Nmin sampling and analysis (Nmin method) as part of the Niederbipp-Gäu-Olten nitrate project (cantons of SO and BE)

Description

A key component of the nitrate project under Article 62a of the Federal Act
on the Protection of Waters, aimed at reducing nitrogen losses into groundwater, is fertilisation tailored to the specific site and based on actual needs. To this end, farms must fertilise their plots within the project perimeter either using the Nmin method or the method of corrected standards, in accordance with the guidelines for the fertilisation of agricultural crops in Switzerland (GRUD 2017). This service contract covers the collection and analysis of soil samples for Nmin analysis. On the basis of these Nmin analyses, the cantonal advisory services provide fertilisation recommendations to farmers.

Brief description of Nmin sampling:
- Project management (planning, meetings, data management, report preparation),
- ravel to the plots,
- mechanised and, in some cases, manual collection of soil samples in the field (composite sample from a specified number of auger holes) for 3 depth intervals in arable farming (0–30 cm / 30–60 cm / 60–90 cm) and 2 to 3 depth intervals in vegetable farming (0–15 cm / 15–30 cm / 30–60 cm) in accordance with reference methods A 1.1 and A 1.2 VDLUFA (Methodology Handbook Volume I: Soils (Basic Work 1991) – VDLUFA),
- delivery of the samples to the laboratory for analysis

Brief description of the analysis:
- Sample preparation
- Extraction and analysis of Nmin (nitrate and ammonium) and dry matter (in accordance with Agroscope reference methods),
- Data transfer to the agricultural advisory services of the cantons of Solothurn (SO) and Bern (BE)

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