Cover Crop Benefits

Catchment Sensitive Farmers Meeting

I had a really fascinating day in Dorset today, exploring the use of cover crops to capture nutrients, (mainly nitrates) and stop them being washed through the soil profile and into ground water. The day was organised by Wessex Water and the Catchment Sensitive Farming organisation. Fellow Nuffield Scholar Tim Stephens and his team have put together a matrix of different cover crop species and seeding rates to look at establishment, nutrient capture and suitability within the field. The catchment also has porous dotted around the fields and every 2 weeks from October to the end of January samples are taken and the levels of nitrate in the water assessed. These values are then turned in to a Kg/Ha of nitrogen to give farmers a vital guide as to where leaching is occurring in the farming rotation and how much is being lost and when leaching occurs.

It seems that the worst leaching occurs after Oilseed Rape and Wheat, probably due to the higher levels of fertiliser they receive but also due to the very inefficient way these plants use the applied nitrogen. Wheat for example is only about 60% efficient when looking at applied or synthetic nitrogen fertiliser. Where cover crops are used the leached level of nitrogen is about 50% that of land farmed without cover crops. This has a significant impact when looking at the catchment as a whole. It is great credit to Wessex Water that they have decided to take this partnership approach to try and reduce diffuse pollution working together with the farmers in the catchment.

Beneficial and Pest Numbers in the Cover Crops

Also on hand were a team of entomologists who have been assessing the impact of cover crops on the insect population. The picture above shows the numbers of insects trapped over a 7 day period. The 2 trays on the left show the beneficial's and on the right are the pests. The top half shows the numbers and type captured in the cover crop field (oil radish and phacelia) and the bottom half shows what was captured from a control field i.e. no cover crop. This level of detail is very encouraging. This clearly demonstrates that cover crops are hosting higher insect levels all round but significantly more beneficial insects that will predate the pests. This is so important when looking at using an Integrated Farm Management approach to try and reduce the amount of pesticides we might want or need to use. There were lots of carabid beetles, who's larvae predate slugs which is also very positive. The benefits weren't just in this cover crop species mix. the photo below shows what was captured within a buckwheat, oil radish and phacelia mix. The predator list includes, carabid beetles, springtails, harvestman spiders (not really spiders at all), ants, spiders, and parasitic wasps. The pest list includes mites, flies, aphids, snails and a slug.

Beneficial Insects and Pests trapped from Cover Crops

The session continued in the local village hall with a great presentation on 'Making the Most of Cover Crops' by Ian from Oakbank. Ian talked about different cover crop mixes, how and when to establish them, and the merits of diverse mixes and the impact of this type of farming can have to the on the bottom line and the better environment. A great day of learning.

Help is on the way!

A very belated post and not really in keeping with the time of year but I have just discovered these photographs on my phone and thought I would share them after a conversation with Caroline Drummond from LEAF (Linking Environment and Farming) about the importance of providing habitat for beneficial insects.  In an ideal world it would be good to farm without insecticides; allowing mother nature to control the pests that predate our crops and impact on the quality of the food they produce or the yield.  Is there a way to enable larger numbers of these biological helpers to control the pests for us? Habitats such as grass margins, beetle banks and pollen and nectar strips have all shown to increase the numbers of beneficial insects that can help control the pests.

Work undertaken at the   Game and Wildlife Conservation Trust at Loddington show how a simple step, like creating a Beetle Bank in fields over 20 Ha (50 acres) have have a huge benefit to providing habitat of overwintering beneficial insects like spiders.  These guys are then able to migrate across the field and help protect the crop from invading pests like the black bean aphid or others.  But what about using biological help in a different form?  Could we spray fungi and bacteria onto our fields to help deter pests, disease and potentially weeds?  All things to be considered in the future which are currently being used in green houses and controlled environments but could they be used in the wider landscape? 

Stewardship Update

I thought that I would just take a quick moment to update you on how the various stewardship options have progressed over the dry summer.  On the whole most seemed to have coped very well although some species have rather taken over!  This first wild bird seed mixture is the Norlands field and was planted with feeding Tree Sparrows through the winter months.  The plants include the wonderful Quinoa whose magnificent autumn colours look a real picture at this time of year.  They will produce a vast amount of small seeds from Christmas onwards.

In this field we have planted a pollen and nectar strip next to a winter bird seed mixture aimed at providing nesting cover and food for corn buntings. The mustard that we planted seems to have overtaken the rest of the seed mix which includes, spring barley, triticale and white millet.  Next year I think I will reduce the mixture from 10 to 5%, although who knows in a different spring 10% might have been the right amount.

This is one of my favourite stewardship margins and one that has already produced a real bounty of winter food.  Both of these mixtures were planted before we entered the Higher Level Stewardship and last year the bird food mix fed lots of small birds, including yellow hammers, dunocks and linnets through the winter period.  What I love about this combination of pollen and nectar and wild bird food is the way that it caters for our farmland wildlife completely.  It provides winter food for adult bird survival, pollen and nectar for insects to live on which then become chick feed and there are nesting sites in the tussocky grass margins and hedge bottom on the right hand side.  It will be fascinating to watch these sights develop over time and hopefully reap the benefits for our farmland wildlife.