Francis Rayns

Changes in microbial community metabolism and labile organic matter fractions as early indicators of the impact of management on soil biological quality

Abstract Changes to the metabolic profiles of soil microbial communities could have potential for use as early indicators of the impact of management or other perturbations on soil functioning and soil quality. We compared the relative susceptibility to management of microbial community metabolism with a number of soil organic matter (OM) and microbial parameters currently used as indicators of changes in soil biological quality. Following long-term cereal cropping, plots were subjected to a 16-month treatment period consisting of either a mixed cropping sequence of vetch, spring barley and clover or a continuous grass-clover ley which was periodically mown and mulched. The treatments had no effect on soil biomass N or respiration of microbial populations inoculated into Biolog Gram negative (GN) plates. After 16 months there were no management-induced changes to total OM, light-fraction OM C and N, labile organic N or water-soluble carbohydrates. However, patterns of substrate utilization by the soil microbial population following inoculation into Biolog GN plates were found to be highly sensitive to management practice. In the mixed cropping sequence, substrate utilization changed markedly following plough-in of the vetch crop, with a smaller change occurring after harvesting of the barley. In the ley treatment, substrate utilization was not affected until the onset of mowing, when the pattern changed to become similar to that in the mixed cropping sequence. Metabolic diversity of the Biolog-culturable microbial population was increased by the ley treatment, but was not affected by the cropping sequence. We conclude that patterns of microbial substrate utilization and metabolic diversity are more sensitive to the effects of management than are OM and biomass pools, and therefore have value as early indicators of the impacts of management on soil biological properties, and hence soil quality.

Guidelines for experimental practice in organic greenhouse horticulture

Content of the chapter 3.2.3 - Aims of compost experiments - General requirements - Quantity of compost used - Reference plots - Experimental design - References and further informationContent of the chapter 3.2.2 - General requirements - Fertilisers - Fertiliser applicatin - Soil and plant samples - EvaluationThe aim of this handbook of experimental guidelines is to help conduct experiments for organic horticulture in greenhouses throughout Europe. It considers vegetables, fruit and ornamental production. Using standardised research procedures for experiments will aid a comparison of results and dissemination of knowledge. The editors have tried to incorporate as many climatic zones, countries and crops as possible in order to represent a wide area of Europe although some smaller crops or certain specific climates could not be included.Content of the chapter 3.2.2 - Setting up experiments - Evaluation of experiments - Determination of pH, EC and nutrients in growing media - References and further informationContent of the chapter 3.4 - Preconditions and site selection - Application technology and water requirement - Assessments and artificial inoculation - Efficacy evaluation - References and further informationA pre-condition for trials concerning organic vegetable and fruit crops is the EU regulation 834/2007 on organic farming, or any other equivalent regulation in countries outside the EU. Inside the EU, in addition to the public (legally binding) EU standard, private standards of certification bodies defining organic or bio-dynamic production are also relevant. Research should always be conducted on well-established organic land (ideally converted for at least 5 years), and the history of conversion should be documented in the Materials and Methods section of any report (for research studying the process of conversion this is obviously not applicable). If the research involves methods and products which are currently not part of organic standards (public or private) the protocol has to be discussed with the certification body first. In the case of on-farm trials the farmer also needs to be involved. Prior approval from the certification body and written documentation on the extent of the trials and the new methods tested should always be kept.Content of the chapter 4.6.2 - Crop requirements - Experimental design - Crop management - Disease and pest infestation, physiological disorders and other abiotic damage - Assessments during growth - Assessments at harvest - Overall value score - References and further information