15. Resource Quality (Water, Air, Soil) Volume One land as viticulture has expanded onto rolling or hill country may change soil in those areas. However, the effects of re-contouring are currently largely unknown. The discharge of contaminants such as plant, animal and human wastes into or onto the soil can also adversely affect soil quality variables. The potential for these adverse effects is covered in Chapter 16 - Waste. Topsoil is the most productive part of the soil profile and any erosion of topsoil adversely affects soil quality. Erosion can occur naturally as a result of normal geologic processes and/or as a result of extreme weather events. However, activities that disturb the topsoil can accelerate soil erosion processes. Excavation, filling, cultivation and vegetation clearance all have the potential to expose bare soil, which in turn creates conditions conducive to accelerated soil erosion, especially on steep slopes. Some soils, such as loess soils, are more susceptible to soil erosion. Eroded soil usually moves downhill (unless eroded by wind) and eventually enters a river or the sea. Once in these waterbodies, the finer soil will settle, a process called sedimentation. Sedimentation can cause damage to marine and freshwater ecosystems and may reduce the quality of the water for instream values and uses such as drinking or irrigation. Larger soil particles, including gravel and cobbles can similarly be eroded and deposited in downstream river channels, thus reducing the waterway area and leading to flood overflows. [RPS, R] Objective 15.4 – Maintain and enhance the quality of Marlborough’s soil resource. The social and economic wellbeing of Marlborough relies on the productive potential of the soil resource, which has been described in Chapter 4 - Use of Natural and Physical Resources as a regionally significant resource. To ensure that this continues, it is important that soil quality is maintained and enhanced. [RPS, R] Policy 15.4.1 – Improve our understanding of the effect of land use on soil quality. Despite the importance of the soil resource, to date only limited soil quality monitoring has been undertaken. This makes it difficult to establish the impact of various land use activities and practices on soil quality. The Council will therefore undertake greater monitoring of the biological, chemical and physical state of soils across the District as part of its state of the environment monitoring. This will include investigating the extent of accelerated soil erosion. It is important that the monitoring is undertaken at locations that reflect the diversity of soil types and land uses across Marlborough. The findings can then be applied to determine whether existing or emerging land management practices should be continued or altered to minimise impact on the quality of Marlborough’s soil resource. The Council will continue to monitor land use changes in the Marlborough environment as it may need to respond quickly to identify any potential adverse effects of the change on soil quality. Often rural resource users themselves are best placed to monitor the condition of the soil resource on their property. The Council will encourage rural resource users to undertake monitoring through the provision of appropriate tools and information. The application of the tools or information may help land owners and resource users to recognise soil quality issues, allowing for modification of land management practices to avoid adverse effects on the soil resource. [R] Policy 15.4.2 – Encourage land management practices that: (a) maintain soil structure by: (i) avoiding or remedying soil compaction; (ii) avoiding the loss of soil organic matter; and 15 – 38