If you add too much manure to your soil, it can create problems for your plants. The excess nutrients in the manure can cause “luxury consumption”, where the plants take up more nutrients than they need. This can lead to nutrient deficiencies in the soil, and it can also make the plants more susceptible to pests and diseases. Additionally, if the manure is not composted properly, it can release harmful toxins into the soil that can damage or kill your plants.