Long-term experiments (LTEs) are a vital source of information contributing to understanding and assessing the sustainability of agricultural systems. The Broadbalk Wheat Experiment at Rothamsted Research, UK, started in 1843, is the oldest continuing LTE in the world. In 1968, and later, major modifications were made to the experiment. These included the introduction of short-straw winter wheat varieties, growing wheat in rotation with other crops, for comparison with continuous (monoculture) wheat and testing higher rates of N fertilizer (up to 288kgNha−1). Other changes included the use of herbicides and other agrochemicals, except on selected sections. Regular liming continued to maintain soil pH. This paper reports crop yields and soil changes since 1968 and summarizes other studies including the incidence of weeds, pests and crop diseases, effects of treatments on nitrate and phosphate movement to drainage water, greenhouse gas fluxes, measurements of N and S inputs from the atmosphere, and many other factors.