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

Change in frequency and intensity of tillage practices alters the soil prop erties, distribution of nutrients, and soil organic matter in the soil prof ile. We hypothesized that 8 yr of no-till (NT), chisel plow (CP), and moldb oard plow (MP) treatments mould affect chemical properties and organic matt er of eroded soil. The corn (Zen mays 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, mi xed, mesic Oxyaquic Fragiudalf) soil in southern Illinois. In the eighth ye ar, soil pH, exchangeable Ca, and Bray P-1 were greater in NT than in CP an d MP in the 0- to 5-cm soil depth. In the 0- to 5-cm soil depth, exchangeab le 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 gre ater 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 N T. The greater reduction of organic C in the POM fraction than in whole soi l 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 d epth of MP and CP was reduced compared with NT. The effects of tillage trea tment and associated soil erosion either resulted in different findings fro m tillage treatments on uneroded soil or affected the trend and magnitude o f the soil property differences between treatments. For the 10-yr period pr ior 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 retent ion and aggregate stability in the 0- to 5-cm laver compared with MP and CP .