Sap analysis
Plants depend on their environment and a precise balance of nutrients to develop well, and tools like sap analysis allow to effectively adjust fertilization according to their actual needs.
Context
To grow, plants depend on their environment to obtain the essential nutrients for their growth. All these elements: macro, micro and trace elements, are indispensable for the proper growth of crops. They participate in the chemical reactions necessary for the formation of plant tissues, amino acids, proteins, as well as key processes such as photosynthesis or the conversion of sugars into more complex compounds.
When the plant is functioning well and produces enough sugars, it can then feed the soil biology. This promotes the development of a trophic network beneficial to the plant itself. Symbioses can then be established, providing the plant with valuable support, especially under difficult conditions.
In a natural ecosystem, the plant benefits from soil biological activity that makes the chemical elements present available in sufficient quantity, in an assimilable form and at the right time.
Conversely, in an agricultural production system, this biological activity is often less active and/or less diverse, which compromises optimal plant nutrition. It then becomes necessary to supply nutrients. It is not only about nitrogen.
Having a balanced plant does not simply mean avoiding deficiencies: it is also necessary to prevent excesses. Nutritional balance relies on a correct availability of elements according to the real needs of the plant. Sap analysis precisely allows to assess this nutritional status and to adjust fertilization accurately.
Objective
Sap analyses aim to ensure the chemical balance of the plant, a key element to preserve its yield potential. Indeed, even the slightest nutritional imbalance can disrupt essential biochemical processes, thus reducing its ability to cope with stresses (climatic or other) and increasing the risk of yield losses.
Analysis
The laboratory NovacropControl in the Netherlands offers comprehensive analyses for many plants, with quick and understandable feedback.
The analysis is performed on fresh leaves and includes:
- Sugars (Brix)
- pH
- Conductivity
- K, Ca, Mg, Na, Cl, S, P, Si, Fe, Mn, Zn, B, Cu, Mo, Al
- N total, NH4, NO3, N in nitrate
Results
With a laboratory
It is possible to send samples directly to the laboratory or to work with an intermediary. In the latter case, you can benefit from support to understand the analysis and possibly receive recommendations on the elements to supply.
The laboratory sends the results in the form of a graph with a bar for each analyzed element, indicating whether the element is deficient, sufficient, or in excess.
With the Nutriscope
Senseen provides an application that allows you to see measurement results directly on your phone. There is a tab:
- "RedOx" for pH, Eh, EC, Brix, stress index.
- "Minerals" for P, K, Ca, S, Mg, Cl, Zn, Fe, Cu, SiO2, total N, NH4+.
- "OAD" to help you interpret these results.
Protocol
Sampling protocols are available on the NovacropControl website or by contacting the intermediary you wish to work with.
In all cases, you must obtain one bag + one label per sample you want to send. Except for the Nutriscope where there is no leaf sampling, but the protocol remains the same.
For crop-specific details, refer to the specific protocols.
When to sample?
Generally, you should sample in the morning, before 9 a.m. (maximum). The goal is to avoid the start of a new photosynthesis cycle.
Dry the leaves by gently patting them with paper towels if necessary.
If needed, you will find the key sampling stages by crop in the specific protocols. Otherwise, contact your interlocutor.
Where to sample?
Make one sample per crop and per plot. Take a representative sample, without mixing diseased leaves with healthy leaves.
What to sample?
To know which parts to sample, refer to the specific protocols or contact your interlocutor.
Sample only the leaves, without petioles. You must have a homogeneous sample in terms of health status and crop development.
Size of the sample: the bag must be filled at least ¾.
Sending the sample
Place 1 sample per bag. Carefully fill out the label and stick it on the bag. The crop must be indicated in English.
Place all samples in an envelope or box (depending on the number of samples).
The sample must be sent directly to the laboratory (unless otherwise indicated by the intermediary).
Warning: Samples must arrive within 5 days MAXIMUM at the laboratory to obtain reliable results. It is recommended to send with tracking.
Labels are prepaid analyses, do not lose them!
Frequency
It is recommended to perform analyses every 2 weeks, otherwise the key stages are generally indicated in the specific protocols. If not, contact your interlocutor.
Points of attention
For soil analyses, as for most analyses, it is essential to always work with the same people and thus ultimately the same laboratories because analysis and interpretation processes differ.
It is important to always sample in the morning before 9 a.m. in order to compare results over time and/or between plots.
Cost
In laboratory: Between €12 - €40 depending on the interlocutor, services and number of analyses.
For the Nutriscope: The investment is made initially to purchase the device. There are no additional costs per analysis, more info here.
Source
This article was written with the kind contribution of Marie-Thérèse Gässler from Gässler SAS.
