Dynamics of Fertilizer Nitrogen Applied to Sweet Sorghum (Sorghum bicolor (L.) Moench) in the Semi-Arid Tropics

Uchino, H and Watanabe, T and Ramu, K and Sahrawat, K L and Marimuthu, S and Wani, S P and Ito, O (2015) Dynamics of Fertilizer Nitrogen Applied to Sweet Sorghum (Sorghum bicolor (L.) Moench) in the Semi-Arid Tropics. Japan Agricultural Research Quarterly, 49 (04). pp. 409-418. ISSN 2185-8896

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Abstract

Although sweet sorghum is in focus as a promising multi-purpose crop in semi-arid tropical regions, information on optimum nitrogen (N) management remains rather limited. To determine and understand the N dynamics in sweet sorghum-soil ecosystem, we evaluated the N recovery of applied fertilizer in the Alfisol field during the 2009 and 2010 rainy seasons. Sweet sorghum was grown under six N rates (0, 30, 60, 90, 120 and 150 kg N ha-1) with split application (at 0, 30 and 60 days after sowing) and N concentration and N recovery efficiency (NRE) were measured. In addition, to determine the fate of basal and topdressed N, 15N-labeled urea was applied at each application timing within main plots of 90 kg N ha-1. There was no significant difference in NRE calculated by the difference method between six N rates and N uptake rose with increasing N rate. The total dry weight and sugar yield increased at rates up to 90 kg N ha-1 and higher N rates did not significantly affect sorghum productivity. As a total of basal and topdressing applications, 33% of the applied 15N-labeled urea was absorbed by the sorghum plant, while 36 and 30% remained in the soil and unaccounted for, respectively. The NRE calculated by the isotopic method was about 39 and 37% for topdressings at 30 and 60 days after sowing, respectively. The distribution ratio of absorbed N in leaves was higher for basal applications and topdressing at 30 days after sowing, while that in grains was higher for topdressing at 60 days after sowing, compared to the other application timings. In contrast to topdressings, the NRE was very low (13%) for basal N application: about 70% of the basal applied N remained in the soil at the physiological maturity. The results imply that the NRE might be increased by improving the ways in which basal N is applied.

Item Type: Article
Divisions: RP-Resilient Dryland Systems
CRP: CGIAR Research Program on Dryland Systems
Uncontrolled Keywords: Biofuels, Soils Fertilizers, Plant Nutrition, 15N-labeled Urea, Fertilizer Application Timing, Nitrogen Recovery Efficiency
Subjects: Mandate crops > Sorghum
Depositing User: Mr Ramesh K
Date Deposited: 02 Nov 2015 06:30
Last Modified: 19 Aug 2016 04:11
URI: http://oar.icrisat.org/id/eprint/9109
Official URL: http://doi.org/10.6090/jarq.49.409
Projects: Development of sustainable soil fertility management for sorghum and sweet sorghum through the effective use of biological nitrification inhibition (BNI)
Funders: Ministry of Agriculture, Forestry and Fisheries (MAFF), Japan
Acknowledgement: This study was conducted under the research project titled 'Development of sustainable soil fertility management for sorghum and sweet sorghum through the effective use of biological nitrification inhibition (BNI)' funded by the Ministry of Agriculture, Forestry and Fisheries Japan.
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