Rothamsted Research is confirming changes to some of its long-term crop study protocols, some of which were initiated almost 200-years-ago.
The long-term soil and crop studies at Rothamsted are well-known as the world’s longest-running continuous field experiments.
Started from 1843 onwards by the founders of Rothamsted, John Lawes and Henry Gilbert, they are an important resource that has been used extensively to investigate the effects of land management, atmospheric pollution and climate change on soil fertility.
Soil and plant samples from the experimental plots have been kept continuously for over 180 years.
While the meticulous record keeping and attention to scientific detail have remained constant, the experiments themselves have undergone changes.
This may seem counter-intuitive – a great part of the scientific value of long-term experiments (LTEs) has been their unchanging nature.
According to Rothamsted research scientists, this consistency yields valuable insights into the complexity of farming systems, since by holding so many factors (like location and overall land use) constant, other variables can be more easily investigated.
However, they also point out that experiments must remains relevant to current agricultural practice, such as the introduction of new cultivars and the judicious use of pesticides.
“Changes to LTEs should not be made just for the sake of change or to investigate aspects of management that could be better resolved in a short-term experiment.
“Rather, modifications should only be made after carefully considered discussion, involving scientists from different disciplines,” he said.
Balanced approach
According to Poulton, this balanced approach can be seen in the oldest experiment at Rothamsted Broadbalk.
Originally set up to study how the application of differing amounts of nitrogen (N), phosphorus (P)and potassium (K) affected the growth of winter wheat over time, some considered changes have been made whilst other factors held constant.
For instance, some fertiliser and manure treatments have been applied on some plots every year since autumn 1843 (except when sections were fallowed).
However, ploughing, drilling and harvesting techniques have changed, lime has been added, and pesticides used, rotations have been included and up-to-date cultivars have been regularly introduced.
He added: “Despite all of these changes, the experiment is still recognizably the same and still serving its original purpose.
“We have concluded from 180 years of experience at Rothamsted, that carefully thought-out changes can be extremely beneficial.
“We have learned that LTEs should not be regarded as static museum exhibits that should never be altered.”
Poulton also pointed out that, sometimes, the only solution to new challenges, is to set up brand new LTEs.
As interest in agro-ecological approaches has grown, for instance, Rothamsted set up a new set of rotational experiments six years ago incorporating variable treatments such as no-till and cover crops.
“Such new experiments are easier to adjust to address new agricultural practices but inevitably lack the benefit of continuity within a traditional LTE.
“Nevertheless, the intention from the outset is for these new system-based experiments to be long-term platforms and to be incorporated into Rothamsted’s general LTE portfolio.
“The two styles of experiment each have their own advantages and limitations, and each is strengthened by the existence of the other,” he said.
