The high water retention capacity available at low tensions, the air supply and a good granulometry are the factors that define the coco peat as the ideal growing media. It can be used in most crops, as those included in consumer horticulture and ornamental production.
The main aspect is to find the substrate behavior about the air and water availability in the plant’s root system. For us is primordial to investigate diverse coir fiber granulometries, emphasizing in the hydric and granulometric characteristics and the agronomic evaluation.
In the coco peat we can distinguish three phases:
- The solid phase: it is made up of the material that makes up the particles.
- The gaseous phase: it represents the air contained in the growing media.
- The liquid phase: it is composed by the water and dissolved substances.
This last phase requires special attention because guarantees the hydric parameters to make the coco peat available to the plant. The pore dimensions have influence in the air and water retention of the substrate. The biggest pores are occupied by air while the smallest pores are filled with water. In consequence, any action that can reduce the biggest pores, also reduces the quantity of air in the substrate.
At the same time, the water retention is increased, being a limiting factor for the crop development. The acceptable values of water and air retention will depend on the type of crop to which it is intended, in addition to the level of technical qualification and type of infrastructure.
These values are represented in the following graphic:
The four graphics of Figure 1 respond to different coir compositions. These coir substrates have been designed to satisfy the requirements of diverse crops and their technical qualification.
Knowing the water retention curves of each growing media, the parameter “R” can be determined, and the information referred to the point where the air and water parameters are equal. This point indicates the container capacity of each substrate. The coco peat mixes have a high porosity up to 90%, which means that exist enough aeration compatible with a high water retention capacity.
The curves reflect a correct general behave of the substrates but with differences in the stress point where the balance between air and water is produced. This indicates that the greater the tension where the air and water curves are equalized, the greater the container capacity of the substrate. Conversely, the lower the tension, the less container capacity. Therefore, each of these substrates require different irrigation management actions to ensure the balance point required by the root system of a specific crop.
Source: Projar International