How to take Fertilizer Samples

FERTILIZER

Introduction

Fertilizers come in different formulations, grades and batches.  Properties can alter during mixing, transport and storage, and they can become contaminated or adulterated.  It is good agricultural practice to check what is in your fertilizer both to ensure that you are getting what you paid for and to ensure that your plants are receiving what you planned.  

There is a risk that fertilizers can contain heavy metals. Once they have been applied to the soil - they are very difficult to remove.  Another good agricultural practice is to check the heavy metal composition of your fertilizers from time to time. 

Analysis values may differ from the expected composition for the following reasons:-

• Adulteration or contamination.
• Excess moisture - fertilizers  may be hygroscopic or contain hygroscopic components that could absorb moisture if stored under humid conditions, or if they get wet during transport / handling / storage.
• Inadequate mixing of components in a fertilizer mixture.
• Segregation of particles of different density and sizes in a fertilizer mixture bag during transport / handling / storage.
• Presence of impurities.
• Incorrect sampling procedure - it is very important to take a representative sample
• Analytical errors - these are generally relatively small and minimized by adhering to ISO 17025 standards and proficiency testing.

Fertilizer sampling 

Procedure

1. For up to 10 bags a sample should be taken from each bag, for over 10 bags a sample should be taken from 10 random bags.
2. For bulk fertilizer 10 random samples from different points should be taken and mixed.

Sampling with a shovel

Procedure

1. The bags to be sampled should be selected randomly. 
2.  Each bag should be emptied on a clean dry surface and blended thoroughly with a shovel, and one shovelful of each taken to make a composite sample.  
3. The composite sample should be thoroughly mixed and any lumps broken up. 
4.  A sub-sample is drawn from this by process of quartering.

Sampling with a special sampling probe

Procedure

1. Lay bags horizontally.
2. Open one end and pass the probe DIAGONALLY through the bag from one corner of the bag to  the other and remove the core - placing in a clean plastic bucket for mixing. 
3.  For samples of up to 10 bags - take one core per bag.  For samples over 10 bags - take a core from 10 randomly selected bags.
4.  The composite sample should be thoroughly mixed and any lumps broken up.
5.  A sub-sample is drawn from this by  process of quartering.

Sub-sampling by quartering

Procedure

1. It is necessary to thoroughly mix the composite sample that has been obtained and to reduce the quantity to a manageable size (200-500g, or 1kg for blended fertilizers) before submission for analysis.
2. 
3. Use a clean dry work surface or plastic sheet. 
4. Tip the composite sample in a cone shape on the surface, flatten out and divide into quarters.
5. Discard two opposite quarters.
6. Mix up the remaining sample and repeat.  
7. Continue the quartering and rejection until the desired amount of sub-sample is left. 

Packaging and labeling

Procedure

1. The sample should be placed in a CropNuts' sample bag, or strong, clean plastic bag. 
2. The bag should be tightly sealed to exclude air.
3. Do not staple.  Use tape.
4. Label the bag well and if the sample is hygroscopic place in an additional sealed plastic bag to protect from water and humidity. 
5. Dispatch to lab with an accompanying sample submission form.  

http://cropnuts.helpscoutdocs.com/article/574-where-do-i-find-your-sample-submission-forms

Where to send your samples

http://cropnuts.helpscoutdocs.com/article/572-how-shall-i-send-the-sample-to-your-laboratory

For more information please contact us through:

Crop Nutrition Laboratory Services Ltd.

Off Limuru Road, Limuru,Kenya

Telephone  + 254 (0) 711094444

Email support@cropnuts.com