Soil organic carbon, aggregate stability and biochemical activity under tilled and no-tilled agroecosystems

Enhancing crop production and productivity, less energy input and reducing soil erosion make no-till (NT) an add-on choice over the conventional till (CT) system. The present study was conducted at three different locations (Beresford, Langford, and Woonsocket) to compare the natural (undisturbed) ecosystem (NE) with the tilled (CT) and no-tilled (NT) practices, and to evaluate the tillage effects on soil organic carbon (SOC) and total nitrogen (TN) contents, bulk density (ρb), enzymatic activities and aggregate stability under a corn (Zea mays L.)-soybean (Glycine max L.) cropping system. Results support that NT practices improved soil aggregation as compared to the CT and stored higher SOC and TN concentrations in the aggregates, however, NE treatment outperformed both the tillage systems. At all three sites, the NT and NE observed the lowest soil ρb than the CT soils and ranged from 1.03 to 1.49 Mg m−3. The 0–5 cm and 5–15 cm layer under NT system showed 72 and 72% higher value for β-glucosidase, 100 and 57% for acid phosphatase, respectively, compared to the CT system at Beresford site. The CT treatment significantly increased the 0.053, 0.25, and 0.5 mm aggregate size fractions at all the three sites. The NT and NE treatments had significantly higher amount of larger macroaggregates (>1 mm) for all the locations compared to the CT treatment. The SOC and TN concentrations associated with 4-mm aggregate fractions (0–10 cm depth) were significantly higher under NT than CT for Beresford, Langford, and Woonsocket (22.4, 14.6, 19.4, 14.6, 19.2, and 33.5%, respectively). Soil disturbance under CT significantly affected soil physical properties, SOC and TN concentrations, enzymatic activities and aggregate formation and stabilization. Thus, comparative evaluation with a NE concludes that tilled practices negatively affect soil properties and making a priority to adopt NT farming to enhance the soil properties in agroecosystems.