Using the long‐term experiments at rothamsted to address current agricultural and environmental issues

Abstract

In the Broadbalk Experiment at Rothamsted winter wheat has been grown in monoculture since 1843; wheat in rotation and additional treatments have been introduced during the course of the experiment. Since 1968, when new crop varieties and fungicides were introduced, yields have averaged over 6 t ha‐1with either inorganic fertilizers or farmyard manure. With high‐yielding varieties of winter wheat on Boardbalk, or spring barley on the Hoosfield experiment, maximum yields are currently achieved with a combination of inorganic and organic inputs. The long‐term experiments have provided much information on the losses of nitrate and phosphate to water from different treatments and also on the impact of recent decreases of sulphur deposition on soil S dynamics and crop composition. Archived samples of soils and crops from the Park Grass Experiment (continuous cut pasture) and experiments in which arable land has reverted to forest have provided information on soil acidification. This has resulted mainly from acid deposition, previously SO2 but now dominated by oxides of nitrogen. Acidification has caused the mobilization of toxic metals including Al, Mn and Zn and their increased uptake in herbage. Archived samples have also made it possible to study the deposition and accumulation of metals and organic pollutants in soils and crops and the changes in soil organic carbon and nitrogen content resulting from different management practices. Such data has been used to construct models of soil C and N dynamics. The on‐going sites provide experimental material for biological studies including fertilizer and management impacts on nitrous oxide fluxes and for testing hypotheses on soil biodiversity and quality.