Effects of Soil Amendments and Fertilizer Levels on the Establishment of Silver Maple

In developing a landscape, establishment of woody ornamentals is a major concern. Most recommendations suggest the use of some form of soil amendment (4, 17). Others go so far as to recommend digging the planting hole a year in advance and filling it with leaves and organic matter to form a composted planting media (3). However, their recommendations are seldom referenced by research findings. The same is true for the addition of fertilizers. Some authors maintain fertilizer should not be applied to newly planted landscape material the first year. They state that it takes year for new feeder roots to develop (4, 5, 8). Other advocate the use of diluted solutions of soluble fertilizers, but fail to mention rate and frequency of application (6, 10, 17). Allison and Anderson (1), using sawdust for soil improvements, observed harmful effects on crop yields when sawdust was applied alone. It depleted nitrogen in the form of ammonia and nitrates. Rigby (8) used ground pine bark as a growing medium for container nursery stock. His results showed the newly planted material required additional nitrogen fertilizer for the first few months. Gartner, et. al., (11) worked with several species of plant material and various mixes of hardwood bark, soil and perlite. The decomposition of the bark in the mix caused a severe nitrogen deficiency that was not corrected by normal fertilization practices. Later studies by Gartner, Meyer and Saupe (12) demonstrated that a slow release fertilizer incorporated in bark-amended mixes prevented nitrogen deficiencies. Allison and Murphy (2) and Matkin (15) found that hardwoods decomposed at a faster rate than softwoods (40-50% in 60 days) and the hardwoods were attacked more readily by the microorganisms and consequently required more immediate nitrogen. In further studies with wood by-products, Viljoen and Fred (22) and Lunt (14) reported that there was no toxic effects on plants due to sawdust and woodchips. Joiner and Conover (13) found that shredded pine bark proved to be an accessible, inexpensive substitute for peat as the organic component of soil mixtures with sand for container-grown pittosporum. Salter and Williams (19) studied the moisture characteristics and crop yields from sandy loam soils amended with farmyard manure and peat. Yield differences between the peat and control plots were small and inconsistent. Feustal and Byers (9) studied the moisture absorbing and retaining capacities of peat-soil mixtures. They stated that moisture retention properties alone should not be the basis for incorporating peat with soil. They did not recommend it as a soil amendment. Pellet (16) found that the addition of peat, vermiculite or sawdust to the soils of central Minnesota resulted in no better growth of landscape plants than unamended soil. In agreement with Pellet, Townsend (21) used a 50% sandy loam soil and 50% peat mixture and tested the effects of soil amendments on the growth and productivity of highbush blueberries. The unamended control plot yielded larger plants and better fruit over a five year period than the peat amended soils. Smalley, Pritchett and Hammond (20) found similar results in experiments with bermudagrass putting greens. However, they found that the addition of vermiculite to a loamy fine sand putting-green soil increased yield significantly. It was not advantageous to