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PHYSICAL AND CHEMICAL SOIL PROPERTIES OF ORCHID GROWING AREAS IN EASTERN TURKEY.

Byline: S. Ors - Email: seldaors@atauni.edu.tr) U. Sahin, S. Ercisli and A. Esitken

ABSTRACT

The aim of this study was to determine and characterize some physical and chemical soil properties of orchid growing areas in Eastern Turkey and to evaluate the differences in soil properties according to orchid species (Dactylorhiza spp., Orchis spp.). A total of 36 soil samples from different orchid growing areas were collected and analyzed based on water retention characteristics, pore size distribution, bulk density, electrical conductivity (EC), pH, organic matter, carbonates and micro elements. The results showed that physical and chemical parameters of soils did not vary regards to orchid species. The amount of water retained at the low tensions (100 mm diameter) supply drainage and aeration, the mesopores (100-30 mm diameter) supply water conductivity, and the micropores (30-3 mm diameter) supply water retention. The water retained in ultramicropores (<3 mm diameter) is unavailable for plant use.

On the other hand, the increase in cultivation intensity with the increasing demand for higher yields and better quality has resulted in increasing demand for micro elements. Plant productivity has increased along the years due to genetic development and selection of high yielding cultivars. These cultivars with intensive cultivation methods were found to remove higher quantities of micro elements from the soil, leading to deficiencies occurring in many soils (Ergene, 1993). Therefore evaluation of microelements in different soils is very meaningful.

MATERIALS AND METHODS

In this study, a total of 36 soil samples where orchids grown from different parts of Eastern Anatolia of Turkey were sampled. The site, coordinates, species of orchids and altitude of sample collection areas were shown in Table 1. The soil samples in each area were collected from effective root deepth of orchid plants (30 cm).

The soil water characteristic curve (pF curve) was determined using pressures plates (Klute, 1986), and was used as the basis for the calculation of the pore size distribution. Water held at 0.001 MPa, 0.01 MPa, 0.03 MPa, 0.10 Mpa and 1.5 MPa was obtained when water output stopped for a given suction. Porosity was estimated according to Danielson and Sutherland (1986) by using bulk densities and specific gravities of soils and bulk density was determined by the cylinder method (Blake and Hartge, 1986), on samples packed by dropping the sample cylinders from a height of 10 cm for 20 times.

Electrical conductivity was determined by an EC-meter in saturation extract (Rhoades, 1996), pH by a pH-meter in saturation extract (Mc Lean, 1982), organic matter using the Smith-Weldon method (Nelson and Sommers, 1982) and carbonates by the calcimeter method (Nelson, 1982). Micro elements (Cu, Fe, Zn, Cd, Pb, Cr and Mn) contents of soils were determined with extraction and analyzed using an atomic absorption spectrophotometer according to Lindsay and Norvell (1978).

Analysis of variance (ANOVA) for the data of pore size distribution, amounts of moisture retained in different tensions, bulk density and soil chemical properties was done. (Steel et al., 1997).

RESULTS AND DISCUSSION

In the field expedition, it was noticed that terrestrial orchids were more populated in the wet meadows, bogs, heath land and in areas sparsely populated by trees.

Some physical and chemical properties of soils in orchids growing areas are shown in table 2 and 3, respectively. There were significant differences (p<0.01) in data of all of the researched characteristics.

The water retention capacity values at the low tensions (<0.03 MPa) of the orchids growing areas soils was between 20.24% and 57.43% (Table 2). These values were higher than 25% for 34 growing area soils. The highest and lowest water retention capacity values of soils between tensions of 0.03-1.5 MPa were 30.96% and 5.15%, respectively, and the values of 30 growing areas soils were between 10% and 20%. The bulk density values of soils varied from 0.19 g cm-3 to 1.01 g cm-3 (Table 2). The maximum and minimum macropores (<100 mm) values were obtained as 36.85% and 13.79%, respectively. These values were higher than 20% for 20 growing areas soils. For suitable air volume in soils, it is suggested that the macropores be greater than 20% (Sahin and Anapali, 2006). The maximum values were determined as 15.26% for mesopores (100-30 mm), as 27.75% for micropores (30-3 mm) and as 41.69% for ultramicropores (<3 mm).

The minimum mesopores, micropores and ultramicropores values were determined as 0.77%, as 1.30% and as 21.66%, respectively. The ultra micro pores values were higher than 30% for 20 growing area soils. Lower bulk density and higher amount of moisture retained at the low tensions (<0.03 MPa) of orchid soils could be explained by the high organic matter in these soils (Table 3). In addition, the pore size distribution could be affected by mineralization of organic matter.

The electrical conductivity EC values of the soils were found to be between 0.47 dSm-1 and 2.97 dS m-1 (Table 3). The EC values of 35 growing areas soils were lower than 2.00. According to the USDA Natural Resources Conservation Service (NRCS), there was no salinity problem in the soils analyzed (Soil Survey Staff,1993). The pH of soil samples varied from 5.71 to 7.81. Orchids can be classified within horticultural plants and most of the horticultural plants prefer a pH around 6.50 (Agaoglu et al., 1995). Organic matter content on the soils searched was between 1.06% and 38.96% (Table 3). The organic matter was higher than 4.1% for 28 areas. Therefore, much of the investigated soils of orchid growing areas could be classified into high organic matter soils (Sezen, 1995).

Table 1: The site, coordinates and altitude of orchids growing areas in Turkey

Area No.###Site###Coordinates###Altitude (m) Orchid species

###1###Ilica-Erzurum###39o 56 N' ; 41o 04 E'###1756###Dactylorhiza spp., Orchis spp.

###2###Ilica-Erzurum###39o 56 N' ; 41o 02 E'###1751###Dactylorhiza spp.

###3###Ilica-Erzurum###39o 56 N' ; 40o 58 E'###1750###Dactylorhiza spp.

###4###Ilica-Erzurum###39o 54 N' ; 40o 53 E'###1710###Dactylorhiza spp.

###5###Kandilli-Erzurum###39o 54 N' ; 40o 48 E'###1698###Dactylorhiza spp.

###6###Dumlu-Erzurum###40o 02 N' ; 41o 20 E'###1774###Dactylorhiza spp.

###7###Dumlu-Erzurum###40o 02 N' ; 41o 20 E'###1779###Dactylorhiza spp.

###8###Dumlu-Erzurum###40o 04 N' ; 41o 21 E'###1811###Dactylorhiza spp., Orchis spp.

###9###Tafta-Erzurum###40o 05 N' ; 41o 22 E'###1831###Dactylorhiza spp., Orchis spp.

###10###Karagobek-Erzurum###40o 09 N' ; 41o 25 E'###1963###Dactylorhiza spp.

###11###Karagobek-Erzurum###40o 10 N' ; 41o 26 E'###2007###Dactylorhiza spp., Orchis spp.

###12###Guzelyayla-Erzurum###40o 12 N' ; 41o 28 E'###2099###Dactylorhiza spp.

###13###Askale-Erzurum###39o 56 N' ; 40o 47 E'###1698###Dactylorhiza spp.

###14###Askale-Erzumm###39o 56 N' ; 40o 45 E'###1690###Dactylorhiza spp., Orchis spp.

###15###Askale-Erzurum###39o 56 N' ; 40o 36 E'###1626###Dactylorhiza spp., Orchis spp.

###16###Pirnakapan-Askale###39o 59 N' ; 40o 33 E'###1818###Dactylorhiza spp.

###17###Kop-Bayburt###40o 02 N' ; 40o 31E'###2376###Dactylorhiza spp.

###18###Nenehatun-Erzurum###39o 57 N' ; 41o 24 E'###1864###Dactylorhiza spp.

###19###Nenehatun-Erzurum###39o 58 N' ; 41o 25 E'###1839###Dactylorhiza spp., Orchis spp.

###20###Nenehatun-Erzumm###39o 58 N' ; 41o 28 E'###1810###Dactylorhiza spp., Orchis spp.

###21###Koprukoy-Erzurum###40o 01 N' ; 41o 59 E'###1583###Dactylorhiza spp., Orchis spp.

###22###Horasan-Erzurum###40o 05 N' ; 42o 19 E'###1522###Orchis spp.

###23###Tasliguney-Cat###39o 46 N' ; 41o 02 E'###2132###Dactylorhiza spp.

###24###Tasliguney-Cat###39o 43 N' ; 40o 58 E'###2242###Dactylorhiza spp.

###25###Cat-Erzurum###39o 36 N' ; 40o 58 E'###1909###Orchis spp.

###26###Cat-Erzurum###39o 36 N' ; 40o 58 E'###1894###Orchis spp.

###27###Karliova-Bingol###39o 35 N' ; 40o 55 E'###1865###Orchis spp.

###28###Karliova-Bingol###39o 33 N' ; 40o 55 E'###1792###Orchis spp.

###29###Yagan-Erzurum###39o 53 N' ; 41o 57 E'###1772###Orchis spp.

###30###Guzelhisar-Erzurum###39o 49 N' ; 41o 59 E'###1934###Dactylorhiza spp., Orchis spp.

###31###Hinis-Erzurum###39o 38 N' ; 41o 56 E'###2022###Dactylorhiza spp.

###32###Hinis-Erzurum###39o 36 N' ; 41o 54 E'###2053###Dactylorhiza spp.

###33###Hinis-Erzurum###39o 35 N' ; 41o 45 E'###1857###Orchis spp, Dactylorhiza spp.

###34###Hinis-Erzurum###39o 23 N' ; 41o 41 E'###1650###Orchis spp, Dactylorhiza spp.

###35###Hinis-Erzurum###39o 34 N' ; 41o 44 E'###1856###Orchis spp, Dactylorhiza spp.

###36###Yagan-Erzurum###39o 47 N' ; 41o 47 E'###1760###Orchis spp

Table 2: The amount of moisture retained at different tensions (% of volume), bulk density (gs) and pore size distribution (%) of soils in orchids growing areas in Eastern Turkey

Area No.###Tensions (Mpa)###Ys###Pore Size (tim)

###Less Than 0.03###0.03-1.5###(g cm3) Greater Than 100###100-30###30-3 Less Than 3

1###36.79###9.69###0.81###25.25###3.42###11.28###26.30

2###29.08###13.58###0.74###18.84###9.18###4.36###34.65

3###31.66###14.25###0.75###23.11###7.21###4.79###32.67

4###37.71###10.69###0.78###27.39###9.22###1.30###29.41

5###35.19###12.73###0.82###25.66###6.58###3.59###30.06

6###29.98###11.95###0.82###16.87###2.74###13.16###31.76

7###33.61###12.04###0.86###16.98###1.61###17.98###27.59

8###29.16###10.66###0.91###16.22###2.81###12.14###30.89

9###35.64###10.75###0.74###21.03###9.33###9.03###28.15

10###39.98###17.47###0.34###25.90###1.30###19.72###33.64

11###28.42###14.36###0.76###17.97###5.30###11.38###32.32

12###40.68###11.53###0.74###31.39###6.05###6.65###25.29

13###30.91###9.46###0.79###22.95###2.94###10.56###31.00

14###27.39###9.62###0.84###18.63###5.75###9.07###31.52

15###40.54###5.15###0.47###21.42###11.15###11.80###32.76

16###57.43###11.37###0.24###36.85###14.32###9.54###25.71

17###31.32###14.41###0.68###18.98###4.14###13.48###33.38

18###30.24###13.21###0.66###18.24###5.40###12.09###35.08

19###49.89###20.54###0.19###30.93###13.56###11.81###32.30

20###20.24###18.60###0.75###14.80###0.77###10.25###41.69

21###30.82###13.33###0.85###23.69###3.19###8.07###30.74

22###45.88###30.96###0.19###32.37###6.60###27.75###21.66

23###37.44###10.71###0.71###29.05###3.75###6.89###30.36

24###33.04###14.11###0.64###18.81###9.37###11.17###29.52

25###32.12###11.80###0.72###21.25###7.22###7.06###32.55

26###25.17###15.89###0.72###13.79###8.21###8.62###37.17

27###34.95###13.18###1.00###24.85###6.60###6.66###22.75

28###31.76###12.35###0.81###21.94###7.89###7.30###28.32

29###40.64###17.36###0.45###17.11###15.26###13.38###33.37

30###40.71###9.65###0.77###27.46###9.44###8.12###23.76

31###39.01###12.12###0.57###23.59###9.78###11.55###29.67

32###31.39###13.32###0.78###18.79###7.46###12.08###29.66

33###35.30###14.02###0.79###22.61###7.35###9.28###26.03

34###29.08###12.38###0.83###17.72###7.86###8.84###28.47

35###25.64###13.56###0.78###15.02###5.26###10.97###32.77

36###23.73###12.61###1.01###15.29###3.62###10.22###25.16

###4.22###1.62###0.03###5.35###2.01###2.73###2.05

Table 3: chemical properties of soils in orchids growing areas in Eastern Turkey

Area###EC###pH###Organic###Matter CaCO3###

Number (dS m-1)###(%)###(%)###Micro Elements (ppm)

###Cu###Fe###Zn###Cd###Pb###Cr###Mn

1###1.32###7.42###5.38###24.03###1.41###6.74###0.69###0.04###0.97###4.19###5.54

2###1.46###7.04###7.38###14.34###2.95###4.98###0.71###0.05###1.28###2.31###4.98

3###1.69###7.34###6.94###13.63###5.01###7.43###0.54###0.05###1.37###1.87###14.03

4###0.90###7.37###4.34###7.44###3.09###5.92###0.09###0.02###0.66###2.26###0.00

5###1.10###7.33###3.77###5.71###2.07###6.23###0.01###0.04###0.68###3.23###13.24

6###0.95###7.60###2.09###4.88###1.70###3.89###0.04###0.03###0.98###2.29###3.50

7###0.84###7.38###4.56###3.06###1.65###4.13###0.13###0.06###1.00###8.36###3.06

8###0.74###7.63###3.25###12.90###1.14###4.25###0.00###0.06###1.31###4.72###5.67

9###0.81###7.46###7.66###6.88###2.90###4.04###0.08###0.08###1.27###2.75###4.67

10###0.91###6.56###17.29###1.25###0.13###47.43###0.08###0.07###0.99###4.36###5.09

11###0.88###7.29###4.75###11.49###3.48###5.03###0.02###0.07###0.99###6.50###12.95

12###0.89###7.53###6.04###16.27###2.65###10.12###0.00###0.05###0.97###5.09###2.79

13###1.90###6.86###4.48###23.90###3.92###15.14###0.00###0.03###0.96###2.37###5.67

14###1.21###6.84###3.94###18.94###2.63###7.90###0.00###0.05###1.11###5.28###4.13

15###0.97###6.89###25.80###7.10###3.66###20.17###0.14###0.06###1.16###6.99###3.34

16###1.31###7,19###34.92###0.78###0.60###24.27###0.02###0.03###0.99###6.65###15.89

17###1.22###7.10###6.53###1.54###4.98###8.00###0.46###0.05###1.24###3.15###15.95

18###0.98###7.22###8.72###13.57###2.50###5.00###0.00###0.12###0.98###6.32###13.98

19###0.89###6.81###38.96###1.49###0.11###105.75###0.01###0.03###1.16###4.34###2.52

20###1.46###7.81###5.00###6.76###3.17###4.56###0.02###0.04###1.36###5.27###0.00

21###0.90###7.46###2.19###5.03###3.77###6.10###0.00###0.04###1.66###4.71###4.30

22###0.47###5.71###33.52###1.09###0.00###131.61###0.03###0.03###1.20###2.82###2.26

23###1.18###6.83###8.82###0.31###4.14###52.82###0.01###0.11###1.43###6.96###16.41

24###2.97###6.95###10.39###11.44###2.65###20.35###0.18###0.12###1.89###5.61###14.00

25###1.52###6.57###7.03###0.71###1.95###8.31###0.02###0.08###1.58###5.46###14.87

26###0.96###6.91###4.88###0.44###4.18###9.65###0.22###0.11###1.59###2.86###14.80

27###1.15###7.53###1.06###36.60###0.23###5.06###0.06###0.05###1.05###2.76###2.09

28###1.18###7.25###4.44###14.02###2.94###6.15###0.12###0.05###1.68###6.03###4.03

29###1.93###7.00###15.33###20.72###2.53###17.62###0.32###0.04###1.91###8.65###12.78

30###0.69###6.78###5.24###0.71###1.14###36.00###0.16###0.05###1.40###6.20###16.57

31###1.54###6.94###14.09###17.69###3.89###18.86###0.41###0.11###2.40###5.46###15.63

32###1.40###7.22###3.48###19.85###3.00###4.79###0.12###0.04###2.55###6.93###5.16

33###0.81###7.46###4.58###5.16###3.14###15.57###0.18###0.06###2.19###6.37###14.43

34###1.09###7.23###3.74###12.99###2.38###5.50###0.17###0.05###2.93###7.50###4.31

35###0.72###7.44###6.46###14.98###3.84###5.73###0.24###0.06###2.58###6.76###12.70

36###0.48###7.54###5.21###43.50###0.71###4.02###0.11###0.05###2.10###6.99###2.81

LSD 0.01.0.36###0.03###0.22###1.33###0.67###2.65###0.04###0.03###0.26###1.43###0.52

soils (Sezen, 1995). The highest and lowest carbonate values were obtained as 43.50 % and 0.31% (Table 3). According to the analysis results, carbonate values of orchid growing areas soils were higher than 5.0% for 25 area soils. Therefore, these soils could be classified as medium, high and very high carbonates include groups (Ergene, 1993).

The statistical differences among the growing areas soils was observed based on Cu, Fe, Zn, Cd, Pb, Cr and Mn contents (Table 3). The Cu, Fe, Zn, Cd, Pb, Cr and Mn values of soil searched were between 0.0 ppm and 5.01 ppm, 3.89 ppm and 131.61 ppm, 0.0 ppm and 0.71 ppm, 0.02 ppm and 0.12 ppm, 0.66 ppm and 2.93 ppm, 1.87 ppm and 8.65 ppm and 0.0 ppm and 16.57 ppm, respectively. The significance of micro elements for plant growth and development is well documented in literature (Ergene, 1993).

Conclusion:

The Chemical and physical analyses of the soils did not show any distinguishable results in relation to orchid species, but in altitude of locations. It was noticed that higher altitudes of more than 2000 m were not suitable for the Orchis spp. whereas the Dactylorhiza spp. was not affected. According to these results, it could be concluded that the type of mycorrhizae in the soil and climate factors of region are more effective in orchid species distribution than soil characteristics.

REFERENCES

Agaoglu, Y. S., H. Celik, M. Celik, Y. Fidan, Y. Gulsen, A. Gunay, N. Halloran, A. I. Koksal, and R. Yanmaz (1995). General Horticulture (in Turkish). Ankara University, Agricultural Faculty, No. 4, Ankara.Ari, E., O. Karaguzel, K. Onal, I. Polat, and M. Gocmen (2005). Phylogenetic relationship of Turkish terrestrial orchids. Acta Horticulturae. 673: 155-160.Bruckner, U. (1997). Physical properties of different potting media and substrate mixtures- especially air-and water capacity. Acta Horticulturae. 450:263-270.Blake, G. R., and K. H. Hartge (1986). Bulk density. In: Methods of Soil Analysis, Part 1, Physical and Mineralogical Methods, eds. A. Klute , Soil Science Society of America Inc, Madison, Wisconsin.Caron, J., and V. K. N. Nkongolo (1999). Aeration in growing media: Recent developments. Acta Horticulturae. 481: 545-551.Danielson, R. E. and P. L. Sutherland (1986).

Porosity. In: Methods of Soil Analysis, Part 1, Physical and Mineralogical Methods, eds. A. Klute, Soil Science Society of America Inc, Madison, Wisconsin.Ergene, A. (1993). Principles of Soil Science (in Turkish).Ataturk University, Agricultural Faculty, No.267, Erzurum.Esitken, A., S. Ercisli, C. Eken and D. Tay (2004). Seed priming effect on symbiotic germination and seedling development of Orchis palustris jacq. HortScience. 39: 1700-1701.Esitken, A., S. Ercisli and C. Eken (2005). Effects of mycorrhiza isolates on symbiotic germination of terrestrial orchids (Orchis palustris Jacq. and Serapias vomeracea subsp vomeracea (Burm.f.) Briq.) in Turkey. Symbiosis. 38: 59-68. Klute, A. (1986). Water Retention: Laboratory Methods. In: Methods of Soil Analysis, Part 1, Physical and Mineralogical Methods, eds. A. Klute, Soil Science Society of America Inc, Madison, Wisconsin. Korkut, A.B. (1998). Flower Production Techniques (in Turkish).

Hasad Yayincilik, No. 221, Istanbul. Lindsay, W.L., and W.A. Norvell (1978). Development of a DTPA soil test for zinc, iron, manganese, and copper. Soil Sci. Society of America Journal.42: 421-428. Mc Lean, E.O. (1982). Soil pH and Lime Requirement. In: Methods of Soil Analysis, Part 2, Chemical and Microbiological Properties, eds. A.L. Page, Soil Sci. Society of America Inc, Madison, Wisconsin.Nelson, R.E. (1982). Carbonate and Gypsum. In: Methods of Soil Analysis, Part 2, Chemical and Microbiological Properties, eds. A.L. Page, Soil Sci. Society of America Inc, Wisconsin.Nelson, D.W., and L.E. Sommers (1982). Total Carbon, Organic Carbon, and Organic Matter. In: Methods of Soil Analysis, Part 2, Chemical and Microbiological Properties, eds. A.L. Page, Soil Science Society of America Inc, Madison, Wisconsin, USA.Orozco, R., R.S. Gschwander, and O. Marfa (1997).Substrate classification from particle size analysis.

Acta Horticulturae. 450: 397-403.Pillon, Y., M.F. Faya, A.B. Shipunova, M.W. Chasea (2006). Species diversity versus phylogenetic diversity: A practical study in the taxonomically difficult genus Dactylorhiza (Orchidaceae), Biological Conservation 129: 4 -13.Rhoades, J.D. (1996). Salinity: Electrical conductivity and total dissolved solids. In: Methods of Soil Analysis, Part 3, Chemical Methods, eds. D.L. Sparks, Soil Science Society of America Inc, Madison, Wisconsin.Sahin, U., O. Anapali, and S. Ercisli (2002). Physico- chemical and physical properties of some substrates used in horticulture. Gartenbauwissenschaft 67(2): 55-60.

Sahin, U., S. Ors, S. Ercisli, O. Anapali and A. Esitken (2005). Effect of pumice amendment on physical soil properties and strawberry plant growth. J. Central European Agric. 6(3): 361-366.Sahin, U., and O. Anapali (2006). Addition of pumice affects physical properties of soil used for container grown plants. Agriculturae Conspectus Scientificus. 71(2): 59-64.Schlegel, M., G. Streinbruck, and K. Hahn (1989).Interspecific Relationship of European Orchid Species as Revealed by Enzyme Electrophoresis. Plant Systematics and Evolution. 163: 107- 119.

Sezen, Y. (1995). Soil Chemistry (in Turkish). Ataturk University, Agricultural Faculty, No. 322, Erzurum. Sezik, E. (2002). Turkish orchids and Salep. Acta Pharmaceutica Turcica 44, 151-157.Soil Survey Staff. (1993). Soil Survey Manual, Handbook 18. USDA, NRCS. U.S. Gov. Print. Off., Washington, D.C.Steel, R.G.D., J.H. Torrie and D.A. Dickey (1997).Principles and procedures of statistics. A Biometerical Approach. 3rd Ed. Mc Graw Hill Book Company. Inc. New York USA.

Ataturk University, Faculty of Agriculture, Department of Agricultural Structures and Irrigation, Ataturk University, Faculty of Agriculture, Department of Horticulture, 25240 Erzurum, Turkey.

Ataturk University, Faculty of Agriculture, Department of Agricultural Structures and Irrigation, Ataturk University, Faculty of Agriculture, Department of Horticulture, 25240 Erzurum, Turkey.
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Author:Ors, S.; Sahin, U.; Esitken, A.
Publication:Journal of Animal and Plant Sciences
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Date:Mar 31, 2011
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