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Aims: Reduced tillage has been advocated as a practical measure to increase soil carbon in long-term cropping soils. We examine three medium-term experiments in sites with contrasting soil and climatic characteristics in the UK. The objectives were to determine the effects of different reduced and zero tillage practices on bulk density and soil carbon storage and depth distribution and to quantify the effect of stones in their calculation. Methods: The treatments were zero tillage, minimum tillage, conventional plough, deep non-inversion tillage and plough compaction. Soil samples were collected from three sites at five depth intervals to approximately 60 cm. Results: Deep non-inversion and minimum tillage led to 6.5 and 1.6 Mg ha−1 greater SOC than conventional plough in sites under rotation systems. In a monoculture system in Scotland, conventional plough had 25.3, 21.6 and 17.7 Mg ha−1 greater SOC than plough compaction, minimum tillage and zero tillage, respectively. After harvest, bulk density was greater in the soil surface of conventional plough compared with minimum tillage. Conclusions: Our results suggest variable impacts of reduced tillage on SOC storage. Overall there is limited benefit in using shallow minimum tillage and zero tillage practices in the UK to increase soil carbon storage when a soil profile of 60 cm is considered but other benefits associated to these systems, such as speed of working and timeliness of operations, should be considered. [ABSTRACT FROM AUTHOR]

Abstract: The effects of field-trial scale, including plot size, and its interaction with fertiliser level and barley germplasm on mixture efficacy in controlling powdery mildew were investigated. Two groups of cultivars, one from cultivars grown in the UK and the other from cultivars grown in Poland, along with all their respective three-component mixtures, were grown in three field trials, one with 13.5m2 plots, one with 0.4m2 plots, and the third in intermediate size plots, which included a mixture of all the cultivars in both groups in equal size treatments of structured spatial arrangements. Another trial utilised similar structured spatial arrangements to trial 3 was carried out using a combination of cultivars with appropriate matching virulence levels (trial 4). Mixtures showed either a reduction in powdery mildew infection compared with the component monoculture mean, or no significant effect. There was a trend towards greater reductions at the low fertiliser level and smaller plot size. The most structured spatial arrangement was most effective for reducing infection in trials 3 and 4, but the complex-homogeneous arrangement in the fourth trial was also effective. Rhynchosporium was reduced by a similar and substantial amount by both spatial treatments in trial 3. The plot size and structuring effects may be explained by the interaction between host heterogeneity structure and pathogen dispersal scale effects, but resource exploitation for yield was best in the complex-homogeneous arrangement in trial 3 where all components were present to respond directly. These findings have implications for methods of trialling mixtures for large-scale field use and for testing component combining ability. [Copyright &y& Elsevier]

Fertile soil is fundamental to our ability to achieve food security, but problems with soil degradation (such as acidification) are exacerbated by poor management. Consequently, there is a need to better understand management approaches that deliver multiple ecosystem services from agricultural land. There is global interest in sustainable soil management including the re-evaluation of existing management practices. Liming is a long established practice to ameliorate acidic soils and many liming-induced changes are well understood. For instance, short-term liming impacts are detected on soil biota and in soil biological processes (such as in N cycling where liming can increase N availability for plant uptake). The impacts of liming on soil carbon storage are variable and strongly relate to soil type, land use, climate and multiple management factors. Liming influences all elements in soils and as such there are numerous simultaneous changes to soil processes which in turn affect the plant nutrient uptake; two examples of positive impact for crops are increased P availability and decreased uptake of toxic heavy metals. Soil physical conditions are at least maintained or improved by liming, but the time taken to detect change varies significantly. Arable crops differ in their sensitivity to soil pH and for most crops there is a positive yield response. Liming also introduces implications for the development of different crop diseases and liming management is adjusted according to crop type within a given rotation. Repeated lime applications tend to improve grassland biomass production, although grassland response is variable and indirect as it relates to changes in nutrient availability. Other indicators of liming response in grassland are detected in mineral content and herbage quality which have implications for livestock-based production systems. Ecological studies have shown positive impacts of liming on biodiversity; such as increased earthworm abundance that provides habitat for wading birds in upland grasslands. Finally, understanding of liming impacts on soil and crop processes are explored together with functional aspects (in terms of ecosystems services) in a new qualitative framework that includes consideration of how liming impacts change with time. This holistic approach provides insights into the far-reaching impacts that liming has on ecosystems and the potential for liming to enhance the multiple benefits from agriculturally managed land. Recommendations are given for future research on the impact of liming and the implications for ecosystem services. [ABSTRACT FROM AUTHOR]