Pyrethrum (Tanacetum cinerariaefolium Trev.), a perennial herbaceous plant of the Asteraceae family, contains in its aboveground parts, particularly the ovary, insecticidal ester compounds pyrethrin I and II. Being environmentally safe, naturally occurring pyrethrins are increasingly given precedence to similar synthetic products. Pyrethrum is an endemic plant growing in coastal eastern Adriatic regions and our investigation aimed to expand the insufficient knowledge of soil properties in Montenegrin wild pyrethrum habitats.
Natural pyrethrum habitats are located in southern Mediterranean and Sub-Mediterranean regions of Montenegro, on the sloppy karst type of relief with inclination mostly exceeding 40 and over 50% of the territory covered with rocks. The main substrate consists of Mesozoic limestones. Four main types of soil were determined: lithosol, calcomelanosol, terra rossa and deposal on the remains of a former quarry.
Soil chemical reaction was found to be neutral or alkaline, with only the cambric horizons of terra rossa showing moderately acid to neutral reaction. Exchangeable acidity was again found solely in the non-skeletal cambric horizons of Terri Rosa. Our analysis of the adsorption complex indicates higher values of cation exchange capacity (32.72-90.82 m.ekv.) and total adsorbed basic cations (21.87.88.0 m.ekv.). Saturation levels ranged between 65.75 m.ekv. for the cambric horizon of terra rossa and 97.82 m.ekv. for the calcomelanosol.
Soils in pyrethrum habitants were found to differ regarding humus content; as much as 28.1% was found in organogenic calcomelanosol and merely 0.36% in the skeletal layers of deposal. Total nitrogen was found to be highest in calcomelanosol, with the maximum of 0.75% and minimum of 0.06% in lithosols or traces in deposols. Available forms of phosphorus were found mostly in traces, while the content of available forms of potassium varied considerably, from medium to high (3.4-48.7 mg/100g soil). Content analysis of the available forms of several microelements that are essential to plant nutrition proved the soils of pyrethrum habitats to be well supplied with Zn and Fe, while the supply of Cu and Mn was medium to high. However, nutrient supply per hectar was highly limited in all types of soil owing to shallow solum, considerable participation of skeletal material and rocky surface.
Key words: pyrethrum, soil, chemical properties.