QUANTITY-INTENSITY RELATIONSHIP OF POTASSIUM IN FCV TOBACCO SOILS OF PRAKASAM AND NELLORE DISTRICTS OF ANDHRA PRADESH

Abstract

Quantity-Intensity parameters of potassium were studied in Flue–cured Virginia tobacco soils by analyzing twenty eight soil samples (0-9") collected from Southern Light Soils (SLS) and Southern Black Soils (SBS) areas of Prakasam and Nellore districts. Textural variation in black soils was silty clay loam to clay whereas in light soils it was sandy loam to clay loam. Soils from SLS and SBS were neutral in soil reaction and low in EC, chlorides and organic carbon. Southern black soils have higher pH, EC, chlorides and organic carbon compared to SLS. Water soluble-K was more in SLS whereas exchangeable K, non-exchangeable-K, total-K and lattice-K were high in SBS which was due to higher clay content and potassium bearing minerals in black soils compared to light soils of Prakasam and Nellore districts. Equilibrium activity ratio ARKo values were high in SLS compared to SBS hence SLS area have more readily available potassium. The ranges for PBCK in SBS and SLS were 80.3 200 and 7.3 – 126.4 c mol (p+)/kg, respectively. PBCK values were more in SBS compared to SLS because of more clay content in SBS (23.8 to 47.4%) compared to SLS (9.43 to 35.64%), which shows that they have more replenishing capacity. Potassium on specific sites (KX) and on non-specific sites (KO) were high in soils of SBS area compared to SLS which is a measure of quantity parameter. Equilibrium activity ratio (ARKo) values were positively correlated with sand, whereas significant positive correlation was observed between PBCK, KO, KX, and KL and silt and clay contents. Water solubleK showed significant positive correlation with ARKo, whereas, exchangeable-K showed significant positive correlation with PBCK , KO , KX, and KL.