Effect of current-season application of calcitic lime and phosphorus fertilization on soil pH, potato growth, yield, dry matter content, and cadmium concentration

Abstract

Two glasshouse and three field experiments were conducted to investigate the effects of current-season application of calcitic lime and phosphorus (P) fertilizer on (i) soil pHw, (ii) growth of haulms (tops), (iii) tuber number, yield and dry matter content, and (iv) cadmium (Cd) concentrations in tubers of the potato (Solanum tuberosum L.) cultivars Russet Burbank, Crystal, and Pontiac grown in acid Entisols. Rates of calcitic lime ranged from 0 to 20 t ha-1, and rates of P, applied as single superphosphate, ranged from 0 to 100 kg ha-1. Liming increased surface (0-15 cm) soil pHw by up to 3.1 units while P fertilization increased it by only 0.3 of a unit. In the glasshouse experiments, total yields of leaves, stems and haulms were not significantly (P0.05) affected by the application of lime while plant height was increased. Phosphorus fertilization increased total leaf, stem and haulm yields and plant height. The number of tubers per plant and tuber yield were either unaffected (4 experiments) or decreased (1 experiment) by liming. Phosphorus fertilization significantly increased tuber yield and number in 3 experiments. The magnitude of the yield responses to applied P was greater in the glasshouse experiments than in the field experiments. Liming did not significantly (P0.05) affect tuber dry matter content which was however, increased by the application of P in the glasshouse experiments. There were no consistent interactions between lime and P in their effects on any of the growth or yield parameters measured. Application of lime, up to 10-15 t ha-1, significantly reduced tuber Cd concentrations in glasshouse experiments but not in field experiments. This discrepancy between field and glasshouse experiments indicates that the effects of liming on Cd availability in acid soils and on plant uptake need further investigation. Phosphorus fertilization significantly increased tuber Cd concentrations in 2 experiments. Based on our field experiments, further investigations are required to determine if banding superphosphate increases tuber Cd compared with broadcasting. It was found that for potato crops grown in acid Entisols, current-season application of calcitic lime was ineffective as an agronomic practice for growers to improve haulm growth and tuber yield response to applied P and to reduce Cd residues in tubers.