Comparing Organic and Conventional Fertilization Methods for Cut Flower Production in Haygrove High Tunnels

Comparing Organic and Conventional Fertilization Methods for Cut Flower Production in Haygrove High Tunnels

Summary

An experiment to generate preliminary data regarding nutrient release from organic versus conventional sources was completed during June to July 2004 in a Haygrove high tunnel at the Eastern Kansas Horticulture Research and Extension Center in Olathe, Kansas, with cut sunflowers. Fertilization treatments resulted in no differences in yield because the natural fertility and organic matter content of the uncultivated soil was so exceptional, despite treatment selection based on soil test results and current fertilizer recommendations. Four subsequent experiments were initiated, but all were destroyed in the wake of a microburst in August 2004 that resulted in high tunnel collapse. The research site was moved to the greenhouses of Kansas State University’s main campus in Manhattan, Kansas.

Objectives/Performance Targets

The goal of this research project was to generate practical information about the use of organic compared to inorganic fertilization for cut flowers produced in Haygrove high tunnels. Unfortunately, all high tunnels at the Eastern Kansas Horticulture Research and Extension Center were destroyed by a microburst in August 2004 (see http://www.hightunnels.org/ForGrowers/GrowersUsing/OlatheStormDamage.htm for photos of damage.) The silver lining is that we have learned a great deal about Haygrove tunnel management that we are passing along to producers in the Midwest who are considering construction of high tunnel structures. Four experiments associated with this project were planted in the Haygrove high tunnels at the time of the microburst and were destroyed (organic versus conventional fertilization studies for cut sunflower, lisianthus, ornamental kale, and ‘Temptress’ poppy).

The research site was moved to the greenhouses of Kansas State University’s main campus in Manhattan, Kansas, where organic versus conventional fertilization of the cut flower lisianthus is planned. In addition, after discussion with our grower-collaborator, the objective of determining optimal environmental conditions for germination and seedling development of ‘Temptress’ poppy has been added to the project. The final objective of the project is to share the information generated with cut flower growers and market farmers via www.hightunnels.org and the Association of Specialty Cut Flower Growers’ (ASCFG) Cut Flower Quarterly.

Accomplishments/Milestones

A preliminary experiment was completed in the Haygrove high tunnels to generate preliminary data for sunflower ‘Pro-Cut Orange’ production with organic versus conventional fertilization systems under three fertility rates. Details follow:

Treatment structure was a split-plot with fertilizer system as the main plots and fertilizer rates as the sub-plots; 3 fertilizer rates x 2 fertilizer systems in a factorial design = 6 treatments; 9 sunflower plants per experimental unit.

Four 25” x 90’ beds were made (in each tunnel) by digging small trenches along a string “guide”. Two rows of drip tape with holes every 12 inches were laid on top of the beds. The drip tape was laid in three distinct areas, so that different crops could be watered separately. Three different rows of header tape (Orchard tape) were laid perpendicular to the rows/drip tape. The 3 different header tapes feed the separate drip tapes. Three foot black plastic was used to cover the beds and soil was piled along the edge of the plastic to keep it in place.

Based recommendations from standard, initial soil test results of the previously uncultivated soil, the soil was amended as follows: Pre-plant: in the Organic tunnel, Hu-More compost at a rate of 10 tons/acre + dolomitic lime at a rate of 58 lbs/1440 ft2; in the Conventional tunnel, dolomitic lime at a rate of 58 lbs/1440 ft2 + triple super phosphate (0-46-0) 13 lbs/1440 ft2 + sulfate of potash (0-0-50) 12 lbs/1440 ft2.

Fertilization practices were as follows: Organic treatments received pre-plant dressing with Hu-More compost at a rate of 10 tons/acre (1,100 pounds/2,400 sq. ft laid June 3, 2004), Daniel’s soluble fertilizer (10-4-3) applied with each watering at a rate of 100 ppm N, and pre-plant slow-release Lawn restore fertilizer (10-2-6) at 3 different rates (0 slow-release, 1.3 lb N/1000 ft2, and 3.9 lb N/1000 ft2). Traditional treatments received Peter’s general purpose soluble fertilizer (20-10-20) applied at each watering at a rate of 100 ppm N and pre-plant slow-release fertilizer Nutricote (20-7-10) at 3 different rates (0 slow-release, 1.3 lb N/1000 ft2, and 3.9 lb N/1000 ft2).

Data collection included height of plant at harvest, diameter of “flower” at harvest, stem caliper, fresh weight (weight and tissue samples taken from the first 3 plants to mature from each plot), dry weight (dry weights taken from the same 3 plants per plot as fresh weight), and tissue samples (youngest fully expanded leaves, but not the leaf closest to head). Soil samples were collected weekly starting on day of transplant for the first month, then every other week for the duration of the experiment. pH, EC, NH4, NO3, PO4 was determined on the samples.

Impacts and Contributions/Outcomes

Though no yield differences were detected from this preliminary study, it exposed two challenges that market farmers face in adapting soil test results to attempt appropriate fertilization amendment and fertilization rates from other production systems, like greenhouses. Standard soil tests from an analytical lab for field crops did not take into account the high organic matter content of the previously uncultivated soil of the Haygrove high tunnels; therefore, based on N content, pre-plant amendments were made which turned out to be overkill. Secondly, basic rates of fertilization used in greenhouse production of a crop do not translate well into a field production situation, and all fertilization treatments resulted in maximum growth and yield of sunflowers in this instance. These preliminary results underscore the need to develop reliable guidelines for producers of cut flowers to use in their sustainable production situations.

Collaborators: