Possibilities in parallel use of soil amendments – circular economy and land management (AIN3)

Soil amendments aim to improve soil structure and water holding capacity, as well as to reduce the transport of suspended solids and phosphorus with runoff water.

Recently, it has been started to spread on the fields mainly products processed from industrial side streams, such as gypsum, structure lime and soil improvement fiber (made of pulp and paper mill sludge), which can affect the soil structure and reduce water pollution. For example, efforts have been made to increase interest in the application of gypsum with various projects in which gypsum and its delivery and application are offered to the farmer for free. There have also been projects of the same type for structure lime and soil improvement fiber, but on a smaller scale. At the same time, information has been produced on the choice of soil amendments and the effects on the soil and nutrient leaching. In the projects, it has been noticed that one and the same substance is not necessarily suitable for all field parcels or areas. That's why it is necessary to start a project that investigates the simultaneous use of three soil conditioners in the same catchment area. The catchment area of Savijoki from Varsinais-Suomi (SW Finland) was selected as the pilot area, in the middle of which it is planned to spread gypsum, soil improvement fiber and structure lime. The comparison area is the upper reaches of the Savijoki catchment, where soil amendments are not applied. For each field parcel, the aim is to find the most suitable soil amendment by utilizing e.g. the information of soil fertility analysis and the soil type.

Guidance for farmers to support the selection and use of soil amendments is available in the guide published by the Water Protection Programme Gypsum, fiber and structure lime - a guide for farmers (Ajosenpää et al. 2021). The guide is available online and has been translated into Swedish and English (ProAgria 2023).

The aim of the project is:

1) evaluate and measure the effects of different soil amendments from the perspectives of reducing environmental emissions, soil growth, and crop yield improvement and usability

2) find out the utilization of data used for the allocation of different soil amendments (soil fertility analysis, geospatial datasets) to support the farmer's choice and to optimize the water conservation benefit

3) find out farmers' interest in using soil amendments and the factors influencing the decision

4) produce the necessary additional information for planners, advisors and farmers about the benefits, environmental effects, cost-effectiveness and usability of soil amendments and the boundary conditions related to their use

5) prepare concrete measures and incentives, both in the short and long term, to increase the widespread use of soil amendments as part of or alongside the common agricultural policy, by presenting alternatives for financing the use of soil amendments and organizing practical implementation.