How to monitor nutrient management in glasshouse crops

How should I monitor my crops

The most straightforward monitoring is regular crop walks, spotting symptoms early is very important and can be done with the help of AHDB crop walking guides. More detailed checking of growing media and plant material can give information before symptoms are seen or can help confirm what a problem is.

Checking growing media

• Media needs to be checked at least once a week with a pH meter to look for trends in pH rise or fall.
• Checking pH can be done on the nursery with simple, affordable handheld kit.
• Checking EC can also be done on the nursery, again with simple equipment.
• If you need to know content of different nutrients, you will need a laboratory analysis done on your growing media.

Checking leaf material

• Leaf tissue can be checked for “greenness” using handheld equipment and phone apps.
• If you need to know content of different nutrients, you will need a laboratory analysis done on your leaf tissue.

Monitoring the growing environment

Checking humidity

It is important to measure humidity at the height of the crop as there can be a big difference between this and the general glasshouse level of humidity.

High light levels can also be damaging when growing for late summer/early autumn sales. If you are shading to reduce heat and light it is even more important to monitor humidity as there can be reduced air movement under shading.

Checking temperature/light

To eliminate sun or temperature damage as a cause of leaf tissue necrosis it could be useful to monitor leaf temperature as well as temperature at crop height. This will help to see if there are any extremes in the growing environment.

Monitoring water quality

Irrigation water has a big impact on plant nutrition as water from different sources will have different chemical make-up.

Routine checks

• pH and EC of irrigation water can be checked on the nursery using the same simple handheld devices as for checking growing media.
• Sending a sample for laboratory analysis will give the detailed information about the different nutrients present.

What are the benefits of checking?

• Knowing the composition of water means that a feed program can be chosen that fits your water quality.
• You may be able to reduce feed concentration if you water is high in certain nutrients, e.g., nitrates.
• Knowing the pH of your water will help you understand what nutrient problems your crops might develop. It will also help you choose your feed as different liquid feeds are available for hard and soft water.