Fertility investigation and taxonomy of the soils of banana research station Kannara

Abstract

Taxonomy and fertility investigation of the soils of Banana Research Station, Kannara, was the main intension of the present investigation. Representative surface soil samples were collected from each block of this research station, namely A, B, C, D, E and F for investigating the fertility status of soil. Profiles considered for the study were P1 and P2 in A block, P3, P4 and P5 in B block, P6 and P7 in C block, P8 in D block, P9 in E block, and P10 in F block. Profiles were excavated to study the characteristics of each of the horizons in the soil profile and classify the soils of each block. After the collection and preparation of soil samples, laboratory analyses were carried out as per the standard methods. With an increase in depth, profile samples showed an increasing intensity of colour of the horizons and increase in clay content whereas a decreasing trend was noticed for apparent density, absolute density, water holding capacity and pore space. Soils were acidic and low electrical conductivity values were observed. Organic carbon and total nitrogen decreased with depth. Total P2o5 content was lower than total K2o. Low reserves of total nutrients were observed for other elements also. Sesquioxide content was very high and intermediate layers showed maximum accumulation. In surface as well as profile samples the predominant cation was calcium followed by magnesium. A general increase of CEC and ECEC with depth was observed. Oxalate extractable iron content was lower than the dithionite extractable iron. Distribution of total iron was irregular. Surface soil showed wide variation in texture. Clay content showed significant positive correlation with water holding capacity whereas silt and organic carbon failed to impart any influence upon the same. Phosphorus fixing capacity was high for all the samples. DTPA extractable micronutrients were more than the adequate amount. Based on the soil test values fertilizers were recommended for various blocks. Nitrogeneous fertilizers can be reduced by 5 to 10 per cent. Applications of phosphatic fertilizers can be reduced by 75 per cent in most of the blocks. Potassium fertilizers can also be reduced considerably. Nutrient indices were calculated and a soil fertility map was drawn. Classification of pedons of various blocks according to soil taxonomy has been attempted and found that P1 of A block belongs to the order Entisol. P2 (A block), P3, P4 and P5 (B block), P6 and P7 (C block), P9 (E block) and P10 (F block) belong to the order Alfisol. P8 of D block belongs to the order Inceptisol. By this investigation, the classification of soil profiles were done and the fertility status of each block was found out. In accordance with the soil test values, fertilizer recommendations were made. Thus, by reducing the inputs, cost of cultivation could be reduced considerably.