Phosphorus Fertility of Alfalfa Hay Stands in Southwest Saskatchewan
Alfalfa based forage stands in SW Saskatchewan are usually established with the intent of harvesting for five or more years. This study was initiated to evaluate the response of alfalfa to P fertilizer additions either once at the start of the study, or applied annually.
IPNI-2002-CAN-SK34
12 Mar 2003
2002 Annual Interpretive Summary
Phosphorus Fertility of Alfalfa Hay Stands in Southwest Saskatchewan, 2002
Alfalfa grown alone, or in mixtures with grasses, is a common feed source for beef cattle producers in the semiarid region of western Canada. These forage stands are usually established with the intent of harvesting for five or more years. In general, very few of these forage lands are fertilized, as decisions regarding production are based on stand and yield decline. This study was initiated to evaluate the response of alfalfa grown alone, or in mixtures with Russian wildrye grass, to fertilizer additions either once at the start of the study, or applied annually. Fertilizer phosphorus (P) as 0-45-0 was in-soil banded using a disc coulter either annually at rates of 0, 9, 18 or 36 lb P2O5/A, or as a pre-plant application at rates of 18, 36 or 72 lb P2O5/A. Forage yields were harvested for five years (1998-2002), with one cut taken most years, two cuts taken in years with above average precipitation.
While no difference in forage yield was observed between the alfalfa and alfalfa-grass mixture in the first two years of the study, alfalfa yields when seeded alone exceeded the mixture in the final three years. Cumulative forage yield over the five years was 0.8 t/A greater for the alfalfa alone versus the mixture. Highest forage yields were achieved with annual applications of 36 lb P2O5/A, followed by the pre-plant banded treatments at 36 and 72 lb P2O5/A. The results of this study indicate that building soil P through one-time or annual applications of P fertilizer were required to support the maintenance of high forage crop yields. SK-34F