Fertilizer Requirement of Irrigated Alfalfa

Results of the last 3 years indicate that a combination of soil and tissue tests provide the best option for predicting P response in alfalfa. However, neither worked well for K.

IPNI-1994-CAN-AB11

17 Apr 2001

Project Description


Surveys have indicated that there is a discrepancy between soil and tissue tests for P and K in many irrigated alfalfa fields in southern Alberta, and that insufficient P and K was being applied to these fields. Results of the last 3 years indicate that a combination of soil and tissue tests provide the best option for predicting P response in alfalfa. However, neither worked well for K. Alfalfa did not respond to K fertilization even when soil and tissue tests predicted it should and when the soils had a long history of alfalfa production without K fertilization. More research is needed to understand this peculiar lack of response. Despite the lack of response to applied K, this study has demonstrated improved yields from applied P and will undoubtedly encourage farmers to use more phosphate fertilizers.


Objectives
  1. To increase the yield and profit and to improve fertility effectiveness for forage alfalfa on irrigated soils and by this to increase the feasibility of growing alfalfa.
  2. To determine if fields which test low in soil phosphorus and adequate in tissue phosphorus respond to phosphorus fertilizer applied with various methods.
  3. To determine if sols which test adequate in soil potassium and deficient in tissue potassium respond to potassium fertilizer.
  4. To compare the Miller, Axley, Kelowna, U. of Sask. Kelowna, Norwest Kelowna, membrane strip and Olsen methods of soil analysis for predicting the phosphate response of alfalfa on high pH irrigated soils.
  5. To enlarge the data base for a DRIS tissue analysis model for alfalfa and evaluate the feasibility of DRIS for alfalfa.