Figure 1
From: Micronutrients decline under long-term tillage and nitrogen fertilization

Mehlich III extractable manganese (top) and copper (bottom) as influenced by the interaction of tillage system and soil depth in 2015. Bars sharing the same letters are not significantly different at 0.05 probability level. Lowercase letters are comparison of tillage system within each soil depth, and uppercase letters are comparison of tillage system across the four soil depths.