Sustainable land management measures in semiarid SE Spain:

the Alagüeces farm (Murcia)

Albert Solé-Benet1, Joris de Vente1, Ashraf Afana1, Jorge López1, Carolina Boix-Fayos2

1 EEZA-CSIC (Almería) 2 CEBAS-CSIC (Murcia)

Los Alagüeces Zarzadilla de Totana LorcaMurciaSpain

Land uses: rangeland, dryland cereals, almonds

Desertification indicators in the area:

- Soil erosion (rills, gullies)

- Water scarcity, droughts

- SLM 1: Green manure

Autumn 2008

Spring 2009)

SLM technologies under test

- SLM 2: reduced tillage in almonds

Reduced tillage = disks + cultivator (2 operations per year)

Conventional tillage = disks + cultivator (3 - 5 operations)

- SLM 3: boquera

= diversion from main channel (water harvesting system)

- SLM 4: mulch

Mulch used: cereal straw

- SLM 5: reduced tillage in cereals

Mouldboard ploughing

Field A (almonds without terraces)

3 subplots, 3 replicates: - green manure (AL1-AL2-AL3),- rreduced tillage (AL4-AL5-AL6),- control (AL7-AL8-AL9).

Implementation plan

Variables monitored: - runoff- sediment yield- almond yield- organic carbon sequestration.

Implementation plan

- Gerlach troughs for runoff and sediment yield monitoring in field A and B

Field B (almonds in terraces): - water harvesting (boquera)- mulch.- control.

Variables monitored:- water height from boquera (capacitive

sensor) runoff rates

− θ at 30-35 cm continuously (4 probes /

SLM technique & control)- θ manually after events at 0-20 cm- almond yield.

Implementation plan

Field C (cereals in 2 subplots, 3 replicates): - control (conventional tillage): CE1-CE2-CE3- reduced tillage: CE4-CE5-CE6.

Variables monitored: - runoff- sediment yield- cereal yield.

Implementation plan

© Joris de Vente

Implementation plan

- Meteorological station

Variables measured:P, T & humidity air, wind direction & velocity

- Sediment data: we need to know the contribution area to every Gerlach trough

© Joris de Vente

Preliminary results

Drainage accumulation flow at 5 cm resolution generated by the D8 method using IDRISI

3D representation of field site A. DEM generated by ANUDEM at 5 cm resolution. Original data from terrestrial laser scanner Leica ScanStation 2

- First sediment data

© Joris de Vente

Preliminary results

Sediment yield in 1 year in site C(cereals)

0

1

2

3

4

5

6

control reduced tillage

sedi

men

t yi

eld

(kg)

Sediment yield in 1 year in site A (almonds)

0

5

10

15

20

25

green manure reducedtillage

control

sedi

men

t yi

eld

(g/m

²)

Field B - average soil water content in 3 SLM systems

0

5

10

15

20

25

30

35

40

45

18-

11-

08

18-

12-

08

17-

01-

09

16-

02-

09

18-

03-

09

17-

04-

09

17-

05-

09

16-

06-

09

16-

07-

09

15-

08-

09

14-

09-

09

14-

10-

09

13-

11-

09

13-

12-

09

12-

01-

10

11-

02-

10

13-

03-

10

12-

04-

10

12-

05-

10

11-

06-

10

11-

07-

10

10

-08

-10

09-

09-

10

So

il w

ater

con

ten

t (%

vol

)

Control

Water harvesting

Mulch

0

5

10

15

20

25

30

35

40

45

18-1

1-08

18-1

2-08

17-0

1-09

16-0

2-09

18-0

3-09

17-0

4-09

17-0

5-09

16-0

6-09

16-0

7-09

15-0

8-09

14-0

9-09

14-1

0-09

13-1

1-09

13-1

2-09

12-0

1-10

11-0

2-10

13-0

3-10

12-0

4-10

12-0

5-10

11-0

6-10

11-0

7-10

10-0

8-10

09-0

9-10

So

il w

ater

con

ten

t (%

vol

)

Control

Water harvesting

Mulch

Field B - maximum soil water content values in 3 SLM systems

- Soil moisture

Preliminary results

Preliminary results

- Almond yields

Almonds yield in site A

-1

1

3

5

7

9

11

13

15

Green manure Reduced tillage Control

annu

al y

ield

(kg

/ tr

ee)

Almonds yield in site B

-1

1

3

5

7

9

11

13

15

Boquera Mulch Controlan

nu

al y

ield

(kg

/ tr

ee)

Preliminary results

Magnitude and intensity during runoff events

0

10

20

30

40

50

60

70

80

90

100

21/0

9/09

30/0

9/09

16/1

2/09

12/0

1/10

02/0

2/10

24/0

2/10

21/0

4/10

04/0

6/10

18/06

/10

25/0

8/10

P (

mm

) &

Inte

nsity

(m

m(h

) P P intensity

- weather Daily Precipitatipon and Average Daily Temperature

'Los Alhagüeces'

0

5

10

15

20

25

30

22/0

8/20

08

05/0

9/20

08

19/0

9/20

08

03/1

0/20

08

17/1

0/20

08

31/1

0/20

08

14/1

1/20

08

28/1

1/20

08

12/1

2/20

08

26/1

2/20

08

09/0

1/20

09

23/0

1/20

09

06/0

2/20

09

20/0

2/20

09

06/0

3/20

09

20/0

3/20

09

03/0

4/20

09

17/0

4/20

09

01/0

5/20

09

15/0

5/20

09

29/0

5/20

09

12/0

6/20

09

26/0

6/20

09

10/0

7/20

09

24/0

7/20

09

07/0

8/20

09

21/0

8/20

09

Pre

cip

itat

ion

(m

m)

0

5

10

15

20

25

30

35

Tem

per

atu

re (

ºC)

Conclusions (to be considered with caution)

- Water harvesting increases soil water content and consequently almond yield. - Clear results on sediment yield depend essentially on contribution areas which calculations are not straightforward from laser scanner data. Consequently final results on sediment yield might change with regards preliminary ones.

- Mulch has not produced positive results so far. Possible causes: technology not properly implemented and/or mulch type (cereal straw). Is this mulching type affecting infiltration negatively causing lower soil water content?

- Green manure has had a positive influence in almond yield with regard reduced and conventional tillage and seem to reduce soil and water loss.

- Results from field C (cereals) are still under process.