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Orhan Yuksel 1 , Yasemin Kavdir 2 , Metin Bahtiyar 3 1 Canakkale Onsekiz Mart University, Bayramic College, Canakkale, Turkey 2 Canakkale Onsekiz Mart University, Lapseki College, Çanakkale, Turkey 3 Trakya University, Tekirdag Agricultural Faculty (emeritus professor), Tekirdag, Turkey Abstract The objective of this study was to determine effect of different concentrations of municipal waste compost (0, 40, 80, 120 and 160 t/ha) on soil physical properties of Vertisol and Non-calcareous Brown Soils. According to results of soil that sampled from pots, waste compost application to soil increased soil porosity, reduced bulk density. In general, adding waste composts to soils positively affected on soil physical properties of Non-calcareous Brown soils. However, addition of waste compost to Vertisol soils with heavy clay did not significantly change soil aggregate stability, field capacity and wilting point. The best compost application levels among applied doses were 120 and 160 t/ha. Results and Discussions Additions of waste composts to soils were more effective on soil aggregate stability for Non-calcareous Brown soils than those of for Vertisols. 160 ton ha-1 compost application to Vertisol soils increased soil aggregate stability more than the control, however all compost application levels increased soil aggregate stability compared to control treatment for Non-calcareous Brown soils. Maximum soil aggregate stability value was obtained (84.13%) with the applications of 80 t ha-1 waste compost on Non-calcareous Brown soils. Waste compost addition was not an efficient application to stabilize soil aggregates for Vertisol soils. The reason for that is high clay contents of Vertisols and naturally, even before the experiment these soils had stable soil aggregates. Besides, Bahtiyar (1997) reported that additions of organic matter on clay soils were not effective to increase soil aggregate stability. Variance analysis showed that compost application levels on soil aggregate stability was found to be significant at the level of p<0.01. 80 and 160 t ha-1 compost levels were the most effective treatment on soil aggregate stability according to Duncan`s LSD test. Additions of waste composts on soils, significantly reduced soil bulk densities (Table 3). Bulk density value of control soils was average 1.59 g cm-3 and bulk density value of 160 t ha-1 waste application treatment was average 1.51 g cm-3 for Vertisols soils. These values reduce from 1.51 g cm-3 (control) to 1.44 g cm-3 (160 t ha-1) for Non-calcerous Brown soils. Numerous studies reported that the additions of waste compost to soils reduced soil bulk densities due to their high organic matter contents (Shiralipour et al., 1992, Tester, 1990, EPA and TVA, 1993). Variance analysis showed that compost application levels on soil bulk density was found to be significant at the level of p<0.01. 160 t ha-1 compost levels was the most effective treatment to reduce soil bulk density according to Duncan`s LSD test. Increasing waste composts additions to soils also increased soil porosity (Table 3). Porosity value changed from average 40.19% (control) to 42.09% (160 t ha-1) for Vertisols soils. Average porosity value for control soil was 42.40% and it increased to 45.25% with application of 160 t ha-1 compost for Non-calcareous Brown soils. Variance analysis showed that compost application levels were found to be significant on soil porosity at the level of p<0.01. 160 t ha-1 compost levels was the most effective treatment to increase soil porosity according to Duncan`s LSD test. Adding soil waste compost to heavy clay soil increased pore volume and porosity (Gupta et al., 1986 and Giusquiani et al., 1995). Additions of waste composts did not significantly change field capacity of soils (Table 3). Field capacity value was greater than the control only at the 40 t ha-1 application level for Vertisols and at the160 t ha-1 level for Non-calcareous Brown soils. However these differences were found to be statistically not significant. Because of high clay content of research soils the amount of water at field capacity was already high. Therefore addition of waste compost did not change field capacity values of these soils. Additions of waste composts significantly reduced wilting point values of Vertisols. In contrast, 120 and 160 t ha-1 compost applications increased wilting point values compared to control for Non-calcareous Brown soils. The reason for this contrariness is due to high clay content of vertisol soils compared to Non-calcareous Brown soils. As a matter of fact, reduction of wilting point and field capacity water contents of heavy clay soils are desired for agricultural practices (Bahtiyar, 1997). Variance analysis showed that compost application levels on the reductions of wilting point were found to be significant at the level of p<0.01. 40 and 80 t ha-1 compost levels were the most effective treatments to decrease wilting point according to Duncan`s LSD test . In general, adding waste composts to soils positively affected on soil physical properties of Non-calcareous Brown soils. However, addition of waste compost to Vertisol soils with heavy clay did not significantly change soil aggregate stability, field capacity and wilting point. Therefore effects of waste compost applications on physical properties of course soils were greater than those of clay soils. Numerous researchers showed positive effects of waste compost on physical properties of course soils (Andres, 1965; Bahtiyar, 1985; Kotze and Joubert, 1992; Serra et al, 1996, Tester, 1990). More and long-term researches need to be done to understand the effects of compost on physical properties of clay soils. |