Determination of potassium and magnesium status of

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Determination of potassium and magnesium status of soils using different soil extraction procedures in the upper part of mesopotamia (in the Harran plain) a

a

Ibrahim Ortas , Nuri Güzel & Hayriye Ibrikçi a

a

Department of Soil Science, Faculty of Agriculture, The University of Cukurova, Adana, Turkey Published online: 11 Nov 2008.

To cite this article: Ibrahim Ortas , Nuri Güzel & Hayriye Ibrikçi (1999): Determination of potassium and magnesium status of soils using different soil extraction procedures in the upper part of mesopotamia (in the Harran plain), Communications in Soil Science and Plant Analysis, 30:19-20, 2607-2625 To link to this article: http://dx.doi.org/10.1080/00103629909370400

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COMMUN. SOIL SCI. PLANTANAL., 30(19&20), 2607-2625 (1999)

Determination of Potassium and Magnesium Status of Soils Using Different Soil Extraction Procedures in the Upper Part of Mesopotamia (in the Harran Plain) Ibrahim Ortas, Nuri Güzel, and Hayriye Ibrikçi Department of Soil Science, Faculty of Agriculture, The University of Cukurova, Adana, Turkey

ABSTRACT It is a common belief that most o f the Turkish soils are rich in potassium (K) and magnesium (Mg) for crop production and that there is no crop response to fertilization of these nutrients. However, it is currently a common agricultural practice by farmers to use an excess amount o f K and, in some instances, Mg fertilizers especially for horticultural cash crops. Two biological (pot and Neubauer experiments) and four chemical extraction methods (0.3 N HCl, 0.5 N HCl, 1 N NH4OAc, and 0.5 N NaHCO3) were employed to measure the amounts of extractable K and Mg in the selected ten soil series of Harran Plain (Fertile Crescent) in the upper part of the Mesopotamia area. Italian grass (Lolium italicum) and barley (Hordeum vulgare L.) were used as test plants in the pot and Neubauer experiments, respectively. The amount of slowly available K extracted using four chemical extraction methods were much higher in two soil series (Ekinyazi and Akçakale) than that of the other soil series. The Akçakale series had more slowly available Mg than the other soil series. Total amounts of slowly available K extracted with both of the biological, and 0.3 N HCl and 1 N NH4OAc chemical extraction methods

2607 Copyright © 1999 by Marcel Dekker, Inc.

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2608

ORTAS, GÜZEL, AND IBRIKÇI

were found statistically significant at 1% level. Correlation coefficients between the biological and chemical methods were calculated. As the number of grass harvests increased, percentage of K content decreased and Mg content increased in plant dry matter. At the last harvest, K content of the soils depleted, whereas Mg content nearly did not change. According to index grouping, Italian grass grown in the pots did not need K and Mg fertilization.


INTRODUCTION Ancient records show that evidence of very early civilization began in the Mesopotamia Plain which is rich in soil and water resources (Hillel, 1994), and situated between the Tigers and Euphrates rivers. The Harran Plain, called a 'Fertile Crescent', is located in the upper part of the Mesopotamia Plain (Figure 1). Early written evidence also showed that the Harran Plain has been under the crop cultivation since 10,000-4,000 B.C. Since crop production in the area has been done without K and Mg fertilizers for thousands of years, it was worthwhile to study the changes of K and Mg status of the common soil series. There is often a poor relationship between the plant growth response and extractable nutrients in the soil. According to Marschner (1995), soil chemical analysis mainly provide indication of the capacity of a soil to supply nutrients to the plants, but do not give any information about plant and other soil parameters. For practical purposes, determination of extractable K and Mg levels in soils gave very useful information compared to plant uptake values. Soil analysis methods have been tested over many years to obtain a suitable index of K and Mg availability of soils (Rowell, 1994; Jones, 1998). Potassium and Mg uptake by plants depend on the change of ionic equilibrium in soils (Conyers and McLean, 1969; Mengel and Kirkby, 1987). Current interest in K and Mg fertility o f a soil is the measurement of extractable and soil-solution K and Mg which can be directly provided to the plants (Oliveira et a l , 1971; Atalay et al., 1986; Güzel and Kaya, 1991). Exchangeable K and Mg are known as short-term available nutrients; when depleted by crops, they replenish from non-exchangeable and mineral sources to the soil solution (Rowell, 1994; Tisdale et al., 1985; Mengel and Kirkby, 1987; Karamanos, 1980). Therefore, it is very important to know K and Mg supplying capacity of the soils for long-term soil fertility and fertilizer applications. Nonexchangeable K is probably associated mainly with layer silicate minerals and is slowly released to replenish the exchangeable form of K to support plant growth. Mengel and Kirkby (1987) and Rowell (1994) reported that behavior of Mg in soils was similar to that of K which was controlled by the type of clay minerals. As it is well known, when concentration of K in soil solution increases, uptake of Mg by plant considerably decreases. Adams and Henderson (1962) stated that a high amount of K in the soil caused a decline in uptake of Mg by sudangrass and

DETERMINATION OF POTASSIUM AND MAGNESIUM STATUS

fe^r-

2609

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*"V


Tigris J MESOPOTAMIA Harran Plain i^T

[SYRIA FIGURE 1.

....--• r

,,

Soil samples were taken from Harran Plain (upper part of Mesopotamia).

alfalfa. McNaught et al. (1973) also found a stronger antagonistic K by Mg interaction in grasses than the other plant varieties. Atalay et al. (1986) used several chemical extraction methods including 0.3 NKCl, 0.5 NHCl, and 0.5 J V N H 4 O A C compared to pot and the Neubauer experiments for evaluating available K in the western part of Turkey. Similarly, Simonis and Nemeth (1985) used 28 different extractants (including 0.5 AfNaHCO3) from the 21 Northern Greece soils. In both reports it has been shown that there is a significant correlation between K availability and cumulative K uptake. Since there is a significant effect o f K on or relationship to the Mg concentration in plant tissues (Murphy, 1980) and soil solution (Tisdale et al., 1985), it was of great interest to know whether K extraction methods could be used for Mg extraction. Although the concentration o f Mg+2 in soil solution was higher than that o f K + , plant uptake of Mg was lower than K uptake per unit of dry matter and root length (Tisdale et al., 1985). According to Mengel and Kirkby (1987), Mg uptake may have been seriously affected by excess K. uptake as a result o f cation competition. Since it is a general belief that most of the soils in Harran Plain are rich in K and Mg contents for crop production, K and Mg fertilization is not recommended. However, very recently with intensive crop production, it has been a common agricultural practice by farmers to use a substantial amount o f K and Mg fertilizers,

to

TABLE 1.

Selected physical and chemical properties of soils.

Soil series

Soil classification

Harran Bozyazi Begdes Kissas

Sirrin

Akçakale Karabayir Ekinyazi GOrgelen Alcören

Sand

Vertic Calciorthid 14.3 Lithic Torriorthent 1.8 Lithic Torriorthent 8.4 Typic Torrcrt 8.7 Vertic Camborthid 8.8 Typic Torrcrt 1.4 Vertic Calciorthid 10.9 Typic Calciorthid 28.9 16.8 Typic Calciorthid Typic Calciorthid 27.4

•Source: Kapuretal.(1991).

Silt 32.4 44.5 47.3 31.3 33.7 39.1 33.6 24.1 40.7 40.2

Clay 53.3 53.7 44.3 60.0 57.5 59.5 55.5 47.0 42.5 32.4

Clav mjneral* Kaol. Illit+Palyg. Verm. Smectite PH — °A) • • • - • • • • • • • • • » • - — 15.0 16.0 27.0 11.0 16.0 25.0

8.0 24.0 20.0 20.0

28.0 17.0 17.0 29.0 16.0 32.0 13.0 29.0 38.0 46.0

11.0 18.0 11.0 14.0 0.0 19.0 22.0 44.0 9.0 0.0

46.0 49.0 45.0 46.0 68.0 24.0 50.7 3.00 33.0 34.0

7.3 7.4 7.4 7.4 7.2 7.4 7.4 7.4 7.4 7.1

Organic matter

CaCOj 30.2 35.5 16.2 35.7 25.5 20.5 23.0 18.7 25.6 34.9

CEC Cmolc kg-1

0/

0.9 1.3 2.4 1.9 0.8 1.5 0.4 0.8 1.6 0.7

35.0 49.5 55.1 37.8 37.3 47.1 48.5 23.5 24.5 34.5

> y o

iÜZEL, AND IBRIKÇ


o


2611


especially for horticultural crops. The area will be under irrigation in the near future and will receive more fertilizers. Thus, it is important to know K and Mg sources and ability of soils for a crop production in the long term. It is also important to know which soil extraction method is more suitable for determination of reserve or slowly available K and Mg. The objectives of the study were a) to determine K and Mg status of the Harran Plain soils, b) to compare four chemical extraction methods to determine slowly available K and Mg, and c) to calibrate extractable K and Mg with plant uptake. MATERIALS AND METHODS Representative soil samples from ten common soil series (Dine et al., 1991) were collected from 0 to 20 cm depth (Figure 1) and were used for soil extractions and pot studies. Soil Analysis Selected physical and chemical properties of the soils were determined (Page et al., 1932) and data are given in Table 1. Prior to seeding and after harvest, exchangeable K and Mg were also extracted using 1 N NH4OAc. The selected four chemical extraction methods shown in Table 2 were employed to extract slowly available K and Mg. Since reserve-soil K and Mg cannot be obtained with one extraction because of buffer power, a sequence o f six extractions were performed on the same soils. Potassium and Mg content o f the extractants were determined using atomic absorption spectrophotometer. Biological Method Used to Extract Potassium and Magnesium Pot Experiment A 3,500-g air-dried soil sample from each soil series was mixed with 1,000 g of quartz sand and placed in plastic pots. Nitrogen (2 g N pot 1 as urea) and P (0.5 g P2O5 pot1 as TSP) were added to soil-sand mixture. Italian grass (Lolium italicum) was seeded to the soil at a rate o f 0.5 mg seed kg 1 soil. The experiment was arranged in a randomized complete block design in three replications. During the growing period, the pots were periodically irrigated with deionized water. The pot experiment was carried out for 6 months and plant tops were harvested four times (at 8, 12, 16, and 20 weeks after sowing).

Neubauer Pot Experiment One-hundred g of air-dried soil sample of the soil series were placed in small plastic pots. A hundred barley (Hordeum vulgäre L.) seeds were planted and grown for 17 days.

2612


TABLE 2. Chemical extraction procedures used for determination of K and Mg.


Soihsolution Shaking Extraction solution ratio time (h) 1/10 1/2 0.3NHC1 0.5 N HC1 1/10 1/2 1.0NNH4OAc 1/10 1/2 0.5NNaHCOj 1/20 1/2

Reference (Atalayetal., 1986) (Karamanos, 1980; Atalay et al., 1986) (Karamanos, 1980; Atalay et al., 1986) (Adams and Henderson, 1962; Simonis and Nemeth, 1985)

Plant Analysis Harvested above-ground plant parts o f both pot experiments were dried at 65°C and ground for chemical analysis. Plant materials were ashed at about 550°C and the residues were dissolved in 3.3% HC1. The contents o f K and Mg were determined using a fiamephotometer. Estimation of Plant Available Potassium and Magnesium Uptake Estimation of plant available K and Mg uptake have been calculated by using differences between total plant uptake and exchangeable nutrient content. The calculation was done as follows. Plant available exchangeable K or Mg=exchangeable K or Mg before seedingexchangeable K or Mg after harvest. Since total uptake of K or Mg was higher than plant available K or Mg, it was assumed that the rest of the uptake had come from the slowly available sources (shown later in Tables 5 and 6). RESULTS Extractable Potassium Extractable soil K values were 191 to 218, 143 to 207, 44 to 114, and 274 to 342 mg 100 g 1 soil for the extraction procedures o f 0.5 NUCl, 0.3 NHCl, 1 N NH4OAc, and 0.5 iV~NaHCO3, respectively (Figure 2). The amounts of measured cumulative K values were considerably higher with 0.5 N NaHCO3 extraction than that of the other three methods. It increased linearly with increasing extraction numbers. Exchangeable K gradually increased in the first three extractions when 1 ArNH4OAc extractant was used, but no additional stimulation of extractable K value was obtained as the number of extractions increased. Potassium values in 0.5 N HCI and 0.3 N HC1 extractant were gradually increased with increasing number of extracts. The results indicated that the highest amount of total reserve K was received from the Ekinyazi soil, which was of the highest exchangeable K and the lowest from the Akören series (Figure 2 a and c).

DETERMINATION OF POTASSIUM AND MAGNESIUM STATUS 0.5NHCI


250

A

250 T

2613

0.3NHCI

»

— m ~ Bozyazi

Harran

•~~2i~" Begdas

—H~ Kisas

—W—Sinn

— • — Akçakale

—1—Karabayir

— — Eklnyazl

CUrglltn

II

111

IV

V

Number of Extractions

II

B

III

••••••• Akären

IV

V

VI


FIGURE 2. Cumulative extracted K in successive six extraction times by different extraction methods.

Extractable Magnesium Extractable Mg was determined within the same extent o f K extractions. In all the methods, cumulative Mg gradually increased with increasing number o f extractions (Figure 3). However, cumulative Mg did not increase in 0.3 NUCl methods after the extraction number 5. Akçakale soil gave higher extractable Mg compared to other soil samples in all the extraction methods. There was a positive, but non-significant correlation between the amounts o f Mg extracted by different methods and Mg taken up by plants (Table 3). No

2614



400T

—•—Bozyazi —«—KIMS Sinn

—•—AKçakal«

Karabayir GQraelen

IM

IV


V

II

III

ERlnyaa —•—AJtören

IV

V


FIGURE 3. Cumulative extracted Mg in successive six extraction times by different extraction methods.

significant correlations were found between the total amounts of slowly available Mg uptake by plants and the chemically extracted Mg. In addition, there was no significant relation between the total amounts of dry matter produced and the plant Mg uptake.


TABLE 3. Correlation between soil and plant parameters which were measured in three methods (the first number is correlation value and second number is probability). XI* 1.000 0.7466 0.0131 X3 0.8656 0.0012 X4 0.7345 0.0155 X5 0.5407 0.1066 X6 0.5368 0.1096 X7 0.7713 0.0090 X8 0.5591 0.0929 X9 0.1469 0.6855 X10 0.7899 0.0066 Xll 0.3395 0.3371 X12 0.6294 0.0512 X13 0.7818 0.0075 X14 0.1994 0.5807

XI X2

X2

X3

X4

X5

X6

X7

X8

X9

X10

Xll

X12

X13

X14

1.000 0.8199 0.0037 0.6607 0.0030 0.4361 0.2076 0.1965 0.6396 0.4771 0.1632 0.6283 0.0517 0.1982 0.9420 0.7366 0.0115 0.2995 0.4005 0.7638 0.0101 0.7561 0.0115 0.3384 0.3386

1.000 0.9321 0.0001 0.3678 0.2956 0.1480 0.6831 0.5250 0.1191 0.6467 0.0433 0.1263 0.7280 0.7942 0.0061 0.1198 0.7412 0.6145 0.0587 0.8623 0.0013 0.2639 0.4612

1.000 0.3460 0.3274 -0.1335 0.7129 0.3379 0.3395 0.5816 0.0776 -0.3865 0.2699 0.5937 0.0692 -0.4360 0.9048 0.3258 0.3582 0.7172 0.0195 -0.0098 0.9784

1.000 0.2926 0.4120 0.4077 0.2421 0.6511 0.0414 0.4326 0.2112 0.0642 0.6802 -0.0365 0.9202 0.0451 0.9015 0.0917 0.8015 -0.1302 0.7199

1.000 0.6996 0.0243 0.1768 0.6249 0.6250 0.0536 0.4279 02173 0.4963 0.1445 0.5962 0.0684 0.2608 0.4665 0.3088 0.3856

1.000 0.3233 1.000 0.3457 0.3747 0.2837 1.000 0.2724 0.4268 0.6032 0.2032 -0.0225 1.000 0.0648 0.5734 0.9509 0.1566 -0.2538 0.0421 0.5571 0.8956 0.4702 0.9079 0.0945 0.2369 0.2423 0.3177 0.8914 0.5098 0.5005 0.5520 0.0005 0.5577 0.2885 -0.1650 0.9653 0.0939 0.4189 0.6484 0.0001 0.4253 0.0318 0.3736 0.5850 0.2205 0.9302 0.2875 0.0775

1.000 0.5393 0.1073 0.4505 0.1913 0.2746 0.4426

1.000 0.8091 0.0004 0.6792 0.0308

1.000 0.5149 0.1284

1.000

*Xl=0.3 N HCl extractable K, X2=0.5 A^HCl extractable K, X 3 = l ArNH4 OAc extractable K, X4=0.5 tfNaHCOj extractable K, X5=0.3 N HCl extractable Mg, X6=0.5 N HCl extractable Mg, X 7 = l N NH4OAc extractable Mg, X8=0.5 JV NaHCO3 extractable Mg, X9=dry matter of Italian grass, X10=uptake of K from Italian grass, X I I=uptake of Mg from Italian grass, X12=dry matter o f barley, X13=uptake of K from barley, X14=uptake of Mg from barley.


2616 120 ••

110 -

§100

I90 £•80•o


; 70 ••

«

Harran

••••&••••

Begda;

—3K—Sinn —1—Karabayir Gürgelen

!60-

—M—Bozyazi • ~ K - Kisas — • — Akçakale • Ekinyazi ••••*•••• Ak6ren

so40 1

"Number of Harvests'"

IV

FIGURE 4. Dry matter production oîLolium italicum after four successive harvests.

Plant Dry Matter Cumulative amounts of grass dry matter in the pot experiment were slightly increased after first harvest (Figure 4). Ekinyazi and Akçakale soil series distinctionally produced the highest amount of dry matter than that of the other soils. Harran soil produced less dry matter. In the Neubauer experiment, Ekinyazi and Akçakale soil series also resulted in high amount of barley dry matter (Table 4). In both Neubauer (barley) and pot (grass) biological methods, plant growth seemed to be the same among the soils (Table 4 and Figure 4). Potassium and Magnesium Uptake by Plants Cumulative amount of K (mg 3,500 g 1 ) taken up from each soil with four successive cuttings of grass, and amount of potassium extracted from soils are shown at Figure 5 and Table 5. Cumulative K uptake was greater in Ekinyazi and Akçakale soils than that of other soils series. In all the soils, the concentration of extractable K decreased with increasing number of harvests. The opposite was true for Mg. Thus, as the concentration of K decreased, concentration of Mg increased with increasing harvest numbers (Figure 6). Ekinyazi and Akçakale soils resulted in higher K concentrations than the other series. Harran soil resulted in less % of K uptake among the ten soils. In all soils, plants took up a high amount of K from the soils in the first harvest, but declined through the successive harvests (Figure 6).


2617

TABLE 4. Barley dry matter production and K and Mg uptake in Neubauer experiment.


Soil scries Harran Bozyazi Begdes Kissas Sirrin

Akçakale Karabayir Ekinyazi Gtlrgelen Akören

Dry matter (gpor1)* 2.90±0.21 3.09±0.23 3.12±0.28 3.10±0.29 3.26±0.23 3.63±0.17 3.14±0.32 4.1Ü0.22 3.55±0.18 3.26±0.20

Potassium Magnesium Plant uptake Plant Plant Plant uptake content (%) (mg pot1) content (%) (mg pot1) 1.96 56.88 0.40 11.61 1.92 59.39 0.55 17.00 2.16 67.35 0.53 16.50 2.23 69.15 0.41 12.70 1.99 64.85 0.42 16.70 2.12 76.85 0.48 17.40 2.14 67.23 0.41 12.90 2.37 97.41 0.47 19.30 1.69 59.99 0.41 14.60 1.72 56.10 0.56 17.10

•Numbers are means of three replications; ± indicates standard error.

The amount of K uptake from the soils in the Neubauer pot experiment which varied from 56.1 in Akören to 97.4 mg 100 g 1 in Ekinyazi soil series (Table 4). Potassium content in plant tissue was also higher in Ekinyazi, Kissas, and Akçakale soils and the least in Akören soil. In both pot experiments, the test plants had taken up higher amounts of K in the Ekinyazi and Akçakale soils than that of the other series indicating that those are rich in exchangeable and slowly-available K than the other soil series. Uptake of Mg by plants in the pot experiment is shown in Figure 5 and Table 6. Cumulative Mg uptake was controversial to the K uptake, plants were took up more Mg from Akören and Bozyazi soils than the other soils, and Kissas soil resulted in less Mg uptake. Although there was a poor relationship between % Mg and cumulative Mg uptake, there was no clear definition in terms of Mg nutrition; and there was also a mass distribution in terms of cumulative Mg uptake between soils. In the Neubauer experiment, the plants grown in Akören, Bozyazi, and Begdes soils have higher Mg contents than the other soils. But, in terms of total uptake, Ekinyazi and Akçakale soils produced the highest amount of dry matter and the greatest amount of Mg was taken up by plants. Harran and Kissas soils resulted in less Mg uptake. DISCUSSION The results measured show that there is a relation between the exchangeable and the slowly available or non-exchangeable K in the soil. In addition, total


2618


»

Himn

—•—Bozyan ••••«••••KlMl —«—Akçakal* Pinyin •••Ekinyazi>Gtirgelen>Kissas> Harran>Karabayir>Bozyazi>Akören>Begdes>Sirrin. Data obtained in both pot experiments and chemical extraction methods were statistically analyzed. Correlation coefficients for the amounts of K extracted by plant of Neubauer and the other pot experiment (Lolium italicum) versus the amounts of K extracted by four different chemical methods were determined. The correlation between the amounts of K extracted by the Neubauer and pot experiments, and K extracted by the chemical methods were found statistically significant indicating that there was a considerable similarity between the amounts of K taken up by plants and that of K extracted by the chemical extraction (Table 3). A positive correlation was also found at 1% level between the amounts of K. extracted by plants in pot experiments and the chemical extraction with 0.3 N HC1 and 1 JVNH4OAc extradants (Conyers and McLean, 1969; Atalay et al., 1986).

Plant available Mg Total Mg uptake Slowly available %ofC2inDin % of D-C in D in soil (mg 3500 g1 soil) (mg 3500 g'1 soil) total taken from in total taken C=A-B exchangeable Mg from slowly available Mg After Cl C2 harvest in in (B) 100 g 3500 g D D-C 15.0 4.0 140.0 360 220.0 38.8 61.2 16.9 1.5 52.5 440 387.5 12.0 88.0 15.8 1.4 49.0 408 359.0 12.0 88.0 16.2 1.6 56.0 303 247.0 18.5 81.5 18.7 0.6 21.0 339 318.0 6.2 93.8 15.6 -1.2 42.0 448 444.0 8.6 91.4 16.2 -0.3 10.5 368 357.5 2.9 97.1 15.8 -2.2 77.0 627 550.0 12.3 87.7 14.4 1.4 49.0 364 315.0 13.5 86.5 13.2 5.5 192.5 491 262.0 39.2 60.3

Exchangeable Mg (mglOOg- 1 soil)*

Soil series

Before planting

(A) Harran Bozyazi Begdes Kissas Sirrin Akçakale Karabayir Ekinyazi Gürgelen Akören

19.0 18.4 17.2 17.8 19.3 15.6 16.2 15.8 15.8 18.7

z

2H 00 00

s Z

2 § oo H

ATUS


The amount of exchangeable and slowly exchangeable Mg in the soil and total Mg uptake by the plant.

DETERMINATIO:

TABLE 6.

*mgMg 100 g'1 soil.

bo

o

2622



The correlation between the amount o f K uptake by the plant from the exchangeable K source and the amount left in the soil after harvest was significant (r=0.785) at 1% level indicating that the level of the exchangeable K taken up by the plant was still high. Therefore, as the level of exchangeable K was depleted by the plant, it was replenished by reserve K through the equilibrium which occurred between two forms of K (Table 3). However, equilibrium between two forms of K was influenced by the level of slowly-available K and the rate of K released from this source (Cooke, 1982; Tisdale et al., 1985; Halvin and Westfall, 1985; Mengel and Kirkby, 1987; Marschner, 1995). As shown in Table 5, following harvest, exchangeable K decreased to 7 and 10 mg K 100 g 1 in Akçakale and Ekinyazi soil series which may indicate that levels of slowly available K and rates of K released in those soils compared to the other ones may be quite high resulting in replenishing the exchangeable forms of soil K. In comparison with those two soils, the level of slowly available K or rate of K release are much lower in the other ones especially the Sirrin, in which the plant absorbed only 9% of total K uptake from the reserve K, whereas 9 2 % and 9 1 % of total K uptake may originate from this source in Ekinyazi and Akçakale, respectively. It may be due to the different decreases in the levels of exchangeable K after growth period, which may be because of the differences in their clay and silt mineralogys, and in the rate of K released from slowly-available K form. Feigenbaum and Kafkafi (1972) found that the rate of K release from illite was sufficient to maintain relative plant growth. The results of Havlin and Westfall (1985) show that clay soils had a long-term supply of plant available K while light-textured soil did not. They also found that the K released was highly correlated to initial NH4OAc-K and to cumulative or relative K uptake and yield. Karamanos (1980) reported that exchangeable K was closely related to the amounts of mica, vermiculite, and montmorillonite. The results suggested that the clay fraction was responsible for the behavior of K and Mg exchange and consequently uptake of those nutrients. As a result of K depletion, the uptake of Mg was increased controversially (Figure 5). The uptake of K and Mg from the soils, which was expressed as cumulative uptake curves (Figure 5), indicated that when the numbers of grass cuttings increased, the uptake of K decreased and Mg uptake increased. This may be due to the effect of Mg release from the soil minerals around rhizosphere. The results of Hinsinger and Jaillard (1993) showed that release o f Mg became significant after several grass harvests. In all soils, the increasing number of grass harvests led to a reduction in K and slightly increased in Mg concentrations (Table 6) in soil solutions. It is a well-known fact that plants behave selectively in absorbing cations from soil solutions (Oliveira et al., 1971; Tisdale et al., 1985; Halvin and Westfall, 1985; Mengel and Kirkby, 1987;Rowell, 1994; Marschner, 1995) and that there are interactions among cations. Although amounts of Mg extracted by Lolium italicum ranges from 9.8 to 14 mg Mg 100 g 1 , amounts of Mg extracted by 0.5 and 0.3 HC1 and ammonium


2623

TABLE 7. Available K and Mg and K and Mg index groups.


Soil series

Harran Bozyazi Begdes Kissas Sirrin Akçekale Karabayir Ekinyazi Gürgelen Akören

Exchangeable (mg 100 g 1 ) before planting K Mg 19.0 62.0 70.0 18.4 78.0 17.2 66.0 17.8 78.0 19.3 71.0 15.6 70.0 16.2 76.0 15.8 43.0 15.8 51.0 18.7

Bulk density K/Mg gem 3 1.20 3.3 3.8 .17 4.5 1.23 3.7 1.27 4.0 .25 4.6 .15 4.3 1.20 4.8 1.39 2.7 .20 2.7 .40

Exchangeable before planting as (mg It"1)* K Mg 744 228 819 215 954 212 838 226 975 242 817 179 840 192 1056 220 516 190 714 262

Index group*» K/Mg K Mg 3.2 5 4 3.8 5 4 4.4 6 4 3.7 5 4 4.0 6 4 4.7 5 4 4.4 5 4 4.8 6 4 2.7 4 4 2.7 5 5

*mg ltr'=bulk density x exchangeable cation mg 100 g"1. ••Index level has been calculated on the basis of mg It"1 of soil.

acetate solutions vary from 100 to 240 and from 4.3 to 18.7 mg Mg 100 g 1 soil, respectively (Figure 3b). Values of 0.5 and 0.3 NRC\ Mg extraction were found much higher than that of 1 iVNH4OAc, which is closer to the amount extracted by Lolium italicum. On the other hand, the amounts of exchangeable Mg prior to the seeding and after harvest were measured. The data (Table 6) indicated that the little amounts of Mg being the lowest (10.5 mg) in Karabayir and the highest (193 mg) in Akören soils were absorbed from the exchangeable and rest of the total Mg uptake by the plant may originate from the reserved sources of Mg, which ranged from 61.2% in Harran (the lowest) and 97% in the Karabayir series. From these findings, it can be concluded that the soils in the Harran Plain, in general, are very rich of reserved and exchangeable Mg, although exchangeable Mg contents of Harran and Akören soils are very high, compared to the other soil series. There may be a relation to release of Mg by soils and their clay and silt mineralogy. According to easiness of Mg release from the slowly available form, the soils in the Harran Plain can be put in order as follows: Ekinyazi>Akçakale> Bozyazi>Begdes>Karabayir>Sirrin>Gürgelen>Kissas>Akören>Harran. When slowly-available K/Mg ratios in soils were compared to the ratios of total uptake of K and Mg in four harvests, the ratio seemed to be similar and high in the Begdes, Akçakale, Karabayir, and Ekinyazi soils. Levels of the available K and Mg prior to seeding were calculated based on Cooke's method (Cooke, 1982) and given in Table 7. According to Cooke (1982), K/Mg ratio must be taken into account, and the ratio was smaller than 4/1 in soils. As seen in Table 7, the K/Mg


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ratios ranged from 2.7 to 4.8 and the values obtained for available Mg according to Cooke (1982) can be classed as index 4. According to Maff (1986) and Cooke (1982), since K/Mg ratio was high in Ekinyazi, Akçakale, Karabayir, and Begdes soils, they were supposed to show Mg deficiency under crop production. Since the available K index in all the soil series studied can be placed in the sufficiency range, most of the cultural plants may not require K-fertilization under field conditions for some years. The results indicated that Mg contents o f soils studied were adequate for grass to be grown. However, levels o f the nutrients under consideration may become inadequate for some high-yielding field and vegetable crops requiring much more Mg under irrigated conditions in near feature.

REFERENCES Adams, F. and J.B. Henderson 1962. Magnesium availability as affected by deficient and adequate levels o f potassium and lime. Soil Sci. Soc. Am. Proc. 26:65-68. Atalay, I.Z., R. Kilinç, D. Anaç, and I. Yokus. 1986. Gediz Havzasi RedzinaTopraklarinin Potasyum Durumu ve bu Topraklardan Alinabilir Potasyum Miktarinin Tayininde Kullanilacak Yöntemler. pp. 1-25. Bilgehan Publishing, Izmir, Turkey. Conyers, E.S. and E.O. McLean. 1969. Plant uptake and chemical extraction for evaluation of potassium release characteristic o f soils. Soil Sci. Soc. Am. Proc. 33:226-230. Cooke, G.W. 1982. Fertilizer for Maximum Crops. p.271. 3rd ed. Granada Publishing, London, England. Dinç, U., S. Senol, M. Sayin, S. Kapur, K. Yilmaz, M. Sari, I. Yegingil, M.S. Yesilsoy, A.K. Çolak, H. Özbek, and E.E. Kara. 1991. The physical, chemical and biological properties and classification mapping o f soil o f the Harran Plain. pp. 1-10. In: U. Dinç and S. Kapur (eds.), Soils of the Harran Plain. Tübitak Publishing, Ankara, Turkey. Feigenbaum, S. and U. Kafkafi. 1972. The effect of illite content in soils on the potassium supply to plants. pp. 109-116. In: Proceedings of the 9th Colloquium of the International Potash Institute, Bern, Switzerland. Güzel, N. and Z. Kaya. 1991. Total slowly available and exchangeable potassium status of soils in the Harran Plain. pp. 39-46. In: U. Dinç and S. Kapur (eds.), Soils o f the Harran Plain. Tübitak Publishing, Ankara, Turkey. Halvin, J.L. and D.G. Westfall. 1985. Potassium release kinetics and plant response in calcareous soils. Soil Sci. Soc. Am. J . 49:366-370. Hillel, D. 1994. Rivers o f Eden: The struggle for water and the quest for peace in the Middle East. Oxford University Press, New York, NY.


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Hinsinger, P. and B . Jaillard. 1993. Root-induced release of interlayer potassium and vermiculization o f phlogopite as related to potassium depletion in the rhizosphere of ryegress. J . Soil Sci. 44:525-534. Jones, B . 1998. Plant Nutrition Manual. CRC Press, Boston, MA.


Kapur, S., M. Sayin., K. Gülüt, S. Sahan, V. Çavusgil, K. Yilmaz, and C. Karaman. 1991. Mineralogical and micromorphological properties of widely distributed soil series in the Harran Plain. pp. 11-20. In: U. Dinç and S. Kapur (eds.), Soils of the Harran Plain. Tübitak Publishing, Ankara, Turkey. Karamanos, R.E. 1980. Potassium status of some soils of northern Greece in relation to clay mineralogy and other soil properties. Commun. Soil Sci. Plant Anal. 11:723-739. Maff, N. 1986. Changes in ADAS lime recommendations. Tech. Bull. SS/R/86/8. Internal Publication, London, England. Marschner, H. 1995. Mineral Nutrition of High Plants. 2nd ed. Academic Press, London, England. McNaught, K.J., F.D. Dorofaeff, and N. Karlovsky. 1973. Effect of some magnesium fertilizers on mineral composition of pasture on Horotiu sandy loam. N. Zealand J. Exp. Agric. 1:349-363. Mengel, K. and A. Kirkby. 1987. Principles of Plant Nutrition. International Potash Institute, Bern, Switzerland. Murphy, L.S. 1980. Potassium interaction with other elements. pp. 183-203. In: W.L. Nelson (eds.), Potassium for Agriculture. Potash and Phosphate Institute, Atlanta, GA. Oliveira, V., A.E. Ludwick, and M.T. Beatty. 1971. Potassium removed from some southern Brazilian soils by exhaustive cropping and chemical extraction methods. Soil Sci. Soc. Am. Proc. 35:763-767. Page, L.A., R.R. Miller, and D.R. Keeney. 1982. Methods of Soil Analysis. Part 2: Chemical and Microbiological Properties. Agron. Monogr. 9. American Society of Agronomy, Madison, WI. Rowell, D. 1994. Soil Science Methods and Application. Longman Scientific Technical, London, England. Simonis, A.D. and K. Nemeth. 1985. Comparative study on EUF and other methods of soil analysis for the determination of available potassium in soils from Northern Greece. Plant Soil 83:93-106. Tisdale, S., C. Nelson, and W.L. Beanton. 1985. Soil Fertility and Fertilizer. 4th ed. Macmillan Publishing, New York, NY.