Productivity and quality of basmati rice (Oryza sativa) in relation to nitrogen management

A field experiment was conducted at the Punjab Agricultural University, Ludhiana during 2010 and 2011 to study the effect of different sources of nitrogen on productivity and quality of basmati rice (Oryza sativa L.). The experiment was conducted in randomized block design with 9 treatment combinations of chemical fertilizer, green manuring with sunnhemp (Crotalaria juncea L.) and farmyard manure (FYM) with 4 replications. Incorporation of green manure 50 days after its sowing resulted in statistically same grain yield (3.05 t/ha) as that with recom- mended nitrogenous fertilizer (3.06 t/ha) and different combinations of organic manures with nitrogenous fertilizer. There was no significant effect of additional application of chemical fertilizer or FYM to green manuring on the grain yield. Green manure, having supplied 77.2 kg N/ha, alone was sufficient to meet the recommended nitrogen requirement (40 kg/ha) of basmati crop. Application of FYM (19.8 t/ha) to supply 40 kg N/ha alone resulted in sig- nificantly lower grain yield (2.65 t/ha) than all the other combinations of nutritional sources. The quality parameters (brown and milled rice recovery, minimum cooking time, water absorption ratio, elongation ratio and cooking coef- ficient) were statistically at par among all the nitrogen sources except brown and milled rice recoveries which were significantly lower with FYM alone. Head-rice recovery and protein content of grains with different nitrogen sources were comparable to that produced with chemical fertilizer except green manure supplemented with FYM or FYM supplemented with 50% of recommended nitrogen which had significantly higher values of these two pa- rameters than the chemical fertilizer. Improvement in soil organic carbon and available N, P, K was observed with green manuring and FYM as compared to chemical fertilizer alone. The benefit: cost ratio was the highest with chemical fertilizer alone due to its lowest cost.