Long-term tillage and irrigation effects on aggregation and soil organic carbon stabilization mechanisms · Knowledge Library

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Long-term tillage and irrigation effects on aggregation and soil organic carbon stabilization mechanisms · Knowledge Library

aggregate size classes <250µm

= 22

no effect
direct drill (DD) vs. intensive tillage (IT)not significant · 0–5 cm · April 2017 · Foundation for Arable Research in Chertsey · m53–250µm and silt+clay<53µm merged headlined absence; marginal tillage means. Abstract no-difference rather than Results' untested tendency.
Numbers
- treatment 9 vs. control 20 % (-55 %) · m53–250µm
- treatment 6 vs. control 10 % (-40 %) · s+c<53µm
Source · p. 1
“while m and s‡c fractions and OC-m and OC-s‡c did not differ between treatments.”
Source · p. 11
“The variability between aggregate size classes *\<* 250 µm between treatments was also insignificant”
no effect
Irrigated vs. Rainfedsignificance not stated · 0–5 cm · April 2017 · Foundation for Arable Research in Chertsey · Headlined absence of differences in the mass proportions of microaggregates (53-250 micrometres) and silt+clay (<53 micrometres); irrigation marginal means across tillage. The abstract and Conclusion state the smaller-fraction absence between treatments, but Table 5 prints no separating letters or irrigation-specific test for these fractions. Significance not_reported pending explicit factor-test clarification; neither blank letters nor the broad treatment statement establishes each pairwise test. Does not include small or large macroaggregates and does not assert zero effect.
Numbers
- treatment 13 vs. control 17 % (-23.53 %) · 0–5 cm · April 2017 · m, microaggregates 53-250 micrometres; Table 5 irrigation marginal means, not a combined <250-micrometre mass total. Independent field replication is two blocks with four within-subplot subsamples; no marginal sample size inferred.
- treatment 5 vs. control 10 % (-50 %) · 0–5 cm · April 2017 · s+c, silt-clay fraction <53 micrometres; Table 5 irrigation marginal means, not a combined <250-micrometre mass total. No marginal sample size inferred.
Source · p. 11
“Similarly, Irrigation *vs.* Rainfed managements did not highlight significant effects on soil structure and SOC content.”
Source · p. 11
“The variability between aggregate size classes *\<* 250 µm between treatments was also insignificant”

Sites

Foundation for Arable Research in Chertsey

Location: Chertsey, Canterbury, New Zealand43.78° S, 171.97° E
Climate: 11.2 °C mean annual temperature699 mm annual precipitation
Soil: Cambisol · WRB
Land use: mixed croppingArable land
Management on the whole site: crop rotation, No organic amendmentsNo organic fertilizer

Soil layers
Depth	Texture	Clay	pH	Organic C	Bulk density
0–10 cm	silty clay loam	40 %	5.9	26.8 g kg-1	–