Soil conditioner mixtures as an agricultural management alternative to mitigate drought impacts: a proof of concept

Abstract. Agricultural activities in the northeastern German plains are at risk due to climate change. Soil amendment with conditioners that improve water storage is a plausible alternative to mitigate such risks. While single-conditioner additions to soil can be positive, doubts regarding their individual scalability have been raised. An unexplored alternative is to apply multiple conditioners as mixtures, thus reducing individual application rates while harnessing possible complementarities derived from the interaction of diverse conditioner types. As an initial test of this concept, we implemented a microcosm experiment in which soils amended with no-, single-, and multiple-conditioner mixtures were incubated in simulated dry conditions at constant temperature for 3 weeks. We found the addition of conditioner blends consistently and significantly increased maximum water-holding capacity and the aggregate stability of soils while decreasing the bacterial-to-fungal ratio in relation to soils amended with only single or no conditioners. These results highlight the practical potential of this concept and offer the opportunity to develop a robust drought mitigation strategy. We encourage further testing and development of the concept via the implementation of greenhouse and field trials and the long-term monitoring of the effects using a wider variety of indicators.