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Penetrasyon Direncine Etki Eden Toprak Özelliklerine Ait Etki Katsayılarının Çoklu Regresyon Analizi ile Belirlenmes / Defining Partial Effect Coefficients of Soil Properties Affecting on Soil Penetration Resistance Using Multiple Regression Analysis

OZET : Bu arastirma Dogu Anadolu Tarimsal Arastirma Enstitusu (DATAE) Ilica Deneme Istasyonu arazisindeki hububat uretim alanlarinda karsilasilan toprak sikismasi probleminin penetrasyon olcumleriyle belirlenmesi ve penetrasyon direnc degerlerine etki edebilecek toprak ozelliklerinin saptanmasi amaciyla yurutulmustur. Bu amacla calisma arazisi kuzey-guney ve dogu-bati yonlerinde 80 m araliklarla hatlara bolunmus ve hatlarin cakisma noktalarinda penetrasyon direnc degerleri olculmustur. Topraklarin fiziksel ve kimyasal ozelliklerini (penetrasyon direncinin belirlendigi andaki nem icerigi, topraklarin kum, silt ve kil icerigi, kutle yogunlugu, agregat stabilitesi, agregat buyukluk dagilimi, pH, kirec icerigi, elektriki iletkenlik ve organik madde miktari) belirlemek amaciyla ust ve alt toprak katmanlarindan ornekler alinmistir. Uygulanan coklu regresyon analizi sonucunda penetrasyon direnci degerlerinde etkili olan toprak ozelliklerinin ust ve sikismis toprak katmani nem icerikleri, sikismis toprak katmani kutle yogunlugu, sikismis toprak katmani organik madde icerigi ve ust toprak katmani silt icerigi oldugu belirlenmistir. Ust toprak katmani penetrasyon direnc degerlerinde etkili olan toprak ozellikleri ust toprak katmani agregat stabilitesi, nem icerigi ve kirec icerigi, sikismis toprak katmani penetrasyon direncinde etkili olan toprak ozelliklerinin ise bu katmana ait kutle yogunlugu ve nem icerigi oldugu belirlenmistir. Anahtar kelimeler: Coklu regresyon, toprak sikismasi, penetrasyon direnci ABSTRACT : The objective of this study was to determine soil compaction problems using penetration measurements and effect of soil properties affecting on soil penetration resistance by multiple regression analysis. The research area is located at the Eastern Anatolia Agricultural Research Institute (EAARI)-Ilica Experimental field in which a severe soil compaction problem is exist in cereal production areas. The experimental field was gridded with 80 m intervals in the E-W and N-S directions, and soil penetration resistance was measured at 72 intersections using a penetrologger. Soil samples from upper and lower soil layers were also taken at the same points for determining physical and chemical soil properties. Soil moisture contents at the time of penetration measurements, sand, silt and clay contents, bulk density, aggregate stability, aggregate size distribution, soil pH, CaCO3 content, electrical conductivity and organic matter content of soil samples were determined. The stepwise regression analysis results indicated that the most important factors affecting on the mean soil penetration resistance through 80 cm soil depth profile were moisture contents of upper soil layer and lower soil layer, bulk density and organic matter content of lower soil layer. It was also determined that the moisture content of upper soil layer, aggregate stability and clay content were the most effective factors on the penetration resistance of the surface soil layer, but moisture content and bulk density for the compacted (lower) soil layer. Keywords: Multiple regression, soil compaction, penetration resistance