Effect of long term application of manures and fertilisers on soil properties, utilization efficiency of nutrients and quality of rice

Abstract

A study was conducted during the first crop season of 1990to assess the effect of long term application of manures and fertilizers on soil properties, utilization efficiency of nutrients and quality of rice making use of the soil and plant samples taken from the existing permanent manurial trial (dwarf indica) at the Regional Agricultural Research Station, Pattambi. This experiment was started at Pattambi during the first crop season of 1973. The soil of the experimental site is laterite. The experiment is laid out in randomised block design with four replications and eight treatments. The treatments consisted of application of entire quantity of N - 90 kg ha 1, as organic alone (cattle manure alone, .green manure alone and cattle manure + green manure) , inorganic alone (ammonium sulphate alone and NPK fertilizers) and a combination of organics with inorganics (cattle manure + NPK fertilizers, green manure + NPK fertilizers and cattle manure + green leaves + NPK fertilizers). Soil samples were collected from all the replications of the various treatments before planting, at different stages of crop growth viz., tillering, panicle initiation, 50 per cent flowering and harvest. Plant samples were also collected at the above growth stages. Data on yield of grain and straw were collected from the Regional Agricultural Research Station, Pattambi. Soil and plant samples were analysed in the laboratory to find out the effect of long term application of manures and fertilizers on physical and chemical properties of soil, uptake of nutrients and utilization efficiency of nutrients and quality of grain and straw. Results of analysis of soil samples collected before planting revealed the beneficial effect of organic matter addition on bulk density, water holding capacity and aggregate stability of soil. Long term application of manures and fertilizers singly and in combination had no significant influence on the soil reaction and CEC of the soil. The application of ammonium sulphate alone to supply 90 kg N ha continuously for the last 17 years has not changed the soil reaction considerably. Addition of organic manures at a high dose of 18 t ha for a long period of 17 years failed to increase the CEC of the soil. Results clearly indicated the favourable influence of cattle manure addition in increasing the content of organic carbon.