|Crop||Dry Bean, Soybean|
|Principal Investigator||Larney, Francis, Agriculture and Agri-Food Canada|
|MPSG Financial Support||$15,000|
|Total Project Funding||$59,087|
|External Funding Partners||Funding for this project has been provided by Agriculture and Agri‐Food Canada through the AgriInnovation Program|
This study is set up to compare agronomic practices for soybean production and quantify their nitrogen benefits in comparison to dry bean. It is a collaborative effort between Agriculture & Agri-Food Canada and Alberta Agriculture & Forestry, conducted over two sites, at Bow Island and Lethbridge, AB.
The comparative benefits in terms of nitrogen fixation and release to following crops in rotation (soft wheat) will be quantified for both dry beans and soybeans. Soybean are grown at different plant densities (30, 50 and 80 seeds m-2) and row spacing (17.5, 35 cm) on different plot land each year (2014, 2015, 2016) and followed by soft wheat used to capture and quantify nitrogen benefits (2015, 2016, 2017).
Baseline soil samples will be taken in spring 2014, 2015 and 2016 to characterize available nitrogen at the outset on each plot of land at each site. Each year, soils will be analysed for (a) microbial biomass, (b) bacterial phylogenetic diversity and composition, and (c) activities of enzymes involved in C cycling (β-glucosidase and β-N-acetyl-glucosaminidase), N cycling (urease), P cycling (acid phosphomonoesterase) and S cycling (arylsulphatase) as indicators of soil health. Nematode populations will also be assessed at mid growing season. Soil samples will be taken each fall to quantify available N to 60 cm depth.
Preliminary results from 2014 show that higher soybean planting density can lead to faster maturity, taller plants at harvest, better pod clearance, higher grain yield, higher thousand seed weight, higher straw yield, higher grain N (protein concentration), higher straw N uptake, and total N uptake.
Narrow-row soybeans can lead to slower maturity, shorter plants, and lower pod clearance but higher grain N uptake and total N uptake. Row width effects on grain yield were inconsistent in 2014. Narrow rows resulted in higher levels of soil nitrate-N in the 0-60 cm depth after harvest. This could be due to (1) higher N fixation during the grower season or (2) or less or more efficient N use by narrow rows, or a combination of the two.
In terms of the comparison between soybean and dry bean, increasing soybean plant density to 80 seeds m-2 can lead to almost similar grain yields as dry bean. Grain N concentration is about double in soybean (~6%) vs. dry bean (~3%). However, the opposite was true for straw N concentration which was about double in dry bean (1.4%) vs. soybean (0.7%). In terms straw N uptake which equates with N mass returned to the soil, as residue is not removed, values were similar at Bow Island, while dry bean had higher N returns via straw due to a combination of higher N concentration and straw yield at Lethbridge. Further results will be forthcoming as the study progresses.