The Rothamsted Archive

This is a unique collection, with continuity from 1843 until now, of some 200,000 samples of crops and soils taken from agricultural field experiments for which the history is fully documented. The samples can be used by scientists worldwide to understand how changes in agricultural practices and external inputs affect soil fertility, the ability to grow wholesome food, and the environment as a whole.

Origins

Not content with just recording the yields of crops grown in the field experiments they started at Rothamsted between 1843 and 1856, Lawes and Gilbert each year retained samples of the harvested produce for chemical analysis. Sampling and storing has continued without interruption for 150 years.

Throughout this long period soil samples have also been taken and stored. The scope by samples taken since 1876 from long-term experiments at Woburn Experimental Farm and more recently with samples from the Saxmundham Experimental Station where experiments were started in 1899. The temporal and spatial origin of each sample is recorded, and this enables a historical panorama of agricultural and environmental chance on soil and crop quality to be developed.

An Unrivalled Resource

The archive is an unrivalled resource for answering established queries and those as yet only dimly perceived. Perhaps more important the samples are available to provide answers to problems not yet recognised, both in agriculture and the environment.

The way that agriculture and the environment interact is important. Sustainable food production needs fertile soils farmed in environmentally benign ways. The effects of changing husbandry practices and external inputs on crop quality and soil health must be measured and understood so that agriculture is not forced to adopt processes that are unsustainable either through over-exploitation or in response to irrational concerns about the environment.

Some plants have specific soil requirements. On Park
Grass, dandelions (Taraxacum officinale) only flourish
where there is sufficient potassium (K) and soil pH above
5.6. On adjacent acid, K deficient soils they are absent.

We thought we were doing the right thing building up soil
organic matter with annual applications of farmyard manure
(FYM) and sewage sludge. But after 20 years sludge-
treated clover became sickly - the soil rhizobium would
not produce effective root nodules; they had been
inhibited by heavy metal contaminants in the sludge.

Potential Uses

Data on measured changes in soil fertility and crop quality from the archived samples can be used in different ways:

To build robust models which seek to explain how systems work.

To develop carefully considered strategies to ensure continued food production.

To measure and predict the extent to which agricultural practices affect other ecosystems and the environment.

To determine the effects of other human activities on soil fertility.

Soil acidity developed slowly on the Rothamsted
Exhaustion Land but after 100 years it was so
severe that spring barley would not grow.

Soil organic matter is an essential component of fertile soils

In temperate climates, amounts change slowly with time. On Hoosfield after 120 years the amount is still increasing where 35 t/ha farmyard manure has been applied each year. With modern, high yielding cultivars this extra organic matter benefits yield. Where 100 kg N/ha is applied as fertiliser, yields are now 4.9 and 6.6 t/ha grain on the low and high organic matter soils respectively.

There are many facets to soil fertility

In many soils the phosphorus (P) and potassium (K) status have been enriched by many years of manuring but if inputs decrease, soil fertility gradually declines and yields eventually suffer as on the Exhaustion Land. Not until the late 1960s did P fall below the critical level. Since then yields of spring barley have declined as plant-available P has continued to decrease. Eventually yields will fall to about 1.5 t/ha of grain - an unacceptably small yield.

Pollution of agricultural soils arises from man's non-agricultural activities

Polychlorinated dibenzo-p-dioxins and -furans, which are carcinogenic and produced by low temperature combustion of organic materials, have been increasing in Rothamsted soil since the beginning of the century. As yet, we know little about their effects on soil fertility or whether there are dangerous levels in soil which should not be exceeded.

In contrast, the lead content of herbage has been declining since the 1950s as a result of decreasing outputs from industry and less use of tetraethyl lead in petrol.

Sustaining Output

Winter wheat has been grown on all or part of Broadbalk each year since 1843. With improving cultivars and the introduction of weedkillers and fungicides, yields have not only been maintained but increased, demonstrating that high yielding agriculture sustainable. But the future depends on our ability to understand the reasons for the success on Broadbalk Year and the extent to which the results are applicable to other farming systems. Long-term experiments, with their archive of crop and soil samples, are essential to enable us to develop sustainable farming systems.

The Value of the Archive

The many studies already made on the samples have to place a value on such a unique collection and still less to guess its future contribution to the science and practice of crop production. Lawes and Gilbert could not have foreseen concern about cadmium and lead as pollutants; they did not even know about polynuclear aromatic hydrocarbons (PAHs), dioxins and polychlorinated biphenyls (PCBs). We cannot foresee the future; we do have a deep conviction that the archive must be preserved but help is needed.

The archived samples and the field experiments from which they were taken are available to assist global agriculture. Both could be more intensively used to investigate fundamental soil processes, show how changes in management practices affect soil and plant composition, and monitor inputs of pollutants from industrial and non-industrial sources. All of these and other factors influence soil health and agricultural sustainability.