A comparative study of the physical, chemical and microbiological status of soils, as influenced by conventional and reduced tillage

Historically, shifts to reduced and no-tillage management for production of crops were fostered by needs to decrease soil erosion and loss of organic matter, reduce fuel and labour costs and conserve soil water, as compared with conventional fallow tillage management. Recent interest in maintaining soil quality has been stimulated by a renewed awareness of the importance of soil condition to both the sustainability of agricultural production systems and environmental quality (Doran and Parkin, 1996). The aim of this project was to determine the impact on the physical, chemical and microbiological status of the soil of conventional and reduced tillage. It has been suggested that the reduced soil disturbance associated with the tine cultivator improves soil structure, increases nutrient content in the top 10cm of soil, increases microbial activity and improves physical characteristics. From this study it was determined that the environmental benefits linked to reduced tillage in literature, did not develop in the first two years of this programmes implementation. The results of this study determined that soil nutrients did not increase in concentration in the top 10 cm of soil under reduced cultivation. The only exception was exchangeable potassium. As potassium is not a mobile nutrient its movement is dependent on soil disturbance, therefore under reduced cultivation its concentration was allowed to accumulate in the upper horizon of the soil profile. Microbial activity was greater in the conventionally tilled treatments, as determined by total aerobic bacterial numbers. This could be due to the increased rates of soil aeration in this treatment. Numbers of aerobic bacteria were greater in the conventional tillage treatments at both incubation temperatures of 22 and 32° C. The physical characteristics of the soil determined, indicate that below the depth of soil cultivation, cone penetration resistance increases. Therefore the reduced cultivation treatments would be more prone to soil compaction, higher in the soil profile.

Environmental management systems implementation

All organisations make some contribution to the degradation of the environment through their use of resources and production of waste. Environmental management systems (EMS) standards can provide a tool for companies to systematically reduce their environmental impacts. ISO 14001 was published in 1996. This fitted in with plans of the case study company to take proactive action in this area, even though there was no legislative requirement for them to do so. As EMS implementation was a new area at the time, appropriate methodologies were developed to address different aspects of the implementation, and ISO 14001 was successfully implemented in the company. The results of the primary research included: ♦ Drawing up a methodology for identifying and interpreting the environmental legislation that may have an impact on the organisation and compiling a register of such regulations. ♦ Developing a robust methodology for assessing significant environmental aspects and impacts and applying this to the software company. ♦ Establishing objectives and targets for those aspects identified as significant and implementing environmental management programmes to meet these. ♦ Developing an internal environmental audit procedure based on auditing against the significant aspects. ♦ Integrating areas of the EMS with the existing quality management system in order to avoid duplication of effort. ♦ Undergoing an external assessment process in order to achieve certification of the system. The thesis concludes that the systematic approach defined in ISO 14001 provided a mechanism that the organisation was able to adopt to bring about improvement in its environmental performance. The system was based on a thorough evaluation of the organisation's significant environmental aspects in order to bring about a reduction in its negative impacts. The ISO 14001 requirement for continual improvement is the key driver of the system, and this is what differentiates it from ISO 9000.