Friday, 11 November 2016

Loosing Our Biggest Asset-or not?

LiDAR Image of the Carrent Catchment - source Environment Agency
Every day is a school day and so we have to keep learning about our environment and how we interact with our natural surroundings.  We are just starting to develop a local group of farmers, with help from Gloucestershire FWAG called the 'Carrant Catchment Restoration Project', with the aim of increasing water quality and biodiversity in the local stream that originates around Bredon Hill.  One of the most staggering bits of information came from our local Environment Agency and uses LiDAR information to look at the erosion risk from farmland.  At first glance this sea of red shows high risk areas all over he top of the hill!  Quite alarming.  We then have to start looking at land use, and some of the red areas are taken out of the equation with woodland and the grassland.  We mustn't ignore the grassland-as significant soil erosion can stem from overgrazed or compacted grassland, but it's the arable area of the hill that is by far and above the largest proportion and so poses the largest risk of erosion.
Surface runoff is caused when the field is at water capacity or when compaction is present, both cause the next rainfall to run downhill taking soil particles with it.  These particles are potentially carrying fertiliser and pesticides off down into the nearest water coarse, causing the very typical brown water often seen after heavy rainfall events.
Winter Barley Rooting Structure on Bredon Hill
Our new system of zero tillage (no till) crop farming is the best way to stop erosion from happening on our fields.  The system means that the soil is not disturbed so it can structure itself to allow more water to enter it, reducing runoff.  By leaving crop residue or by growing cover crops the soil surface is protected form rain droplets, stopping surface compaction from happening.  By not cultivating the land we are not burning the organic content of the fields, reducing green house gas emissions.  From a water storage position the organic matter acts like a sponge so the more we have, the more water we can store before it runs off through the soil profile into the groundwater.  The picture above is from a field that has been in zero tillage for 4 years and is really starting to come to life in many ways.  The crop residue is present and under that a crumbly mixture of roots and soil particles attached to the roots of the plants.  This is just the start of what I hope our soils will turn into over time.

Reed Bed Catchup

Reed bed on water Coarse
It was November 2011 when we dug out the reed bed and silt trap at the far end of the farm to try and intercept the ditch water and improve the quality of the outfall into the Carrant Brook.  The silt trap was used to slow down the water and allow the heavier particles (of silt) to drop out of the water.  The water then carried on through the reed bed in a shallow wide spread to allow the roots of the reeds to take nutrients, nitrate and phosphate, are he main two form the water and capture those nutrients in the form of plant material.
After quite a slow start the reed bed has really taken off providing a great habitat for bird species like reed buntings as well as a more general habitat improvement next to the hedge and copiced willows. We have just started a water sampling project with Gloucestershire University, so it will be really interesting to see what effect a very small investment in time and energy can have on the water leaving the farm.