In recent years more extreme weather and increased intensity of rainfall have highlighted the vulnerability of much of the UK’s grassland to waterlogging, and run off and soil erosion from poached and compacted soils. There is currently increased interest in drainage and the management of land to extend the grazing season and improve grassland production. There is good evidence that well designed and maintained land drainage systems have a significant other benefits including health and welfare of grazed livestock.
ADAS National Specialist on Land drainage Kirk Hill said “the basics of agricultural field drainage in the management of soils are often forgotten. Properly designed and installed drainage systems mean that land can be accessed more quickly after wet weather and damage to swards through compaction, trafficking and poaching is reduced.
Good field drainage and soil management reduces the susceptibility of soils to waterlogging and removes excess soil water, leaving the land more resilient to storms or prolonged wet weather. Field drainage needs to be considered as a whole package, involving soil condition, design and maintenance of piped drainage systems and ditch and watercourse networks. Poorly designed and maintained drainage can increase soil and water management problems so it is important to do things properly. “Well managed soils are vital for environmental protection, agricultural production and sustainable farm business and land drainage is key to all of this” said Kirk Hill.
ADAS has a wealth of knowledge of the current state of the UK land drainage infrastructure indicating a considerable proportion of the drained area pre-dates modern design standards, and poor maintenance of outfalls and changes in sub-soiling practice may have contributed to a reduction in the efficiency of secondary drainage on impermeable soils. Kirk commented that after many years of decline there is a resurgence of interest in land drainage. Over 6 million ha of land in England has been drained, much of it in the years after World War II, when grant aid was available. Fields in areas with heavy soils or high rainfall are likely to have been previously drained but systems may not be adequate for current farming needs and in the face of climate change. Field drainage is expensive and careful assessment of the current system and the costs and benefits of upgrading, or possible maintenance and repairs is advisable. Simple measures like clearing blocked outfalls or installing mole drains should be considered before opting for a new system.
Kirk will be providing expert advice of the benefits of drainage for grassland and arable farmers at LAMMA 2018 on 17th and 18th January 2018. See ADAS on stand 7102.