Improved Corn Yields When Humic Acid Extracted from Composted Manure Is Applied to Acid Soils with Phosphorus Fertilizer

Figure 1

Root diameter (a), root dry weight (b), and root volume density (c) of corn 7 and 10 weeks after planting (WAP). CB is Bisi 2 hybrid corn, CP is Pioneer 35 hybrid corn. H₀P₀ is the control, H₀P₁ is 0 mg kg⁻¹ composted manure (MHA) + P fertilizer, H₅P₁ is combined 35 mg kg⁻¹ MHA + P fertilizer, H₁₀P₁ is combined 75 mg kg⁻¹ MHA + P fertilizer, and H₁₅P₁ is combined 110 mg kg⁻¹ MHA + P fertilizer. The rate of P fertilizer in each P₁ treatment was equivalent to 120 mg P₂O₅ kg⁻¹ air-dried soil. Values followed by the same lowercase or uppercase letter were not significantly different based on Duncan’s multiple range test at . Results presented are the mean + standard error of 3 replicates.

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