Effects of tillage with controlled wheel traffic on soil properties and root growth of corn

An experiment was conducted to determine effects of tillage with controlled wheel traffic on corn (Zea mays L.) root growth and soil properties. Measurements were made following five years of four tillage treatments with controlled wheel traffic on a Nicollet-Webster soil in south central Minnesota. Only one side of each crop row was used for equipment wheel traffic. Tillage method had no significant effect on bulk density or gravimetric water content. However, it had a significant effect on cone index when measured during the sixth year of continuous tillage. Wheel tracks and traffic pattern, soil depth, and the two-factor interaction had significant effects on measured parameters, including mechanical resistance and root length density. Root length density was least and mechanical resistance was significantly greater in the trafficked positions. Tillage method had an over-shadowing impact on root length density and root distribution pattern. No-till and ridge till plant management on a fine-loamy soil resulted in relatively high mechanical resistance near the soil surface. This mechanical resistance coupled with wheel traffic effects, caused maximum root accumulation in the 0- to 10-cm soil depth. The overall differences in soil physical properties, due to continuous tillage, caused a relatively wide range in total root length and root distribution patterns. Maximum root distribution occurred with the ridge till plant system.