Response of three cereal crops in continuous arable or ley-arable rotations to fertiliser nitrogen and soil nitrogen at Rothamsted's Woburn Ley-arable experiment

The concept of improving soil fertility by ley-arable farming, developed in the 1930s in England, was practised on many “mixed” farms that had both arable crops and permanent grass. The practice declined from the 1960s as farms became predominantly arable or grassland. However, there is increasing interest in including leys in arable farming to fix carbon from carbon dioxide in the atmosphere in soil organic matter (SOM). For example, in the United Kingdom a project “Grass and herbal leys in farm network” was launched in 2018 (adas.uk, 2020) and in the European Union (EU) farmers are now required to grow a wider range of crops (ec. europa.eu, 2020. The Woburn Ley-arable experiment started in 1938 has compared six rotations, two with 3-yr leys, two with 8-yr leys and two with continuous arable crops on the yields of two cereal test crops. The effect of these rotations on SOM is given elsewhere (Johnston et al., 2017). Here we give the yields of both test crops in each of the six rotations for 21 years starting in 1981. We discuss the response to four levels of applied fertiliser nitrogen (N), the effect of rotation, the level of SOM and the availability of soil N. Where no fertiliser N was added, crop yields increased as % N in soil increased, but, with sufficient fertiliser N there was little benefit from the extra N in the soil. Yields of winter wheat were larger after the 3-year grass ley than in the all-arable rotations and larger again following the grass/clover ley. Less fertiliser N was needed to achieve the yields after the leys than in the all-arable rotations. Yields of the second cereal crop following 3- or 8-yr leys were also larger than those in all-arable rotations but there was no difference between the leys. However, the extra N available from the leys and the increases in yield were modest. If leys are to be introduced into mainly arable farming systems, they may need to be subsidised to make them financially viable

The Rothamsted long-term experiments: are they still relevant?

Maintaining soil fertility and sustaining or increasing crop yield is of worldwide importance. Many factors impact upon the complex biological, chemical and physical processes which govern soil fertility. Changes in fertility caused by acidification, declining levels of organic matter, or P and K status may take many years to appear. These properties can in turn be affected by external influences such as atmospheric pollution, global change, or changes in land management practice. Long-term experiments provide the best practical means of studying changes in soil properties and processes and providing information for farmers, scientists and policy makers. This paper shows how the experiments run at Rothamsted in southeast England continue to provide data which are highly relevant to today's agriculture and wider environmental concerns. Examples are given of how crop yield is affected by soil organic matter, by pests and disease and by P nutrition. The effect of atmospheric pollution on soil acidity and the mobilization of heavy metals are also examined. The need for making better use of existing long-term experiments is stressed. Key words: Soil fertility, sustainability, long-term experiments, global change </jats:p

Management and modification procedures for long-term field experiments

Long-term experiments like those at Rothamsted in southeast England offer the best practical means of studying the effects of land management or global change on soil fertility, sustainability of yield or wider environmental issues. For the data from such experiments to be of use, farmers, scientists and policy makers must be certain of their validity. This is best assured by the rigorous management of the experiment, by ensuring that any changes are carefully considered and that all operations are well-documented. A steady flow of well-interpreted, published data is also essential. This paper gives examples of how the long-term field experiments at Rothamsted have been managed and how modifications have been made to ensure their relevance to modern agriculture. Key words: Rothamsted, sustainability, long-term experiments, global change </jats:p

Natural resources inventory and monitoring in Oregon with ERTS imagery

Multidiscipline team interpretation of ERTS satellite and highflight imagery is providing resource and land use information needed for land use planning in Oregon. A coordinated inventory of geology, soil-landscapes, forest and range vegetation, and land use for Crook County, illustrates the value of this approach for broad area and state planning. Other applications include mapping fault zones, inventory of forest clearcut areas, location of forest insect damage, and monitoring irrigation development. Computer classification is being developed for use in conjunction with visual interpretation

Providing marketing information to smallholders in Zimbabwe: What can the state usefully do?

In recent decades, significant international assistance has been provided to assist the establishment of market information systems (MISs) in a range of developing countries, including many in Africa. However, experience with state-run MISs, looking to provide current price information to market participants, has not been encouraging. Volatile horticultural markets provide particular challenges for such MISs. Therefore, it is suggested that it might be more appropriate to provide other types of marketing information to inform the production and marketing decisions of smallholder producers. This paper reports on recent efforts by the national extension agency, Agritex, to provide such information to smallholder horticultural producers in two districts of north-eastern Zimbabwe. Drawing on an initial evaluation of this pilot programme, the paper suggests that: 1) in the Zimbabwe case, the extension service may provide a viable vehicle for dissemination of marketing information to smallholder (horticultural) producers; 2) information on new crops and market opportunities is valued more highly by farmers than information on current market prices; 3) such information should complement, not supplant, traditional production extension advice. The paper concludes by considering some of the issues pertaining to the continuation and expansion of the pilot programme.Marketing,