Assessment of Soil Quality in Andosols Using Silvopastoral Systems

An experiment was conducted to evaluate the effect of redesign and management upon soil quality variation using three agro-ecosystems: agro-ecosystem A1 (grasses, Alnus acuminata Kunth); agro-ecosystem A2 (grasses, Acacia melanoxylon R. Br.) and agro-ecosystem A3 (Rangeland).

The trees were planted along the contour lines in December 2015. The total area was divided into three agro-ecosystems (AES). These consisted of 7.50, 4.64 and 6.25 ha managed with ten to eleven cows in A1, A2 and A3 respectively. The AES were divided into paddocks by means of electric fences. Composite soil samples were evaluated at the baseline and ten months later. Principles of rational grass management were applied with low input sustainable agriculture. The tree population density was 1000 ha^-1, planted in double rows, separated two meters apart. The genetic composition of dairy cows was 80 and 20% of Holstein and crossbreed Holstein x Jersey, respectively.

The effect of interaction between AES x year was not found. The effect of the agro-ecosystems upon the soil quality only showed significant differences (p <0.05) in pH (5.64, 5.68, 5.55); SOM (14.65, 16.11, 16.23); P₂O₅ (34.67, 19.50, 33.48) and K₂O (.16, .19, .12) meq 100 mL^-1 to A1, A2 y A3, respectively. On the contrary, the year´s effect showed differences (p <0.05) on chemical variables: NH₄ (-83.00 ppm); SOM (-1.91%); P₂O₅ (-10.79 ppm); K₂O (-.04) meq 100 mL^-1 and Mg (-.42) meq 100 mL^-1, excepted pH (.025) and Ca (1.04) meq 100 mL^-1 when it was compared 2015 vs. 2016. It is suggested to continue evaluating the dynamics of soil chemical variables in the subsequent two years to find out the real potential capacity of soil-plant-animal-management interactions to enhance soil quality of Andosols in dairy sector, Carchi province, Ecuador.