Can Long-Term Experiments Help Us Understand, and Manage, the Wider Landscape—Examples from Rothamsted, England

As the world population continues to increase so will the demand for food which, for the foreseeable future, will be based on growing crops in soil. Thus, a fertile soil is one of the world’s most precious assets, and maintaining the soil’s productive capacity is essential if humankind is to continue to exist. Yet, experience shows that globally, through ignorance or greed, large areas of productive soils are being lost to urban growth and its infrastructure, or to soil degradation or erosion. At the same time, the need to produce food at almost any cost, as in Europe at the end of World War II, is being replaced by the concepts of sustainability and environmental stewardship of the landscape and land used for agriculture in particular. In England, where soil and topography are suitable, the land is managed for agriculture, but increasing specialization has resulted in arable crop production in the drier eastern half of the country with animal husbandry on the wetter, western side and this has had an impact on the visual appearance of the landscape. However, whether growing arable crops or grass, optimum production requires the best possible soil conditions where the biological, chemical and physical properties of the soil are maintained at their optimum levels by appropriate management practices. Changes in cropping and management can be needed for economic, environmental or policy reasons, but it is not always possible to know what the effects of any change might be. They can be beneficial like accumulating soil organic matter to benefit soil structure and thus the ability of plant roots to efficiently explore the soil to find plant nutrients, or catastrophic like the adverse effects on crop yields from the build-up of soil borne pests and diseases. Experience shows, and we give examples here, of both beneficial and adverse effects from changes in agricultural practice, but to identify both required long-term field experiments as we show for changes in soil organic matter and the acidity of soil.