The properties of the soil have a major influence on drought sensitivity and leaching into groundwater, for instance, of fertilisers. Both agriculture and the drinking water utilities that abstract groundwater have an interest in a healthy soil. But what is a healthy soil? And how can one achieve a healthy soil? This research attempts to provide answers to these questions by defining the interests involved and describing what good soil quality entails.
Vision of a circular agriculture
The properties of the soil strongly determine how sensitive the subsurface is to drought and leaching. This is why soil properties provide an important ecosystem service to drinking water utilities and Water Authorities. But intensive land and soil use are undermining this service. Large-scale soil tillage with heavy machinery has led to soil compaction. Intensive use of fertilisers and pesticides, as well as veterinary pharmaceuticals like penicillin, have had a negative impact on soil life. As a result of developments of this kind, the detrimental consequences of climate change and of emissions on the supply and quality of groundwater and surface water can be further aggravated.
This is addressed in the agriculture vision of minister Carola Schouten (Agriculture, Nature and Food Quality), through its commitment to a transition from the current agriculture system to a circular agriculture system. This involves concentrating not on increased productivity, but on product value and environmental quality. Conscious soil management is one of the instruments that will reduce the dependence on external resources, so that less artificial fertilisers and concentrated feeds need to be imported (Figure 1). The details of how the transition to a circular agriculture needs to be realised are elaborated within a bottom-up process with the Interbestuurlijk Programma Vitaal Platteland (Vital Rural Areas Inter-Administrative Programme). In order to take proactive part in this, as the drinking water sector, a clear, well-founded vision of a circular agriculture is desirable.
Previous research, conducted together with farmers, shows that measures aimed at improving the soil and water quality should not be taken in isolation. It is more effective to include them within an overarching strategy, which focuses on enhancing the supply and quality of the water (Van Loon, 2018 among others). Nor does it work to make the measures obligatory, since this shifts attention away from achieving the intended effects. It is much better to take measures that are also of positive value to farm management. Another challenge lies in the fact that, because of the siting of the catchment areas, the soils are by their nature more sensitive to drought and leaching than elsewhere. This makes soil quality improvement more complicated. This could mean that a different approach is required compared to the rest of the Netherlands, or perhaps that the drinking water utilities’ ideal vision of good-quality soil is not attainable, at least not in the short term.
Achieving an optimal soil quality
The first objective of this study is to identify, describe and inasmuch as possible underpin, the shared interest that water managers, land users and drinking water utilities have in good soil quality. Secondly, the aim is to deepen our insight into the perspective of achieving an optimal soil quality, and into the degree to which this contributes to the harmonisation of multiple functions.
Consolidation and further extension of successes achieved
Initiatives are underway worldwide which take an innovative approach to soil problems and the creation of healthy soils. The Netherlands can learn from these initiatives, particularly by connecting with what is happening in Europe. Moreover, over the last few years, Dutch farmers and drinking water utilities have conducted lots of joint practical research on measures to increase the resilience of water systems. The resulting successes can, through cross-pollination between projects and reflection on the results achieved, be consolidated and further extended. Also, knowledge about the impact of measures is needed for the development of a real vision on the transition to a circular agriculture.