Main authors: Fernando Teixeira and Gottlieb Basch
iSQAPERiS editor: Jane Brandt
Source document: Teixeira, F. and Basch, G. (2019) Performance of promising land managment practices to populate recommendations of SQAPP. iSQAPER Project Deliverable 6.1, 45 pp

 

Contents table
1. Results of the 2016 campaign
2. Results of the 2018 campaign

1. Results of the 2016 campaign

The sample size of this study is n=264. For an overview of the results see Figure 5.

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Figure 5

The correlations between VSA structure and other VSA indicators are positive and weak with 4 out of 7 VSA indicators, 3 statistically significant, and there’s a moderate positive correlation with VSA porosity (rs=0.42).

VSA porosity shows positive, statistically significant correlations with all other VSA indicators. Besides the above said moderate correlation with VSA structure, it also shows a moderate correlation with VSA soil colour (rs=0.38).

VSA stability (slaking test) shows a positive and statistically significant correlation with 5 out of 7 VSA indicators, being the correlation with VSA soil colour moderate (rs=0.37). Noteworthy is the lack of correlation with VSA structure and tillage pan (it will be discussed in the next section).

VSA tillage pan shows positive weak correlations, statistically significant, with 4 VSA indicators, the highest being with VSA porosity (rs=0.28).

VSA soil colour, besides the already mentioned moderate correlation with VSA porosity and stability, shows weak, statistically significant correlations with all other VSA indicators.

VSA biodiversity (earthworm count) shows positive weak correlations, statistically significant, with 5 VSA indicators, the highest being with VSA soil colour (rs=0.28). No correlation with VSA tillage pan, and not statistically significant with VSA structure (rs=0.12).

VSA baseline indicators surface ponding and susceptibility to erosion, show only weak correlations with all other VSA indicators.

2. Results of the 2018 campaign

For an overview of the results see Figure 16.

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Figure 16

VSA structure shows a positive, strong Spearman’s correlation with VSA porosity and VSA degree of clod development, respectively rs=0.72 and 0.68; moderate, statistically significant correlations are observed with VSA colour, VSA subsoil compaction and VSA erosion, of respectively rs=0.52, 0.48 and 0.42 (Figure 16). The weak correlation with VSA stability (slaking), rs=0.28, is discussed in the next section.

VSA porosity, besides the above said positive strong correlation with VSA structure, also shows a positive strong correlation with VSA degree of clod development, rs=0.78, and, as expected by the nature of the observations, with VSA subsoil compaction, rs=0.69. Moderate, statistically significant correlations are observed with VSA susc. erosion, colour, stability and surface ponding. The lack of correlation with VSA earthworm count is discussed in the next section.

With exception of earthworm count, VSA degree of clod development shows a statistically significant Spearman correlation with all other VSA indicators and, besides the strong correlation with VSA porosity and structure, it also shows a relatively high correlation with VSA subsoil compaction (rs=0.66).

VSA stability, besides the above mentioned moderate correlation with VSA porosity, it also shows moderate, statistically significant correlations with VSA degree of clod development, subsoil compaction, susceptibility to erosion and earthworm count, respectively rs=0.51, 0.49, and 0.40 for the last two.

VSA subsoil compaction shows, besides the already mentioned relatively high correlation with VSA porosity and degree of clod development, moderate positive correlations with all other VSA indicators with exception of VSA earthworm count (non-existing correlation) and surface ponding (rs=0.27).

VSA number and colour of mottles shows positive, moderate correlations, statistically significant, with VSA degree of clod development and subsoil compaction, respectively rs=0.43 and 0.39. Correlation with VSA stability borders statistical significance (rs=0.31).

VSA earthworm count shows a positive, moderate correlation, statistically significant, only with VSA stability (slaking test) rs=0.40. All other correlations are either weak or non-existing.

VSA soil colour shows positive, moderate correlations, statistically significant, with VSA structure, porosity, subsoil compaction, degree of clod development and susceptibility to wind and water erosion. Correlations with the rest of VSA indicators are either weak or non-existing.

VSA surface ponding shows a moderate, positive and statistically significant correlation with VSA porosity and degree of clod development, rs=0.36 for both VSA indicators. Correlations with other VSA indicators are weak or non-existing.

VSA baseline indicators susceptibility to wind and water erosion shows moderate positive correlations with most VSA indicators, exceptions are: weak correlation VSA earthworm count; non-existing correlations with surface ponding and number of mottles.

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Figure 17

 


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