Author(s):

Rajeshwar Malavath and S Mani

Abstract: The study was carried out in the three new research stations of Tamil Nadu Agricultural University with varied soil types viz., Maize Research Station, Vagarai of Dindigul district, Cotton Research Station, Veppanthatai of Perambalur district and Dryland Agricultural Research Station, Chettinad of Sivagangai district of Tamil Nadu were selected for developing the strong soil resource database for proper appraisal of their productivity potential and their rational use. This study was an embodiment with an objective of distribution of physico-chemical properties, available macro and micro nutrients in some red, red laterite and black soils of semi arid region of Tamil Nadu. Based on the morphological characteristics and land elevation, thirteen representative geo-referenced pedons were selected and horizon wise soil samples were collected. The red laterite soils had lower pH values ranged from moderately acidic to slightly acidic followed by red (neutral to strongly alkaline) and higher pH values in black soils (moderately alkaline to strongly alkaline) with non saline in nature. The organic carbon showed wide variation and the values were found to be vary from low to medium (2.8 to 6.5 g kg-1) in surface horizons whereas in subsurface horizons it was low and ranged from 0.70 to 5.0 g kg-1. The CaCO3, CEC, base saturation and CEC/clay ratios were higher in black soil pedons compared to red and red laterite soils. Higher values of CEC/clay ratios indicating that the black soils are less weathered than the red soils and red laterite soils. The exchangeable bases in the red and black soil pedons are in order of Ca+2 > Mg+2 > Na+ > K+ on the exchange complex. The exchangeable bases of red laterite soils were in order Ca+2 > Mg+2 > K+ > Na+. The soils are low in available N, low to high in available P in red and black soils and low to medium in red laterite soils, medium to high in available K and high in available S in surface horizons when compared to subsurface horizons. The soils are deficient to sufficient in available Zn, Cu, Fe and B and sufficient in available Mn. The red soils are shallow, marginally suitable to highly suitable for cultivation of maize, greengram, sorghum, redgram and blackgram. The black soils are very deep, moderately suitable to highly suitable for cultivation of cotton, sorghum, soybean, greengram, blackgram, redgram, sunflower, sesamum, maize and pearlmillet. The red laterite soils are very shallow to deep, marginally suitable to moderately suitable for cultivation of groundnut, greengram, blackgram, redgram, horsegram and pearlmillet.

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