Soil nutrient distribution as influenced by crop rotation and fertilization
Based on the agronomic and economic implications of including alfalfa in rotation with annual crops, what is the optimum and annual/perennial crop rotation for producers to utilize?
IPNI-1990-CAN-MB5
24 May 2001
Methodology
- Rotation experiments were established on an Osborne clay at Winnipeg, and on a Newdale clay-loam at Portage la Prairie in the spring of 1990. The site at Winnipeg has been in a crop-summerfallow rotation for approximately 80 years, and has significant levels of nitrate-N at depth (> 100 kg/ha available nitrate-N below 60 cm depth). At the Portage la Prairie site, soil water table levels range from 0.75 and 1.5 meters. Hence, any leched N could very quickly affect groundwater quality. This site has been continuously cropped for the past 15 years.
Rotations under investigation are: 1) spring wheat - field pea - barley, and 2) alfalfa for 1-3 years-spring wheat-field pear-barley.
Each annual crop plot is split into an N fertilized (to soil test recommendations) and an unfertilized (no N, but fertilized with all other nutrients) check. This way the N contribution of alfalfa to subsequent crops can be measured. Fertilization with other nutrients will be based on soil test recommendations. The experimental design is a split plot with crop rotation as the mainplot and N as the subplot. The experiments at both sites are replicated 4 times.
The dimensions of the subplots are 5m by 8m at Winnipeg and 8m by 6m at Portage la Prairie. Although this proposal only considers 1-3 years of alfalfa, the study is set up to run for 10 years at both locations.