Long-term tillage effects on soil chemical properties and organic matter fractions

Change in frequency and intensity of tillage practices alters the soil properties, distribution of nutrients, and soil organic matter in the soil profile. We hypothesized that 8 yr of no-till (NI), chisel plow (CP), and moldboard plow (MP) treatments would affect chemical properties and organic matter of eroded soil. The corn (Zea mars L.)-soybean [Glycine max (L.) Merr.] rotation study was established in tall fescue (Festuca arundinacea L.) sod on a previously eroded, moderately well-drained, Grantsburg (Fine-silty, mixed, mesic Oxyaquic Fragiudalf) soil in southern Illinois. In the eighth year, soil pH, exchangeable Ca, and Bray P-1 were greater in NT than in CP and MP in the 0- to 5-cm soil depth. In the 0- to 5-cm soil depth, exchangeable K and Mg were greater with the CP than with the NT and MP. In the 5- to 15-cm soil depth, exchangeable Ca and Mg were greater in the MP and CP than in NT, due to mixing. Soil pH and P were greater for CP than MP and NT in the 5- to 15-cm layer. Exchangeable K in the 5- to 15-cm soil depth was greater in the MP than CP and NT. In the 0- to 5-cm soil depth, NT, CP, and MP had 38, 35, and 31% of their total C as particulate organic matter (POM), respectively. After 8 yr, CP and MP had less total organic C than NT in the 0- to 5-cm depth. In the 0- to 5-cm depth, CP and MP had less POM C than NT. The greater reduction of organic C in the POM fraction than in whole soil showed that POM was the most tillage-sensitive fraction of organic matter. After 8 yr of study, the water-stable aggregates in the 0- to 5-cm soil depth of MP and CP was reduced compared with NT. The effects of tillage treatment and associated soil erosion either resulted in different findings from tillage treatments on un-eroded soil or affected the trend and magnitude of the soil property differences between treatments. For the 10-yr period prior to the establishment of the tillage experiment the site was managed as hay-land. At the end of 8 yr, the NT maintained or improved nutrient retention and aggregate stability in the 0- to 5-cm layer compared with MP and CP.