ISSN 2167-0447
International Journal of Agricultural Sciences ISSN: 2167-0447 Vol. 2 (12), pp. 330- 336, December, 2012. © International Scholars Journals
Full Length Research Paper
Recovery of 15N labelled rice and soybean residues by maize grown on an inceptisol of Malang, Indonesia
Anis Sholihah1*, Sri Rahayu Utami2, Sugeng Prijono2 and Eko Handayanto3
1Department of Agrotechnology, Faculty of Agriculture, Malang Islamic University, Jl.M.T. Haryono 193 , Malang 65144-Indonesia.
2Department of Soil Science, Faculty of Agriculture, Brawijaya University, Jl.Veteran, Malang 65145- Indonesia.
3The International Research Centre for the Management of Degraded and Mining Lands, Brawijaya University, Jl. Veteran, Malang 65145, Indonesia.
Received 23 October, 2012; Accepted 19 December, 2012
Abstract
A study was conducted to evaluate the N recovery of 15N labelled crop residues (rice straw=RS; soybean=SY) with 15N isotope dilution technique on growth of maize. The 15N labelled crop residue from the rice and soybean crops that were grown in glass-house under three 15N concentrations, that is, 0.625 mM N (N1), 2.5 mM N (N2) , and 10 mM N (N3) supplied as CO(15NH2)2, in 30 cm diameter plastic pots containing 5 kg of quartz sand. Eight weeks after planting the above-ground biomass was pruned and oven dried at 60°C for 48 h and analyzed for polyphenol, lignin, N, C, C/N and % 15N-abundance. The seven treatments (six types of crop residues and one treatment with no added residues) were arranged in a completely randomized block design with four replicates. The maize was plant pots containing 10 kg of soil and placed in a glass-house. The varying supply of 15N concentrations resulted in varying quality of crop residues. The amounts of mineral N in the soil supplied with crop residues were significantly greater than in the control at 2, 4 and 8 weeks. The amounts of mineral N in soils amended with residues of SY and RS with a 10 mM N supply were significantly (P<0.05) greater than those grown with 2.5 mM and 0.625 mM N supplies during the incubation time. The N recovery by maize shoot from residues with 10.0 mM N was greater (80.86% on average) than that from residues with 2.5 mM N (70.06% on average) and that from residues with 0.625 mM N (58.43% on average). On average, the %N recovery of crop residue N by maize estimated by the 15N method was 10.73% more than that estimated by the difference method.
Key words: Soybean, 15N labelled, N recovery, rice straw, N mineralization.