Growth, Yield attributes and Yield of Rice ( Oryza sativa L.) as affected by Application of Organic Sources of Nitrogen

A field experiment was conducted at the Agricultural

Indiscriminate use of chemical fertilizers leads to development of several problems like decline in soil organic matter, increase in soil salinity, soil pollution and severe attack of pest and diseases (Chakraborthi and Singh, 2004). Due to these problems, organic farming is gaining popularity in recent years. In view of escalating prices of nonrenewable resources of nitrogen and the concern about environmental degradation and pollution, the need for cheaper sources of nitrogen is recognized. Balanced use of nutrients through organic sources like farm yard manure, vermicompost, green manuring, crop residues, neem cake and poultry manure are the pre requisites to sustain soil fertility and to produce the maximum crop yield with optimum input level (Dahiphale et al., 2003). Nitrogen is pivotal in realization of rice yields. Basal application of organic manures has low nitrogen use efficiency and higher losses due to volatilization, leaching and denitrification. Hence, application of appropriate quantity of nitrogen as split doses will meet the crop demand and enhance the nutrient uptake at critical stages (10 days before panicle initiation) without causing much loss. Hence, use of organic sources like FYM, poultry manure, vermicompost and neemcake deserves priority for sustained production and better utilization in organic rice production. Therefore, an attempt has been made to study the response of rice to organic nitrogen sources on growth and yield in order to achieve the maximum production.

Materials and Methods
A field experiment was conducted on clay loam soil of Agricultural College Farm, Bapatla, Andra Pradesh during kharif season of 2012. The experiment was laid out in a randomized blocks design with three replications. The soil of the experimental site was clay loam in texture, slightly alkaline in reaction (pH 7.9), with 0.43 % organic carbon and 210, 29 and 385 kg ha -1 of N, P and K, respectively. The experiment consisted of nine treatments viz., 100% RDN through inorganic sources (120:60:40 kg N, P 2 O 5 , K 2 0) (T 1 ), 100% RDN through poultry manure (10 days before puddling) (T 2 ), 100% RDN through FYM (10 days before puddling) (T 3 ), 100% RDN through neem cake (10 days before puddling) (T 4 ), 100% RDN through vermicompost (10 days before puddling) (T 5 ), 50% RDN as basal +50% at 10 days before PI stage through poultry manure (T 6 ), 50% RDN as basal +50% at 10 days before PI stage through FYM (T 7 ), 50% RDN as basal +50% at 10 days before PI stage through neem cake (T 8 ), 50% RDN as basal +50% at 10 days before PI stage through vermicompost (T 9 ).Well decomposed poultry manure, FYM, neemcake and vermicompost with 2.0 %, 0.5%, 2.5 % and 1.2 % N, respectively were used as organic sources for nitrogen. Based on the equal N basis, and required quantities of organic manures were incorporated in the soil 10 days before puddling. In the treatment T 1, recommended doses of 120:60:40 kg ha -1 of N, P and K, respectively in the form of urea (46% N), single super phosphate (16% P 2 0 5 ) and murate of potash (60% K 2 0) were applied to the rice crop. The nitrogen was applied in three splits i.e. 1/2 as basal, 1/4 at maximum tillering and 1/4 at panicle initiation stages. Entire dose of phosphorus was applied basally before sowing. Half of potassium was applied basally and the remaining half applied at maximum tillering stage. The consumer preferred rice variety, BPT-5204 (Samba Mahsuri) was raised. Thirty day old seedlings were transplanted using two seedlings hill -1 on 17-08-2012 with a spacing of 20 cm × 15 cm. Recommended agronomic practices and plant protection measures were followed.

Growth
Plant height, number of tillers and drymatter accumulation at maturity were significantly influenced by organic manures and recommended NPK through fertilizers (Table 1). Application of recommended dose of chemical fertilisers (T 1 ) recorded significantly taller plants which were on par with 50% RDN as basal+ 50% at 10 days before PI stage through poultry manure (T 6 ). The rapid rate of mineralization in fertilizer treated plots might have led to more availability of nitrogen in initial stages of crop growth. Whereas, increased plant height in poultry manure treated plots might be due to its higher content of N, which was readily available to crops. These results are in agreement with the findings of Suvarna Latha and Sankara Rao (2001) Significantly higher number of tillers were observed with the application of recommended dose of chemical fertilisers, which was on a par with 50% RDN as basal+50% at 10 days before PI stage through poultry manure (T 6 ). The chemical fertilizers offer nutrients which are readily soluble in soil solution and there by instantaneously available to plants. Better performance of poultry manure treated plots might be due to the involvement of certain growth promoting substances, which might have accelerated the number of tillers. This is in consonance with the findings of Helen Belefant-Miller (2007).
The highest drymatter accumulation was observed with the application of recommended dose of chemical fertilizers, which was on a par with 50% RDN as basal+50% at 10 days before PI stage through poultry manure (T 6 ). Significantly higher drymatter accumulation in fertilizer treated plots might be due to greater solubility and accelerated release of nitrogen, thereby providing an opportunity time for rice to utilize higher quantum of nutrients. Increased drymatter accumulation in poultry manure treated plots might be attributed to the continuous slow release of nutrients, which might have enabled the leaf area duration to extend, thereby, providing an opportunity time for plants to increase the photosynthetic rate which in turn, could have led to higher accumulation of dry matter. Similar results were also obtained by Amanullah et al. (2006).

Yield attributes
Yield attributes viz., productive tillers m -2 , total number of grains panicle -1 and filled grains panicle -1 were significantly influenced by time and application of organic sources of nitrogen. Application of recommended dose of chemical fertilizers recorded significantly higher productive tillers m -2 , total number of grains panicle -1 , filled grains panicle -1 , which was on a par with 50% RDN as basal+50% at 10 days before PI stage through poultry manure (T 6 ), but proved significantly superior to the rest of the treatments. Test weight was not significantly influenced by application of organic sources.
Better yield attributes recorded with the application of chemical fertilizers might be due to better nutrition especially, quick nitrogen availability to the crop (Table 2). Among the organic manures, better performance of T 6 might be due to the continued supply of N until the reproductive stage of the crop growth, due to faster decomposition by making the nutrients more available and also better supply of macro and micro nutrients which might have helped for more enzymatic activity and physiological processes of plant, which resulted into better translocation of the photosyntates and portioning of drymatter to the sink (grain). This might have helped in increasing the yield attributes. These results are in conformity with the findings of Begum et al. (2001).

Yield
The highest grain yield of 5856 kg ha -1 was obtained with the application of 100% RDN through fertilizer (T 1 ), which was however, on par with 50% RDN as basal+50% at 10 days before PI stage through poultry manure (T 6 ), but proved significantly superior to the rest of the treatments ( Table 2).
The grain yield was the highest when recommended dose of chemical fertilizer was applied. It is due to better growth and yield attributes in these treatments, which might have resulted in increased rice yields compared to added levels of N in organic form (Manivannan and Sriramachandra sekharan, 2009). Poultry manure contains about 60 per cent of its nitrogen as uric acid, 30 per cent as more stable organic form of N and less than 10 per cent as mineral N (Srivastava, 1998). The uric acid N changes rapidly to ammonical form of nitrogen. Similar results were also reported by Datta et al. (1994) and Channabasavanna (2002).

Conclusion
From the present study, it can be concluded that use of 50 % recommended dose of nitrogen as basal +50% at 10 days before PI stage through poultry manure (T 6 ) or 100% RDN through poultry manure (T 2 ) is one of the cheap and efficient source of nitrogen in organic farming in order to get higher growth and yield of rice.