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Proceedings of the Sixth International Drainage

SymposiUD!

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13-15 December

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1992'

Nashville, Tennessee

Published by American Society of Agricultural

Engineers

2950Niles Rd., St. Joseph, Michigan 49085-9659 US~ , ,

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PakBnokCorp~r~tiafi 21 - Queens IZu,lu, Azjz Cbamb(;1's. Labore. Ph: No. 6363222-636088.?

EFFICACYOF ACID RECLAIMANTS IN COMBINATION WITH NONCONVENTIONAL FERTILIZERS FOR SALINITY CONTROL.

M.H.K. Niazi, N. Hussain, S.M. Mehdi, M. Rashid, G.D. Khan.

Soil Salinity and sodicity are the major limiting factors of crop production in the irrigated arid/semi arid regions of the world including Pakistan. The problem has become very acute and poses a serious threat to agriculture. To address the problem a field trial was conducted in a saline-sodic soil for assessing the impact of H2SO4 (100, 200 Kg ha-1) and HCI (325, 650 kg ha-1) in combination with ammonium sulphate and ammonium chloride as source of nitrogen (125 kg N ha-1) on the yield of rice (lR 6). The results indicated that both the reclaim ants in combination with N sources and SSP (50 kg ha-1) increased the paddy yield significantly over control. Post harvest analysis of the soil revealed that ECe, ESP and pH values of the soil were lowered through sprinkling H2SO4 and HCI in the flooded water during rice growth. Acid-Grain Ratio and ValueCost Ratio indicated a clear superiority of H2SO4 over HCI. Key Words:

Salimty, Acid Reclaimants, Fertilizer, Rice.

INTRODUCTION:

Salinity and sodicity are among the major identified factors restricting land utilization and causing low crop production in Pakistan. But the dilemma is that the situation will remain in the days to come as long as the present climatic conditions (low precipitation coupled with high temperature) prevHil. Therefore planners, researchers and farmers will be ever-busy in the fight against ~;alinity/sodicity. Enough information has been generated and packages of technology do exist for the reclamation of almost all classes of salt affected soils. However, the developed recommendations could not find their way into practice due to limited financial resources of the farmers as well as the federal and provincial governments. Hence the problem has been aggravated and more and more hectares of land are drifting out of cultivation. This fact demands that a simple low-cost technology be evolved to manage the saited soils in which inputs are directly used on crop production instead of prior reclamation and then growth of crops. Such a peculiar type of management is called the "Saline Aqriculture".

Ameliorants are necessarily required to convert the salty soil environment into a favourable medium for crop production. A variety of chemical reclaimants (Gypsum, Calcium Chloride, Iron Sulphate, Aluminum Sulphate, Sulpher Sulphuric Acid, Hydrocloric Acid, Pyrites etc.) have been investigated and each proved beneficial under certain set of conditions (Mathers, 1970, Pooma and Bhumbla, 1974, Prather, 1978). Soil

Salinity Research Institute, Pindi Bhattian. PAKISTAN

387

Acids or acid forming amendments perform better on calcareous soils (Milap et aI., 1971, Prather 1978) through bodily dissalution of CaCO3, Ca replacing sodium from sol complex and producing an aggregated Ca saturated soil with good air and water premeability. Soils of Pakistan are generally calcareous having 5 to 12% lime in p. and Sind and 20% or more in NWFP and Baluchistan provinces. Thus acids wiDbe preferred using soil Ca potential for reclamatio'l. Rice plant is well adopted 10 salinity /sodicity and possesses reclaiming effect by increasing percolation rate, ~ biological activity of roots and reduction in soil ESP (Chabara and Abrol, 1977, Abrol and Bhumbla, 1978). Therefore, this crop is preferably placed in selected rotations under "Saline Agriculture". Hence, acids when applied in standing water used for rice production increase the process of improvement on calcareous soil and enhance the yields (Rashid and Majid 1979).

Chemical fertilizers are basic inputs in modern agriculture and needed in higher quantities on saline/sodic soils (Rashid and Bhatti, 1985). Efficiencies of fertilizers are low in Pakistan and lowered further under saline conditions (Ahmad, 1985). Acids can increase this efficiency as a results of decreased pH, more availability of P and micronutrients and improving the clay complex of these soils. Present studies were carried out to investigate the probabilities of ascending fertilizer efficiency, achieving reclamation and increasing amen-ability of calcareous saline sodic soils for rice production through use of acids. Thus, a simple low-cost practicable technology was sifted in field studies.

MATERIAL AND METHODS.

A field study was conducted on a saline sodic soil situated in the typic rice growing area of Pakistan. This site was analysed for various soil characteristics before transplantation of rice. Plant bed was prepared as desired for low land rice and IR-6 variety was tested under flooded conditions. Thirty days old seedlings were transplanted for this purpose at a distance of 20 x 20 cm. Nitrogen and Phosphorus were applied at the rate of 100 kg ha-1 and 50 kg ha-1 respectively seven days after transplanting. Source of basal phosphorus dose was single super phosphate. Nitrogen was added as ammonium chloride (NH4CI) and ammonium sulphate (NH4hSO4. Sulphuric acid (H2SO4) and hydrochloric acid (HCI) were also sprinked in the standing water as reclaimants. Concentration of HCI was 30% and that of H2SO4 was 98%. A. supplemental dose of nitrogen was also applied as 25 kg ha-1 to all treatments 30 days after transplanting of seedlings. Following were the details of the treatments:-

388

~ N

, 1.

2. 3. 4. 5. 6. 7. . 8. 9. 10.

125(NH4CI)

Treatment.§. P20S Kg ha'1

-do-do-do-do125 (NH4hS04 -do-do-do-do-

Acid

50 (SSP) -do325 (!-:tCI) -do650 (HC!) -do100 (H2SO4) -do200 (H2SO4) -do0 -do325 (HCI) -do650 (HCr) -do100 (H2SO4) -do200 (H2SO4)

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The design of the experiment was randomised complete block comprising of eereplications. The plots were kept under continuous flooded conditions, 5-6 cm ~r layer always standing on the surface. The low land rice crop was harvested at .Jl8lurity and yield data was recorded. Soil samples were obtained after the harvest and [~lysed in detail. Analysis of variance and economic analysis of the yield data was also ltarried out by computing increases over control, acid-grain ratio and value-cost ratio. tFormulae used were as under:r4.i11

(Yield of Acid Treatment-Yield without acid) Yield without acid

Yield of Acid treatment-Yield without acid Quantity of acid added

Value of increased yield Cost of acid used

.The experimental soil having ECe of 5.5 dS m-1 and ESP of 35.7 was greatly 'oved as a result of various treatments (table-1). A noticeable decrease was erved in ECe, pH, ESP, Na+, HC03-, CI" and SO-24 while an increase was recorded

389

in soluble Ca2+ + Mg2+. Allthe treatments of the experiment proved' Llset(J1 C8I.ISIii or partial reclamation, as adjudged by the criteria layedout for ciassification:d'i affected soils. Application of (NH4hSO4 + SSP + H2SO4 (200 kg ha-1) to,riceW8llf best observation of the experiment bringing ECe from 5.5 to as low as 2.5 dS mendl from 35.7 to 9.5. Same was the case with other parameters. Sulphuricacld superior to HCI in combination with (NH4hSO4 as well as NH4CI. However..,tta.,

favoured reclamationand affectedpositively.Higherdoses of both the acidsWQJO efficient in this regard. Growing rice with the addition of fertilizers (ammonium~ or chloride + SSP) was also a good practiceto improvethe propertiesof a saline soil but remained the most inferior among the treatments of these studies. ArTI/1:II sulphate proved superior to NH4CI. Similar results were also reported' by Akrartt.. (1990). " When H2SO4 or HCI acid is applied to calcareous soils, the following may take place (Agri. Hand Book No. 60, 1954). CaCO3 + H2SO4 2Nax + CaSO4

> Cax2 + NaSO4 !I

CaCO3 + HCI

> CaCI2 + CO2 + H2O

2Nax + CaCI2

> 2NaCI + Cax2

"I

...

390

5

SOIL PROPERTIES

BEFORE

AND AFTER

2. HCO3 C03 moL-I

Ca2+ + Mg2+

Na+

4.5 7.0 7.5 7.0 8.5

32.5 19.5 18.5 12.5 12.0

Nil -. ... ...

-

2.5

4.0

31.0

7.0 8.0 7.5

18.0 15.0

-... ...

4.5 3.5

13.0 12.5

-.. .-.

HARVEST

CI

2SO.

OF RICE.

ECa dSm.1

pH

4.5 3.5 3.2 3.1

6.3 6.2 8.1 8.2

.(

POST HARVEST ANALYSIS.

8.0

ANALYSIS 3.0

51.0

4.5 3.5 3.0 3.0

6.0 7.5 8.5 5.0 5.5 9.0 9.0 8.5

3.1 3.0

6.0

2.5

5,0

ESP

26.5 15.5 14.5 11.5

27.5 16.5 15.5 11.5

12.5

3.1

8.1

10.5

21.5 12.5 11.5

4.5 3.6 3.2

8.3

25.0

11.5 13.0

3.0

8.2 8.1 8.2

19.5 15.0 12.0

2.5

8.1

9.5

5.5

8.3

35.7

BEFORE FLOODING THE FIELD. Nil

5.0

12.5

35.0

RICE YIELD AND ECONOMIC ANALYSIS.

(NH4CI + SSP) -