Spatial variability of Soil fertility using soil chemical data, Atrush area, Duhok, Kurdistan region, Iraq

Lida I., Omar A.O. Rekani, Vahil I. H. Barwari, Sipal M. Taher

Department of Soil and Water Sciences, Faculty of Agriculture and Forestry, University of Duhok



One of the basic factors in sustainable crop production is enhancing soil quality based on the soil fertility and returning absorbed nutrition by plants to the soil. In this spatial research variability of soil properties in Atrush area in Duhok province, Iraq was conducted based on the 15 soil samples with randomized method were taken from different locations. Statistical analysis by SPSS and spatial distribution and interpolation of soil properties by GS+softwarewas done. Results showed all studied soil parameters such as pH, EC, %OM, percent of sand, silt and clay, %total N, available P and K hadanormal distribution. Strong spatial dependence related tothepercent of organic matter, sand and clay percent, percent of total nitrogen, available phosphorus and potassium while pH, EC, and percent of silt showed moderate spatial dependence. The variogram model were spherical for pH, EC, %OM, %clay and % total nitrogen while for sand percent and available P were linear and for available K and percent of silt were exponential. Spatial interpolation accuracy and precision by MAE, MBE and RMSE showedKriging prediction maps for pH, EC, %OM, %N, and available K had most accurate predictions with the lowest error, therefore, it can provide useful information about urban planning and environmental management.

Key Words:
Geostatistics, Semi-variogram, Soil properties, spatial variability


[1] Backett PHT and Webster R. "Soil variability: A review". Soil Fert Vol.34, pp 1-15, (1971).

[2] Dahiya IS, Richter J, and Malik RS. "Soil spatial variability:A review". Int J Trop Agric Vol.11, pp 1-102, (1984).

[3] Yost RS and Fox RL."Partitioning variation in soil chemical properties of some Andepts using soil taxonomy". Soil SciSoc Am J Vol. 45, pp 373-377, (1981).

[4] Jafarzadeh AA, Dawatgar N and Hakaimian M. "Investigation normality of selected soil variables in different physiographic units in Khazar Sea".Tabriz agriculture journal.Vol 8, pp. 147-170. (1998).

[5] QuineTA, and Zhang Y. "An investigation of spatial variation in soil erosion, soil properties and crop production within an agricultural field in Devon, UKJ". Soil and Water Cons Vol. 57, pp 50- 60, (2002).

[6] Yemefack M, RossiterDG and yomgang RN."Multi-scale characterization of soil variability within an agricultural landscape mosaic system in southern Cameroon".Geoderma Vol.125, pp 117- 143, (2005).

[7] Sun Bo, Shengiu Zhou, Qiguo Zhao. "Evaluation of spatial and temporal changes of soil quality based on geostatistical analysis in the region of subtropical China". Geoderma Vol.115, pp 85-99, (2003).

[8] Mohammadi J. "Evaluation and mapping of soil salinity hazard in Ramhormoz area (Khuzestan) using disjunctive kriging". Journal of Agricultural Research Vol. 25, pp 45-57, (2000).

[9] Cetin M and Kirda C. "Spatial and temporal changes of soil salinity in a cotton field irrigated with low-quality water". J Hydrol Vol. 272, pp 238-249, (2003).

[10]Young FJ, Hammer RD and Larsen D. "Freqency distribution of soil properties on a loessmanted Missouri watershed". Soil SciSoc Am J Vol. 63, pp 178-185, (1999).

[11]Wang YQ, Zhang XC, Zhang JL and Shun-Ji LI. "Spatial variability of soil organic carbon in a watershed on the loess Plateau".Pedosphere Vol.19, pp 486-495, (2009).

[12]Ghasemi VR, Shahbazi K, MohammadiJ and Mashayekhi HM. "Spatial variability of some soil fertility properties in the north part of Khuzestan plain". 8th soil science congress, Rasht, Iran. (2003).

[13]Bouyouscos, G. J. "Hydrometer method improved for making particle size analyses of soils". Agronomy Journal, Vol. 54, pp 464-465, (1962).

[14] Walkley A, Black IJ. "An examination of the Degtjaref method for determining organic carbon in soils: effect of variations in digestion conditions and of inorganic soil constituents". Soil Sci. Vol. 63, pp 251–263, (1934).

[15]Olsen SR and Sommers LE. Phospharous, Al, Miller RH and Keeney DR (Eds). "Methods of Soil Analysis. Part 2", Soil SciSoc of Am. Madison, WI , pp 403-427, (1986).

[16]Godwin, R. J., and Miller, P. "A review of the technologies for mapping within- field variability". Biosystems Engineering, Vol. 84, pp 393-407, (2003).

[17]Cambarrdella CA, Moorman TB, Novak JM, Parkin TB, Karlen DL, Turco RF and Konopka AE."Field-scale variability of soil properties in central Iowa soils". Soil Sci. Soc Am J Vol. 58, pp 1501-1511, (1994).

[18]Tesfahunegn G.B., L. Tamene, P.L.G. Vlek. "Catchment-scale spatial variability of soil properties and implications on site-specific soil management in northern Ethiopia".Soil Till. Res. Vol.117, pp 124-139. (2011).