Net N mineralisation in acid sulfate soils amended with different sources of organic matter, lime, and urea
Nguyen My Hoa A B , Trinh Thi Thu Trang A and Tran Kim Tinh AA Soil Science & Land Management Department, College of Agriculture, Can Tho University, Can Tho, Viet Nam.
B Corresponding author; email: nmhoa@ctu.edu.vn
Australian Journal of Soil Research 42(6) 685-691 https://doi.org/10.1071/SR03081
Submitted: 16 May 2003 Accepted: 24 May 2004 Published: 17 September 2004
Abstract
Acid sulfate soils in the Mekong Delta, Vietnam, are often high in organic matter content, but net N mineralisation is low. This may be due to low soil pH or low easily decomposable organic matter content. This study aimed at investigating net N mineralisation in acid sulfate rice soil (anaerobic incubation) and acid sulfate upland soil (aerobic incubation) amended with 1% biogas sludge, 1% straw, 1% starch, 2.5‰ CaCO3 (about 10 t CaCO3/ha for acid sulfate soils), and 0.22‰ urea. Non-acid alluvial soils were used for comparison.
Results showed that addition of straw and starch to acid sulfate rice soil decreased net N mineralisation, but addition of biogas sludge increased cumulative N-NH4 due to both the increase in soil pH after submergence and the supply of low C/N organic matter. Addition of biogas sludge can therefore increase N-supplying capacity in acid sulfate rice soil. During aerobic incubation of acid sulfate upland soil with biogas sludge, cumulative N (NH4 + NO3) was also increased compared with the control, although pH was not increased. It is concluded, therefore, that in acid sulfate soils in the Mekong Delta, the supply of easily decomposable organic matter with low C/N ratio can increase activity of microorganisms and hence increase net N mineralised compared with soils not supplied with biogas sludge. Liming can increase net N mineralisation in acid sulfate rice soil during anaerobic incubation, but not in acid sulfate upland soil during aerobic incubation. Addition of rice straw and starch to soil amended with urea increased N immobilisation; therefore, urea can be temporally immobilised in soils and hence may reduce loss of N in field conditions.
Additional keywords: anaerobic, aerobic, immobilisation, rice soil, upland soil, biogas sludge.
Acknowledgments
We would like to thank the SAREC (Swedish Agricultural Research and Education Center) Project in funding us to conduct this research and the Committee of The 5th International Acid Sulfate Soils Conference in funding us to attend and present this research.
Acharya C
(1953) Comparison of the course of decomposition of rice straw under anaerobic, aerobic and partially aerobic condition. Biochemical Journal 29, 1116–1120.
Becker M, Ladha JK
(1997) Synchronizing residue N mineralization with rice N demand in flooded condition. ‘Driven by nature: Plant litter quality and decomposition’. (Eds G Cadisch, KE Giller)
(CAB International: Wallingford, UK)
Bremer E, van Kessel C
(1992) Seasonal microbial biomass dynamics after addition of lentil and wheat residues. Soil Science Society of America Journal 56, 1141–1146.
FAO
(1998) World Soil Resources Report 84. World Reference Base for Soil Resources, FAO, Rome.
Jandl R, Sollins P
(1997) Water-extractable soil carbon in the relation to the below ground C cycle. Biology and Fertility of Soils 25, 196–201.
| Crossref | GoogleScholarGoogle Scholar |
Keeney DR
(1982) Nitrogen-availability indices. ‘Method of soil analysis. Part 2 - Chemical and microbiological properties’. (Eds AL Page, RH Miller, DR Keeney)
(American Society of Agronomy, Inc., and Soil Science Society of America, Inc.: Madison, WI)
Paul, EA ,
and
Clark, FE (1989).
Ren Do Thi Thanh,
Tinh Tran Kim,
Nguyen Thi Ngoc, Linh Tran Ba
(2004) Applying mixed manure and inorganic phosphorus fertiliser to improve rice yield on acid sulphate soil (Hydraquentic Sulfaquept). Australian Journal of Soil Research 42, 693–698.
Sahrawat KL
(1980a) Nitrogen supplying ability of some Philippine rice soils. Plant and Soil 55, 181–187.
Sahrawat KL
(1980b) Soil and fertilizer nitrogen transformations under alternate flooding and drying moisture regimes. Plant and Soil 55, 225–233.
Titan G,
Kang G, Brussard L
(1992) Biological effects of plant residues with contrasting chemical composition under humid tropical conditions- decomposition and nutrient release. Soil Biology and Biochemistry 24, 1051–1060.
| Crossref | GoogleScholarGoogle Scholar |
