SOIL TYPE A

site one provided more yield and economic return compared to compared to sites 2 and 3. As yield increased fertilizer use efficiency also increased along with yield.

TABLE 7. RICE YIELD RESPONSE TO FERTILIZER APPLICATION IN WETLANDS

TABLE 8. RICE GRAIN YIELD, NITROGEN UPTAKE, FERTILIZER USE EFFICIENCY AND NET FARM INCOME UNDER WETLAND RICE PRODUCTION

Wetland other treatments. The no of tillers per unit area is the most important component of yield. The more the tillers especially fertile tillers, the more the yield. More no of tiller (m²) in the 150kg N/ha treatment might be due to more N availability that played a vital role in cell division.

Significantly higher dry matter accumulation (0.60 and 0.55kgm²) was obtained on plots treated with 150 and 100kg/N/ha respectively.

The best economic rice yield (4.39+/ha) was obtained using fertilizer rate based on soil test at site 1. The recovery by rice of ¹⁵N labeled was much higher using 150kg N/ha at sites 1 and 2,

while it was higher using 100kg N/ha at site 3. This is expected because the total nitrogen for each of the sites differed. The higher N use efficiency (57%) at site 3 can be attributed to the considerably low soil fertility obtained at that site. An important reason for the low N use efficiency at site 2 when compared to sites 1 and 3 may be due to the high total nitrogen content obtained at this site

The result obtained in this study for NFUE at site 3 and 1 showd that when input (fertilizer) is properly managed, rice grown on wetland soils usually make use of higher proportion of N applied from isotopic dilution method. The economic analysis of rice production result showed that site 1 using fertilizer rate base on soil test gave the highest net from income of USD 5244 per hectare. The NFUE values measured (43.3 to 63.3%) in this study are comparable to those reported for soil with low fertility [15]. The percentage of N recovery varies with soil properties/type, methods amounts and timing of fertilizer applications and other management practices as evidenced in this study. Nitrogen fertilizer use efficiency is usually ranges between 30 to 50% in the tropics [16].

4. CONCLUSION

The N rates applied in this experiment significantly influenced no of panicles, no of tillers, dry matter yield (t/ha) and Grain yield of rice on these three wetland soils. The best economic yield of 4.39t/ha of rice was obtained on a Typic Endoaquept soil using fertilizer application based on soil test value. N Recovery of rice of ¹⁵N labeled was much higher using the soil test fertilizer application rate at site 3. Results obtained for NFUE at site 1 and 3 shows that when input (fertilizer) is properly managed, rice grown on wetland soils usually makes use of higher proportion of N applied.

REFERENCES

[1] FASINA, A.S., 2005. Properties and classification of some selected wetland soils in Ado Ekiti, Southwest Nigeria. Applied Tropical Agriculture, 10:76-82

[2] OLALEYE, A.O.. Characterization, Evaluation, Nutrient dynamics and Rice Yields of Selected Wetland soils in Nigeria. PhD Thesis, Department of Agronomy, University of Ibadan (1998) 202.

[3] BABALOLA T.S., ET AL., Land evaluation studies of two wetland soils in Nigeria.

International Research Journal of Agricultural Science and Soil Science 1 (2011) 193-204.

[4] FASIN A.S., ADEYANJU, A., Comparison of three land evaluation systems in evaluating the predictive value of some selected soils in Ado-Ekiti, Southwest Nigeria.

J. Soil Sci. 17 (2007) 113-119.

[5] PENG, S., R.J., BURESH, J., HUANG, J., YANG, Y., ZOU, X., ZHONG, G., WANG, and F., ZHANG,. Strategies for overcoming low agronomic nitrogen use efficiency in irrigated rice systems in China, Field Crops Research 96 (2006) 37-47.

[6] DE DATTA, S.K., Improving Nitrogen Fertilizer, Efficiency in Lowland Rice in Tropical Asia Fert. Res. 9 (1996)171-186.

[7] FAGERIA, N.K. and BALIGAR, V.C.. Lowland Rice Response to Nitrogen Fertilization. Commun. Soil Science. Plant Analy 32 (2001) 1405-1429.

[8] FASINA, A.S., Policy and Agricultural Development in Nigeria. Proc. 26^th Annual Conference of Farm Management Association of Nigeria (FAMAN) held at Federal College of Agriculture, Akure, (2011) 15.

[9] BAMBA, I., DIAGNE, A., MANFUL, and J. AJAYI. O.,. Historic Opportunities for Rice Growers in Nigeria. Special Report. Grain de sel. No. 51, July – September 2010 [10] CHEN, AD, H. SUTER A. A. ISLAM A, R. EDIS A, J. R. FRENEY A B, C. N.

WALKER C. 2008. Prospects of improving efficiency of fertiliser nitrogen in Australian agriculture: a review of enhanced efficiency fertilisers. Soil Research 46(4) 289–301.

[11] AKINBOLA, G. E. 2001. Characterization and classification of some valley bottom soils on basement complex of southwestern Nigeria. In Proceedings of the 27th Annual Conference of Soil Science Society of Nigeria. Calabar. Pp. 100 - 111.

[12] FAO 1976. Framework for land evaluation. Soil Bulletin No. 32, FAO, Rome, pp. 19.

[13] FAO 1979. A Provisional Methodology for Soil Degradation Assessment. FAO, Rome [14] NACHTERGAELE F. A., Riccardo Biancalani B, Sally Bunning C and Hubert George

D. 2010 Land Degradation Assessment: the LADA approach. Proceeding: 19th World Congress of Soil Science, Soil Solutions for a Changing World. 72-75.

[15] ASAGIE, N.H., VENO AND A. EBID 2007: Effects of Sewage Sludge Application in Rice growth, Soil Properties and N-rate in Low Fertile Soil. Int. J. Soil Science 2:171-181.

[16] PRASAD, R. AND DE DATTA, S.K. 1979. Increasing fertilizer nitrogen in wetland rice. Pages 465-484 in International Rice Research Institute. Nitrogen in rice. Las Banos, Philippines.

DYNAMICS OF GREENHOUSE GAS EMISSIONS FROM RIPARIAN BUFFER emissions in agricultural landscapes of northern and north-eastern Europe. In particular, the impact of pulsing water regime, continuous loading and several alterations of environmental conditions on greenhouse gas emissions are taken into the consideration. In two case studies the isotopologue uphill agricultural activities had been abandoned since the middle of 1990s, and the second area was a 55-year-old alder stand in Viiratsi (Vi), which still receives polluted lateral flow from uphill fields applied with pig slurry. Gas fluxes were measured in six sampling sessions, and water samples were analysed for NO3 the dominant gas emission from these alder stands. The isotopic signatures of N2O and NO3

were not significantly different between PJ and Vi study sites suggesting possible conversion of NO3

to N2O in both areas. The greater prevalence of N2 emissions over N2O in both areas, and the strong relationship between NO3

and N2O concentrations (r2= 0.846, with p < 0.01) further suggested that denitrification is the main source of N2O and N2 fluxes in these grey alder stands. The dominant emission of N2 over N2O showed that these riparian zones play an important role in reducing the emissions of N2O while removing NO3

from water and improving the water quality.

1. INTRDOUCTION

Riparian ecosystems are important landscape in agricultural catchments that control water quality in rivers and other water bodies but they are also potential hot-spots of nitrous oxide (N2O) emission to the atmosphere [1]. Nitrous oxide plays an important role in altering stratospheric chemistry, including depletion of the ozone layer. The radiative forcing of N2O is 296 times higher than that of the same amount of carbon dioxide (CO2), and is therefore a potent greenhouse gas (GHG). Despite its relatively minor contribution to global warming (6 percent), a small increase in emissions can lead to a large accumulation of N2O in the troposphere, a phenomenon resulting from the long residence time of N2O, approximately 120 years [2]. Nitrous oxide is produced by (i) reduction of nitrate (NO3

-) to nitrogen gas (N2), and (ii) oxidation of ammonium hydroxylamine (NH2OH) to nitrite (NO2

-), and the reduction of NO2- to N2O and N2 under aerobic conditions. Apportioning N2O to these source oxidation-reduction processes is a challenging task. A better understanding of the N2O processes is, however, required in order to improve mitigation strategies [3].

Considerable NO3- reduction is possible, especially in agricultural areas with high N fertilizer inputs. Dinitrogen (N2), the main gaseous component of Earth’s atmosphere, is the final product of this process, and thus the quantification of groundwater N2 arising from