Wiersma joined the Royal Netherlands Navy in 2002, serving as a sailor on the HNLMS Jacob van Heemskerck in locations such as the Mediterranean Sea.

[2] In 2015, the abolition of the European milk quota led to a growing livestock population, which increased manure production and created a risk of the Netherlands exceeding its phosphate limit.

The agricultural sector anticipated a phosphate rights system, which some extensive dairy farmers such as Wiersma found unfair because they were able to manage their manure fully.

Wiersma started a campaign on social media platform Facebook in 2015 to protest the new system, and she became a lobbyist for Netwerk GRONDig, which had been founded shortly before to represent extensive dairy farmers.

She said that experts were circulating one-sided information to cast livestock farmers in a negative light, and she stated that organizations such as Wakker Dier and Natuurmonumenten were spreading propaganda.

[2] NRC reported that Wiersma previously voted for the Labour Party and moved towards the political right while a care consultant, believing that the system of benefits was being abused.

[5][6] She eliminated budgets for fair trade and LGBTQ policy, arguing they were not "core tasks" of the province, and she halted construction of nature-friendly shores against the advice of her staff.

[2] Wiersma suspended the province's nature and nitrogen policy in June 2024, weeks after a coalition agreement had been reached nationally by the PVV, VVD, NSC, and BBB.

[3][7] The Netherlands had been mandated by the European Union to stop the deterioration of nature in Natura 2000 sites by 2030, and goals with regard to nitrogen deposition had been enshrined in national legislation.

Furthermore, Wiersma plans to postpone enforcement of nitrogen emissions regulations for a group of farmers left without a permit due to a 2019 Court of State ruling for another three years.