Forage yield trend of alfalfa cultivars in the Canadian prairies and its relation to environmental factors and harvest management

Abstract

AbstractAlfalfa (Medicago sativa L.) is one of the most important forage crops in the world. The objectives of this study were to assess alfalfa yield improvement in the Canadian prairies, and determine critical climatic factors influencing alfalfa yield in different soil zones. Forage yield data of alfalfa cultivars tested from 1997 to 2011 in the Western Forage Variety Testing System were used for the analysis. There was no significant trend of alfalfa yield increase in western Canada except at Saskatoon, SK. Regrowth yield of alfalfa cultivars released from 2000 to 2011, however, showed a significant (p ≤ 0.05) increase under irrigation. Based on structural equation modelling (SEM), at rain‐fed sites, precipitation from April to June was the most important driver for the farm hay yield (1st‐cut). Forage yield of alfalfa, however, was not associated with winter extreme temperatures, or number of days with freeze‐thaw temperatures in April. Alfalfa yields were greatest under a 3‐cut than 1‐ or 2‐cut systems in the first production year, but this difference declined as stands became older. Alfalfa stands that were harvested more frequently were less responsive to growing season rain, but responded more strongly to increased snow cover, which may indicate reduced growth and less winder hardiness. At the irrigated sites, 1st‐cut forage yield increased with accumulated temperatures above 5°C from April to June. Development of alfalfa cultivars with tolerance to early season drought and improved regrowth, without reducing winter hardiness, would be necessary to stabilize alfalfa production under changing climate in the Canadian prairies.