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Indian Agric., Vot. Sl, No. I & 2,pp.4l-42,200f

Effect of SoiI Drying on Dynamics of Zn, Zn-Nutrition, Growth and yield ofRice in Four Soils

P. K. PatraAgricultaral Chemistry & Soil Science, Bidhan Chandra Krishi Viswavidyalaya,

PO. Krishi Viswavidyalaya, Mohanpur-74L 252, Nadia, West Bengal, IndiaAbstract

Dyrramic of Zn in relation to the electro-chemical changes ia two cach of Alfisots and Ultisols, undcr intemittently dried andreflooded conditions and their effect on growth, Zn-nutrition and yield of rice (cv. IR- 54) were studied in the greenhouse. Six differentsoil drying and reflooding cycles were imposed to measure their influence on pH, Eh, Ec and Zn* concentration of soil sotution. Ondrying, soil solution pH decreased, Eh increased, Ec decreased and concentration ofZn*. increased. Reflooding raised pH, decreased Eh,raised Ec and decreased Zn* concentration at a much lower rate. Soil drying and reflooding increased the Zn concentration of rice ptantduring the vegetative stage. Zinc concentration and total Zn uptake at harvest were influenced by the interaction of soit type and waterre8ime' Zinc concentration of straw was higher in Ultisot soils than in Alfisol soits. Soil drying, in general, increased Zn concentrationof straw in Alfisol soils- soil drying at any stage decreased rice yield, except in Tropudult soil, where the reverse happened.

Introduction

Rice growth in the rainfed low lands,comprising more than 4ovo of the wet land rice soilsof south and South:east Asia, is vulnerable to extremesfrom a near dry to submerged condition. Nutrientavailability and rice yield, which is very poor in thesesoils, are largely controlled by the balance ofmineralisation - immobilization, oxidation - reductionand toxicities and deficiencies associated withchemical and electro-chemical changes due to variablemoisture conditions caused by alternate wetting anddrying (Goswami et al.,1986). The nature and severityof the problems depend upon soil properties and thetime and duration drying (ponnamperuma andIkehashi, 1979). Chemical and electro-chemicalchanges, brought about by soil submergence, result inincreased concentration of most nutrient elements,except Zn. The concentration of water soluble Zndecreased and reaches values as low as 0.03 ppm,

.despite desorprion frorn Fe (IID and Mn (IV) oxidehydrates (Ponnamperuma, Lg77) resulting in widespread Zn deficiency in areas of intensive ricecultivation with high yielding varieties (IRRI, lg7 I ;

Giordano and Mortveldt, tgTz; Halder and Mandal,1979). variations in water regime, experienced inrainfed low lands, are likely to bring about considerablechanges in chemical and electro-chemical propertiesof soil, which in turn influe.nce the dynamics of Zn++in soil solution and thereby zn-nutrition of rice.

Available information regarding the effect of thesevariable moisture regimes on the dynamics of differentnutrient elements including Zn, is not only insufficientbut also sometimes contradictory in nature. The presentinvestigation was undertaken to study these effects andthe present paper aims at highlighting these on thedynamics of Zn# in soil solution,Zn-nutrition and riceyields in four different soils.

Materials and Methods r

Bulk surface (0 .,15 cm) soils collected fromfield were air-dried and crushed to 0,6 cm clods.Chopped rice straw @ o.25vo (WIW) were mixed with10 kg portion of each soil and placed in I 6 L galzedporcelain pots fitterj at the bottorn with a glass tubewrapped in glass wool and quartz sand. A tensiometerand 2-bright platinum electrodes were placed in eachpot for in - situ measurement of moisture tension andEh. The pots were flooded with deminerulized waterand after 2 weeks, N, P, K and S @ 100, 50, 75 and100 mg kg-I, respectively, were added to each pot andmixed thoroughly with the soil. Four healthy 2 week-old rice seedlings (cv. IR 54) were transplanted ineach pot. Before transplanting, roots of seedlings weredipped inTvo ZnO solution again stZndeficiency. Foursoils yiz, (i) Maahas - I (Tropaqualf), (ii) Maahas -2 (Tropudalf), (iii) Luisiana - I (Tropudutt) and (iv)Luisiana 3 (Paleaquulr) were included in theexperiment to study the effect of six water regimes viz.,

4t

42

(a) continuously flooded (CF), (b) CF with 4 weeks

soils drying imposed on the day of transplanting and

reflooding, there after (SD 0 - 4), (c) CF with 4 weeks

soil drying imposed at 4 weeks after transplanting(WAf) and reflooding there after (SD 4 8), (d) CFwith 4 weeks soil drying imposed at 6 WAT andreflooding there after (SD 6 l0), (e) alternate soildrying and reflooding for 2 weeks irnposed on the dayof transplanting (SD Ol4l8) and, (0 alternate soil dryingand reflooding for 2 weeks imposed at 2 W}JT (SD 2/6/10), on thek Zn++ dynamics in relation to rice growthand yield. While the pots with CF' were maintained at

3 5 cm standing water the pots receiving dryingtreatments were drained and allowed to dry upto 0.3

bar tension, after which again saturated with calculatedamount of drained or de-mineralized water. The general

characteristics of the soils are presented in Thble 1.

At -2,0, 2, 4,6,8, 10 and 12 !YAT, soilsolution from each pot was collected by gravitythrough drainage tube in 125 ml halgene flaskspreviously flushed with nitrogen. Soil solution fromdry soil was collected, first by saturating the soil

Indian Agriculturist

Tast.,r L. Characteristics of the soils.

and then imposing a water head as in CF treatment.

After equilibrating the soil solution samples at 250C

by keeping the flasks in a thermostaticallycontrolled water bath, the pFI. Eh and Ec were

determined simultaneously in the electrometric cell

fitted with a glass electrode, a calornel reference

electrode, 2 platinum electrodes and a conductivitycell (IRRI, I 964). These measurements wereperformed under anaerobic condition, immediately

after collection of soil solution. Concentration ofsoil solutio n Zn++ was determined directly by atomic

absorption spectrophotometer.

Two plants frorn each pot were harvested at8 WAT, Grain and straw yields of the remaining 2

plants were recorded after maturity. Plant samples

including shoot, grain and straw were analysed fordifferent nutrient elements including Zn followingprescribed methods. Charactefization of soils was

done following standard rnethods. The experimentwas laid out in a factorial randomized complete blockdesign consisting of three replications. Theobservations were anlaysed following standardstatistical methods.

Characters Maahas-l(Tropaqual0

Maahas-2(Tropudalf)

Luisiama-l(Tropudult)

Luisiama-3(Paleoquult)

Sand (?it

silr (%)

Clay (Vo)

Texture

pH (water)

Organic carbon (g kg-t)

Total N (%)

Olsen P (g kg-I)

Exchangeable KlC mol (p+) kg-rl

Active Fe (Vo)

Active Mn (Vo)

0.05 N HCI extracted

Zn (mg kg-l) (Ponnamperuma

et al., l98l)

7

35

2

35

2t

50

l4

33

53

Clay

6.4

20.0

1.7

5.s

2.28

1.93

0.t2

a.s2

29

Silty clay

loam

6.6

16.5

1.4

30.9

I.80

2.90

0.19

0.36

58

Clay

4.8

34.9

2.6

2.9

0.23

3.88

0.09

3"06

63

CIay

4.8

22.0

2.4

z.t

0.38

6.71

0.04

2.64

PnrRn et al" : Effect of soil drying on dynamics of zinc

Results and Discussion

Changes in pH

The solution pH in all the four soils increased

to neutrality within a period of 2 weeks after flooding(Fig. 1), Drying of the soils resulted in decreased

solution pH which on reflooding started rising again

but not to the level of CF. The rates of pH change on

flooding the subsequent drying were more sharp in the

acid Ultisol soils due to their higher contents of organicmatter and active iron (Table 1) and also due to additionof rice straw which resulted in faster reduction of ironon flooding the soit (Sadana and Nayyar, 2000).

Changes in Eh

In all the four soils, soil solution Eh fell sharplyand reached a value of around - 100 mv within 2 weeks

after flooding (Fig . 2). Drying soils far 2 or 4 weeks

increased soils solution Eh as a result of oxidation. Onreflooding, the soil solution Eh again deceased butcould not attain the same reduction level as in CF. Theiorver Eh values, to the tune of -100 mv, of soil solutiorrunder CF was due to the microbial activities in the

presence of rice straw.

Changes in EC

Electrical conductivity (Ec) of soil solutionreached the peak value in all the four soils 2 weeks

after flooding which declined to a fairly stable value

in the next 4 weeks (Fig. 3). Soil drying for 2 or 4weeks decreased the soil solution EC which started

rising again on reflooding. In Maahas - i soil (Fig. 3).

reflooding the dry soil raised the Ec to the level beyond

that in CF water regime. The increase in EC onflocding the soils was due to the reduction of FC (I[),Mn (IV), formation of organic acids, HCO, and release

of NHo+, K*, Ca**, Mg** and Na+ in soil solution(Ponnamperurrn, 1972). In the ultisol soils the effectof Fe+2 was very pronounced (Patra, 2000) and thisraised the EC. Decrease in EC on soil drying was

obviously due to re-oxidation and precipitation of Fe+2

and Mn+2 and also precipitation of Ca+Z and Mg*2 and

loss of HCO3- and RCOO- frorn the soil solution.Increase in EC on reflooding the dry soil, especiallyin Maahas - I soil, was due to increase in HCO3-, Kt,Ca*Z, Mg*2, SO+= and Mn+Z in soil solution.

43

Changes in Zn++ concentration

Concentration of Zn++ in soil solutiondecreased during the first 2 weeks after flooding (Fig.

4). The adsorption and/ or concomitant co-precipitation

in the matric of hydroxides of Fe and Mn(Ponnamperuffi&, lg72; Sajtvam and Lindsay, 1986)

and formation of ZnCO, was due to increasedproduction of COz es a result of addition of rice straw.

In acid Ultisol soils, the decrease in Zn++ concentration

may be due to partly to the increase in pH followingsoil reduction, because solubility of Zn++ in waterdecreases 100 times when the pH inireases by one unit.

Soil drying and reflooding clearly and consistentlyincreased soil solution Zn++ coRcentration in all the

four soils because of reversal of the reactions of the

flooded soils.

Zinc nutrition of rice

Zinc concentration of rice plants, duringvegetative stage, were lower in the alfisol thanin ultisol soils (Table 2) but total Zn uptakeduring this stage was higher in the alfisols thanin ultisol soils (Table 3). Soil drying, in general,

increased Zn concentration of .rice shoots.Influence of soil drying and reflooding on Zn

trptake during vegetative growth stage was not

significant in the ultisol soils but in alfisol soils2 week cycles of soil drying and refloodingincreased total Zn uptake by rice plants . Zincconcentration of mature straw and total Zn uptake

at harvest were significantly influenced by soiltypes . Zinc concentration of straw and total Zn

uptake at harvest were higher in the Ultisol soils

as compared to the Alfisol soils (Table 2, 3) whilewater regime- influenced the total Zn uptake at

harvest, it did not influence Zn concentration ofmature straw, but the interaction of soil and waterregime significantly influenced both, Znconcentration in straw as well as total Zn'uptakeby the plants at harvest (Table 2,3). Soil dryingand reflooding increased Zn concentration ofstraw in the Alfisol soils but in Ultisol soils it didnot influence Zn concentration of straw. Soil drying

and reflooding in the Alfisol soils decreased total Zn

uptake by rice plants at harvest.

44 Indian Agriculturist

TAsrr 2" Influence of water regime on Zn (ppm) content of rice shoot (8 WAI) and straw on four soils.

Treatments Maahas- I Maahas-2 Luisiama- I Luisiama-3 Mean

Zn (ppm) in shoot

CF

sD-0-4

SD 4-8

sD 6- 10

sD 0/4/8

sD 2/6/10

Mean

3r.3

43.0

75.3

53.7

64.3

66.7

55.6

35.0

35.7

38.7

36.8

41.7

32.2

36.7

44"2

44"0

74.5

56.0

64.0

6l "7

57 "4

44.7

40.8

s9.5

55.0

69.3

67.A

56.1

38.8

40.9

f2.a

50.r

s9.8

56.8

Zn (ppn) in straw

CF

sD-0-4

SD 4-8

sD 6-10

sD 0/4/8

sD 2/6/10

Mean

28.7

38.9

63.7

65.0

57.7

55.5

51.6

39.2

62.3

54.2

41.2

35.7

69.3

50.3

61"5

65.0

65.5

69.2

78.s

66.3

67.7

80.3

46.7

6r.9

69.5

66.0

67.2

65.3

52.4

53.2

61"3

61.2

59.5

64.6

Zn (ppm) in shoor Zn (ppm) in straw

SEm +

LSD (0.05)

LSD (0.10)

S

3.?

6.4

8.5

w

3.9

7.9

10.4

SxW

7,9

15.6

24.9

S

4.2

8.5

ll.4

w

5.2

,,10.4

13.9

SxW

I0.4

20.9

27.8

Dry ,natter yield

Soil types, water regime and their interactionsignificantly influenced the dry matter yield of g-week-old rice plants (Table 4). The dry matter yield of ricewere higher in the two alfisol soils compared to the 2ultisol soils. While soil drying did not influence thedry matter yietd in the 2 ultisor soils, it decreased drymatter yield in both the alfisol soils.

Grain yield

Soil types, water regime and theirinteraction inftuenced the grain yieldsignificaptly. Grain yields in the Alfisol soils werehigher as compared to Ultisol soils (Table 5). Soildrying at any stage decreased grain yield in theAlfisol soils while yield reduction in Maahas-I soilranged from 34.Tvo to as high as 78.Svo, these in

Fernn et al" : Effect of soil drying on dynamics of zinc 45

Teslr 3. Influence of water regime on Zn uptake by rice shoot (8 W\T) and grain plus straw on four soils.

Treatments Maahas- I Maahas-2 Luisiama-l Luisiama-3 Mean

7n uptake in shoot {me pofi )

CF

SD O-4

SD 4-8

sD 6-t0

sD 0/4/8

sD 2/6/10

Mean

t.0

0.4

0.9

1.8

1.5

0.9

I.l

0.9

0"5

0.9

1"0

l.l

0.5

"0.8

0.3

0.6

0.5

0.4

0.5

0.7

0.5

0.5

0.3

0.3

0.5

0.8

0.4

0.5

0.7

0.5

0.7

0.9

1.0

0.6

Zn uptake in shoot (mS pof I )

CF

SD O-4

SD 4-8

sD 6-10

sD 0/4/8

sD 2/6/10

Mean

4.t9

1.39

4.06

5"63

3.06

3.25

3.60

5.08

2.61

5.15

4.88

2.58

3.93

3.86

3.64

3,96

5.40

3.87

6.15

4.63

4.61

4.74

2.39

2.54

3.55

3.55

2.89

3.29

4.41

2.59

4.29

4.51

3.83

3.65

Zn uptake in shoot (mg porl) Zn uptake in shoot (mg porl)

SEm t

LSD (0.05)

LSD (0.r0)

S

0.1

0.2

0.3

w

' 0.1

0.3

SxW

0.2

0.5

0.'l

S

0.35

0.70

0.93

w

0.42

0.85

t.l4

Sxtff

0.85

L70

2.27

N{aahas-2 soil ranged from 19.4Vo to 66.4Vodepending on the time and duration of dryingperiod. In Luisiana- I soil, soil drying andreflooding increased grain yield ranging from33.5 to 76.3Vo instead of decreasing it. Thisincrease in grain yietd was related to decreasein water soluble Fe+2 due to soil drying in thissoil (Patra, 2000).

Straw yield

Soil type, water regime and their interactionsignificantly influenced rice straw yield (Table 4).Highest straw yield was obtained in Luisiana-tr soilwhile the lowest was obtained in Luisiana-3 soil. Soildrying and reflooding decreased straw yield in boththe alfisol soils while it increased straw yields inLuisiana-l soil.

16 lndian Agriculturist

TABm 4' Influence of water regime on dry matter yield of 8-week old shoot and straw at harvest on four soils.

Treatments Maahas- I Maahas-2 Luisiama- l Luisiama-3 Mean

Dry rnatter yield of shoot (g port )

cF 3 r,o

sD 0-4 8,5

SD 4-8 il.;i

sD 6-10 33.3

sD 0/4/8 2t.5

sD 2/6/10 t4.t

Mean 2A.t

27.0

t4.7

24.0

27.0

26.7

16.5

22.7

6.2

13.1

7.3

6.7

7.7

I 1.5

8.7

l, .4

7.3

5.0

9.2

r 1.3

7.1

8.5

r 8.9

r0,9

12.2

lg,l

16.8

12.3

Straw yield at kantest (g port )

CF

sD 0-4

SD 4-8

sD 6-10

sD 0/4/8

sD ?J6l10

Mean

52.6

t7.5

37.2

50.9

28.9

3A.7

36.3

5 r.6

24.6

49.5

45.9

34.2

2s.8

38.6

37.4

34.9

49.7

37.4

54.4

44.1

43.0

39.8

29.6

29.1

33.1

36.5

34.9

33.2

45.4

26.7

4t "4

4l .8

38.5

32.9

Shoot dry matter

' (g pot-t;

yield Straw yield at harvest

G pot-t)

SxW

3.9

7.8

l0.s

2.4

4.7

?.e

5.8

SxW

5"8

I 1.6

15.5

3.2 3.9

w w

SEm *

LSD (0.05P)

LSD (0.10P)

1.6 1.9

4.3 5,2 6.3 7.8

Parna et al- : Effect of soit drying cn dynamics of zinc

Tesln 5. Influence of water regirne on grain yield and A GYn of rice (IR 54) on four soils

47

Maahas-l Maahas-2 Luisiama-I Luisiama-3Treatments Grain

yield

( g porr)

Grain

yield

(g pot-r)

AGY{'/a

AGY%

Grain

yield A cy( e porr) (W

Grain

yield

(g pot-r)

Mean

AGY(%)

CF

SD O-4

SD 4-8

sD 6-10

sD 0t4l8

sD 2/6/t 0

Mean

69.4

14.9

32.t

45.8

37.6

29.6

38.2

- 78"5

-s3.7

-34.0

-45.8

-57.3

-s3.9

-66.4

-19.4

-21.6

"58.8

-45.2

-42.3

+44.9

+76.3

-4.1

+39.2

+33.5

+38.0

-39.3

-55.1

-33.0

-45.9

-20.8

-38.9

64.3

21.6

5 r.8

50.4

26.5

35.2

41.6

24.s

35.5

43.2

23.5

34. I

32.7

32.3

30.3

18.4

13.6

20.3

t6.4

24.0

20.s

47.1

22.6

35.2

35.0

3A.4

28.6

Grain yield (g porl)

I.,SD 6.2 7.6(0. l0)

Literature Cited

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Goswami, N.N., s. K. De Dattta and M. v. Rao 19g6. Soilfertility and fertirizer rnanagement for rainfedlowland rice. pages 275-293. In ; InternationalRice Research Institute. progress in RainfeciLowland Rice. Los Bonos, philippines.

Halder, Ir{- and L..N. Mandal tgTg.Influence of soil moistureregimes and organic matter application on theextractable zn and cu content'in rice soils. plant

International Rice Research tnstitute I 964. Annual Report, 1963.The International Rice Research Institute, LosBonos, Philippines.

International Rice Research Institute I g7l. Annual Report .,,A.The Internationat Rice Research [nstitute, LosBonos, Philippines.

Patra, P.K. 2000. Influence of drying and reflooding on

AGY* Yield in a treatment- yield in CF00

Yield in CF

phosphorous and iron dynamic affecting ricegrowth. Oryza, 37 : 48-53.

Ponnamperuma, F.N. 197?. The chemistry of submerged soils.Adv. Agron. 24 : 29-96,

Ponnamperurna, F. N. 1977. Behaviour of minor elements inpaddy soils. IRRI Research paper series No. g,

pp.l-15.

Ponnamperurna, F.N. and H. Ikehashi ,glg.varietal tolerancefor mineral stresses in rainfed wetland rice fields.Pages 175-185. In International Rice ResearchInstitute. wetland soirs, characterization,

" classification and utilization. Los Bonos, .

Philippines.

sadanq fr. s. and v. K. Nayyar 2000. Amelioration of irondeficiency in rice and transformations of soil ironin coarse textured soils of punjab, Ind ia. J. pl.Nutr., (USA), 23 :2061-2069.

Sajwan, K. S. and w. L. Lindsay I9g6. Effects of redox on zincdeficiency in paddi rice. Soit ,Scr. So c. Am. J.,50:1264-1269.

w SxWSEm t 2.3 Z.B

LSD 4.6 5.7(0.05)

5.7

It.4

t5.2