More on Composting and Fertilization Practices

Compost Practices

In 2008, the Arboretum did extensive compost, soil, and water testing to determine if our fertilization practices are having any negative effects on the environment. 

The compost results indicated that phosphorus levels are excessive in the composted animal manure; soil results indicated that phosphorus and potassium levels are excessive in several flower beds; and water results show excessive levels of phosphorus in the Iris Pond. 

To reduce additional accumulation of phosphorus and to obtain a sustainable, environmentally safe fertility program, the following recommendations were developed:  1) phosphorus and potassium fertilizers should be avoided on established flower beds; nitrogen fertilizers such as ammonium sulfate can be used at lower rates; 2) only composts with low phosphorus levels should be used; 3)  water-soluble fertilizers  for hanging baskets and pots should be minimized and alternative fertilizers should be investigated; 4) flower beds should be routinely sampled and tested for nutrient levels to monitor changes in fertility levels; and 5) shoreline vegetative buffers should be planted around the Iris Pond to protect it from fertilization of the iris.