Steel grow gutters have been widely used in various types of greenhouse projects in the world, and these greenhouses integrate many types of innovative technology, such as fully automatic ventilation and cooling facilities, special materials for internal and external shading or insulation, balanced CO2 mitigation systems, more accurate light compensation systems, or the widespread use of new energy storage facilities make the modern smart greenhouse more like a display platform of high-tech facility agriculture.

With the addition of these high-tech facilities, the construction cost of smart greenhouses has increased significantly, and it has become the tireless pursuit of material suppliers to make the initial investment in large assets to obtain a longer-term return. In this article, we will discuss how to make the plant growing gutters last longer and get a longer payback by choosing more suitable materials for Steel grow gutters

Inside greenhouse natural environment places high demands on the steel grow gutters

Temperature and direct sunlight

In the process of temperature management in the intelligent greenhouse, three stages of temperature management measures are generally used: the first stage is from sunrise to before sunset, this stage of greenhouse temperature is set to 17-27°, the second stage is from sunset of the first day to the early morning of the second day, the temperature range of this stage is 12-18°; the third stage is from the early morning of the second day to before sunrise of the next day, the temperature of this stage is set at 17-20°. This shows that the temperature inside the greenhouse is usually around 20° Celsius, which is high and is not conducive to the long-term preservation of steel cultivate gutter.

Meanwhile, in modern intelligent continuous glass greenhouses, every effort is made to increase the intensity of greenhouse light in order to increase the absorption of light by plants and thus increase crop yield. The diffuse reflective glass on the roof, the white ground cloth and the white baking paint on the main structure of the greenhouse increase the number of reflections of light inside the greenhouse, while some greenhouses also increase the duration of light through supplemental lights, and these direct or indirect UV rays to the cultivation tank can also have a bad effect on the surface coating of the grow through.

Daily high humidity and humidity fogging

Moderation in the greenhouse is closely related to transpiration of the crop. 90% of the water absorbed by tomato plants is evaporated. Transpiration promotes the absorption and transport of nutrients by the crop and also acts as a cooling agent for the crop itself. Some studies have shown that the ideal saturation humidity for tomatoes is between 2-5 g/m³. Therefore, the high humidity inside the greenhouse, especially during the rainy season when light is poor, is equally detrimental to the preservation and protection of steel planting gutters.

At the same time, during the hotter summer months, the high-pressure fogging device inside the greenhouse is pneumatic, spraying mist into the air, and these fine water droplets can drift onto the surface of the planting trough, while affecting the surface of the steel grow gutter.

EC and PH of hydroponic nutrient solutions

Soilless culture mode is usually used in large projects using steel grow gutter, combined with integrated water and fertilizer systems for irrigation. EC values during production are typically 2.0-4.0 mS/cm in tomato cultivation, and the PH of the irrigation solution is typically controlled at 5.0-6.0, slightly acidic, to ensure proper growth of the tomatoes. The Cl ions in these acidic fluids can accelerate the destruction of metal surface oxidation layers while accelerating steel corrosion.

Key technical parameters of steel grow gutter raw materials

The key parameters of steel coils used to make steel planting trough systems discussed in this paper are all physical technical parameters and do not involve the production scale of the manufacturer, paint brand, equipment line production capacity, etc., nor do they discuss whether they are full process or short process steel mills.

Steel grow gutter zinc layer.

The zinc layer factors that have an impact on steel grow gutter are mainly divided into the type of zinc layer and the thickness of the zinc layer. The type of zinc layer we usually divide into pure galvanized layer, aluminized zinc layer, or the zinc-magnesium alloy layer. The thickness of the zinc layer is generally based on the requirement of 100g on both sides. Usually, it is prudent to choose color coated raw material panels with a zinc layer lower than 100g for steel grow gutter systems.

Steel grow gutter by polyester coating

PE coating has good adhesion to the material, color coated steel plate is easy to process and form to steel grow gutter, the price is relatively low, and the color gamut of its color is relatively wide. However, polyester coating itself is relatively poor in UV resistance, so there are relatively few steel grow gutter made of ordinary polyester material in large greenhouse projects. Theoretically, the anti-corrosion life of ordinary PE steel grow gutter is about 10 years.

Steel grow gutter by high durable polyester

HDP is a modified coating variety based on PE material, data show that HDP material can reach 60-80% weathering resistance of PVDF coating HDP polyester coating, and better than ordinary silicon modified polyester coating, especially the use of aromatic-free polyol and polyacid to reduce the absorption of UV light by the resin, to achieve high weathering performance of the coating. Therefore, this material type is relatively more stable under high irradiation intensity inside the greenhouse and has the highest relative price/performance ratio. This material is widely used in large scale greenhouse projects in the world. Theoretically, planters using HDP growing gutters have a corrosion resistance of about 12-15 years.

Steel grow gutter with PolyVinylideneFluoride

PVDF is currently one of the most corrosion resistant materials in the agricultural industry, and its corrosion resistance is usually able to be greater than 20 years. This is because PVDF has very good corrosion resistance and color retention stability due to the very stable energy absorption between chemical bonds within PVDF. In addition to this, its UV resistance is also outstanding. At present, there are relatively few growers using PVDF as raw material for steel grow gutter in medium and large projects, and the few steel cultivate gutter using PVDF material are mainly for display or experimental projects.

Processing and installation process of steel grow gutter

We have already discussed the material factors of steel grow gutter, which are physical properties of the material and are usually determined after the raw material leaves the factory and cannot be changed. So, what are the other factors that we need to be aware of during the on-site production of the project?

First of all, the on-site production technology of steel grow gutter is important. The bending of the plates during the forming process can affect the coating and zinc layer on the surface of the plates, especially the small angle shape bending can directly damage the physical protection layer on the surface of the steel cultivate gutter, and most of the time these damages cannot be directly detected by the naked eye. Most of the time these damages cannot be detected by the naked eye. Therefore, it is important that the forming process is scientifically smooth.

Secondly, with single row steel grow gutter often tens or over a hundred meters long after production, it is also important that workers are able to move and install them properly during the transfer and installation of the steel grow gutter. In some projects, manual workers can scrape against the brackets of the output cultivators during the process of transferring cultivators. Some workers without greenhouse building experience may twist the steel grow gutter during the transfer process because of the long length of the steel grow gutter, which can also damage the steel grow gutter surface.

Also, inevitably, since the main installation method for steel grow gutter is hanging or bracket installation, these gutter bodies are bound to come into physical contact with the rest of the accessories, which are most often metal parts, and these contacts usually scratch or scrape the protective layer of the cultivator surface. In addition, some small projects do not have the technology to produce steel planting gutter on site, so most of the time, we process the grow gutter into fixed length and transport them to the project site for splicing, and most of the time the cultivators have surface damage during transportation.

To sum up

In general, the selection of the material for the steel grow gutter inside the greenhouse is not an easy job. If you choose the right material not only depends on the grower’s own economic conditions, the grower should consider more the overall life of the entire greenhouse facilities using this steel grow gutter system, taking into account the diminishing marginal effect and fully considering the depreciation of the relevant facilities and equipment, I hope that the analysis of the raw materials of the planting tank in this article can help you choose the right raw materials of the steel grow gutter.