educational material for plasticulture

8/14/2019 Educational Material for Plasticulture

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Production of Vegetable Crops in Alabama Using Plasticulture Techniques

Leonard Githinji, Ph.D.Assistant Professor / Horticulture Specialist

Tuskegee University Cooperative Extension Program (TUCEP)

204 Vocational Building

Tuskegee, AL 36088



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Introduction

Plasticulture is a branch of agriculture or horticulture that is concerned with the

enhancement of crop production using plastics. This practice include the use of plastic

film mulches, row covers, low tunnels, high tunnels or hoop houses, drip irrigation using

drip tape, silage bags, hay bale wraps, and plastic trays and pots used in transplant and

bedding plant production. Use of plastic in horticulture crop production has increased

dramatically in the last ten years (Pool, 2009) even though the number of agricultural

plastic manufactures has been reduced by 40% over the same period (Orzolek, 2003).

The term plasticulture describes a drip-irrigated production system using beds covered

with a thin sheet of plastic mulch and in some cases there is an additional use of

protective covers over the crop to allow for production of crops when production is not

normally possible.

The use of plasticulture in the production of horticultural crops (vegetables, small

fruits, flowers, tree fruits, and ornamentals) helps to mitigate the sometime extreme

fluctuations in weather, especially temperature, rainfall and wind, which occurs in may

parts of North American. Many growers in North America experience some extreme in

weather conditions during the growing season that can kill or injure the crops, or reduce

marketable yield. Row covers, low tunnels and high tunnels all have the potential tominimize the effect of these extreme weather events on the crop and optimize plant

growth and development in a protected environment.

Plastic mulch has been used on vegetables since the 1960s. Plastic mulch is a

product used, in a similar fashion to mulch, to suppress weeds and conserve water in crop

production and landscaping. Certain plastic mulches also act as a barrier to keep methyl

bromide, both a powerful fumigant and ozone depleter, in the soil. Crops grow through

slits or holes in thin plastic sheeting. Plastic mulch is often used in conjunction with drip

irrigation. Some research has been done using different colors of mulch to affect crop

growth. This method is predominant in large-scale vegetable growing, with millions of

acres cultivated under plastic mulch worldwide each year. Disposal of plastic mulch is

cited as an environmental problem, however, technologies exist to provide for the



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recycling of used/disposed plastic mulch into viable plastic resins for re-use in the

plastics manufacturing industry.

Many significant developments for using plastic mulches have occurred since the

13th National Agricultural Plastic Congress in 1977. These include: degradable mulches,

solarization techniques, colored and reflective mulches, wavelength-selective mulches,

and refinement of plastic culture techniques (Giacomelli et al., 2000).

Row covers and high tunnels do not offer the precision of conventional

greenhouses for environmental control, but they do sufficiently modify the environment

to enhance crop growth, yield, and quality. Although they provide some frost protection,

their primary function is to elevate temperatures a few degrees each day over a period of

several weeks.



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http://www.nj.nrcs.usda.gov/programs/images/mulched_field.JPG

In low tunnel plasticulture system, plastic mulch along with drip irrigation systemis installed to cover the seed bed and holes are perforated where seeds or seedlings are

planted. There are several benefits associated with low tunnel plasticulture.

These include:

• Extension of the growing season and earliness of yields

• Improvement of crop health and growth

• Enabling vegetable producers to realize greater returns per acre of land

• Cleaner and higher quality of produce

• Efficient use of water resources

• Reduced leaching of fertilizers

• Reduced soil and wind erosion

• Potential decrease in the incidence of diseases, insect pests, and weeds problems



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Plastic mulches directly affect the microclimate around the plant by modifying the

radiation budget (absorbitivity vs. reflectivity) of the surface and decreasing the soil

water loss (Liakatas et al. 1986, Tanner 1974). The color of mulch largely determines the

energy-radiating behavior and its influence on the microclimate around a vegetable plant.

Color affects the surface temperature of the mulch and the underlying soil temperature.

Benefits of Mulch

(Information for this section comes from UF Extension Circular 805 "Polyethylene

Mulching for Early Vegetable Production in North Florida" by G. J. Hochmuth )

1. Increases early yields. The largest benefit from black polyethylene mulch is the

increase in soil temperature in the bed, which promotes faster crop development and

earlier yields. For growers in northern Florida, this means producing a crop in between

the time that southern Florida growers and growers to the north in Georgia and South

Carolina produce their crops. Growers in these states to the north have adopted mulch

and are producing crops earlier that compete with northern Florida growers who do not

use mulch.

Research has been conducted over several years at the North Florida Research and

Education Center in Live Oak and Quincy on the effect of black mulch on watermelon

production. Results indicate mulching consistently produces higher earlier yields. In

addition, in about half of the years, higher total yields were also attained in mulched

watermelon versus no mulch. The use of transplants and polyethyelne mulch resulted in

the highest early yields.

2. Aids moisture retention. Mulch reduces evaporation from the bed soil surface. As a

result, a more uniform soil moisture regime is maintained and the frequency of irrigation

is reduced slightly. Irrigation is still mandatory for mulched crops so that the soil under

the mulch doesn't dry out excessively. Scheduling aids such as tensiometers or resistance

blocks placed in the bed between plants can help indicate when irrigation is needed.

Almost all polyethylene mulch used in North Florida is used in combination with drip



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irrigation. Overhead irrigation on mulched beds in deep sands is very challenging. It is

critical to keep up with irrigation demands when using overhead irrigation.

3. Inhibits weed growth. Black, white-on-black, and silver-on-black mulches greatly

inhibit light penetration to the soil. Therefore, weed seedlings cannot survive under the

mulch. Nutsedge can still be a problem, however. The nuts (tubers) provide enough

energy for the young nutsedge with sharp leaves to puncture the mulch and emerge.

Other pests, such as soilborne pathogens, insects, and nematodes, are not reduced by

most mulches. Some benefit has been shown from high temperatures under clear mulch

when used for solarization. Research on solarization is continuing at the University of

Florida. Currently, the best measure for nutsedge and pest control under the mulch is

labeled fumigation. The loss of methyl bromide fumigation will make nutsedge control

difficult in many vegetable crops.

4. Reduces fertilizer leaching. Fertilizer placed in the bed under the mulch is less subject

to leaching by rainfall. As a result, the fertilizer program is more efficient and the

potential exists for reducing traditional amounts of fertilizer. Heavy rainfall that floods

the bed can still result in fertilizer leaching. This fertilizer can be replaced if the grower is

using drip irrigation, or it can be replaced with a liquid fertilizer injection wheel.

5. Decreases soil compaction. Mulch acts as a barrier to the action of rainfall, which can

cause soil crusting, compaction, and erosion. Less-compacted soil provides a better

environment for seedling emergence and root growth.

6. Protects fruits. Mulch reduces rain-splashed soil deposits on fruits. In addition, mulch

reduces fruit rot caused by soil-inhabiting organisms, because there is a protective barrier

between the fruit and the organism.

7. Aids fumigation. Mulches increase the effectiveness of soil fumigant chemicals. They

do not provide a barrier but allow a water layer to form under the mulch and it is this

water layer that slows down the loss of the fumigant. Virtually impermeable films (VIFs)

have recently come on to the market as a new mulch film technology for improving

fumigant gas capture under the mulch.

8. Aids in managing other pests. Highly reflective mulches assist pest management

strategies for pests and the diseases, especially viruses, they may carry. Metalized



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mulches have been shown to repel thrips and reduce incidence of tomato spotted wilt

virus in tomatoes.

Types of Mulch

Three major colors of mulch have been used commercially: black, clear, and

white (or white on black). Several other colored mulches have been researched, including

silver, aluminized, red, blue, yellow, and green. Black mulch is used most widely because

it retards weed growth, resulting in less chemical usage. Black is popular for cool seasons

because it warms the soil by contact (Hochmuch G.H, 2009).

Clear polyethylene is used in the northern states because it promotes warmer soil

temperatures than black mulch by heating soil directly and trapping the heat via the

greenhouse effect. Clear mulch requires use of herbicides underneath to prevent weed

growth, unless it is used for solarization (Hochmuch G.H, 2009).

Clear mulch is not used much in Florida because of the higher temperatures and

weed growth underneath. White or white-on-black mulch is used for fall crops, which are

established under hot summer conditions. Soils under white mulch or white-on-black

mulch remain cooler because the mulch absorbs less radiant energy (Hochmuch G.H,

2009).

Some growers create their own “white” mulch by painting the surface of black-

mulched beds with white latex paint or other similar products, a common practice where

fall crops are double cropped on black mulched beds of a spring crop. Highly reflective

silver or metalized coatings on polyethylene have become important in North Florida and

South Georgia as a method of reducing thrips and tomato spotted wilt virus in tomato

crops. These mulches repel the tomato spotted wilt virus vectors, western flower thrips,

( Frankliniella occidentalis) and the tobacco thrips ( F. fusca) (Hochmuch G.H, 2009).

Only small acreage of other colored mulches are used in the U.S. Consistent

repeated benefits with most colored mulches have been difficult to find (Hochmuch G.H,

2009).



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Objectives of the training material

The overall objective of this educational material is to help farmers increase

earliness of yield, produce quality and protect the environment. The specific objectives

are to increase the farmers’ knowledge on the following topics:

i. Plastic mulch, drip system and their installation.

ii. Correct fertilizer rates and timing of their application in plasticulture.

iii. Seed procurement, planting, correct spacing/seeding rates.

iv. Weed control in plasticulture. Pesticide application rates, types and safety issues.

v. Irrigation water management.

vi. Marketing of produce.

vii. Economics of plasticulture.

Outcome of the training material

The outcome of this educational material is that more farmers will adopt

plasticulture technology and this will lead to increased yield, better crop quality and

hence increase in farm profitability.

Land Preparation for Plasticulture

Before the installation of the plastic mulch, plowing or disking to a depth of at

least 6 inches is required followed by pulverization of the soil. It is important to have as

level a field as possible. A fresh water source is required for supplying irrigation water,

and this is typically a 2 inches-diameter faucet.

Plastic Mulches, Drip System and their Installation

Bed preparation is critical when laying plastic mulch: typically, beds are raised 4

to 6 inches with mulch machine, this aids in increasing soil temperature, improving water



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drainage, aiding air movement through foliage and ultimately, increasing profitability via

good plant growth.

Seed procurement and Crop Establishment

Crop establishment in a vegetable plasticulture production system involves either

transplanting or direct seeding. Well-grow vegetable transplants in suitable containers are

an integral part of this production system. For early harvests of pepper and tomato, large

seedlings in large individual containers (cells) of 9-10 cm across are recommended. For

other vegetable crops, a cell size around 5 cm in diameter is a good general

recommendation. Transplants can be set by hand or machine. The following vegetables

have been transplanted successfully: Tomato, pepper, eggplant, watermelon, muskmelon,

honeydew, summer squash, cucumber, onion, and okra. In specialty or niche marketing

situations, other crops such as sweet corn, herbs, leaf lettuce, and cole crops can also be

transplanted. Mechanical seeders are available in single or multirow models that will

plant directly through the plastic mulch. This equipment is good for direct-seeded crops

of sweet corn and cucumber, as well as other crops.

LITERATURE REVIEW

George J. Hochmuch and Robert C. Hochmuth and Stephen M. Olson. 2009. American

Vegetable Grower. http://www.growingproduce.com/americanvegetablegrower/ (verified 25 November, 2009).

Giacomelli, G.A., S.A. Garrison, M. Jensen, D.R. Mears, J.W. Patterson, W.J. Robertsand O.S. Wells. 2000. Advances in Plasticulture Technologies 1977 – 2000.

Proceedings of the 15th International Congress for Plastics in Agriculture,

Hershey, PA Sept. 23-27, 2000. NJAES Paper No. P-03130-20-00.

Liakatas, A., J.A. Clark, and J.L. Monteith. 1986. Measurements of the heat balance

under plastic mulches. Part I. Radiation balance and soil heat flux. Agriculture for Meteorology 36: 227-239.

Orzolek, M. D. 2003. Plasticulture in North America. Plasticulture (4) 122:33-47.

Pool, K. 2009. Introduction to Season Extension in Organic Vegetable Production

Systems. www.extension.org/article/18366 (verified 25 November, 2009).

educational material for plasticulture

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