PresentationPresentationbyby

Prof. Dr. Mohamed Fahmy HusseinProf. Dr. Mohamed Fahmy Hussein

The 4The 4thth Conference on Recent Technologies in Agriculture Conference on Recent Technologies in Agriculture

Challenges of Agricultural Modernization Challenges of Agricultural Modernization

Faculty of Agriculture,Faculty of Agriculture,

Cairo UniversityCairo University

Tuesday, 4 November, 2009Tuesday, 4 November, 2009

Mohamed Fahmy Hussein*, , Salah El-AMIR* and Essam RAMADAN**

Application of Structure-Index Technique Application of Structure-Index Technique to Detect Soil Degradation to Detect Soil Degradation

فحص تقنية دليل بناء لرصد تدهور فحص تقنية دليل بناء لرصد تدهور األراضىاألراضى

* Cairo Univ., Fac. of Agric., Soil & Water Dept., Egypt** Ministry of Agriculture, Cairo, Egypt

Location Map, Nile-Delta Apex, Bagour, Monofyah, EgyptLocation Map, Nile-Delta Apex, Bagour, Monofyah, Egypt

Some Experimentral DataSome Experimentral Data

ESP ECaP EMgP EKP CEC Clay% K, cm/hr S.I.MAX 32.21 64.78 40.32 8.33 48.85 54.78 1.470 11.52MIN 3.57 39.50 18.89 0.92 29.11 34.99 0.002 1.68ratio MAX/MIN 9.03 1.64 2.14 9.08 1.68 1.57 735.00 6.86

ESP = Exchangeable Sodium%ECaP = Exchangeable Calcium%,EMgP = Exchangeable Magnesium%EKP = Exchangeable Potassium%CEC = Cation Exchange Capacity, meq/100 gram soilK = Hydraulic Conductivity (Saturated)SI = Structure Index

Structure index = highest (silt+clay) ratio in 3 treatments

mean (stable aggregates+coarse sand) ratio in 3 treatments - (0.9 * C.S. ratio)

Prelude – page-1Prelude – page-1

1) Soil degradation is an environmental problem world-wide.

2) Under irrigated-agriculture, soil degradation is controlled by soil water-regime.

3) A principal change in soil-water regime started in the Nile alluvial-soils of Egypt about 150 years ago, through the replacement of the basin-irrigation by perennial-irrigation.

4) That change has resulted in humid soils with shallow water-table, almost everywhere in the Nile-delta and valley.

5) The over-recharge of the semi-confined (lower) and the unconfined (upper) aquifers was estimated by tritium data-series for GW, and construction of a tritium input-function for Nile water affected by thermo-nuclear bombs of the 1960’s.

Prelude – page-2Prelude – page-2

6) Soil structure is extremely important soil property, expressing the stresses under which the irrigated-soils are cultivated . Unstable aggregates would be formed in clayey-soils under hydraulic and chemical problems (salinity/sodicity development) due to irrigation without field-drainage.

7) Elegant technique has recently been introduced for the evaluation of soil-structure status through estimation of the stable aggregates% under three treatments (1- Alcohol then Water, 2- Benzene then Water, and 3- Water alone.)

8) The Benzene will over-destruct the aggregates, while Alcohol protects the aggregates, and the Water alone treatment is somewhere in-between.

SynopsisSynopsis11

• Fourteen profiles were sampled in the Nile-Delta Apex, Bagour Monofya Govr. for estimation of Structure-Index.

• The samples were also analyzed for salinity level, the exchangeable cations, and the cation-exchange capacity.

• The obtained results are discussed in this work and compared to older results for saline soils at the north of the Nile Delta.

• The increase of the Structure-Index value indicates significant soil-structure degradation (more unstable aggregates.)

• The rise of the piezometric level of the semi-confined aquifer, hydraulically-connected to the unconfined aquifer, during the last 120 years is about 10m (as estimated from tritium model.)

SynopsisSynopsis22

• The chemical change of soil-water chemistry and the rise of the water-table is believed to be behind the observed soil-structure degradation in the study area.

• The value of the Structure-Index, SI, of the studied samples was in the range of about 2-12.

• The linear relationships obtained between the Structure-Index with salinity (EC) and sodicity (ESP) has a high scatter due the contribution of other factors.

• The Structure-Index method seems more sensitive than the classic Structure-Factor method

Tritium Prediction Model for Nile WaterTritium Prediction Model for Nile Water

(425) an excluded value

1

10

100

1000

1950 1960 1970 1980 1990 2000

TU

Years

Reconstructed Tritium Content in Nile water

Fahmy & R.Michel

Old model

measured

precipitation

Stable Aggregates and the Structure-Index ValuesStable Aggregates and the Structure-Index Values

Profile 3

Profile 4

Profile 5

Profile 6

Profile 7

Profile 8

Profile 9

Profile 10

Profile 11

Profile 12

Profile 13

Profile 14

Profile 1

Profile 2

123456789

10111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970

0 10 20 30 40 50 60 70

Ser

ial

nu

mb

er o

f all

sam

ple

s

Stable aggregates, %

(the data-points representing the 5 surfac-layer samplesare shown by triangle, orthogonal and squar symbols)

Alchol

Water

Benzine

Profile 1

Profile 2

Profile 3

Profile 4

Profile 5

Profile 6

Profile 7

Profile 8

Profile 9

Profile 10

Profile 11

Profile 12

Profile 13

Profile 14

123456789

10111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970

0 1 2 3 4 5 6 7 8 9 10 11 12

Ser

ial

nu

mb

er o

f al

l sa

mp

les

Structure index

(low = stable structure, high = poor stucture)

index

lowest

highest

mean

Structure-Index Values in Fourteen ProfilesStructure-Index Values in Fourteen Profiles

Structure-Factor Values in Five ProfilesStructure-Factor Values in Five Profiles

Structure-Index Structure-Index andand Structure-Factor Structure-Factor versusversus ESP ESP

y = 0.124x + 2.696R² = 0.243

0

2

4

6

8

10

12

0 5 10 15 20 25 30 35

Structure index

ESP

y = 0.167x + 0.044R² = 0.401

0

5

10

15

20

0 10 20 30 40 50

(1/SF ) *100

ESP

SI SI versusversus EC, and ln ESP EC, and ln ESP versusversus ln EC ln EC

y = 0.295x + 3.250R² = 0.233

0

2

4

6

8

10

12

0 2 4 6 8 10 12 14 16

Structure index

EC, dS.m-1

y = 0.482x + 1.921R² = 0.579

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

-0.5 0.0 0.5 1.0 1.5 2.0

ln ESP

ln EC, dS.m-1

this work

unpublished data

linear fit

Exchangeable Cations Exchangeable Cations versusversus ESP ESP

0102030405060708090

100

0 20 40 60 80 100

EXP

ESP

X = Ca+Mg

regr. (ECa+MgP)-ESP

X = Ca

regr. ECaP-ESP

X = Mg

regr. EMgP-ESP

X = K

regr. EKP-ESP

Log-transformation of KLog-transformation of Ksatsat, ESP, and Structure-Index, ESP, and Structure-Index

-3.0-2.0-1.00.01.0

0.5 1.0 1.5 2.0

logKsat

log ESP

this work unpublished data all Linear (all)

-3.0

-2.0

-1.0

0.0

1.0

0.0 0.5 1.0

logKsat

log structure index

ملخصملخصأوضحت البيانات وجود تدهور ملحوظ بالبناء األرضى فى نحو نصف –

عدد القطاعات محل الدراسة، حتى بالطبقات العليا ال السفلى يمتاز بسهولته عند structure-index, SI )دليل البناء(فقط . وظهر أن

م=عامل البناء ( مقارنة عدد كبير من العينات ويعطى داللة أوضح منstructure-factor, SF( التقليدى، كما يمكننا ربطه بغيره من المتغيرات -

وهو أمر هام -كتملح وصودية التربة وتوصيلها الهيدروليكى المشبع لما لتلك المتغيرات من عالقة بتدهور بناء التربة بفعل التغيرات

.المائية( ESP( والصودية )EC( بتملح الترية )SIالحظنا ارتباط قيم دليل البناء )–

( عالية SI-ESP( و)SI-ECخطياP، وإن كانت نقاط البيانات فى العالقتبن )التبعثر خصوصاP بالمراحل المتأخرة من تزايد التملح والصودية . وكان

(، مما يعنى أن تدهور SI-ESP( أكبر من ميل الخط )SI-ECميل الخط )التربة يظهر بمجرد بدء تملحها وقبل تحولها لتربة صودية، والحظنا أن

أدى النخفاض رقم الدليل )وهو تحسن وهمى dS/m16تزايد التملح عن سببه تزايد التماسك بفعل التملح المفرط( مما جعل الخط المستقيم

، 12 و 2يلتوى ألسفل . تراوحت قيمة رقم الدليل بين حوالى (، ESP( والصودية )ECوظهرت عالقات خطية موجبة بين التملح )

وانخفض التوصيل الهيدروليكى المشبع بنزايد رقم الدليل . ولحأنا ( ESPلتحويل قيم التوصيل الهيدروليكى ودليل البناء والصودية )

لوغاريتمياP إليضاح االنحدارات الخطية .الحظنا نفع الدليل كمؤشر على حالة بناء التربة، ونعتقد أنه يفيد –

مشروعات صيانة األراضى ثقيلة-القوام، خاصة المتأثرة باألمالح، ألن .التعرف على مدى التدهور هو أولى خطوات تحسين األراضى

� شكرًا

Thank You