Nitrogen Acquisition of Pea-Oat and Pea-Canola Intercrops and Their Impact on Subsequent Wheat Crops

The increased diversity provided by intercropping systems can provide many benefits, including increased nitrogen (N) use efficiency (NUE). The ability of legume crops to fix atmospheric N can increase in an intercrop, leading to increased productivity compared to monocrops. However, limited research has tested the efficiency of intercropping systems in western Canada and their effect on subsequent crops. Therefore, pea-oat (PO) and pea-canola (PC) intercrops (mixed row) were grown at Swift Current, Melfort, and Redvers, Saskatchewan followed by wheat in the subsequent year. Each of the intercrops were supplied with three N fertilizer rates (0, ¼, ½ of their recommended rate), while the monocrops (pea, oat, canola) received their full recommendation of N fertilizer, except pea which received no N fertilizer. In the following year, wheat was supplied with its full recommendation of N fertilizer. The 15N dilution method was used to measure the percentage of N derived from the atmosphere (%Ndfa), %N transfer, N fertilizer recovery, and residue recovery in the succeeding wheat crop. The %Ndfa measured the percentage of N in pea that was derived from the atmosphere. In contrast, biological N fixation (BNF) determined the amount of N uptake that was from the atmosphere. The %Ndfa increased in pea intercrops compared to the pea monocrop but due to reduced pea biomass in PO, it decreased the amount of N derived from fixation by 8% compared to the pea monocrop; however, PC increased this amount by 23%, on a per-plant basis. These differences in BNF did not influence productivity, where the intercrops were similar to monocrops. The intercrops produced grain land equivalent ratios (LER) of 0.94 (PO) and 0.98 (PC). In contrast, PC accumulated more above-ground dry matter N than PO and had a 3% advantage over its respective monocrops. This enabled wheat to produce 5% more yield following PC compared to PO but no differences were found between intercropping and monocropping systems. The recovery by wheat of above-ground residue N was higher in monocrops than the intercrops but the low recovery (4%) did not have any impact on wheat yield between the two systems. Overall, PC intercrops appear to be a viable option for producers as they increased BNF, N uptake, and produced slightly higher yields of the following wheat crop than PO. This intercrop also provided comparable intercrop and wheat yields to its monocropping systems; therefore, its ability to utilize N more efficiently made up for reduced fertilizer applications.

Name thesis:degree_name

Master of Science (M.Sc.)

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Soil Science

Grantor

University of Saskatchewan

Year dc:date.issued

2024

Author dc:creator

• Choo-Foo, Kennedy

Advisors dc:contributor.advisor

• Knight, Diane
• Liu, Kui

Committee members dc:contributor.committeemember

• Congreves, Kate
• Schoenau, Jeff
• Shirtliffe, Steve

• biological nitrogen fixation
• residue recovery
• land equivalent ratio
• nitrogen use efficiency
• fertilizer

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10388/15754

OAI identifier oai:identifier

oai:harvest.usask.ca:10388/15754