12 March 2015
The current Greening of the Common Agricultural Policy (CAP), with its associated requirement for Ecological Focus Areas (EFA), has raised awareness of techniques which are in danger of becoming lost to UK agriculture.
Green cover and catch cropping can now form part of the EFA requirement for Greening, with a generous weighting of 0.3 for every hectare grown. There is nothing new with green covers and catch cropping, with many of the old farming textbooks describing their use and benefits. Modern, simplified rotations and the drive for short-term efficiencies have led to the use of green cover and catch cropping falling out of favour in many parts of the country.
So what actually constitutes a catch and a cover crop and perhaps more importantly, what doesn’t?
Catch crops are designed for the capture of nutrients and their utilisation rather than them being lost to the environment: a classic win-win situation for farming and the environment. Farmers may choose to implement catch cropping purely for agronomic benefit. However, if the area is to be utilised for EFA there are important factors to consider: EFA catch crops cannot, for example, be grazed during their period of implementation (31 August to 1 October). The list of available constituents includes rye, vetch, phacelia, oats, mustard and Lucerne.
Green cover crops are designed to provide a cover to soils over the high rainfall months of the year and potentially also increase soil organic matter levels. For areas of green cover to be eligible for EFA, the same list of constituents is allowed, again with one cereal and one non cereal component required. A notable exception in the list of permitted constituents is oil radish. This appears to be an oversight that will hopefully be corrected in the coming months and years in order to allow the use of this very valuable plant. Maize-only game covers are not permitted for EFA green cover. Land managers may choose to include green cover crops in their rotations without utilising them for EFA, with many enlightened farm businesses already doing this.
So what kind of benefits can we expect to accrue from the use of green cover crops? Firstly, nutrient capture and fixing. Depending on the make-up of the mix, anything from 30–130kg+ of nitrogen can be held within the green cover until it is incorporated back into the soil to be utilised by the following crop. Trials by some seed suppliers have suggested that significant yield benefits have been achieved in the crops following green covers. Benefits to soil structure undoubtedly occur. Oil radish, for example, will usually put down a tap root beyond plough depth and the root structure arising from this will help tremendously in re-structuring the soil. Long-term benefits are difficult to quantify, but any tool which effectively extends the window soils are workable has to be of major benefit – timeliness of field work is so important given the extremes in weather the UK has experienced in recent years.
The new cross-compliance standards for 2015 include some challenging requirements for soils, one of these being the provision of minimum soil cover. Green cover is one of the ways in which this cover can be maintained (although its use in this context is not mandatory). Most land managers would prefer to have some kind of cover on their arable land over the winter rather than allowing it to lie ‘sad.’ The establishment of green covers does, however come at a cost. For the most simple of green covers, for example, straight oats, an establishment cost of around £30-40/ha can be expected. This can potentially rise to £60/ha or more for more complex mixes. This can be difficult to justify at a time when many arable commodity prices are hovering around, or just above, the cost of production, particularly on land taken on shorter term lets. However, perhaps the question on land managed for the long term should be, ‘can I afford not to include green covers?’
Various agronomic factors need to be assessed before the decision is made on what kind of green cover to commit to. Not least of these is the introduction of potential weeds to the rotation. Mustard in a rotation including oil seed rape is an obvious example where future problems could occur. Soil type, cultivation techniques employed and weed burdens are other factors which need to be considered.
We have recently run events we have run on behalf of the Campaign for the Farmed Environment in Lincolnshire, and have highlighted benefits already being achieved by pioneering farmers J.E. Piccaver & Co on the Fens and A.W. Smith & Son on the Lincolnshire Wolds.
The continued inclusion of green cover as an EFA option would seem to be fairly likely in the coming years. The widespread uptake of green covers across the region will potentially follow as more land owners start to recognise the benefits.