Comparison of tillage practices on soil health in the lower Colorado River basin region of the Sonoran Desert
Jessen, Heidi Kirsten.
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There is interest in learning how agriculture impacts the greater desert riparian ecosystem. Focus on tillage practices revealed information as to how soil functions on rotation and mono-crop managed systems in comparison to undeveloped land. The purpose was to determine if tillage increased soil health. The secondary question looked at the effect non-tilled soil has on biological activity. Background research studies focused on measuring potential indicators of soil health or quality. Three adjacent fields in the Lower Colorado River Basin in Arizona were used to measure indicators of soil health. Each field differed by tillage and crop management system. Soil health testing methods for biological, chemical and physical indicators were conducted through laboratory analysis and fieldwork. Colony forming units and laboratory soil analysis indicated soil organic matter and soil bacteria were higher as tillage levels increased. Physical indicators of moisture, compaction, and texture showed soil composition of tilled soils was similar to, but not the same in to no-till. Biological indicators showed that except for bacteria colonies, biological activity was highest in reduced and no-till levels. This revealed that conventional tillage is a good habitat for soil bacteria but it potentially does not provide for a diverse number of organisms. The overall assessment showed that each tillage level offered benefits to the soil ecosystem.