What is the impact of applying biosolids with a pH above 7.5?

Applying biosolids with a pH above 7.5 is prohibited because high pH levels can negatively affect soil health and nutrient availability. When the soil pH rises above this threshold, several critical factors come into play. Firstly, nutrient solubility and availability can be compromised, particularly for essential nutrients like phosphorus and micronutrients which can become less available for plant uptake. High pH conditions can also lead to imbalances in nutrient uptake by plants, which can adversely affect plant health.

Moreover, soil microorganisms that are essential for maintaining soil structure and health may become less effective or even inhibited in such alkaline conditions. This could lead to decreased organic matter breakdown and affect the overall microbial community balance in the soil. Prohibiting the application of biosolids with a pH above 7.5 is thus a protective measure to maintain soil health and ensure that the application of these nutrients does not lead to more substantial long-term issues in the soil ecosystem.