Organic matter amendments to a calcareous forest nursery soil
1987
Mexal, J.G. | Fisher, J.T.
Organic amendments were added to a southwestern United States forest nursery sandy loam soil to determine the effects on soil nutrient reserves and subsequent growth of 1.5+0 ponderosa pine (Pinus ponderosa Laws.) seedlings. Treatments included irradiated sewage sludge, peat moss and pine bark each at 67 t/ha, sawdust at 43 t/ha, and a control that received no organic matter. Sludge caused immediate increases in soil nutrients, especially N and P. Sawdust resulted in near complete N immobilization 45 d after application. Peat moss and bark did not significantly alter soil nutrients. All treatment effects disappeared within 6 months of application. Amendments did not significantly alter seedling survival, biomass or yield (caliper ⩾ 3 mm). Seedling biomass was positively correlated with early soil nutrient status, but growth was not significantly improved. The modest, short-term nutritional benefits indicate single applications of organic amendments are ineffective in improving the nutrient status of sandy nursery soils of the Southwest.
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