Long-term cropping system impact on quality and productivity of a Dark Brown Chernozem in southern Alberta

Abstract

Smith, E. G., Janzen, H. H. and Larney, F. J. 2015. Long-term cropping system impact on quality and productivity of a Dark Brown Chernozem in southern Alberta. Can. J. Soil Sci. 95: 177–186. Long-term cropping system studies offer insights into soil management effects on agricultural sustainability. In 1995, a 6-yr bioassay study was superimposed on a long-term crop rotation study established in 1951 at Lethbridge, Alberta, to determine the impact of past cropping systems on soil quality, crop productivity, grain quality, and the relationship of yield productivity to soil quality. All plots from 13 long-term crop rotations were seeded to wheat (Triticum aestivum L.) in a strip plot design [control, nitrogen (N) fertilizer]. Prior to seeding, soils were sampled to determine soil chemical properties. Total wheat production for the last 4 yr of the study was used as the measure of productivity. The 1995 soil analysis indicated crop rotations with less frequent fallow and with N input had higher soil quality, as indicated by soil organic carbon (SOC) and light fraction carbon (LF-C) and N (LF-N). SOC had a positive relationship to total wheat yield, but was largely masked by the application of N in this bioassay study. Frequent fallow in the previous crop rotation lowered productivity. The concentration of LF-C had a negative relationship, whereas LF-N had a positive relationship to total wheat yield, with and without N fertilization in this bioassay study. Grain N concentration was higher with applied N and when the long-term rotation included the addition of N by fertilizer, livestock manure, annual legume green manure or legume hay. This study determined that long-term imposition of management practices have lasting effects on soil quality and crop productivity.

Soil carbon dynamics in wheat plots established on grassland in 1911 as influenced by nitrogen and phosphorus fertilizers

“…Nitrogen fertilization, with or without P application, significantly increased SOC concentration (Table 1), in agreement with other findings (Smith et al 2015;Poeplau et al 2017). Applying P fertilizer had no consistent influence on SOC concentration.…”

“…The experiment, as described earlier (Smith et al 2015;Karimi et al 2017), was established in 1911 on recently broken land at the Agriculture and Agri-Food Canada Research and Development Centre at Lethbridge, Alberta, on land previously under prairie (predominantly blue grama (Bouteloua gracilis); needle and thread (Hesperostipa comata); Sandberg bluegrass (Poa secunda); western wheatgrass (Pascopyrum smithii), and June grass (Koeleria cristata)) (Johnston 1957). The experiment currently consists of six large plots (277 m × 23 m), one for each phase of three rotations: rotation A (continuous spring wheat (W) (Triticum aestivum L.)), rotation B (fallow-wheat (FW)), and rotation C (fallow-wheat-wheat (FWW)).…”

Soil organic carbon changes as influenced by carbon inputs and previous cropping system

“…As reported by Smith et al (2015), the 1995 SOC concentration for the 0-to 7.5-cm depth was significantly influenced by the prior cropping system, with the highest SOC content Table 1). …”

“…-1 ), H=hay (grass and alfalfa), W C =wheat only if adequate spring soil moisture, otherwise the plot was fallowed, and G=a mixture of native grass species. The SOC for 1995 was previously reported (Smith et al 2015) and is provided in this table as a reference point.…”

“…For the period from 1995 through 2000, the cropping system treatments and associated amendments were suspended, no-till was used, and the entire area was sown to hard red spring wheat (cultivar 'Katepwa'; 84 kg ha -1 ) as a bioassay of soil productivity (Smith et al 2015). Each of the four replicate blocks was divided into two strips, and each year N fertilizer was applied to the same randomly assigned strip, such that all plot halves (3.2 x 18.3 m) on one side of the block received fertilizer N while the halves on the other side did not receive N..…”