Forage Rejuvenation with Phosphorus Fertilizer

Established forage stand productivity is seriously limited by nutrient supply in most areas of western Canada. While only limited acres of forage grass crops are fertilized, past research has shown it to be one of the most responsive crops to nitrogen (N) application. The objective of this study is to evaluate the management of dry and fluid phosphorus (P) fertilizers, applied with N, to restore the productivity of established, low-yielding forage stands.

Final year results indicate a strong forage yield response to fertilizer P additions in all 3 years of this study. In fact, addition of N alone resulted in little or no yield increase over the unfertilized check, indicating a very P-limited condition in the field. Yield response from fertilizer addition ranged from 0.4 t/A in year 1, 0.8 t/A in year 2, and 1.0 t/A in year 3. As has been previously reported, annual fertilizer P additions result in a progressive increase in forage yields in each year the fertilizer is added. The best treatment in all years of the study was when the 3-year supply of fertilizer P was added with the annual N rate in year 1. Even though no fertilizer P was added in subsequent years, this was always the best yielding treatment. The results of this study clearly show the benefit of using fertilizer N and P to improve old established forage stand yields. SK-35