The importance of soil sampling

During November I gained a valuable insight into the ForFarmers Forage department. This national team is made up of Forage Specialists who work alongside farmers to ensure that they achieve high quality crops that grow and yield economically. The starting point with forage often begins with the soil. It’s important to understand what nutrients are already in the soil as this can help reduce fertiliser costs and improve the nutritional value of the crop.

Soil sampling

It is now a legal requirement to test your soil and this must be completed on cultivated land a minimum of every 5 years. In order to nurture and improve the soil, ForFarmers Forage Specialists take a range of soil samples from across the assigned field.

Structure, scent and compaction

Whilst taking samples of the soil, it is a good time to look at the structure of the field which can also have an impact on growth. By digging a square sized hole, a Forage Specialist can review if a soil is compacted through the root formation. It is also an opportunity to look and count worms as this can help evaluate the organic matter levels within the soil.

As shown in the photograph, we found a worm in stasis. This means the soil is too dry for movement and therefore the worm ties itself up into a knot to essentially hibernate until the soil contains more moisture. If a worm cannot freely move, they cannot feed, so in order to survive they shutdown.

When reviewing the soil it should have an ‘earthy’ smell and not a stagnant scent. An earthy scent indicates healthiness and that a good amount of organic matter is present.

Compacted ground reduces pore space, meaning water drainage is reduced and this can restrict root extension. This can be caused by heavy machinery driving over the field or livestock being present on the ground when it’s saturated.

Once the soil samples have been collected, they are sent off to the lab to be analysed. The Forage Specialists then receive a NMP summary which shows the organic traits and nutrient levels that are present in the field. By reviewing the analysis you can work out the fertiliser requirements for each field.

Not every field on the farm will require the same fertiliser inputs. By reviewing with the farmer what they already have and what they need, allows for an economic application process.

The ‘cake’ theory

Healthy soils on our farms are essential for good crop growth. In order to create a healthy soil it can be related to the analogy of baking a cake. The main ingredients of a healthy soil bed is a good balance of pH, phosphorus (P) and potash (K). These are the core ingredients, just like the flour, eggs and milk.

Nitrogen is also a main compound and can be found on a NMP summary. It’s important to note that this nutrient doesn’t carry over from year to year, so it needs to be applied to the soil annually.

pH levels should be around a 6 - 6.5 range, to maintain a healthy organic environment. A drop in pH can make a soil become toxic which will evidently have a negative effect. On the other hand, a high increase in pH level can make some micro and macro nutrients less available. By knowing your pH levels can help decipher how much lime you apply to your fields.

Phosphorus is essential for being a constituent for ATP which helps transfer energy in plant cells. It also allows for a more efficient uptake of nitrogen, increased root development and many other vital roles.

Potash is important for metabolic processes as it allows crops to synthesise proteins and sugars, which increases growth and also maintains water content in the plant’s cells.

These are some of the most essential nutrients and by measuring them, you can create an accurate fertiliser application plan. Fertiliser can be one of the biggest costs on a farm, so you don’t want to be buying and applying more than you need.

Micro nutrients

Next in the cake are the micro nutrients, these are the trace elements in the soil. They are like the currants and cinnamon that spice the cake and make it better. They are usually required in small quantities and include iron, zinc and copper. However, not all trace elements are essential. For example boron is not important for certain crops however for fodder beet it couldn’t be more crucial.

These nutrients amongst others will then be discussed by the Forage Specialist and farmer. The objective is to get the most out of the current fields and also to maximise the potential of future crops. Fertiliser and crop rotations can be planned as well as visits throughout the growing season to ensure that crop growth is maintained.

Even if your soil results say that you have some nutrients, it doesn’t necessarily mean that they are available. More investigation would be recommended if your crops aren’t performing, which is something a Forage Specialist could help you with. By looking at the whole balance of your nutrients in a field and can help identify the root cause of the problem.

Forage knowledge

There is so much more that goes on in the Forage department at ForFarmers, fertiliser plans, additive requests, silage analysis, marketing and sales.

I have been really lucky to be able to shadow and visit customer’s farms with Forage Specialist, Chris Woodget. I have had the opportunity to learn so many things that stem from soil sampling. I would like to thank Chris for taking me out on farm, sharing his knowledge with me and answer my questions.

Let’s hope we can have more time out on farm safely in 2021.