SOIL HEALTH INDICATORS FOR ANALYZING SUSTAINABILITY IN CONVENTIONAL AND TRADITIONAL AGROECOSYSTEMS

Abstract

Background. Rice production is a major economic activity in the department of Tolima, Colombia. However, conventional agronomic practices have led to soil depletion. In contrast, within the same region, traditional Indigenous Pijao systems persist, characterized by a high degree of crop diversification as well as no or reduced use of agrochemicals and mechanization. Objective. To evaluate soil health over time in rice monocultures and traditional Pijao agroecosystems in Colombia. Methodology. Data was collected between May and September 2019 at four municipalities in an Andean valley. Experimental units were arranged in four treatments classified according to a chrono sequence of consecutive rice monoculture: agroecosystems in which rice has never been planted or ‘traditional Pijao agroecosystems’ (TPA); rice monoculture for 5 to 10 years or ‘young rice agroecosystems’ (YRA); for 10 to 20 years or ‘medium rice agroecosystems’ (MRA); and for more than 20 years or ‘old rice agroecosystems’ (ORA). Twelve indicators were evaluated in each experimental unit: physical (penetration resistance, water infiltration, bulk density, and soil structural index), chemical (pH, CEC/CL%, EC, SOC), and biological (microbial respiration, earthworm abundance, and diversity of arthropods and plants) indicators. Results. Physical and chemical indicators did not present significant differences among the four chrono sequences evaluated. However, TPA obtained the highest values for SOC, structural stability index, and microbial respiration in comparison with conventional rice agroecosystems. Diversity of arthropods and plants significantly differed among the four treatments. Implications. Results suggest that traditional Pijao agroecosystems promote arthropod diversity and plant (weed and crop species) diversity, contributing to a greater sustainability of the region’s agroecosystems. Conclusions. The study illustrates the most relevant soil health indicators for the tropical dry forest zone of southern Tolima are those providing information on soil diversity, structural stability, compaction, and microbial respiration.