Abstract

The stock assessment of organic carbon and total nitrogen in the soil in addition to their relationships with site characteristics is of major importance whether at local, regional or global scale. The improvement of pedotransfer functions for these stocks evaluation in soils is a key for sustainability of agro-systems, especially in erodible systems of Mediterranean semi-arid areas. This work aimed to study relationships between total nitrogen stocks and other physico-chemical properties of clayey and sandy soils of Tunisian database and to do this, we used pedotransfer functions and structural equations modeling. For modeling total nitrogen stocks, two Tunisian soil databases composed from 450 horizons of clayey soils and 602 horizons of sandy soils were used. The optimal models of nitrogen stocks were given by two significant pedotransfer functions: (i) that of clayey soils with a standard error of prediction of 18.51 and associated p-value of 0.000 and (ii) that of sandy soils with a standard error of prediction of 5.76 and associated p-value of 0.016. Then, we perform a path analysis using structural equations modeling and Bayesian analysis to investigate simultaneously the interactions between the different components of the soil properties and their relationships with total nitrogen stocks. Results show that, in both soil types, the stock of total nitrogen is always controlled in the same way; it is significantly linked to chemical properties and bulk density more than by physical properties. The root mean square errors of the approximations were 0.080 and 0.043 for the clayey and sandy models, respectively.

Keywords:

Mediterranean region, modeling, nitrogen stock, path analysis,

References

1. Batjes, N.H., 1996. Total carbon and nitrogen in the soils of the world. Eur. J. Soil Sci., 47(2): 151-163.
   CrossRef    Direct Link
2. Bedison, J.E. and A.H. Johnson, 2009. Controls on the spatial pattern of carbon and nitrogen storage in Adirondack forest soils along a gradient of nitrogen deposition. Soil Sci. Soc. Am. J., 73: 2105-2117.
   CrossRef    
3. Belkhodja, K., L. Bortoli, J.P. Cointepas, P. Dimanche, A. Fournet, J.C. Jacquinet and A. Mori, 1973. Soils of Tunisia. Ministry of Agriculture of Tunisia-Division Sols.
   Direct Link
4. Benites, V.M., L.O.A. Machado, C.C. Fidalgo, M.R. Coelho and B.E. Madari, 2007. Pedotransfer functions for estimating soil bulk density from existing soil survey reports in Brazil. Geoderma, 139(1-2): 90-97.
   CrossRef    
5. Bentler, P.M., 1989. EQS Structural Equations, Program Manual. BMDP Statistical Software, Los Angeles, CA.
   
6. Bentler, P.M., 1990. Comparative fit indexes in structural models. Psychol. Bull., 107(2): 238-246.
   CrossRef    PMid:2320703    
7. Bentler, P.M., 1992. On the fit of models to covariances and methodology to the bulletin. Psychol. Bull., 112(3): 400-404.
   CrossRef    PMid:1438635    
8. Bernoux, M., D. Arrouays, C. Cerri, B. Volkoff and C. Jolivet, 1998. Bulk densities of Brazilian Amazon soils related to other soil properties. Soil Sci. Soc. Am. J., 62(3): 743-749.
   CrossRef    
9. Bernoux, M., M.C.S. Carvalho, B. Volkoff and C.C. Cerri, 2002. Brazil's soil carbon stocks. Soil Sci. Soc. Am. J., 66(3): 888-896.
   CrossRef    
10. Brahim, N., T. Gallali and M. Bernoux, 2011a. Carbon stock by soils and departments in Tunisia. J. Appl. Sci., 11(1): 46-55.
    CrossRef    
11. Brahim, N., M. Bernoux and T. Gallali, 2012. Pedotransfer functions to estimate soil bulk density for Northern Africa: Tunisia case. J. Arid. Environ., 81: 77-83.
    CrossRef    
12. Brahim, N., M. Bernoux, D. Blavet and T. Gallali, 2010. Tunisian soil organic carbon stocks. Int. J. Soil Sci., 5(1): 34-40.
    CrossRef    
13. Brahim, N., D. Blavet, T. Gallali and M. Bernoux, 2011b. Application of structural equation modeling for assessing relationships between organic carbon and soil properties under clayey and sandy soils at semi-arid Mediterranean region. Int. J. Environ. Sci. Tech., 8(2): 305-320.
    CrossRef    
14. Browne, M.W. and R. Cudeck, 1989. Single sample crossvalidation indices for covariance structures. Multivar. Behav. Res., 24(4): 445-455.
    CrossRef    PMid:26753509    
15. Browne, M.W. and R. Cudeck, 1993. Alternative ways of assessing model fit. Sociol. Method Res., 21(2): 230-258.
    CrossRef    
16. Byrne, B.M., 2009. Structural Equation Modeling with AMOS Basic Concepts, Applications and Programming. 2nd Edn., Routledge Taylor and Francis Group.
    
17. Crowley, S.L. and X. Fan, 1997. Structural equation modeling: Basic concepts and applications in personality assessment research. J. Pers. Assess., 68(3): 508-31.
    CrossRef    PMid:9170298    
18. Fan, X., B. Thompson and L. Wang, 1999. Effects of sample size, estimation methods and model specification on structural equation modeling fit indexes. Struct. Equ. Modeling, 6(1): 56-83.
    CrossRef    
19. Feller, C. and M.H. Beare, 1997. Physical control of soil organic matter dynamics in the tropics. Geoderma, 79: 69-116.
    CrossRef    
20. Feller, C., A. Albrecht and D. Tessier, 1996. Aggregation and Organic Matter Storage in Kaolinitic and Smectitic Tropical Soils. In: Carter, M.R. and D.A. Stewart (Eds.), Structure and Organic Matter Storage in Agricultural Soils. Lewis Publishers, CRC Press, Boca Raton, Florida, pp: 309-359.
    
21. Hassink, J., 1997. The capacity of soils to physically protect organic C and N. Plant Soil, 191: 77-87.
    CrossRef    
22. Hu, L.T. and P.M. Bentler, 1999. Cutoff criteria for fit indexes in covariance structure analysis: Conventional criteria versus new alternatives. Struct. Equ. Modeling, 6(1): 1-55.
    CrossRef    
23. Ibrahim, H., N. Brahim and T. Gallali, 2009. Test digital mapping the distribution of nitrogen in soils of Tunisia. National day management of stock in organic soils. Le Kef, Tunisia June 4, (French).
    
24. James, L.R., S.A. Mulaik and J.M. Brett, 1982. Causal Analysis: Assumptions, Models and Data. Beverly Hills, Sage, CA.
    
25. Jones, C.A., 1983. Effect of soil texture on critical bulk densities for root growth. Soil Sci. Soc. Am. J., 47: 1208-1211.
    CrossRef    
26. Kenny, D.A. and D.B. McCoach, 2003. Effect of the number of variables on measures of fit in structural equation modeling. Struct. Equ. Modeling, 10(3): 333-51.
    CrossRef    
27. Ladd, J.N., L. Jocteur-Monrozier and M. Amato, 1992. Carbon turnover and nitrogen transformations in an alfisol and vertisol amended with [U-14C] glucose and [15N] ammonium sulfate. Soil Biol. Biochem., 24: 359-371.
    CrossRef    
28. Lentzsh, P., R. Wieland and S. Wirth, 2005. Application of multiple regression and neural network approaches for landscape scale assessment of soil microbial biomass. Soil Biol. Biochem., 37: 1577-1580.
    CrossRef    
29. MacCallum, R.C., M.W. Browne and H.M. Sugawara, 1996. Power analysis and determination of sample size for covariance structure modeling. Psychol. Methods, 1(2): 130-49.
    CrossRef    
30. Marsh, H.W., K.T. Hau and Z. Wen, 2004. In search of golden rules: Comment on hypothesis-testing approaches to setting cutoff values for fit indexes and dangers in over generalizing Hu and Bentler's findings. Struct. Equ. Modeling, 11(3): 320-341.
    CrossRef    
31. Miles, J. and M. Shevlin, 2007. A time and a place for incremental fit indices. Pers. Iindiv. Differ., 42(5): 869-74.
    CrossRef    
32. Mishra, U., D.A.N. Ussiri and R. Lal, 2010. Tillage effects on soil organic carbon storage and dynamics in Corn Belt of Ohio USA. Soil Till. Res., 107: 88-96.
    CrossRef    
33. Mulaik, S.A., L.R. James, J. Vanaltine, N. Bennett, S. Lind and C.D. Stilwell, 1989. Evaluation of goodness-of-fit indices for structural equation models. Psychol. Bull., 105(3): 430-445.
    CrossRef    
34. Pandey, C., G.B. Singh, S.K. Singh and R.K. Singh, 2010. Soil nitrogen and microbial biomass carbon dynamics in native forests and derived agricultural land uses in a humid tropical climate of India. Plant Soil, 333: 453-467.
    CrossRef    
35. Pansu, M. and J. Gautheyrou, 2006. Handbook of Soil Analysis: Mineralogical Organic and Inorganic Methods. Springer, Berlin, pp: 993.
    CrossRef    
36. Pansu, M., Z. Sallih and P. Bottner, 1997. Modelling of soil nitrogen froms after organic amendments under controlled conditions. Soil Biol. Biochem., 30: 19-29.
    CrossRef    
37. Schoenholtz, S.H., H. Van Miegroet and J.A. Burger, 2000. A review of chemical and physical properties as indicators of forest soil quality: Challenges and opportunities. Forest Ecol. Manage., 138: 335-356.
    CrossRef    
38. Sharma, S., S. Mukherjee, A. Kumar and W.R. Dillon, 2005. A simulation study to investigate the use of cutoff values for assessing model fit in covariance structure models. J. Bus. Res., 58(1): 935-943.
    CrossRef    
39. Six, J., C. Feller, K. Denef, S.M. Ogle, J.C. Moraes and A. Albrecht, 2002. Soil organic matter, biota and aggregation in temperate and tropical soils effects of no-tillage. Agronomie, 22: 755-775.
    CrossRef    
40. Smith, P., 2004. Carbon sequestration in croplands: the potential in Europe and the global context. Eur. J. Agron., 20(3): 229-236.
    CrossRef    
41. Sorensen, L.H., 1971. Stabilization of newly formed amino acid metabolites in soil by clay minerals. Soil Sci., 114: 5-11.
    CrossRef    
42. Steiger, J.H., 2007. Understanding the limitations of global fit assessment in structural equation modeling. Pers. Iindiv. Differ., 42(5): 893-98.
    CrossRef    
43. Tabachnick, B.G. and L.S. Fidell, 2007. Using Multivariate Statistics. 5th Edn., Allyn and Bacon, New York.
    PMCid:PMC2724990    
44. Torn, M.S., S.E. Trumbore, O.A. Chadwick, P.M. Vitousek and D.M. Hendricks, 1997. Mineral control of soil organic carbon storage and turnover. Nature, 389: 170-173.
    CrossRef    
45. Trasar-Cepeda, C., C. Leiros, F. Gil-Sortes and S. Seona, 1998. Towards a biochemical quality index for soils: An expression relating several biological and biochemical properties. Biol. Fert. Soils, 26: 100-106.
    CrossRef    
46. Wang, S., X. Wang and Z. Ouyang, 2012. Effects of land use, climate, topography and soil properties on regional soil organic carbon and total nitrogen in the upstream watershed of miyun reservoir, North China. J. Environ. Sci., 24(3): 387-395.
    CrossRef    
47. Wheaton, B., B. Muthen, D.F. Alwin and G. Summers, 1977. Assessing reliability and stability in panel models. Sociol. Methodol., 8(1): 84-136.
    CrossRef    

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