Hydroponic cultivation is divided into two categories: substrate-free cultivation and substrate cultivation, so how to choose a suitable substrate in substrate cultivation? What is the difference between commonly used substrates?

Factors affecting the selection of substrate materials for hydroponic culture

1. Performance

physical properties

An ideal substrate must have a good physical structure and be able to create an appropriate water and air balance for the healthy growth of crop roots, which must be sustainable throughout the crop's growth cycle. The matrix structure is determined by the size, shape, structure and physical arrangement of the particles that make it up. Currently, in addition to physical properties such as bulk density, particle size distribution, and porosity of organic and inorganic matrices as factors in the selection of matrix materials, the determination of matrix hydraulic properties is transformed to describe the mechanism of matrix absorption, retention, and release of water, especially the matrix. The water-holding mechanism has been taken as an important factor in the selection of matrix materials. The water-holding capacity and air permeability of different matrix materials, including water-holding porosity, air-filled porosity and water-holding capacity, etc., these conditions provide general and specific ranges for the porosity of the matrix.

Chemical properties

 An ideal substrate must also provide a suitable environment for plants to absorb nutrients. The chemical properties of the matrix such as acidity and alkalinity, electrical conductivity, cation exchange capacity, and availability of nutrients are all within the scope of the study for matrix material selection.

Biological properties

Biological properties are an important factor in judging whether an organic material can be used as a hydroponic culture substrate, because it has a great influence on the performance of the substrate. This impact includes three aspects: first, the organic substrate cannot contain any organisms that may harm plant growth or human health, including disease-causing pathogens, plant pests, and weed seeds; second, the organic substrate is easily decomposed by microorganisms, resulting in its physical properties Changes occur (this change is known as organic matrix instability); finally, when microorganisms decompose carbon compounds in organic matter, they consume nutrients available to plants, which can affect crop growth if not properly replenished.

2. Economy

The factor of economic benefit is crucial to the selection and development and utilization of the substrate. A high-quality soilless cultivation substrate must have a certain cost performance, and its economic cost includes the market value per unit volume, transportation costs and secondary processing costs. The market value of materials is dynamic and determined by two factors: supply and demand. Secondary processing refers to the investment required by a substrate manufacturer to perform specific processing to produce usable substrates after the initial purchase of raw materials. The degree of processing can vary widely, from simple addition of fertilizers, grading, crushing, to compound transformations of pyrolysis. In general, the more complex the machining process, the higher the associated costs.

3. Environmental protection

The impact of crop cultivation on the environment is causing widespread concern. At present, the research on the environmental effect evaluation of different matrix materials has made great progress, but there are still many research gaps, such as the determination of environmental costs and benefits and measurement methods. In the process of selecting a substrate, it is necessary to accurately understand the impact of the selected substrate on the environment and consider its entire life cycle. For example, different organic substrates fix and release nutrients in different ways, which has implications for both crop nutrient availability and potential contamination during crop production. In addition, the effect of the substrate on irrigation efficiency and pest control should also be considered. Therefore, no matter from the perspective of applicability and economy to crops, or from the aspects of market demand and environmental requirements, it is necessary to choose an organic type of environmentally friendly substrate that can be recycled, does not pollute the environment, and can solve environmental problems.

Common hydroponic cultivation substrates

Common inorganic substrates for hydroponic cultivation include vermiculite, perlite, ceramsite, volcanic rock, gravel, rock wool, etc.

Among them, rock wool is a relatively high-quality substrate in modern greenhouse cultivation. Because of its special structure and excellent physical and chemical properties, rock wool is recognized as one of the best substrates in hydroponic culture. It provides plants with a good rhizosphere environment that retains fertilizer, water, sterility, and sufficient air supply.

The Netherlands is the country with the largest hydroponic cultivation area and the most advanced technology in the world. The area where rock wool is used as hydroponic cultivation substrate accounts for more than 80%, and it is the country with the largest application area of rock wool cultivation. The United Kingdom, Belgium and other countries are also vigorously developing. At present, in the hydroponic cultivation in the world, the cultivation area of rock wool cultivation substrate ranks first.

If you want to know more about the advantages of rock wool substrate planting, please see the introduction of related UPuper® product advantages.