics.

Trees established with a Bird’s Foot Trefoil Alleyway as opposed to grass match tillage, weed fabric and conventional control treatments in growth despite considerable tree-row weed pressure.  Mowing and blowing legume alleyway biomass into the tree-row contributes an average of 106 g N per tree per season.

Trees established with grass alleyway are stunted relative to the tillage control (first two trees) and legume alleyway treatments (in distance). Soil under legume and tillage treatments has significantly more available N. There are significantly fewer tree roots under the grass alleyway than the legume alleyway.

Alyssum living mulch did not persist beyond the second growing season. The living mulch treatment now consists of mowed weeds. A narrow weed free strip is maintained on each side of the tree-row. Compost and fertilizer is applied to this strip only and tilled in. This is called the Swiss sandwich system. The living mulch stunted tree growth in combination with a grass alleyway but not a legume alleyway.

Wheat or barley straw applied each season in March suppresses early season weed growth but not mid-season weeds. Straw mulch stunted tree growth in combination with a grass alleyway but not a legume alleyway.

Organic industry standard treatment with tillage weed control. Tree growth equaled the conventional check in this treatment.

Industry standard organic treatment with weed fabric mulch as weed control. Tree growth equaled the conventional check in this treatment.

Field day at the Kaysville Experiment Station.

Follow this link to the 2012 ISHS organic fruit symposium talks.