Wednesday, November 15, 2006

A Survey of Home Lawn Soil Phosphorus Levels in North Central Indiana.

Jared R. Nemitz1, Victoria Caceres1, Kristina S. Walker1, Cale Bigelow1, and Douglas Richmond2. (1) Purdue University, Lilly Hall of Life Sciences, 915 W.State Street, West Lafayette, IN 47907, (2) "Purdue Univ. - Dept, of Entomology", 901 W. State St., 901 W. State St., West Lafayette, IN 47907, United States of America

Sufficient soil phosphorus (P) is important for rapid seedling establishment and to sustain the health of mature turf. High soil P levels have been implicated in declining water quality. The potential contribution from lawns, however, has not been well documented. Soil samples taken from 0-8 cm depth from 102 home-lawns of varying age and management intensity located in Tippecanoe County, IN were analyzed for their nutrient status. The lawns were divided into four management programs; professionally managed, five step garden center programs, fertilizer only and no input lawns. Organic matter ranged from 2-12.3% with a mean of 7.2%. Soil pH numbers on average were 7.1 and available potassium levels were adequate. Soil P levels were determined using the Bray 1 method and ranged from 2.5-100+ mg P kg -1. Among samples only 12% of the samples were low in P (<12.5 mg P kg -1), 22% had acceptable levels (12.5-25 mg P kg -1) and 68% had high P levels (> 25 mg P kg -1) according to Purdue University’s recommended levels. Among management programs, samples from the professional lawn care program had the lowest P values, averaging 41.8 mg P kg -1. The no input lawns had the highest average P values with 49.9 mg P kg -1. These data indicate that soil P levels in most lawns throughout Tippecanoe County are sufficient and that when fertilizing products containing low P levels should be selected to minimize any risk for P loss.