Abstract. Soil compaction is a common problem of mineral soils under conventional tillage practices. Organic matter addition is an efficient way of reducing the effects of field traffic in soil compaction. The aim of this study was to investigate the effects of number of tractor passes (one, three, and five) on depth-dependent (0-10 and 10-20 cm) penetration resistance, bulk density, and porosity of clay-textured soil (Typic Xerofluvent) under organic vegetable cultivation practices in the 2010-2013 growing seasons. Fields were treated with farmyard manure (FYM, 35 t ha −1 ), green manure (GM; common vetch, Vicia sativa L.), and conventional tillage (CT). The number of tractor passes resulted in increases in bulk density and penetration resistance (CT > GM > FYM), whereas the volume of total and macropores decreased. The maximum penetration resistance (3.60 MPa) was recorded in the CT treatment with five passes at 0-10 cm depth, whereas the minimum (1.64 MPa) was observed for the FYM treatment with one pass at 10-20 cm depth. The highest bulk density was determined as 1.61 g cm −3 for the CT treatment with five passes at 10-20 cm depth; the smallest value was 1.25 g cm −3 in the FYM treatment with only one pass at 0-10 cm depth. The highest total and macropore volumes were determined as 0.53 and 0.16 cm 3 cm −3 respectively at 0-10 cm depth for the FYM treatment with one pass. The volume of micropores (0.38 cm 3 cm −3 ) was higher at 0-10 cm depth for the FYM treatment with three passes. It can be concluded that organic pre-composted organic amendment rather than green manure is likely to be more efficient in mitigating compaction problems in soil.

Abstract. The purpose of this research is to assess the geochemical mass-balance and weathering intensity of Typic Haplustert and Lithic Ustorthent soils represented by four profiles that developed in a Quaternary-age basaltic toposequence under semi-humid conditions in the central Black Sea region of Turkey. The researchers employed mass-balance analysis with a view to measuring elemental gains and losses along with alterations concerning the soils formed on the basaltic parent material. For this end, geochemical properties, elemental mass-balance changes and certain physicochemical features were identified to benchmark the weathering levels of the profiles. Lithic Ustorthents are distinguished by having a rough texture along with a low organic substance ingredient, whereas Typic Haplusterts have a high clay texture with low bulk density and slickenside features. X-ray diffraction showed that smectites were the prevailing minerals inside the Typic Haplusterts, while a significant amount of kaolinite and illite was observed in the Lithic Ustorthents. Mass-balance computations indicated that massive mineral weathering resulted in substantial Si losses through leaching as well as an exchange of cations, such as Na+, K+, Ca2+ and Mg2+, particularly from the upper horizons. The study also took into account other features such as the pedogenic evolution of soils using weathering indices such as CIA, CIW, bases/R2O3, WIP, P and PIA. According to the results, CIA, CIW, PIA, P, WIP and bases/R2O3 index values of all soils varied between 42.33 to 73.83, 44.46 to 80.43, 37.53 to 65.63, 75.39 to 84.31 and 0.45 to 1.27 respectively, to solum depth. This result indicated that soils classified as Entisol and Vertisol have similar pedochemical properties. In spite of similar weathering rates, the soils were classified under different groups as a result of erosion. This showed that the conditions for soil development in the studied area had a far more impact on weathering and elemental loss than the parent material on the site.

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