Soil assessment prior to a grassland reseed

Before reseeding grassland, it’s crucial to assess the soil's condition and suitability to ensure success. This involves checking the drainage system, soil fertility, structure and any potential barriers to successful growth. Find out what to assess and how to prepare.

It’s important to assess the soil up to six months before reseeding so you have time to make any necessary amendments.

Field drainage system: Ensure the drainage system is working properly. Poor drainage can lead to waterlogging, which can affect grass seed germination and establishment.

• Check for wet areas in the field, which can indicate drainage problems
• Look for indicator species, such as rushes, which thrive in poorly drained soil

Drainage ditches and outflows: Ensure that any drainage ditches are clear and functioning properly.

Soil testing: Conduct a thorough soil test to assess nutrient levels, pH and other soil health indicators.

Soil structure assessment: Evaluate the soil’s structure to determine whether ploughing or a minimum tillage approach is best for reseeding.

Soil testing is essential to understand the nutrient profile of your field and identify areas that may need adjustments, e.g. fertiliser or lime.

How to test soil:

1. Walk the field in a ‘W’ pattern: Start from one corner of the field and walk in a ‘W’ pattern to collect samples, avoiding gateways, feeding areas and tracks, which can have altered soil conditions.
2. Sampling depth:
   • If you plan to plough the field, sample to a depth of 15 cm
   • If you’re only cultivating the surface, sample to a depth of 7.5 cm
3. Collecting soil samples: Use a sampling auger or soil corer to collect soil plugs from various locations across the field. Aim for 25 plugs in total, evenly distributed across the ‘W’, to provide a representative sample.
4. Mixing the soil samples: Place the plug samples into a clean bucket and mix them thoroughly to ensure the sample is representative of the entire field.
5. Prepare the sample for lab testing: Take a subsample of the mixed soil, place it in a clean plastic bag and label it with the details of your field.
6. Send to a soil laboratory: Send the soil sample to a laboratory for testing. This can be done through a local co-op, fertiliser merchant or an independent company. Ensure that the sample is sent at least two months after the last application of manure, fertiliser and lime to avoid skewed results.

Assessing the soil structure is crucial for determining the type of tillage required for reseeding.

The visual evaluation of soil structure (VESS) is a straightforward and quick way to test soil structure in a few simple steps. The soil quality score produced can help highlight where soil structure needs to be improved and guide your reseeding approach.

How to assess soil structure:

1. Take a soil sample: Dig a soil pit or use a soil auger to extract a soil sample from the field.
2. Evaluate the soil: Examine the soil’s texture and structure by looking at how easily it breaks apart and how cohesive it is.
3. Score the soil: Using the VESS system, assign a score based on soil structure:
• Score 1–3 (good to moderate structure): The soil is well structured and minimal tillage is required; a ‘minimum-till’ reseed could be sufficient
• Score 4–5 (poor structure): The soil is compacted or poorly structured. Ploughing is recommended to break up the compacted layers and improve soil aeration
4. Decision tree: If your soil scores poorly (4 or 5), refer to a decision tree to determine whether additional steps such as subsoiling, deep tillage or adding organic matter are needed to improve soil structure before reseeding – order a free copy of our Resilient grassland soils guide which includes a decision tree