Effect of Levels of Nitrogen on Uplant Rice Cultivars Under Raifed Condition
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Date
2003
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Birsa Agricultural University, Ranchi
Abstract
Upland rice accounts for 17 % of the total rice area (42.7 m ha), but it contributes only 10 % of rice production (93.08 mt). Since nitrogen is the most limiting factor in uplands, selection of nitrogen responsive cultivar for the specific location helps in improving and stabilizing production and profitability. Hence, a field experiment was conducted on a sandy clay loam, acidic in nature (pH 5.5) low in available N (278.56 kg/ha), medium in available P (12.6 kg/ha) and available K (157.7 kg/ha) at Birsa Agricultural University during kharif season of 2001 to find out optimum nitrogen level for maximum yield and profitability of upland rice cultivars. The experiment was laid out in a split plot design and comprised of three levels of nitrogen (20, 40 and 60 kg/ha) in main plots and four cultivars (Ashoka 228, Ashoka 200, Kalinga III and Birsa dhan 102) in sub plots and replicated thrice.
Results revealed that application of 60 kg N/ha produced significantly higher grain (19.27 q/ha) and straw (34.16 q/ha) yield which was 43.69 and 142.69 % more than the grain yield obtained by application of 40 and 20 kg N/ha, respectively. Among four cultivars tested, Birsa dhan 102 was superior to the other cultivars with 18.52 and 34.89 q/ha grain and straw yield respectively. Birsa dhan 102 fertilized with 60 kg N/ha produced significantly higher grain (24.38 q/ha) and straw (39.57 q/ha) yields with 81.27 and 69.51 kg/ha/day grain and biomass production rate, respectively. This was attributed to high physical productivity (26.5 kg/ha/day) maximum number of effective tillers (180.67/m²), filled grains per panicle (69.67). 1000-grain weight (25 g) and panicle length (17.43 cm). Accumulation of dry matter, crop growth rate, relative crop growth rate, area index and plant height were also maximum with Birsa dhan 102 at 60 kg N/ha. This was followed by Ashoka 200 grown with 60 kg N/ha leal (20.65 q/ha), which was similar to that of Birsa dhan 102 fertilized with 40 kg N/ha (17.98 q/ha) and Kalinga III with 60 kg N/ha (17.49 q/ha). Similarly, maximum net returns (Rs.7678.5/ha) and benefit cost ratio (Rs 1.6 per rupee investment) was recorded under Birsa dhan 102 grown with 60 kg N/ha. This was followed by Ashoka 200 grown with 60 kg N/ha which recorded similar net returns (Rs.6210.9/ha) and benefit cost ratio ( Rs 1.29) per rupee investment) as that of Birsa dhan 102 fertilized with 40 kg N/ha (Rs.5348.4/ha and Rs. 1.18 per rupee investment, respectively). The monetary productivity was similar for Birsa dhan 102 (Rs.83.46/ha/day) and Ashoka 200 (Rs.73.07/ha/day) fertilized with 60 kg N/ha.
Thus, application of 60 kg N/ha and use of cultivar Birsa dhan 102 proved to be the best for this area. Among different combination of nitrogen level and cultivars, Birsa dhan 102 grown at 60 kg N/ha was superior to other treatments and was followed by Ashoka 200 grown at 60 kg N/ha which was similar to Birsa dhan 102 at 40 kg N/ha. Considering resource poor farmers, Birsa dhan 102 at 40 kg N/ha may also be recommended as this was superior to Kalinga III and Ashoka 228 at 60 kg N/ha and was similar to that of Ashoka 200 at 60 kg N/ha. However it requires further experimentation to corroborate the findings.