In practise

Measuring oxygen in the root environment

The root-zone of a crop is very important for plant growth and plant disease resilience. Water and nutrition are to be optimally adapted to the need of the plant. But the oxygen level in the root-zone largely determine the efficiency for the uptake of nutrients and water and the quality of roots. A sufficient oxygen level in the root-zone assures healthy roots causing the plant to have a better resistance against pathogenic micro-organisms. A sufficient oxygen level in the substrate also minimises the risk of anaerobic situations thus minimising the risk on pathogenic microorganisms. The innovative Sendot oxygen sensor provides deeper insights of substrate quality. This gives direction for possible strategy improvements.

Case: Root zone oxygen optimization at a strawberry grower.

At a strawberry grower root-zone oxygen and regular important climate parameters were monitored during several months using the “normal” growth control strategy. These data were used as a reference level and interpreted to get insight in the effects of watering, light-level on oxygen levels in the root-zone. Two typical days were selected to determine the status of the crop, show how growth parameters influence root-zone oxygen and where improvements are possible.

Figure 1 shows lightsum, watering volume and root-zone oxygen in one graph. It can be concluded that on this day the grower gives too much water per Joule light. The light level is too low to get enough plant-activity to reduce the water content of the substrate resulting in low root-zone oxygen levels. The roots consume the oxygen in the water but the oxygen in the water is depleted pulling the oxygen levels down. After the first watering the oxygen level decreases. Between the last watering and the first of the next day the oxygen level is partly restored. Such low levels of oxygen reduce the uptake of water and nutrients by the roots.

The 27th of February the light levels are high. The grower does not give too much water in relation to the lighting level. The oxygen level in the root-zone decreases slightly during watering but the oxygen level is quite high during the complete day. The plant is able to take up water and nutrients efficiently with these oxygen levels.

It is essential to realise a high oxygen level in the root-zone with optimal watering and EC. There is a clear correlation between light-level, watering and oxygen level in the root-zone. Such parameters can become the basis of a simple watering strategy with improved root-zone oxygen. The EC should evidently taken into account too.


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