Soil Crop Monitor: the ideal sampling moment

17 June 2021 - Livestock - Arable farming

This year is characterized by special circumstances. A cold and wet spring is followed by high temperatures. Emergence is often a little later and crops are now growing very fast. It is important to keep a finger on the pulse. Are there sufficient nutrients available? And can the crop absorb them? Now is the time to check this!

Although summer seems to have already arrived, the spring was somewhat colder and wetter than other years. In particular, the lower temperatures delayed the emergence date of many crops and mineralization in the soil got off to a slow start. Meanwhile, growth is in full swing and, with the high temperatures of the past few days, crops can absorb a lot of nutrients in a short period of time, given enough moisture.

With such rapid growth, it is important to pay attention to whether the crop can continue to have sufficient nutrients at its disposal and if so, whether it can absorb enough. Research then gives clarity. But what is the ideal time to start fertilizer testing?

Combination soil- and crop analysis

Soil Crop Monitor combines a soil and crop analysis. This provides insight into the availability of nutrients and the uptake by the crop. Sometimes nutrients are sufficiently present in the soil, but the uptake is insufficient.

The combination of a soil and crop survey provides additional information on which nutrients are the weakest link and whether there is, for example, displacement at uptake. Last year Eurofins Agro expanded the test with a number of trace elements, pH and EC. The number of requests for fertilizer testing in for example corn and grassland has increased in recent years.

Variety and cultication type

Soil Crop Monitor provides fertilizer recommendations for some 250 crops and varieties. Crops for which crop requirements are determined at the variety level include consumption, seed and starch potatoes, apple, pear, grass seed and Brussels sprout cabbage. For a range of other crops, distinctions are made between first-year and perennial, early or late sowing, low, medium or high need, rootstock cultivation, etc.  If there is a specific variety or crop type available for your crop, provide it to the sampler when they come for sampling or fill it out on the self-test kit form.

Crop emergence date

In addition to the information about the variety and cultivation type, the emergence date is also important for optimal advice. Soil Crop Monitor and Soil Check are based on a specific growth curve per crop or variety from a certain emergence date. Based on this growth curve, the advice for the next four weeks and until the end of the cultivation is determined.

Now that the emergence date for a number of crops differs from other years, this information can be used to further tailor the advice. With short crops and crops of which several crops are cultivated per season, the statement of the emergence date is always necessary.

New! Advice based on own yield

What's new is that from the end of June 2021, growers will be able to communicate their own expected yield. This will be used to adjust the crop requirement upwards or downwards. The crop requirement is central in the fertilization advice from Soil Crop Monitor and Soil Check. The standard fertilization recommendation is based on the average yield in the Netherlands. However, many growers achieve higher or lower yields than the average. By calculating the company- or field specific yield, an optimal advice can be given.

Read more about expected yield here

Sample taking

A Soil Crop Monitor sample can be taken from two weeks after the emergence date. However, the ideal time depends on the crop. The table below shows when and which plant parts can best be sampled. A number of crops, such as maize, have several phases that are suitable for monitoring throughout the growing season. You can choose to take samples at several consecutive times to keep track of the situation. Sampling at one time is also possible. Make sure that sufficient time has elapsed between fertilization and sampling (6 weeks). For grassland, grass clippings can be sent in during the summer for fertilizer testing.

Tabel 1: Information about the sample taking time and the plant parts to sample of a selected number of crops.






20 most recent fulgrown leaves

Apples, pears, cherries and blue berries


50 most recent fulgrown leaves


- Early summer 
- Middle/late summer

10-12 leaves from 15 cm outgrowth

Ware-, seed- en starch-potatoes

Phase II: Plant 30 cm high
Phase III: tuber setting
Phase IV: first bloom
Phase V: start of ripening

25 compound leaves incl. petiole; 1e fulgrown leaf etage from top


Fulgrown plant (not blooming)

15 most recent fulgrown leaves


Young plant
For bud/flower setting (swelling)

25 most recent fulgrown leaves

Cut corn, CornCobMix (CCM), Corncob Silage 
  1. Plant <30cm high
  2. 30-50cm high plants
  3. Stem elongation phase 
  4. Cob setting phase
  5. Pellet filling phase 
  6. Full plume to appear brush


  1. 15 whole tops
  2. 15 whole tops
  3. 12 leaves of base cob start
  4. 12 leaves of base cob start
  5. 8-12 rolled out leaves (5th leaf from top)
  6. 8-12 rolled out leaves (5th leaf from top)


25-30 days after emergence of mature plants

20 most recent fullgrown leaves


50-80 days after planting (June/July)

25 most recent fullgrown leaves

Wheat, rye, barley and triticale

Beginnig of stem elongation (feekes 6)
 End of stem elongation (feekes 10)

25 x above ground biomass



25 most recent fullgrown leaves

Seed-, silver- en plant onions

1/3th of growing season
1/3th until1/2th of growing season
From 1/2th of growing season

12-15 pieces entire top plant (green parts only)