Rainfall

    Couldn't see the climate for the weather

    Based on data from the Met Office, it looks as though the wet weather in 2012 may not have been a one off.

    Now may be the time to dust down the drainage plans to repair old schemes and invest in new schemes.  The cost of drainage can be small compared to the cost of land purchase or lost crop.  Where extra machinery capacity is the solution, tax allowances have been temporarily increased to help ease the strain.  Where farming for the long term, it looks like a good time to plan investment strategy.  

    The weather
    UK rainfall in 2012 was the second highest since at least 1910.  It is too easy and perhaps dangerous to put it down to chance, hope that it was a one off, and look forward to a dryer autumn this year.  The problem is that it might not be a one off.  View the Met Office data of the five wettest years since 1910.

    Below average temperatures in 2012 meant that evaporation levels were also low, so the impact was worse in 2012 than it would have been in some of the other wet years. There were also differences in when the rain occurred.

    The 30–year averages also suggest a change towards wetter weather (see below).  In the last 10-years, we have also had one of the driest years ever, suggesting that the weather is also  becoming more erratic.  This has been the message from climate change specialists for at least the past 5 years.

    View the graph of 30-year rainfall averages.

    Drainage
    Most field drainage took place from 1949, but was particularly prevalent in prevalent in the 1960s and 1970s when there was a 50% or even 100% grant available. Many schemes have now deteriorated and are desperately in need of maintenance.

    We could make the glib statement that since arable land costs are now in the region of £8,500 per acre, if drainage provides another farmable acre it returns another £8,500.  Sadly, this is not the case since it is unlikely that a buyer would discount the value of a wet hole by the entire land value.  In addition, it is likely that the land would still on most occasions be eligible for subsidy.

    The more accurate way of calculating the return on drainage is to calculate the current value of the future discount on profit from: the occasional crop failure; the periodic substitution of a winter with spring crop; and/or the reduction in yield from more frequent take-all, higher black grass populations and greater loss from slugs. 

    Assessing whether drainage is worthwhile is not an exact science but this should not prevent anyone from putting together a spreadsheet to make a rough assessment. 

    The major problem is establishing the yield loss since in a dry year it might be zero while in a wet year a spring crop might replace a valuable winter wheat crop or in the extreme, land may be fallowed. 

    Once  the physical loss has been calculated it has to be converted into a financial loss.  In practice, the loss of profit is often simply the fall in gross margin i.e. value of crop output less seed, fertiliser and sprays, or even just loss of output, where the failed area continues to be managed in the same way as the remainder of the field. 

    This is one of those occasions, when the lost financial return, may be identified from the combine yield maps.  There are other decisions such as the life of the scheme and the appropriate interest rate to bring future losses back to the value of the loss today.
     
    View a graph which shows the likely loss under a range of assumptions and annual financial losses. 

    Even a modest yield loss would justify expenditure of a £1000 per acre, such as digging out ditches or putting larger culverts in place.  If the field had any previous drainage, additional work would probably be treated as a repair allowing the entire cost to be set against tax. 

     
     

    Key contacts

    Andrew Wraith

    Andrew Wraith

    Director
    Food & Farming

    Savills Lincoln

    +44 (0) 1522 508 973

    +44 (0) 1522 508 973

     

    Steve Hollis

    Steve Hollis

    Director
    Food & Farming

    Savills Salisbury

    +44 (0) 1722 426 853

    +44 (0) 1722 426 853

     

    Ashley Lilley

    Ashley Lilley

    Director
    Food & Farming

    Savills Cheltenham

    +44 (0) 1242 548 012

    +44 (0) 1242 548 012

     

    Giles Hanglin

    Giles Hanglin

    Director
    Rural Research

    Savills Margaret Street

    +44 (0) 207 016 3786

    +44 (0) 207 016 3786