Influence of Surface Liming on the Yield and Nutrient Concentration of Alfalfa Established Using No‐Tillage Techniques1

Abstract

AbstractSoil acidity is believed to be an important cause of limited root penetration and low herbage yields of alfalfa (Medicago sativaL.). Alfalfa was seeded into an orchardgrass (Dactylis glomerataL.) sod to evaluate the influence of surface‐applied limestone on alfalfa growth under acidic soil conditions. Alfalfa was planted without tillage in April of 1981 and 1982 on an Ernest silt loam soil (fine‐loamy, mixed, mesic Aquic Fragiudult). Dolomitic agricultural limestone was surface applied at 0 or 6.7 kg ha−1either 8 or 20 months before or at planting. Yield (from 1982 through 1984) increases, greater than two‐fold, resulted from surface application of limestone. Time of lime application had no influence on yields. Roots were more prevalent at the 1.0‐ and 1.5‐m depths due to surface limestone application. Soil pH (0‐ to 10‐cm depth) ranged from 6.4 to 6.9 in the surface limed plots as compared to 5.3 to 5.9 in the unlimed plots. The pH averaged 5.1 at and below the 45‐cm depth irrespective of limestone application. Exchangeable Al ranged from 22 mg kg−1at the 0‐ to 5‐cm depth to 186 mg kg−1at the 145‐ to 150‐cm depth on unlimed plots. Lime application reduced Al 2‐ to 20‐fold in the upper 15 cm, but had no influence on Al concentrations at depths of 95 cm and greater.