07 April, 2017
Improving grassland soil and drainage
As with arable soils, grassland soils need to be well drained and free of compaction. Poor soil structure inhibits the flow of air, water and nutrients and will lead to a reduction in the sown species in the sward resulting in a reduction of both grass growth and quality.
Compaction down to 8-10cm generally indicates poaching or over-stocking. For near surface compaction, slit aeration may help to restructure the soil. General compaction at a greater, 10-15cm depth is likely to be due to machinery damage.
If the zone of compaction is in a more discrete layer at ploughing depths, this is more likely to be due to repeated cultivations. Deep ploughing, subsoiling or moling will help to alleviate any deeper compaction of this nature.
Impeded drainage – as evidenced by gleying or mottling of the soil – leads to reduced grass production, shorter grazing seasons, increased poaching and poor nutrient use efficiency. High levels of yorkshire fog or creeping bentgrass are also indicative of poor drainage.
Where poor drainage occurs, it may be possible to use mole drains to help take water to permanent field drains; cleaning or jetting existing drains, especially at ditch outlets.
Soil pH must be addressed before reseeding
In order to optimize soil conditions and avoid local compaction and/or impeded drainage, farmers need to plan farm layout with stand-off pads, adequate permanent roadways and multiple entrances to paddocks which will prevent cattle compacting or poaching regularly trampled areas. The optimum soil pH for continuous grassland is 6.5 for mineral soils and 5.5 for peaty soils. Reseeding is unlikely to be successful unless the soils pH and fertility is addressed at the same time.
Find more advice in our fertilizer programmes for grass reseeds
