Two Pulse-oilseed Intercrop Combinations to Enhance Yield and Nutrient Availability in Saskatchewan

Abstract

The interest in growing pulse-oilseeds together as intercrop combinations in western Canada is increasing, but little is known about the operative nutrient dynamics that drive the observed synergies. Two promising pulse-oilseed combinations (kabuli chickpea-brown flax and dry pea-white mustard) were grown as intercrops in mixed and alternate row configurations in two contrasting soil zones (Brown Chernozem and Black Chernozem) in southern Saskatchewan in 2019 and 2020 without added fertilizer along with their corresponding traditional monocrop systems. Comparison was made of grain and straw yields and nitrogen (N) and phosphorus (P) uptake, proportion and amount of biologically fixed N contributed from the pulse crops, and the transfer of fixed N to the oilseed crops. The two pulse-oilseed intercrops grain yield land equivalent ratios (LER) values, N uptake LER values, and P uptake LER values were at or above 1 for the four site-years, indicating benefit from intercropping in increasing total yield, N and P uptake from a land area. The proportion of N derived from biological N fixation (BNF) was not enhanced in the two intercrop combinations, but significant biologically fixed N (9% - 41%) was transferred from the pulse crops to the oilseed crops that reduced depletion of soil N and contributed additional N in the intercrops compared to monocrops. Supporting evidence for synergy in nutrient availability in the intercropping systems was found in consistently greater concentrations of water extractable organic carbon (WEOC) and total dissolved N (TDN) found in the root zone of the pulse crop partners (kabuli chickpea, dry pea) alone and in the mixes with non-pulse partners (brown flax, white mustard) at both Redvers and Central Butte sites in both years. Enhanced nutrient availability was provided by the pulse crop partner with greater Plant Root Simulator (PRS™) nitrate (NO3-N) supply rates observed in the root zone of the pulse crop mixes over the season. Overall, the results of this study show benefits can be realized from intercropping of kabuli chickpea-brown flax and dry pea-white mustard in yield and nutrient utilization efficiency from a land area, improved nutrient use efficiency, and synergies.