Response of containerized nursery crops to level of turkey litter compost and time of fertilizer application

Turkey litter compost has potential for use as a substrate amendment for growing nursery crops in containers. The objective of this study was to determine the level of turkey litter compost in binary mixtures with pine bark that would support optimum growth of selected container-grown woody shrubs. Silverleaf dogwood (Cornus alba I,. 'Argenteo-marginata'), common ninebark (Physocarpus opulifolius L.), and slender deutzia (Deutzia gracilis L.) were grown in trickle-irrigated 6-L containers filled with bark amended with 0, 25, 50, 75 or 100% (by vol) of turkey litter compost. Plants were fertilized by topdressing with Nutricote 16-10-10 (16.0N-4.4P-8.3K) T140 controlled-release fertilizer with micronutrients at a rate of 34 g/container at planting (T-0), or two (T-2), or four (T-4) weeks later. Elevated and potentially toxic levels of soluble salts present at planting in the 100% turkey litter compost (5.9 dS.m(-1)) and binary mixtures (2.1-4.3 dS.m(-1)) leached rapidly to non-toxic levels (less than or equal to0.9 dS.m(-1)) within days. Regression analysis showed that all species responded positively (curvilinear) to the turkey litter amended substrates and grew best with the T-2 topdress. The maximum (calculated) levels of turkey litter compost with this fertilizer treatment were 63% for dogwood, 76% for ninebark, and 82% for deutzia.