Integrated Nitrogen Management in Direct Seeded Upland Rice Under Vertisole of Maharashtra (Oryza sativa L.)

A field experiment was conducted at college of agriculture, Kolhapur on medium black soils during kharif, 2014 to study the effect integrated nitrogen management in growth, yield, nutrient uptake and economics of upland paddy. The organic fertilizers viz., FYM, vermicompost, castor cake, neem cake were combined with inorganic fertilizers. The result revealed that application of 75% RDN through inorganic fertilizer + 25% N through castor cake (T6) recorded significantly higher values of growth and yield attributing characters resulting into higher grain and straw yields and nutrient uptake by paddy and it was on par with 75% RDN through inorganic fertilizer + 25% N through vermicompost (T4) and GRDF(T1). Application of 75% RDN through inorganic fertilizer + 25% N through castor cake and 75% RDN through inorganic fertilizer + 25% N through vermicompost were comparable in respect gross and net monetary returns and also the B:C ratio was maximum in these treatments.

Rice is the staple food for about 50 per cent of the world's population that resides in Asia, where 90 per cent of the world's rice is grown and consumed.It is planted on about one-tenth of the earth's arable land and is the single largest source of food energy to half of humanity.
Fertilizer is one of the inputs which bring quantum jump in the yield of rice.The nutrient uptake by rice plant is different from other field crops.To improve the production efficiency of rice and to synchronize the application of nutrients with the demand of the plant, it is necessary to apply required dose of NPK fertilizers, along with other organic and biofertilizer inputs.Continuous and an inappropriate use of only chemical fertilizers in intensive cropping system results into imbalance of nutrients in the soil had deleterious effect leading to decline in productivity due to limitation of one or more of micro-nutrients (Nambiar and Abrol, 1989).
The integrated nutrient supply system is the most logical concept for managing long-term soil fertility and productivity (Ramesh et al. 2009).It brings about equilibrium between degenerative and restore activities in the ecosystem (Upadhyay et al. 2011).Among the major nutrients, nitrogen application is essential to obtain the higher yields in rice.It deserves special status among the major nutrient and is the "Mineral of life'' for rice (Yadav and Meena 2014).It is one of the most important and essential nutrient which directly influences the growth, development, yield and quality of rice.
An integrated nutrient management in which both organic manures and inorganic fertilizers are used simultaneously is the most effective method to maintain a healthy and sustainably productive soil.To achieve food security through sustainable agriculture, the requirement for fixed nitrogen must be increasingly met by biological nitrogen fixation rather than by industrial nitrogen fixation.In view of this, the present field experiment was planned on the integrated nitrogen management in upland paddy at Kolhapur, during kharif season of 2014.

MATERIALS AND METHODS
A field experiment in randomized block design which consists of 11 treatments with three replications was conducted at Post Graduate Research Farm, College of Agriculture, Kolhapur during kharif, 2014.The experimental site was located at 16 0 42' North latitudes and 74 0 14' East longitudes with average annual rainfall of 1057 mm.The soil of experimental field was medium black (vertisols) with 90 cm depth, slightly alkaline pH (7.7), low in organic carbon content (0.36%), medium in available N (272 kg ha -1) , available P 2 O 5 (19 kg ha -1 ), available K 2 O (242 kg ha -1 ).The seeds of paddy variety Indrayani, which matures in 135-140 days and yields about 40-45 q ha -1 was sown at 2 nd fortnight of June at a distance of 22.5 cm between the lines in each plot with seed rate of 60 kg ha -1 direct seeded unpland condition.The treatment comprised of T 1-GRDF (RDF [100:50:50 kg NPK ha -1 ] + 10 t FYM ha -1 ), T 2-100% RDN (through inorganic fertilizer), T 3-75% RDN through inorganic fertilizer + 25%N through FYM, T 4-75% RDN through inorganic fertilizer + 25%N through vermicompost, T 5-75% RDN through inorganic fertilizer + 25%N through neem cake, T 6-75% RDN through inorganic fertilizer + 25%N through castor cake, T 7-75% RDN through inorganic fertilizer +12.5%N through FYM+ 12.5%N through vermicompost, T 8-75% RDN through inorganic fertilizer +12.5%N through FYM+ 12.5%N through neem cake , T 9-75% RDN through inorganic fertilizer +12.5%N through FYM+ 12.5%N through castor cake , T 10-75% RDN through inorganic fertilizer + seed treatment with Azotobacter + PSB , T 11-No fertilizer .At the time of sowing, 40 per cent nitrogen, full dose of P 2 O 5 and of K 2 O was applied as basal dose.The remaining 60 per cent nitrogen was applied in two splits at 30 and 60 DAS.The quantity of FYM required for each plot was calculated as per the treatments based on the nutrient content and applied uniformly 15 days before sowing to all the plots and mixed in to the soil.The quantity of vermicompost, neem cake and castor cake applied at the time of sowing as per treatment to each plot.The data on different growth and yield attributes were recorded and analysed statistically as per the standard procedure suggested by Panse and Sukhatme (1985).

Effect on growth parameters
All the growth characters viz., plant height, number of tillers per meter row length, number of functional leaves, leaf area and dry matter production per plant were found significantly higher with an application of 75% RDN through inorganic fertilizer + 25% N through castor cake (T 6 ) as compared to remaining treatments and it was on par with 75% RDN through inorganic fertilizer + 25% N through vermicompost (T 4 ) and GRDF (T 1 ) at harvest.Enhanced value of growth parameters in the treatment T 6 was due to minimal loss of nitrogen in case of organic sources and nitrogen was available to the crop for longer period.

Effect on yield and yield attributes
Yield and yield attributes of paddy viz., grain and straw yields, number of panicles per meter row length, panicle length, number of grains per panicle, test weight and panicle weight were significantly influenced by different integrated nitrogen management treatments.Among the different sources of N substitution, significantly higher values of yield and yield attributes were obtained with 25% N was substituted through castor cake i.e. (T 6 ).However it was on par with 75% RDN through inorganic fertilizer + 25% N through vermicompost (T 4 ) and GRDF (T 1 ).The application of nitrogen through combination of organic and inorganic sources had significant effect on yield and yield attributes as compared to inorganic fertilizer alone.
The higher grain and straw yield of paddy under integrated nitrogen management was mainly be due to significant improvement in growth and yield attributes resulting into higher grain yield of paddy.The results corroborated with those reported by Meena et al. (2014), Barik et al. (2006), Chaudhary et al.(2011), Yadav and Meena (2014).

Effect on nutrient uptake by paddy
The total uptake of nitrogen, phosphorus and potassium by paddy was significantly influenced by different integrated nitrogen management treatments.The total uptake of nitrogen recorded significantly the highest with application of 75% RDN through inorganic fertilizer + 25% N through castor cake (150.48 kg ha -1 ) as compared to rest of treatments.Application of 75% RDN through inorganic fertilizer + 25% N through castor cake (33.80 kg ha -1 ) recorded significantly higher total uptake of phosphorous over rest of the treatments and it was on par with 75% RDN through inorganic fertilizer + 25% N through vermicompost (T 4 ) (30.51 kg ha -1 ), 100% RDN (T 2 ) (27.94kg ha -1 ), 75% RDN through inorganic fertilizer + 25% N through neem cake (T 5 ) (28.19 kg ha -1 ) and GRDF (T 1 ) (28.21 kg ha -1 ).The total uptake of potassium was significantly higher in 75% RDN through inorganic fertilizer +25% N through castor cake (165.07 kg ha -1 ) over rest of the treatments.However, this was on par with 75% RDN through inorganic fertilizer + 25% N through vermicompost (T 4 ) (155.25 kg ha -1 ) and GRDF (T 1 ) (143.85 kg ha -1 ).
This may be accounted for improved soil environment encouraged root proliferation and root surface absorption zone, which in turn increased grain and straw yield (Sharma, 2002)

Table 1 .
Effect of integrated nitrogen management treatments on growth parameters of paddy at harvest

Table 2 .
Effect of integrated nitrogen management treatments on yield and yield attributing characters of paddy at harvest

Table 3 .
Effect of integrated nitrogen management treatments on Nitrogen, Phosphorus and Potassium uptake by grain and straw

Table 4 .
Effect of integrated nitrogen management treatments on economics of paddy at harvest