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<br />2.1 Macronutrients <br />Nitrogen and phosphorous are the two most important macro- <br />nutrients utilized by plants. Nitrate-nitrogen content of new <br />refuse material was significantly lower than in topsoil. The <br />nitrate-nitrogen content of old refuse material was lower than <br />topsoil and higher than new refuse, although, paired t-tests <br />showed no significant differences. A possible explanation for <br />this difference is the availability of nitrate at differing pH's <br />and varying aeration regimes. Nitrogen is most available at a pH <br />between 6.0 and 8.0. The pH averaged 8.48 for new refuse <br />material and 6.89 for older refuse, thus allowing greater <br />availability of nitrogen at a pH of 6.89. Higher NO3 concentra- <br />tions may also reflect a lesser degree of compaction, which was <br />not quantified in the study. <br />Phosphorus content of the refuse material was lower than <br />levels in topsoil, although paired t-tests showed no significant <br />differences. The lack of statistical significance was probably <br />due to small sample size. New refuse material contained less <br />water soluble phosphorus than older refuse material. Again, this <br />appears to be a function of pH. Phosphorus is more available at <br />a pH between 6.50 and 7.50. At higher pH's typical in new <br />refuse, phosphorus is less available. Agricultural soils which <br />contain less than 5 ppm soluble phosphorus are considered <br />deficient and are generally fertilized to improve yields (Bing- <br /> <br />2-4 <br />