Development and Demonstration of Low-Cost, Easy-to-Manage Zero Runoff Systems for Small-Sized Pot Plant Growers 1994 Proposal
Executive Summary
Adoption of zero runoff crop production systems to protect surface
and ground water, more efficiently
utilize water and fertilizer resources, and comply with public
policy is a special challenge for managers of
small greenhouse operations. Often these operators lack capital
and the technical background to initiate and
manage change. While mass producers invest in prefabricated,
imported zero runoff systems, smaller specialty
producers require less expensive, easier-to-manage options.
Preliminary conclusions after several years of applied research
experience on zero runoff technology
include: 1.) systems in which all fertilizer the crop will need
throughout its production cycle is placed in the
substrate before planting are very easy to manage and 2.) cropping
systems subirrigated with tap water and
with no excess solution applied (no runoff or need to recycle)
- e.g. capillary mat on benches or troughs - will
provide crop growth and quality comparable to systems more technically
complex, more expensive, and
requiring more technical training to manage.
This proposal requests resources to 1.) complete the final stages
of zero runoff systems studies emphasizing
inexpensive, easy-to-manage options and 2.) establish demonstration
projects in commercial greenhouse
operations to verify and modify if necessary recommended practices
with these systems and then to transfer this
technology for adoption by numerous greenhouse operators.
Introduction and Literature Review
Extensive agriculture, including landscapes and turfgrass, uses
0 to 150 lb N/acre/year; but intensive
agriculture, such as in greenhouses and container nurseries,
uses 2000 lb N/acre or more annually (Green
1991, Weiler 1991). While yields are greater from greenhouses
because (1) crops are produced year around
and (2) higher yields are derived through environmental optimization,
most greenhouse operations rely on crop
production systems that waste water and fertilizer. Estimates
indicate 50-67% of the water and fertilizer
applied is leached to surface and ground water. This runoff may
also contain other agricultural chemicals such
as pesticides, growth regulators, surfactants; although studies
increasingly suggest that exposure of these
chemicals to moisture and soil leads to their microbial breakdown.
Therefore, at this time, nitrogen is
considered to be the most serious pollutant in runoff from greenhouses
(Pickerell 1993), although sites at which
agricultural chemicals are found may be expensive to clean up
or difficult to sell (Logsdon 1990).
Historically, leaching was a recommended practice for greenhouse
operators because it permitted
uneducated growers to be successful. Leaching permitted growers
to optimize root zone conditions and
reduced risk to the high value crops produced since they could
maintain high levels of nutrients and rely on
leaching to prevent:
• fertilizer (salts) accumulation in the root zone
• nutrient imbalances (excess is washed out)
• toxins (especially Na and Cl found in some water sources)
Most private and public sector leaders agree that this intensive,
“point source” runoff into the environment
cannot continue because the environment may be adversely affected
and development and enforcement of
public policy to prohibit such runoff is likely (Martens 1991,
Wilkerson 1990).
Facing this public concern, the dilemmas being voiced by greenhouse
operators include: 1) how much
runoff will be allowed and how will these limitations be met,
2) which water- and fertilizer-efficient systems
will produce crop growth and quality comparable to current systems,
3) where can affordable capital be found
to invest in these new systems, and 4) will slim profit margins
be further eroded by investing in more efficient
systems (i.e. is risk of crop loss greater, e.g. due to disease
organisms in the recirculating solution; are not
fertilizer and water costs minor compared to depreciation of
the fixed costs for installing a new system, e.g. is
not payback slow, zero, or negative) (Daughtrey and Weiler 1992,
Martens 1991)?
Large operators (mass producers) when constructing new CEA facilities
routinely mobilize sufficient
capital and technology to achieve zero runoff. Usually these
systems are imported from The Netherlands or
Denmark. Cost of new state-of-the-art facilities including this
technology are approximately $25/square foot
covered or about $1,000,000/acre. Usually subirrigation systems
are installed, such as ebb-and-flood or
troughs and excess fertigation solution is collected, reoptimized
by computer assisted monitoring of electrical
conductivity and pH, and recirculated. Managers are sufficiently
educated to be able to synthesize monitored
information about crop growth and substrate, plant, and solution
nutrient levels into adjusted fertigation plans.
These systems are part of highly mechanized crop production and
movement systems which yield large labor
savings (Biernbaum 1990, Lieberth 1991, Sulecki 1990).
Small, family operators (specialty producers) face severe challenges
in the marketplace because of inroads
of mass producers. These operations are too small to supply mass
marketers, and they are finding it necessary
to vertically integrate into retail-growing or face niche-markets
and technically demanding challenge of
producing specialty products for top-end retailers. Few of these
operations are expanding, some are closing,
so large expenditures of capital for retrofitting or replacing
existing facilities is not feasible. Finding low cost,
simple-to-use options to achieve zero runoff for these operations
is imperative.
Hammer and Langhans (1972) described subirrigation with a capillary
mat wetted by tap water; controlled
release fertilizer was incorporated into the substrate before
planting. This system meets most of today’s
heightened environmental standards, is inexpensive to construct,
and is easy to use. Additional modifications
of the substrate and control technology may be beneficial (Biernbaum,
Carlson, and Heins 1989). In this
system, water is efficiently used, supply of fertilizer is separated
from supply of water, and since no excess
water is applied, no recirculation is necessary. Variations of
this basic system are the focus of our current
attention.
Over the past 4 years, Cornell’s Controlled Environment Agriculture
Program has studied numerous facets
of zero runoff technology, including:
• characterization of runoff from an old greenhouse area - drainage
tiles under an old rose-growing house
were plumbed so all runoff was collected, amount and content
of runoff after irrigation was
measured; in some cases runoff exceeded tolerable levels for
release to the environment (Dreesen
and Walker 1990)
• minimal fertilizer application - finished plants (plant and
substrate) of several growers were analyzed
for nutrient content, e.g. nitrogen content was approximately
0.4 g for a 4-inch pot and 0.8 g for a
6-inch pot; effects on growth were studied when only those amounts
of fertilizer were applied to
crops grown on zero runoff systems, fertilizer applied was a
combination of soluble and controlled-
release sources (Weiler 1991)
• runoff remediation - in-greenhouse constructed wetlands were
studied for their ability to “purify”
runoff or other waste water from greenhouses; zero runoff wetland
water was evapotranspired from
the wetlands, pesticides and other organic chemicals were broken
down by microorganisms in the
root zone, nitrogen was volatilized into the atmosphere which
contains about 80% N, and
remaining nutrients were taken up by bog plants which were periodically
harvested and composted
(Pickerell 1993)
Objectives and Anticipated Benefits
Minimal fertilizer application to crops on zero runoff systems
offers the opportunities of:
• less water use
• less fertilizer use
• no potential environmental contamination
• little or no runoff remediation
Zero runoff systems which do not require recirculation of used
nutrient solution provide the additional
benefits of:
• less expensive construction (fewer pumps, no holding tank)
Zero runoff systems, no recirculation, with fertilizer incorporated
into the potting substrate and only tap
water applied provide the additional benefit of:
* least expensive construction and maintenance since no proportioner
or computer-assisted system
management is required
* least demanding fertilizer management since all decisions about
types and amounts of fertilizer are
made during substrate formulation and/or at potting
These last 2 benefits, least expense and easy management are
the overall objectives of this project.
Specific objectives are to:
1. complete development of these low cost, easy-to-manage systems
2. demonstrate the systems in commercial enterprises as a primary
way of transferring this technology to
small greenhouse operators
Materials and Methods,
With grants from the Kenneth Post Foundation and the College
of Agriculture and Life Sciences, numerous
zero runoff systems were constructed between 1990 and 1992. These
growing systems include:
1. traditional drip-tube top-down fertigation with leaching
2. ebb-and-flow recirculating subirrigation or subfertigation.
3. trough recirculating subirrigation or subfertigation
4. capillary mat zero runoff subirrigation or subfertigation
5. capillary mat on trough recirculating subirrigation or subfertigation
6. drip tube top-down recirculating irrigation or fertigation
on troughs
Their purpose is to:
• compare efficiency of water and fertilizer use among systems
• compare crop growth among systems, especially to compare the
technology of incorporating all
fertilizer into the substrate before planting and irrigating
with tap water against other fertilizing and
irrigating options
Results to date suggest that capillary mat subirrigation remains
a highly efficient, inexpensive, and easy-to-
use approach to minimal fertilizer and water use whether the
mat is installed on flat, zero recirculation and zero
runoff benches or on subirrigated troughs. However, the highly
fertilizer efficient approach of incorporating
soluble and controlled release fertilizer (CRF) into the substrate
followed by subirrigation with tap water results
in plants which weigh less and are lighter green than those grown
on other systems. Based on a conversation
with Dr. John Biernbaum (Michigan State University), several
hypotheses for this suboptimal growth can be
advanced, centering around the notion that some fertilizer may
rise to the substrate surface through upward
movement of water and become unavailable to the root system below.
Using the systems described above, experiments will be carried
out on 6-inch poinsettias and geraniums.
The goal will be to optimize growth of crops on capillary mat
systems to a level comparable to any other
production system.
1. Comparison of Crop Growth and Final Fertilizer Distribution
in the Substrate When Fertilizer is
incorporated into the Substrate and Crops are Subirrigated with
Tap Water VS. Fertilizer is Provided in
Recirculating Fertigation Solution - geraniums with all fertilizer
in the substrate before planting at the rate of
0.8 g N/pot (50% as CRF dibbled to the bottom of the pot) and
irrigated with tap water will be compared with
plants provided fertilizer through fertigation solution on growing
systems 2-6.
2. Comparison of Approaches to Incorporating Fertilizer into
The Substrate of Geraniums Subirrigated with
Recirculating Tap Water - crop growth and final fertilizer distribution
in the substrate will be compared for 18
treatment combinations: rates of fertilization (0.4 g N as soluble
fertilizer and 0.4, 0.8, or 0.24 g N as CRF),
location of CRF in the root zone (distributed throughout substrate,
dibbled to bottom of pot, or dibbled to 1-
inch below pot surface), and presence or absence of a plastic
collar at the substrate surface to reduce
evaporation from the substrate surface.
Based on results of these experiments, all or part of these treatments
will be repeated with a crop of
poinsettias, then another crop of geraniums if necessary. This
experimental phase is expected to be completed
by April 1994.
3. Demonstration of Inexpensive, Easy-to Manage Zero Runoff Systems
at 3 Small Greenhouse Operations -
best treatments of the above research will be set up in the greenhouses
of 3 geographically separated
cooperating small greenhouse operations which will be provided
with instructions on how to grow a crop of
their choice.
The 3 locations are expected to be Erie County (Buffalo area), Long
Island, and Central New
York (Syracuse-Binghamton areas) because of concentrated greenhouse
operations and strong extension
programs in these areas. Two objectives will be pursued:
1. gain insights into adequacy of systems and instructions and
revise as needed
2. provide sites for technology transfer programs as well as
credibility based on grower experience with
the purpose to stimulate other greenhouse operators to begin
retrofitting to zero runoff systems.
Literature Cited
Biernbaum, J. A. 1990. Get Ready for Subirrigation. Greenhouse
Grower 8(8): 130-131, 133.
Biernbaum, J., W. Carlson, and R. Heins. 1989. Limit Runoff With
Slow Release Fertilizers, Quality Media,
Wetting Agents, and Absorbent Gels. GrowerTalks 53(5): 48, 50,
52.
Daughtrey, M. and T. Weiler. 1992. Managing disease in recirculating
systems. GrowerTalks 55(10): 59,
61, 63, 65, 67, 69, 71.
Dreesen, D. and M. Walker. 1990. Investigation of Environmental
Effects of Pesticides and Fertilizers Used
at Cornell University Greenhouse Facilities. Phase I Report.
Center for Environmental Research, New
York State Water Resources Institute, Cornell University, Ithaca
NY. 36 pp.
Green, J. L. 1991. Fertilization Technology and Management Practices.
Illinois Nurserymen’s Assn.
February: 10-12.
Hammer, P. A. and R. W. Langhans. 1972. Something new for capillary
watering. Florists Rev.
150(3900):15, 54.
Lieberth, J. A. 1991. DeWit’s Designs. Greenhouse Grower 9(2):
14-15.
Logsdon, G. 1990. Ag Bankers Shun Chemical Risks. The New Farm.
September/October: 42-44.
Martens, J. A. 1991. Growing in the Year 2000: Making Zero Runoff
a Reality. GrowerTalks 54(9): 21-22,
24, 26, 28.
Pickerell, C. H. 1993. Controlled Environment Constructed Wetland
Treatment of Greenhouse Drainage.
M.S. Thesis, Department of Floriculture and Ornamental Horticulture,
Cornell University, Ithaca NY.
Sulecki, J. C. 1990. Flooding the Floor. Greenhouse Grower 8(3):
20, 22-23, 25.
Weiler, T. C. 1991. Approximation of Fertilizer Need for Selected
Greenhouse Crops. In. Systems That
Minimize Environmental Impact Resource Notebook. Department of
Floriculture and Ornamental
Horticulture, Cornell University, Ithaca NY. 25 pp.
Wilkerson, D. C. 1990. Know Your Options for Treating Greenhouse
Runoff. GrowerTalks 54(5): 34, 36,
38, 41-42, 44.
Budget
Funds proposed in this grant would permit completion of zero
runoff projects of 2 graduate students and
the transfer of this technology to the greenhouse industry.
Component $
Nutrient Analysis (Cornell Research Rates)
* Geraniums
plant @ $11.50 322
x 5 systems x 2 fert/irrig treatments
x 18 CRF/collar treatments
substrate 2 $7.50 x top 1/3 and bottom 2/3 420
x 5 systems x 2 fert/irrig treatments
x 18 CRF/collar treatments
recirculating nutrient solutions @ $10.00 500
x 5 systems x 2 fert/irrig treatments
x 5 sampling dates
* Poinsettias (repeat of above) 1,242
Demonstration Project
* Materials for systems (including capillary mat, 1,000
trough construction, pumps, recirculating solution
reservoirs, time clocks)
* Travel to greenhouse trial sites @ $0.21/mile x 1,000 miles
plus rooming and meal expenses 1,000
Publication page charges (American Society for Horticultural
Science)
a $85/page, 6 pages 510
TOTAL 4,994
Leader Qualifications
The project leader studied floriculture at the University of
Wisconsin and Cornell University, earning a
Ph.D. degree in 1969. He was a member of the faculty at Purdue
University for 15 years, and joined the
faculty of at Cornell in 1984 with an appointment in extension
(applied research and technology transfer)
and teaching in the Controlled Environment Agriculture program.
His long term interests relate to crop
growth and development, and since 1984 he has been involved with
reorganization of the nutrient analysis
laboratory unit related to greenhouse crop production and fertilizer
recommendations for greenhouse
operators. He is currently involved with developing a new resource,
“Integrated Root Zone Management
for Greenhouse and Container Nursery Crops”, to be published
fall, 1993.
Currently 2 research assistants, funded from University sources
are involved with this project. Dawn
M. Alleman and Ricardo Valdez are pursuing Master of Science
degrees. Dawn is focusing on comparisons
of water and nitrogen use efficiency for different production
systems, while Ricardo is focusing on
controlled-release-fertilizers as a means of optimizing crop
fertility levels under zero runoff conditions.
