Friday, 14 July 2006

Response of Paddy to Identified Soil Fertility Constraints in Coastal Agro Eco System of Karnataka, India.

G.S Dasog, P.L. Patil, Dhanya Mathews, Harikrishna B.L, K.M. Anegundi, and Tejaswini N.B. University of Agricultural Sciences, Krishinagar, Dharwad, 580005, India

The coastal agro eco system of Karnataka receives an average rainfall of 3500 mm per annum in about five month's period. The high rainfall cause extensive leaching of soil constituents. There is no choice for the farmers except plantation crops on raised lands and paddy at low lands. Paddy yields are low due to leaching of nutrients and majorities of the farmers are not applying fertilizer except organic manure. In view of this, an investigation was carried out to find out the soil fertility constraints in paddy production. A pilot site ( Mirjan village) in coastal agro eco system of Karnataka was the study area. The soil samples at two depths (0-15 cm and 15-30 cm) were collected from the pilot site and sampling locations were recorded by GPS. The soil samples were analysed for available nutrients by standard techniques. The nutrient status was categorised as low medium and high based on the standard limits and mapped by GIS technique. The nutrient maps of the study area indicated that available N,P,K and Zn were the constraints in the study area. Hence a field experiment was conducted to study the response of paddy to the identified soil fertility constraints along with bio-fertilizers (Azospirillum and Bacillus polymixa ). The results on the experiment revealed that, plant height, number of leaves, dry matter accumulation and leaf area index at different growth stages increased significantly with the application of N,P,K and Zn as well as bio-fertilizers. Grain and straw yield of paddy followed the similar trend. A highest grain and straw yield was recorded at 150% RDF + 25kg ZnSO4 + bio-fertilizers . At this treatment, the increase in yield was more than two times compared to control. The experiment stresses the importance of soil test based site specific fertilizer recommendation.

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