Interest In Cover Cropping

In the run up to Christmas I hosted almost 100 farmers on three different visits to look at the Cover Crop trials that we planted back in August and September.  The seed was generously supplied by Kings and used in a trial to look at the benefits and costs of using cover crops in the farm rotation. Cover crops have only recently come to my attention through my Nuffield Farming Scholarship Trust award to look at increasing wheat yields n the UK.  Although we have been using turnips and forage rape for years as a sheep feed through the winter period, there is so much more a cover crop can deliver other than feeding ewes or lambs through the winter.  The cover crop idea has also sprung into life as they can count towards Ecological Focus Areas (EFA's) in the the new Common Agricultural Policy.  In total we have planted 11 different mixes or single variety species to see what benefits or negative effects can be measured..

Paul Brown (above) from Kings, demonstrating the tap rooting ability of radishes to push down into the soil to break up compaction caused by farm machinery.  The ability of all of the mixes to scavenge for nitrogen and phosphate that would otherwise be lost from the field is tremendous, and if your include vetches into the mix their ability to fix nitrogen form the atmosphere is staggering.  The plot of straight vetch analysed at over 30% protein and was holding over 200Kg/Ha of nitrogen that will be available for the following crop!  Species in the various mixes included, mustard, forage rye, vetch, radish, oat, berseem clover, phacelia, buckwheat and linseed.  The mixes have been assessed by NIAB as part of our Kellogg's Origins Group, looking at ways in which we can farm in a more environmentally and financially sustainable way.

The crops certainly tick all of those boxes by: intercepting sunlight through the autumn and winter, turning it into carbon (plant matter) to improve soil organic matter levels (when decomposing); help remove compaction by aggressive rooting; locking up nutrients that would otherwise be washed through the soil into the environment; provide valuable late season pollen and nectar sources (bees using ours until November), provide a nutritious balanced diet for overwintering stock: stabilise and protect the soil surface from heavy rainfall events.  It is almost all positive effects form these crops bar the creation of a lovely slug habitat.  This will need watching and monitoring through the winter and into the drilling period to keep on top of the slippery problem!

Day 8 - Time for a Tour of the District

Our host Alec Wright; Nuffield Scholar, in Methven graciously showed us around the district this morning visiting his sons farm first thing to drop off some lunch made by Jean, Alec's wife. We looked at the silage operation before moving up to some higher and stony ground to look at some direct drilled grass reseed.  This field was coming up beautifully due to the reduced disturbance retaining moisture win the soil.  There is no luxury of irrigation this far up the slopes on Mt Hutt. The swedes were also direct drilled into grass stubble that had been sprayed off and were emerging well on the whole although as temperatures reached 29 degrees today and with a stiff breeze soil moisture was paramount.  This would also go for wheat production.  A single cultivation will reduce the soils water holding capacity by 25mm, which could be important later on in the season.

If cultivated and a North Westerly gale blows, the wind is funnelled down through the mountains and the soil will be eroded by the wind, leaving the field and being caught up by the nearest obstacle, in this case a small hedge.  The depth of this top soil was 2 ' deep and seeing this brought back thoughts of the great dust storms of the 1930's and my time in Oklahoma.

The wind can also do some serious damage to the infrastructure of the farms when really unleashed.  Earlier this year about 800 irrigators were blown over during winds that reached 200Km/hr in places. This is putting huge pressure on the mechanics required to repair all this damage but without water there are no crops or grass.  Production in some areas has fallen away simply because there is no water to keep the crops alive.

We drove passed one terrific looking crop of wheat being irrigated.  The plant population was thinner than our UK target but the plants had tillered out very well.  The stems and upper leaves were clean of disease and the potential of thigh yield was definitely present.  I think  this picture sums up the advantage that New Zealand has over the UK when it comes to wheat production.  It seems that an abundance of water, (for the time being), and lots of sunshine are the key ingredients to very high yields.  But the plants need to be fed correctly and the soil has to have the correct structure to support root development that will enable faster, less restricted uptake of nutrients. 

This is where crops like this fodder radish can help in restructuring the soil.  The tap root, along with the other 30/m2, are all pushing down through the soil profile, finding a way through any compacted layers in search of water and nutrients.  The field had a good population of plants all creating drainage for water infiltration, for when it does rain, and removing any compaction layers.  The obvious next step would be to direct drill the next crop to reduce the erosion risk; as evident above, reduce cost of establishment and increase the amount of water available to the following crop.  By not tilling; the soil will increase it's organic matter content allowing further increases in the water holding capacity.  Seems to me like a good way to progress?

Cover Up or Laid Bare?

One of the key messages I have learnt from my Nuffield travels this year has been the need to look after  and feed the soil whenever possible.  This is fundamental to the farming system here in the UK.  If we look back 10,000 years the country was covered in trees and grasses; fields weren't created and there was no bare land.  It had something growing on it all of the time and this is what I feel we have to recreate now.  The soil is alive, or at least it should be.  It should be alive with bacteria, fungi and worms constantly re-cycling dead and decaying matter to release nutrients that we can then recycle.  With this in mind, the area of land going into spring cropping that doesn't not have a cover crop on it is down to the bare minimum 30Ha that we have as part of our Stewardship Agreement.

The picture below shows a field that has been split with two scenarios.  Half is in cover crops and half has been left as over winter stubble; although we had to do a light cultivation to get anything to green up.  Modern combines do not leave much grain behind.  The field will be direct drilled with spring barley next year and I can't wait to see what difference the cover crop will have made to the soil health, friability and structure.  Will it warm and dry faster with a crop on it?

The mix contains mustard, to produce organic matter, peas to fix a little nitrogen; oats, forage rye and volunteer wheat to mop up residual nitrogen, fodder radish to push tap roots into the soil and reduce compaction and turnips, just in case we run some sheep over the field.  I have a few observations so far that I would like to share.  The crop needs to be established as soon as the combine leaves the field to maximise the moisture left in the soil.  Any soil surface exposure to sunlight and no crop cover and vital moisture is rapidly lost.  This was a lesson learnt in Oklahoma where a second crop of sesame was being planted directly into wheat stubble in 45 degree heat!  Where the soil is moved we are getting a nice germination of weed seeds as well, so there is a nice flush of black grass and brome, all adds to reducing the seed bank in the top few inches of soil.  The field also walks well, it's hard to describe but it appears to have a cushioned effect, that can only be the organic matter that later will be returned to the soil.  Did you know that a 1% increase in organic matter in the top 6" of top soil means an additional 27,000 gallons/acre can be stored?  Well it's true, meaning that periods of dry weather will have less impact on our potential yields, especially on lighter, thinner soils.  I'm not expecting a fix in a year but over a rotation we should start to see a difference.  A more volatile climate is something that we should expect more often and we need to make plans to have a more resilient farming system. Prof Sir Brian Hoskins only mentioned last night at the Sainsbury's and Grantham Imperial College Lecture that temperatures could rise between 2-4 degrees by the end of the century, this will only cause more volatility in the climate, causing more weather extremes.  Last year for example 3,200 of the 5,000 weather stations in the United States recorded a record weather event  e.g. highest temperature, lowest rainfall, highest rainfall etc.

Another key benefit is the stabilisation of the soil.  All of the roots actively growing through the periods of heavy rainfall and the canopy above, shielding the soil surface will reduce water run-off and increase filtration rates.  Reducing run-off keeps soil particles in the field where they belong but also keeps phosphate fertiliser and any residual pesticides in the field rather than in the local stream.  I haven't even mentioned the amount of carbon that is being sucked out of the atmosphere and stored in the soil,  hopefully helping to turn around the recent losses of organic matter levels in the soil. Which ever way you look at it there are many positives.  But what are the negatives?  Well I guess there is the cost of the seed and establishment which when added together could be in the region of £80/Ha.  There is also the requirement for extra labour, and potentially machinery, at an already busy time of year when everyone is focused on the harvest. Do the positives out way the negatives?  Well it's early days but I would have to say that so far they do.  Are we creating a longer period for slugs to breed and feed?  Are we continuing the 'green bridge' and providing habitat for aphids transmitting BYDV (Barley Yellow Dwarf Virus) or too many brassica's potentially increasing the risk of club root?  Time will tell but as always with farming it's a long term game and there are many obstacles in the way before the results will be shown.  What I am certain of is that building soil carbon and reducing the level of tillage (cultivation) will, overtime increase the crop yields and reduce the variability of production and that can only be beneficial.

Planting Time is Here Again

The start of the new farming year has begun.  It's a time of optimism when the seeds from last years harvest are planted again to multiply up for harvest in about 11 months time.  We usually start planting, or drilling, up on the hill as the soil temperature there cools down faster in the autumn so the crops need to get established before this happens to optimise their yield potential.  Then we move down the hill to the heavy land, lias clay, to get those fields planted before the weather breaks.  We have to delay drilling in some fields to get a weed called black grass to germinate so that we can spray them off with glyphosate before we plant the crop.  This is needed as these weeds are resistant to many of the herbicides we can use in the crop.  The more we can remove, before planting, the better.  One of the things we have been trailing this year is a Cross Slot drill.  The idea of this drill, developed in New Zealand, is to cut a slot in the soil and plant the seed just under the surface on a little ledge and then fold back down the little flap of soil sealing the seed just under the surface. The drill is shown above planting directly into a standing crop of mustard.  That's another part of the story.

Our soil is a living organism and using this planting technique helps to keep the soil in the best health that we can get it.  Think of it as a natural environment.  Our landscape was once covered in trees.  Seeds fell from the mother tree and were not really cultivated in but rather mulched in with falling leaves.  That is what the drill is trying to mimic.  Low disturbance, slotting the seed under the surface.  This should in time reduce the amount of herbicides needed because the soil surface is not being disturbed so weed seeds will not germinate.  It also helps feed the worms in the soil by not mineralising soil carbon.  It also saves a lot of diesel in establishing the crop, all good for the environment, and the bank balance! In the picture above a worm hole can definitely be seen.  These worms take the organic matter from the surface down into the soil profile redistributing the nutrients to the rooting zone.  These worm holes have been known to go down 6'.  I've been watching out for these much more recently. The small piles of give away crop residue, hide the entrance to the underground world of these 'night crawlers'.   These channels provide fantastic drainage for surface water, stopping runoff keeping nutrients and pesticides in the field, we just need more of them and that will come with less disturbance and more time.  Did you know that ploughing kills 50% of the worms in that plough zone and every cultivation afterwards can potentially kill off a further 25%.

This is our current drill direct drilling into another cover crop mixture.  This mix was of mustard, phacelia and fodder radish.  The soil structure is fantastic with fabulous roots creating a fine tilth that should hold moisture and encourage a very good establishment of the winter wheat we have just planted.  The experiment continues!

All Covered Up?

Well this year is certainly making me think long and hard about the long term benefits of cover cropping when there is no other crop planted in the ground.  It is also making me think about leaving ground bare and I'm coming to the conclusion that we should be having crops growing all the time.  The soil microbes, fungi and bacteria all need to be fed to keep them healthy, this would seem logical wouldn't it?  Keeping the soil microbes healthy recycles nutrients within the system, keeps the soil structure maintained reduces soil erosion and increases water quality. It can also dry the land out faster and more evenly.  It also provides a great habitat for  our wildlife, I see an abundance of brown hare; we have skylarks serenading me as I walk the fields and lapwing swooping down to ward of visitors from their nests and young fledglings.

The field above is a mixture of Phacelia, Fodder Radish and a mixture of winter and spring beans.  The beans can, with the help of nitrogen fixing bacteria, turn atmospheric nitrogen into a form that the plants can use later in the season or it should be available for the next crop.

This is a fodder radish plant that has a tap root very similar to a parsnip by the looks of things.  It is penetrating the soil with the equivalent force of 400lb/square inch.  The picture above shows the root development 5 weeks since the crop was planted in a very cold and difficult spring (aren't they all these days).  I am hopeful that where the crop has established well there will be no need to subsoil this year.

As the cover crop plants die; the following crop, in this case winter wheat, their roots will be able to follow these roots down to the moisture in tracks already provided.  This means the wheat will use less energy to produce their roots enabling more efficient use of energy.  All in all there is no immediate financial return for doing this but the long term benefits will pay back with better yields and we'll have a farming system that is more resilient to the challenges of climate change that are all to obvious.  There will also be opportunities for moving livestock around the farm, returning more organic manure, I just have to work out how!