International Journal of Science and Advanced Technology (ISSN 2221-8386) http://www.ijsat.com
Volume 1 No 10 December 2011
Evaluation of porosity in some paddy and non paddy soils by image analysis technique Alireza Raheb Soil Science Department, College of Agriculture and Natural Resource, University of Tehran, Karaj-Iran Email:
[email protected] Abstract—Evaluation of soil porosity employing micromorphology and image analysis can provide a better understanding of the peculiar behavior of paddy and non paddy soils. Eight pedons (13 thin section) located at the station of Rice Research Institution of Iran, (Mzandaran, Northern Iran) with longtime rice cultivation land use, which one of them has recently changed to kiwi fruit cultivation, were described and sampled for disturbed and undisturbed samples. Images were taken from each sample and were analysed using two techniques consisting of Image J and Olympus AnalySIS software for evaluation of porosity and recognition of plow pan by image analysis. Micromorphological and image analysis results indicated that due to unsaturated condition at the upper layers and high biological activities, pore volume in kiwi pedons is higher than paddy soil pedons. Also image analysis results of two softwares prove that exist of hardpan in the studied paddy soils. Results showed that AnalySIS software (r2=0.59) compared to the Image J (r2=0.49) high accuracy in image analysis. Keywords- Kiwi; Micromorphology; Rice; Thin section.
I.
INTRODUCTION
Porosity is the fraction of the total soil volume that is not occupied by solid material [5].The characterization of pore space is a vital and fruitful aspect of soil investigation. Liquid, solid, and gas constituents of the soil govern the form and development of pores, whose character in turn profoundly influences the nature and behavior of the soil. Management practices in agriculture as well as meteorological factors, amelioration, and root and earthworm activity, induce changes in soil porosity [7, 8, 14]. Soil macroporosity is also a well-known factor influencing soil fertility, gas exchange, and water movement [6, 7]. Pore size plays a key role in various proposed means of quantifying soil structure. It also has a major practical role in the prediction of hydraulic properties. New pore-size concepts, measurement techniques, and relations to transport phenomena are likely to remain a major emphasis in the study of soil [3, 5]. Conventional tillage and planting method for rice production in northern Iran is wet tillage and manual transplanting [13].
Ahmad Heidari Soil Science Department, College of Agriculture and Natural Resource, University of Tehran, Karaj-Iran Email:
[email protected] During the secondary tillage, farmers mix water and soil (puddling) to prepare land for transplanting rice seedlings [13, 15] and reduce water percolation during the growing period. Rice crop in paddy field requires a good puddled soil condition to create a favorable physico-chemical and microbiological environment for normal growth [8]. Seasonal cycles of puddling (wet tillage) and drying, over the long term, lead to the formation of hardpans or plow pans in paddy soils. A plow pan is a subsurface horizon or soil layer having a high bulk density and a lower total porosity than the soil directly above or below it as a result of pressure applied by normal tillage operations, such as plows, discs, and other tillage implements [14]. Image analysis and image processing applications in soil science have gained increasing acceptance over the last 40 years. The development of sophisticated computer systems that provide fast, easy handling and processing of complicated data make these applications much more successful and attractive [9. 10]. The use of image analysis techniques to characterize soil pore space is finding growing acceptance. Traditionally, pore space has been described and evaluated visually in the field, estimated indirectly from measurements of various soil physical properties, or manually measured in thin sections [11, 12]. Visual evaluation is only qualitative and is limited by the resolution of the naked eye. Indirect estimation of pore space characteristics through measurements of soil physical properties fails in many cases to produce true values because of problems such as sample disturbance, especially in poorly aggregated sandy soils [12]. The development of image acquisition and image analysis techniques provides new opportunities for quantitative analysis in micromorphology, for example, void space [10]. Image analysis of thin sections or soil blocks has been used to quantify soil pore size distribution and structure, and to characterize the irregularity, orientation and shape of soil pores [6, 9]. This technique allows a quantitative evaluation of soil features that are usually established in the field using the naked eye [2, 3, 11]. Thorough understandings of the nature of soil porosity and identity of hard pan in paddy soils increase our knowledge on crop production and maintenance of soil quality for sustainable agriculture. Compared with the surface soil, a plow pan has higher bulk density and less porosity. Therefore,
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International Journal of Science and Advanced Technology (ISSN 2221-8386) http://www.ijsat.com assessment of pores and its quantitative in the soil is extremely important to increase the product in wet lands especially paddy soils under rice cultivation. Thus, the aim of the present research was to evaluate the pores using two techniques of image analysis, in paddy soils with hardpan and non paddy soils in northern Iran, discover which one of these two techniques, the accuracy is higher and recognition of puddled layer and its underlying plow pan by image analysis techniques. II. A.
MATERIALS AND METHODS
Study Region and Field Sampling
This study examined paddy and non-paddy soils (recently changed to kiwi fruit cultivation) (about 10 ha) obtained from the Rice Research Institute of Iran (36º51΄53΄΄ to 36º51΄48΄΄ northern latitudes and 50º46΄56΄΄ to 50º46΄44΄΄ eastern longitudes, 20 m below sea level) (Figure 1). Mean annual precipitation in this region is 1253 mm, and mean annual air temperature is 15.8 ºC. Soil moisture and temperature regimes, calculated according to the Newhall Simulation Model were udic and thermic respectively. Eight pedons were dug, described and sampled for disturbed and undisturbed samples. B.
Physical analysis
Determination of routine soil physical properties was performed according to standard methods. To measure the variation of bulk density with depth, undisturbed soil samples were also taken by a cylindrical sampler. C.
Volume 1 No 10 December 2011
Figure1. Map of studied region in Mazandaran province, northern Iran.
III.
Table 1 shows the image analysis results of soil porosity by two techniques in some thin section of paddy and non paddy soils and their bulk density results in some of studied thin section. An example of the voids image analysis by two software and have shown in Figure 2 and 3. TABLE 1. Mean of total porosity by two techniques of image analysis in some thin section Pedon No.
Horizon
Depth (cm)
Micromorphological analysis
Undisturbed soil samples dried at oven dry and room temperature for 4 weeks .then samples were impregnated with a mixture of polyester resin (500ml), 14 drops of catalyst (peroxide 50%), and 7 drops of accelerator (cobalt). Acetone (500ml) was added to this mixture to decrease the viscosity [2]. The blocks of hardened soils were mounted on 75-100 mm frosted microscope slides, cut to by diamondedged saw, then polished to about 20-30 µm thickness initially by polishing Machine, followed by hand polishing. Thin sections were studied under the polarizan microscope (Olympus BX51) and described according to Bullock et al. (1985) and Stoops (2003). Thirteen sample of thin section from 25 were selected for image analysis. An average of 12-15 images were taken from each sample and Olympus AnalySIS and Image J software was used for quantification of total porosity at several separated parts of thin sections and their averages were reported for each thin sections.
RESULTS AND DISCUSSION
2 3 4 5 5 5 6 6 7 7
Bg Btg2 2Bg2 Apg Btg1 3Bg2 Apg Bg Apg Bg1
8 8 9
Ap Bg1 Btg1
Mean of total porosity % AnalySIS
Paddy soils 7.77 7.78 10.18 13.05 14.11 9.17 9.41 9.24 12.45 8.03 Kiwi fruit 6-10 13.82 15-22 13.64 38-45 13.04 80-90 75-85 55-65 6-12 20-25 85-95 8-15 25-35 8-15 25-35
Image J
B.D gr/cm3
19.52 13.78 15.15 15.38 21.53 31.06 15.73 15.33 17.89 12.8
1.53 0.92 1.18 0.85 1.19 0.71 1.06
15.7 16 16.37
-
Average high percentage of pores in the paddy soils thin sections to the samples of kiwifruit cultivated clearly is indicates that the soil drainage in the soil under kiwi cultivation due to unsaturated condition at the upper layers and high biological activities is more suitable than the paddy soils. Voids image analysis results of the first and second horizon pedons No.6 and 7 clearly illustrate with increasing depth voids are reduced (especially in pedon No.7) (Table 1), while the bulk density is increased with increasing depth in these
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International Journal of Science and Advanced Technology (ISSN 2221-8386) http://www.ijsat.com samples. Figure 2 and 3 also show a significant reduction of total porosity in two different depths of profiles 7 (8-15 and 25-35 cm) .These results prove that exist of hardpan or plow pan in the studied paddy soils. The plow pan refers to compacted subsoil that is 5-10 cm thick at depth of 10-40 cm from the soil surface. Density of soil is considered the most important physical properties of agricultural soils especially for plow pan of paddy field. Behera et al. (2007) stated that bulk density of puddled soil was higher than unpuddled soil. The effect of puddling on bulk density depends on soil aggregation before puddling [13, 15]. Mousavi et al. (2009) reported that bulk density increases linearly as puddling intensity increases.
Volume 1 No 10 December 2011
Figure 3. A: original image void of Bg1 horizon pedon No.7
Figure 2. A: original image void of Apg horizon pedon No.7 Figure 3. B: void image analysis of Bg1 horizon pedon No.7analysis by Olympus AnalySIS software
Figure 2. B: void image analysis of Apg horizon pedon No.7analysis by Olympus AnalySIS software Figure 3. C: void image analysis of Bg1 horizon pedon No.7analysis by Image J software
Figure 2. C: void image analysis of Apg horizon pedon No.7analysis by Image J software
Statistical analysis of the results indicates a relationship between the percentages of voids by AnalySIS software and bulk density (r2 = 0.59) (Figure 4). Higher correlation between these two parameters on the results of image analysis with AnalySIS (r2 = 0.59) compared to the results of the Image J (r2 = 0.49) showed high accuracy in the AnalySIS software. Mohammadi et al. (2011) in study of voids image analysis in compacted and incompacted forest soils in northern Iran by image tools software, stated that percent of pores, pore size and shape of pores in the compacted soils is very different with another forest soils.
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International Journal of Science and Advanced Technology (ISSN 2221-8386) http://www.ijsat.com [6]
Mean void area (%)
20
Image J: y = -6.8022x + 21.917 R² = 0.486
[7]
16 [8]
12 8
[9] AnalySIS: y = -6.745x + 16.207 R² = 0.5881
4
[10]
0 0
0.4
0.8 Bulk Density (gr/cm3) image J
1.2
1.6 [11]
AnalySIS
Figure 4. Relationship between bulk density and mean void area in two techniques in studied thin section
[12]
[13]
IV.
CONCLUSION
The aim of this paper was to recognition of puddled layer and its underlying plow pan by image analysis techniques and evaluates the extent to which image analysis could be applied to measure change in void space on soil thin sections from paddy and non paddy soils by two image analysis softwares. The importance of micromorphological methods in special using image analysis techniques for characterization of soil properties is a growing field in soil genesis and classification studies which can be a useful source of data beside the other methods. Moving from descriptive pedological studies and soil profile descriptions consist of qualitative characteristics such as porosity to a more quantitative science is needed, resulting in data more amenable to image analysis. The use of image analysis techniques may help to better understand the particular behavior exhibit by soil porosity such as soil fertility, soil air, and water movement. Image analysis results prove that exist of hardpan or plow pan in the studied paddy soils due to with increasing depth, voids are reduced, while the bulk density is increased with increasing depth in some thin section.
[14]
[15]
Volume 1 No 10 December 2011
M. L. Thompson, P. Singh, S. Corak, and W. E. Straszheim, ―Cautionary notes for the automated analysis of soil pore-space images‖, Geoderma, vol. 53, 1992, pp.399-415. P. Bullock, N. Federoff, A. Jongerius, G. Stoops, T. Tursina, and U. Babel, ―Handbook for soil thin section description‖, Wainer Research Pub., Wolverhampton, U. K., 1985. P. M. C. Bruneau, D. A. Davidson, and I. C. Grieve, ―An evaluation of image analysis for measuring changes in void space and excremental features on soil thin sections in an upland grassland soil‖, Geoderma, vol. 120, 2004, pp.165–175. R. Bouabid, E. A. Nater, and P. Barak, ―Measurement of pore size distribution in alamellar Bt horizon using epifluorescence microscopy and image analysis‖, Geoderma, vol. 53, 1992, pp. 309-328. R. J. Walter, and M. W. Berns, ―Digital image processing and analysis‖, in: Video Microscopy, S. Inoue, Ed., Plenum Press, New York, NY, 1986, pp. 327-392. R. Protz, M. J. Hipitalo, A. R. Mermut, and C. A. Fox, ―Image Analysis of Soils - Present and Future‖, Geoderma, vol. 40, 1987, pp.115-125. R. Protz, S. J. Sweeney, and C. A. Fox, ―An application of spectral image analysis to soil micromorphology, 1. Methods of analysis‖, Geoderma, vol. 53, 1992, pp.275-287. S. F. Mousavi, S. Yousefi-Moghadam, B. Mostafazadeh-Fard, A. Hemmat, and M. R. Yazdani, ―Effect of puddling intensity on physical properties of a silty clay soil under laboratory and field conditions‖, Paddy Water Environ ,vol. 7, 2009, pp.45–54. T. Glab, ―Application of image analysis for soil macropore characterization according to pore diameter‖, Int. Agrophysics, vol. 21, 2007, pp.61-66. Z. Mohammadi, M. Akef, R. Naghdi, I. Bagheri, and A. R. Sayyadi, ―Comparison of percentage of porosity in compacted and incompacted forest soils by image analysis‖, 12th Iranian Soil Science congress, Tabriz, 2011 (in persian).
REFERENCES [1]
[2] [3] [4]
[5]
B. K. Behera, B. P. Varshney, and S. Swain, ―Effect of puddling on physical properties of soil and rice yield‖, Agric. Mech. Asia Afr. Lat. Am., vol. 38, 2007, pp. 23–28. C. P. Murphy, ―Thin Section Preparation of Soils and Sediments‖, A B Academic Publ., Berkhamsted, 1986. E. N. Bui, ―Applications of image analysis to soil micromorphology‖, Agriculture, Ecosystems and Environment, vol. 34, 1991, pp.305-313. G. Stoops, V. Marcelino, and F. Mees, ―Interpretation of Micromorphological Features of Soils and Regoliths‖. SSSA. Madison, WI, p 752, 2003. J. R. Nimmo, ―Porosity and pore size distribution‖, in Encyclopedia of soils in the environment, vol. 3, D. Hillel, Ed. Academic Press, Columbia University, New York, USA, 2005, pp.295-303.
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