Fig. 4. Summary of crop residue coverage of soil (Project Year 3) for 36 crop sequence combinations of three crops with higher residue coverage the following year (proso millet, grain sorghum, and spring wheat) and three crops with lower residue coverage the following year (lentil, chickpea and sunflower). Bars with the same letter do not differ significantly with Student-Newman-Keuls' test analyses (P 0.05). Low = lower crop residue coverage of soil surface, High = higher crop residue coverage of soil surface.