Soil quality assessment to compare tillage systems in Cukurova Plain, Turkey

Abstract

Agricultural practices should be carefully monitored for long-term impacts on soil quality to avoid further deterioration in ecosystem services provided by soils. The aim of this study was to evaluate and compare the effects of two conventional (CT), three reduced (RT) and two no-till (NT) tillage practices on soil quality of a clayey soil in a ten-year experiment using Soil Management Assessment Framework (SMAF). The field experiment was established in 2006 with six tillage methods, and winter wheat (Triticum aestivum L.), soybean (Glycine max. L.) – grain corn (Zea mays L.) crop rotation. The NT plots were divided into two parts, i.e., half of them were plowed with a moldboard plow during November 2015, and this practice was defined as strategic tillage (ST), while the remaining half was left undisturbed (NT). Disturbed and undisturbed soil samples were collected at three depths (0−10, 10−20 and 20−30 cm) from experimental plots in 2016. Fourteen soil quality indicators, including physical, chemical and biochemical properties were determined to assess soil quality. Soil productivity, water relations (WR), resistance and resilience (RR), and physical stability and support (PSS) functions defined in SMAF were calculated. The RR and PSS function scores were significantly higher at 0−10 cm depth under conservational tillage methods (RT and NT) compared to CT methods. Low nutrient content, compaction, aggregate size and stability values in 10−30 cm depth decreased the functioning potential. The RR function at 0−10 cm depth in NT method was 103 % and 72 % higher than CT-1 and CT-2, respectively. All soil functions under RT and NT methods decreased with depth. The ST significantly increased PSS and WR functions in all sampling depths and overall soil quality in 10−20 and 20−30 cm depths compared to long-term NT method. The comparison of soil functions and overall soil quality indices helped to identify the effects of different tillage practices on functional potential of the soil. Furthermore, soil quality assessment using soil functions provides an overview to distinguish the pros and cons of tillage practices on sustainability of the crop production.