Essential Greenhouse Structures and Cover Materials

Posted on Nov 21, 2024 in Geology

Conditions for Effective Greenhouse Use

  • Clarity and optimal light utilization
  • Efficient ventilation system
  • Weather-resistant construction
  • Cost-effectiveness
  • Ease of maintenance

What are Greenhouses?

Greenhouses are agricultural structures designed for systematic, off-season crop production, enabling effective monitoring of quality and quantity. They provide an artificially sheltered environment using transparent materials to protect plants from harsh weather conditions. These facilities consist of a frame or structure covered with a transparent material.

Types of Greenhouse Covers

Polyethylene Films

Multi-Layer (TRICAPA)

  • Available with or without UV protection
  • Enhanced thermal properties and durability
  • Improved UV additive dispersion for better homogeneity
  • Superior mechanical properties
  • Options for special additives like EV to (Ethyl Vinyl Acetate) for enhanced thermal properties and light transmission
  • Better thickness control
  • Incorporation of dust or antistatic additives in outer layers, and drip and antipesticide additives in inner layers
  • Color variations (milky white, blue, red) for specific crop needs
TRICAPA Technology Products
  • TricapaUV 1 season (80 microns/3.2 mils, transparent yellow-green or colorless)
  • TricapaUV 2 seasons (150 microns/6 mils, transparent yellow-green or colorless)
  • TricapaUV 2 seasons Thermal (180 microns/7.2 mils, transparent yellow-green or colorless)
  • Imported AT Plastics

Single-Layer (MONOLAYER)

  • Special colors for light diffusion
  • Monolayer 1 season (80 microns/3.2 mils, transparent yellow-green or colorless)
  • Monolayer 2 seasons (150 microns/6 mils, transparent yellow-green or colorless)

Tips for Optimal Greenhouse Plastic Use

  • Install during cooler hours (March-June)
  • Ensure proper tension (not too loose or tight)
  • Protect plastic from wood supports with water-based acrylic white paint
  • Replace corroded wires
  • Use solarization techniques for soil disinfection
  • Cover soil with plastic when using plant protection products
  • Ventilate properly after treatments to avoid shortening plastic lifespan
  • Avoid acid for cleaning; use water spray
  • Recycle used plastic covers

Applications of Plastics in Agriculture

Plastics have transformed unproductive land into modern farms. For example, Almeria, Spain, has become a model for agricultural development with its extensive greenhouse concentration.

Benefits of Greenhouses

  • Year-round cultivation
  • Increased production
  • Improved product quality
  • Water-efficient irrigation
  • Reduced weather damage
  • Comfortable working environment

Disadvantages of Greenhouses

  • Requires specialized knowledge
  • Higher production costs

Greenhouse Structures

Structures vary based on climatic conditions. Plastic is used in various applications, including macrotunnels, microtunnels, padding, mesh, pest control (photoselective plastics), disease control (solarization), and irrigation.

Properties of Greenhouse Cover Plastics

  • Physical Properties: Weight, density, thickness, breaking strength, aging resistance
  • Optical Properties: Solar radiation transmittance (PAR)
  • Thermal Properties: Heat loss coefficient (K)

Types of Greenhouse Covering Materials

  • Glass
  • Rigid Plastics (PMMA, PC, fiberglass, PVC)
  • Flexible Plastics (PVC, PE, EVA, co-extruded materials)

Types of Greenhouse Structures

  • Wood
  • Metal
  • PVC

Tunnel Greenhouses

  • Suitable for various crops and weather conditions
  • Arch shape reduces condensation and supports snow loads

Multi-Bay (Multinave) Greenhouses

  • Straight walls and strong structure for additional crop loads
  • Optimal use of internal space
  • Suitable for forestry, floriculture, vegetables, and more

Macrotunnels

  • Cover large areas of crops
  • Easy to install and remove
  • Protect crops from rain and hail
  • Enable earlier harvesting

Greenhouse Dimensions (Example: MT4)

  • Width: 5-7.2 meters
  • Length: Minimum 30 meters
  • Height: 4.0-4.5 meters
  • Air Volume Ratio: Minimum 3.3
  • Post Distance: 2 meters

Greenhouse Management

Temperature is crucial for plant growth and is managed through:

  • Ventilation: Lucarnes (zenith ventilation), windows, curtains
  • Ventilation aims to lower temperature and relative humidity
  • Plant distribution varies with the time of year