soil conservation structures on soil …[email protected] 2 instituto de investigaciones...
TRANSCRIPT
11/1016/10
22/1029/10
5/1113/11
19/1127/11
3/123/01
18/0125/02
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30-50 cm profundidad40 – 60 cm depth
SOIL CONSERVATION STRUCTURES ON SOIL WATER CONTENT AND PLANT SURVIVAL ON HILLSLOPES IN MEDITERRANEAN CENTRAL CHILE
CHRISTIAN PRAT1, MARTÍNEZ INGRID2,3, OVALLE CARLOS2, HAMIL URIBE2, DEL POZO ALEJANDRO4, VALDERRAMA NATALIA5, RUÍZ GERMÁN6
1 Institut de Recherche pour le Développement, IRD-France, Marseille. [email protected] Instituto de Investigaciones Agropecuarias INIA, Chillán, Chile.
3 Universidad Técnica del Norte, Facultad de Ingeniería en Cienicas Agropecuarias y Ambientales (FICAYA), Ibarra, Ecuador.4 Universidad de Talca, Facultad de Ciencias Agrarias, Talca, Chile.
5 Universidad de Concepción, Facultad de Ingeniería Agrícola, Chillán, Chile.6Servicio Agrícola y Ganadero SAG, División Protección de los Recursos Naturales, Santiago, Chile.
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The agroforestry activity of central Chile is developed under Mediterranean climate. It is characterized by long periods of water deficit conditions, particularly on hillsides with degraded and compacted soils.
Soil erosion processes are very actives and chilean government (SAG) promote different techniques to stop them. But as some proposals have not been tested in the different soil and climate conditions in Chile, the results can be very negatives!
The objective of this study was to evaluate the effect of two soil conservation techniques on soil water content and the survival and growth of two exotic(Chamaecitisys proliferus and Quercus suber) and one native (Quillaja saponaria) multipurpose woody species. Two conservation techniques were evaluated:subsoiling with contour ridges (SB) and infiltration trench (IT), which were compared to a control treatment without soil management (CO), during four years (Fig. 1).
Soil conservation structures allowed higher soil water content especiallyin the years of higher rainfall. At 20-40 and 40-60 cm depth soil watercontent was higher in SB followed by IT and CO, whereas at 60-80 and80-100 cm depth no significant differences were found.
Experimental plots of 1500 m2 (30 x 50 m) were set up in a hillside with a 25% slope. Soil water contentwas determined with a neutron probe (TROXLER, 4300 USA) in aluminum access tubes with a diameterof 50 mm and 120 cm long. These tubes were installed vertically at a 110 cm depth when the trial wasestablished. Four tubes were installed in each replicate and located at a distance of 50 and 100 cm upand down the conservation system. Readings were taken every 20 cm up to the 100 cm depth.
Methodology
Results
Objectives
Conclusions
The survival rate of Q. saponaria was lower in the CO system (57%), while C. proliferus andQ. suber had similar survival rates in the three systems (97% and 87%, respectively).
It is concluded that subsoiling with ridges has a great potential for degraded and compact soils of the Mediterranean region,allowing higher soil water content in the profile and better tree establishment and growth. In that’s way, it is possible toestablish effective agroforestry systems. In other hand, the infiltration trench is dangerous because lambs, which are one of themain resources of farmers in this region, can drown.
Conservation techniques had a significant effect on plant height and crown and trunkdiameter in the three evaluated species. Plant height in C. proliferus was higher inIT>SB>CO, while in Q. suber it was higher in SB>IT>CO; Quillaja saponaria exhibitedsimilar growth in both conservation systems, but it was significant higher (P<0.05) than inCO.
Fig. 1. Conservation techniques a) subsoiling with contour ridges (SB) and b) infiltration trench (IT), and c) Control (CO).
C. proliferus Q. suber Q. saponaria
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Survival rateQ. proliferus
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SbZITs
11/1016/10
22/1029/10
5/1113/11
19/1127/11
3/123/01
18/0125/02
0
10
20
30
40
50
mm
10-30 cm profundidadSbZITs
SBITCO