Land management between crops affects soil inorganic nitrogen balance in a tropical rice system
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Sustainable production of lowland rice (Oryza sativa L.) requires minimising undesirable soil nitrogen (N) losses via nitrate (NO3 −) leaching and denitrification. However, information is limited on the N transformations that occur between rice crops (fallow and land preparation), which control indigenous N availability for the subsequent crop. In order to redress this knowledge gap, changes in NO3 − isotopic composition (δ15N and δ18O) in soil and water were measured from harvest through fallow, land preparation, and crop establishment in a 7 year old field trial in the Philippines. During the period between rice crops, plots were maintained either, continuously flooded, dry, or alternately wet and dry from rainfall. Plots were split with addition or removal of residue from the previous rice crop. No N fertilizer was applied during the experimental period. Nitrogen accumulated during the fallow (20 kg NH4 +–N ha−1 in flooded treatments and 10 kg NO3 −–N ha−1 in treatments with drying), but did not influence N availability for the subsequent crop. Nitrate isotope fractionation patterns indicated that denitrification drove this homogenisation: during land preparation ~50 % of inorganic N in the soil (top 10 cm) was denitrified, and by 2 weeks after transplanting this increased to >80 % of inorganic N, regardless of fallow management. The 17 days between fallow and crop establishment controlled not only N attenuation (3–7 kg NO3 −–N ha−1 denitrified), but also N inputs (3–14 kg NO3 −–N ha−1 from nitrification), meaning denitrification was dependent on soil nitrification rates. While crop residue incorporation delayed the timing of N attenuation, it ultimately did not impact indigenous N supply. By measuring NO3 − isotopic composition over depth and time, this study provides unique in situ measurements of the pivotal role of land preparation in determining paddy soil indigenous N supply.
KeywordsPaddy soils Indigenous nitrogen supply Nitrate isotopes Denitrification Fallow management Rice
Thanks to Angel Bautista, Sonny Pantoja, and Jerone Onoya for assistance with field work at the IRRI experimental farm and to Mia Bunquin (International Rice Research Institute) for assistance in preparing samples for isotope analysis. Thanks especially to Jun Correa for management oversight of the field trial. Thanks to Roger Cresswell and Joy Jiao at Lincoln University for analytical assistance. Research funding came from Lincoln University, W. Troy Baisden at GNS Science, plus additional funding to N.S.W. from the U.S. Student Fulbright Programme/PAEF and the European Community’s Seventh Framework Programme (FP7/2007-2013 under Grant Agreement Number 265063).
- Blakemore LC, Searle PL, Daly BK (1987) Methods for chemical analysis of soils. NZ Soil Bureau Sci Rep 80:7Google Scholar
- Bouman BAM, Humphreys E, Tuong TP, Barker R (2007) Rice and water. In: Sparks DL (ed) Advances in agronomy, Vol 92. Elsevier Academic Press Inc, San Diego, pp 187–237. doi: 10.1016/s0065-2113(04)92004-4
- Buresh RJ, Reddy KR, Van Kessel C (2008) Nitrogen transformations in submerged soils. In: Stuart J, Schepers WR (eds) Nitrogen in agricultural systems. Agronomy Monograph, vol 49. American Society of Agronomy, Madison, WI pp 401–436Google Scholar
- Dong NM, Brandt KK, Sorensen J, Hung NN, Hach CV, Tan PS, Dalsgaard T (2012) Effects of alternating wetting and drying versus continuous flooding on fertilizer nitrogen fate in rice fields in the Mekong Delta, Vietnam. Soil Biol Biochem 47:166–174. doi: 10.1016/j.soilbio.2011.12.028 CrossRefGoogle Scholar
- Endo A, Mishima S-I, Kohyama K (2012) Nitrate percolation and discharge in cropped Andosols and Gray lowland soils of Japan. Nutr Cycl Agroecosyst 1–21. doi: 10.1007/s10705-012-9544-7
- Fujii C, Nakagawa T, Onodera Y, Matsutani N, Sasada K, Takahashi R, Tokuyama T (2010) Succession and community composition of ammonia-oxidizing archaea and bacteria in bulk soil of a Japanese paddy field. Soil Sci Plant Nutr 56(2):212–219. doi: 10.1111/j.1747-0765.2010.00449.x CrossRefGoogle Scholar
- Johnson-Beebout SE, Angeles OR, Alberto MCR, Buresh RJ (2009) Simultaneous minimization of nitrous oxide and methane emission from rice paddy soils is improbable due to redox potential changes with depth in a greenhouse experiment without plants. Geoderma 149(1–2):45–53. doi: 10.1016/j.geoderma.2008.11.012 CrossRefGoogle Scholar
- Kool DM, Wrage N, Zechmeister-Boltenstern S, Pfeffer M, Brus D, Oenema O, Van Groenigen JW (2010) Nitrifier denitrification can be a source of N2O from soil: a revised approach to the dual-isotope labelling method. Eur J Soil Sci 61(5):759–772. doi: 10.1111/j.1365-2389.2010.01270.x CrossRefGoogle Scholar
- Mariotti A, Germon JC, Hubert P, Kaiser P, Letolle R, Tardieux A, Tardieux P (1981) Experimental determination of nitrogen kinetic isotope fractionation: some principles: illustration for the denitrification and nitrification processes. Plant Soil 62(3):413–430. doi: 10.1007/bf02374138 CrossRefGoogle Scholar
- Santiago-Ventura T, Bravo M, Daez C, Ventura V, Watanabe I, App AA (1986) Effects of N fertilizers, straw, and dry fallow on the nitrogen balance of a flooded soil planted with rice. Plant Soil 93(3):405–411. doi: 10.1007/bf02374291
- Wells NS, Clough TJ, Baisden WT (in press) Ammonia volatilisation is not the dominant factor in determining the isotopic composition of soil nitrate in pasture systems. Agric Ecosyst Environ Google Scholar