McAllister, J.S.V., and P.S. Savill. 1977. “Effects of Pig and Cow Slurry on the Growth of Sitka Spruce on Oligotrophic Peat and Gley Soils in Northern Ireland.”. Irish Forestry, November. https://journal.societyofirishforesters.ie/index.php/forestry/article/view/9374.