Banding increases effectiveness of fertilizer P for alfalfa production

A field experiment was conducted from 1992 to 1996 on an existing alfalfa (Medicago sativa Leyss) stand located on a P-deficient Black Chernozem (Typic Boroll) soil at Ponoka, Alberta, to compare the effectiveness of broadcasting (spread over the soil surface) versus banding (1.5 cm wide band placed 5 cm deep and 15 cm apart, using a coulter-type disc drill) of annual and one-time applications of P fertilizer on dry matter yield (DMY), P-use efficiency of applied P (PUE), protein yield (PY), recovery of fertilizer P (PR), net returns (NR) and non-renewable energy performance of alfalfa hay. There was a marked increase in DMY and PY from all the P application treatments in all the five years. Banding produced greater increase in DMY and PY than broadcasting, with both the annual (by 954 kg DMY ha−1 and 205 kg PY ha−1) and one-time application (by 742 kg DMY ha−1 and 173 kg PY ha−1) applications. The PUE (averaged across P rates and years) was greater with banding as compared to broadcasting by 58 kg DMY kg−1 P ha−1 for annual applications, and by 47 kg DMY kg−1 P ha−1 for one-time applications. In the same order, PR values were 16.0 and 12.1% greater with banding than broadcasting. Despite the higher costs of banding than broadcasting, net returns were significantly higher with banding in nearly all years. The differences between banding and broadcasting were generally greater at lower than at higher P rates. Based on the 5-year means, annual and one-time P applications produced similar increase in DMY, PY, PUE, PR and NR. In contrast, non-renewable energy inputs were higher for banding than broadcasting, but energy use efficiency was similar for both methods of application. In conclusion, method of P placement had the greatest effect on DMY, PY, PUE, PR, NR and energy performance, whereas annual and one-time applications showed similar results. The results suggest that alfalfa forage productivity and profitability can be improved by banding the P fertilizer with a coulter type disc in comparison to the conventional application method of broadcasting.