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The interest in growing pulse crops and oilseeds together as intercrop combinations is increasing. However, little is known about nutrient dynamics in pulse–oilseed intercropping systems in western Canada, particularly the contributions from biological nitrogen fixation (BNF). Kabuli chickpea and brown flax were grown without added fertilizer as monocrops and as intercrops in mixed and alternate seed row configurations at sites located in the Brown (Central Butte, SK) and Black (Redvers, SK) soil zones in 2019 and 2020. Comparison was made of grain and straw yields, nitrogen (N) and phosphorus (P) uptake of grain and straw, and proportion and amount of biologically fixed N contributed from the chickpea and transferred to the flax. The intercrop grain yield land equivalent ratio (LER) and N and P uptake LER values were at or above 1 for the four site-years, indicating benefit from intercropping in increasing total yield and crop N and P uptake from the land area. The proportion of N derived from BNF was not enhanced in this intercrop combination, but considerable biologically fixed N (8%–22%) was transferred from the chickpea to the flax during the growing season. This was associated with reduced depletion of soil N compared to monocrop flax in part due to the contribution of biologically fixed N in the chickpea–flax intercrop system. [ABSTRACT FROM AUTHOR]

Liquid hog manure (LHM) and solid cattle manure (SCM) are valuable soil amendments for the nutrients and organic matter they augment. However, desire to mitigate the N2O, CO2, and CH4 fluxes attendant with their use has led to the question of whether biochar co-applied with LHM and SCM could mitigate these greenhouse gas fluxes. A split-plot design was used at two agricultural field sites with contrasting soil types (Brown Chernozem and Black Vertisol) in Saskatchewan, Canada, to assess the effect of LHM and SCM (100 kg N ha−1), alone and in combination with two different biochars applied at 8 Mg C ha−1; produced using either slow or fast pyrolysis of willow (Salix spp.) feedstock. Intact cores were collected from the plots and the N2O, CO2, and CH4 fluxes were measured during a 6-week (42 days) lab incubation. The impact of manure amendment on greenhouse gas fluxes, was more apparent with LHM than SCM; reflecting higher inorganic N content, narrower C:N, and more easily mineralizable carbon in LHM. Co-applying biochar with the manure sources reduced the manure-related N2O emissions 31.5 to 43.1% and increased CH4 consumption 94.1% to 2.1 × compared with manure alone. Regardless of soil type, neither biochar co-applied with the manures affected the net CO2 fluxes compared with manure alone. The N2O emissions were principally influenced by the impact of biochar addition on NO3-N supply and pH, while the net CO2 fluxes were controlled by the opposing effects of heterotrophic (i.e., CO2 production) and postulated autotrophic (i.e., CO2 consumption) respiration. The CH4 consumption was related to the NH4-N supply and its influence on autotrophic methanotrophy. [ABSTRACT FROM AUTHOR]

A soil test for estimating mineralizable N in soil is needed to improve fertilizer use efficiency. Our objectives were to: (i) test the effectiveness of two chemical indices in estimating potentially mineralizable N ([N.sub.0]) in soils, and (ii) determine if these indices could be used to differentiate the impact of cultural practices on the N-supplying capacity of soils. We collected samples from the 0- to 0.15-m depth of 42 soils representing all agroecological regions in Saskatchewan, Canada. We determined (i) N mineralized ([N.sub.min]), [N.sub.0], and the rate constant (k) by aerobic incubation at 35 [degrees] C for 24 wk, and (ii) the [NH.sub.4]-N extracted by (a) 2 M KCl heated at 100 [degrees] C for 4 h, and (b) a steam-distilled phosphate-borate solution buffered at pH 11.2. The association between [N.sub.0] and the hot 2 M KCl extracted [NH.sub.4]-N was close ([r.sup.2] = 0.78, significant at P < 0.001); the relationship between [N.sub.0] and the phosphate-borate [NH.sub.4]-N was slightly less precise ([r.sup.2] = 0.73, P < 0.001). When [NH.sub.4]-N extracted with cold 2 M KCl was subtracted from the [NH.sub.4]-N extracted with hot extractants, the association with [N.sub.min] was weaker ([r.sup.2] [less than or equal to] 0.50). The value of k for the 42 soils was generally constant (avg. 0.067 [+ or -] [S.sub.x]t 0.05 = 0.040 [wk.sup.-1]). In a second experiment, we compared the two chemical extractants vs. the N mineralized in a 24-wk incubation regarding their effectiveness in differentiating the effects of eight 37-yr crop rotation treatments on N-supplying capacity. These three indices performed effectively in this regard. For example, the 2 M KCl [NH.sub.4]-N was closely associated with N mineralized in 24 wk ([r.sup.2] = 0.92), as was phosphate-borate [NH.sub.4]-N ([r.sup.2] = 0.88; both significant at P < 0.001). We concluded that the chemical extractants may provide a quick test for assessing N-supplying capacity of the soil.

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Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)