LETTUCE RESPONSE TO COMPOSTED BROILER LITTER AS A POTTING SUBSTRATE COMPONENT

A glasshouse study was conducted to evaluate the suitability of compos ted broiler chicken (Gallus gallus) litter as a potting substrate usin g lettuce (Lactuca sativa L.). Broiler litters containing wood shaving s or peanut hulls as bedding materials were composted with either shre dded pine bark or peanut hulls. Composted materials were then combined with a commercially available potting substrate. Greatest fresh weigh t yield was obtained when peanut hull compost was mixed with commercia l potting substrate at a ratio of 3:1. Fresh weight was less with pine bark compost than with peanut hull compost. However, there were no di fferences in lettuce dry weight among composts except for pine bark co mposted with wood-shaving broiler litter. The pH of this material was below the lettuce tolerance level for mixes at or above 50% compost, T here was no evidence of lettuce physiological disorders resulting from excessive nutrient concentration. Most elements analyzed (N, P, K, Ca , Mg, Fe, Mn, Cu, Zn, and Al) were within or slightly above sufficienc y ranges for Boston-type leaf lettuce. It appears that composting broi ler litter for use as a potting substrate or component would be one su itable alternative to land application in the southern United States. We recommend, however, that the pH of substrates be adjusted to suit d esired crop requirements.