The intensive usage of synthetic fertilisers and pesticides helps Dutch arable farmers to secure high yields at low costs. However, this intensive arable production system also results in environmental degradation in terms of biodiversity loss and reduced soil and water quality. Adopting sustainable agricultural practices (SAPs) reduces arable farmers’ reliance on fertilisers and pesticides. Therefore, SAPs contribute to enhancing farm sustainability and resilience. Despite the promising potential of SAPs, their adoption rates remain low. We investigate which combinations of SAPs are jointly adopted in portfolios and how the adoption rate of SAP portfolios can be improved. Specifically, this paper aims to explore the relationship between knowledge and the adoption of SAP portfolios. First, we investigate the SAP portfolios that are jointly adopted using Correlation Explanation. Second, we estimate a multivariate probit model to explore if SAP portfolios are complementary or substitutionary to each other. Finally, we run a partial least squares structural equation model to investigate how the level of knowledge and informal knowledge are associated with the adoption of SAP portfolios. Results show that both the level of knowledge and informal knowledge are positively related to the adoption of these SAPs that require initial investments or aim to reduce pesticide and fertiliser usage. However, we find no significant relationship between knowledge and the adoption of SAPs that are already subsidised by policymakers. We conclude that persuading farmers to adopt more SAPs requires policymakers to consider combinations of economic (e.g. subsidies) and behavioural policy interventions (e.g. facilitating peer-to-peer knowledge sharing).