Assessment of Soil Condition Using Soil Quality Index of Different Land Use Types in Liliw, Laguna, Philippines

Soil degradation is a serious problem caused by various anthropogenic activities, which threatens sustainability. An assessment of the soil quality of existing land use types is needed to come up with land management solutions for achieving sustainable use of the land. Soil health is a crucial indicator for sustainable land management and can be evaluated using the soil quality index (SQI). SQI is one of the useful tools that provide an easy understanding of the actual soil condition of different land use types. Hence, this study was conducted to evaluate the soil quality of three land use types – agriculture, agroforestry, and forest – in Liliw, Laguna through the calculation of its SQI. Soil quality was examined within the 0–20 cm soil depth of each land use having five replicates. Soil attributes such as total nitrogen, pH, organic matter, earthworms, and phosphorus served as the minimum data set for the determination of SQI. Results revealed that the SQI of the land use types followed this trend: forest (76.39%) > agroforestry (76.21%) > agriculture (49.43%). SQI of the forest and agroforestry was classified as very high, whereas agriculture had a low classification. The SQI value of agroforestry was higher than that of agriculture and closer to that of the forest. The most vital soil indicator to the overall SQI was the total nitrogen. It was confirmed in the study that agroforestry is a much better farming system approach than agriculture. Interventions such as incorporating trees – especially nitrogen-fixing tree species – using leguminous short-term crops, and prioritizing the utilization of organic fertilizers should be taken into consideration to enhance the quality of the soil in both cultivated land use types in the area. Generally, this study recommends the prioritization of agroforestry as a technology to be implemented in various programs related to sustainable farming.