Contrary to earlier studies, this study suggests that even one year of tillage within a long-term no-till agroecosystem adversely affected the soil quality, with possible negative impact on crop yields. Worldwide interest in conservation tillage is increasing, because conventional tillage adversely impacts the long-term quality of the soil and its vulnerability to erosion. No-till agriculture minimizes adverse impacts of an intensive arable land use. In some cases, occasional tillage is used as a means of weed or pathogen control. Therefore, this study was conducted in eastern Ohio to examine soil quality as affected by occasional tillage, i.e. disk plowed every 3-4 years, within a long-term no-till agroecosystem. The study compared the soil characteristics between two fields, both under corn ( Zea mays L.) at the time of the study. Soil properties were studied for three depths of 0-6, 6-12, and 12-18 cm. Compared with the continuous no-till field, the field under occasional tillage had significantly higher bulk density of 1.45 versus 1.31 gcm -3, and somewhat higher soil penetration resistance of 1.77 versus 1.56 MPa. Also, compared with the no-till field, the field under occasional tillage had significantly lower water stable aggregate of 475 versus 834 gkg -1, mean weight diameter of 1.4 versus 3.4 mm, field moisture capacity of 293 versus 360 gkg -1, equilibrium infiltration rate of 2.0 versus 6.7 mm min -1, and cumulative infiltration of 353.4 versus 1,211.8 mm. The field under occasional tillage had somewhat lower soil organic carbon of 16.0 versus 19.2 gkg -1, soil water sorptivity of 16.3 versus 36.5 mm min -0.5, and transmissivity of 2.1 versus 4.9 mm min -1. The occasional tillage had no effect on the soil shear strength. In general, the effect of tillage on soil properties decreased with increase in soil depth. Also corn yields were compared between the two agroecosystems. Compared with the no-till field, the field under occasional tillage had significantly lower grain moisture content of 22.4 versus 28.2%, and somewhat lower wet stover biomass of 14.6 versus 20.2 Mg ha -1, wet corn ear yield of 10.0 versus 11.4 Mg ha -1, and dry grain yield of 8.2 versus 9.4 Mg ha -1. As contrasted with earlier studies which were conducted under controlled research plots, this study was conducted under on-farm conditions.
