`Jewel' sweetpotato was no-till planted into crimson clover, wheat, or winter fallow. Then N was applied at 0, 60, or 120 kg·ha–1 in three equal applications to a sandy loam soil. Each fall the cover crop and production crop residue were plowed into the soil, beds were formed, and cover crops were planted. Plant growth of sweetpotato and cover crops increased with N rate. For the first 2 years crimson clover did not provide enough N (90 kg·ha–1) to compensate for the need for inorganic N. By year 3, crimson clover did provide sufficient N to produce yields sufficient to compensate for crop production and organic matter decomposition. Soil samples were taken to a depth of 1 m at the time of planting of the cover crop and production crop. Cover crops retained the N and reduced N movement into the subsoil.
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