|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|
Here we summarise relationships between soil properties determined by visual assessment and by measurement and how those properties are affected by different agricultural management practices (AMPs). This empirical evidence was used in the development of »SQAPP the soil quality assessment app to enable the app to make recommendations for agricultural management practices based on their effects on soil quality and mitigation of soil threats.
|1. Soil properties determined by visual assessment (VSA) and measurement|
|2. Effects of AMPs on soil properties|
In general terms, the following applies:
- Organic matter (OM) has weak positive to moderate correlation with VSA structure (depending on the data set) and moderate positive correlations with VSA porosity, VSA soil stability and VSA soil colour.
- pH has weak positive correlation with VSA structure, VSA porosity (moderate correlation), VSA soil stability and VSA tillage pan.
- pH has a moderate positive correlation with VSA soil colour.
- Stone content and bulk density show a moderate negative correlation with VSA earthworm count. Decrease in earthworm abundance where mechanical impediments exists.
- Bulk density shows a negative correlation with VSA surface ponding. Susceptibility to compaction also has a correlation with VSA surface ponding (slightly weaker).
- There is a positive correlation between VSA earthworm and VSA soil stability (weak/ moderate). Based on the data available, earthworms may play a substantial role in the decrease of soils’ OM C/N ratios.
- VSA structure, VSA porosity and VSA tillage pan have weak positive correlations with infiltration rate. VSA soil stabilityhas no correlation with water infiltration.
- VSA structure and VSA tillage pan have no correlation with VSA soil stability.
- VSA number and colour of mottles show no statistically significant correlations with measured soil properties (mottles must be checked in situ). Moderate positive correlations with VSA degree of clod development (and VSA subsoil compaction), indicates that the degree of clod development can and should be used as a telltale for further soil profile examination.
- No statistically significant correlation exists between AMPs and measured properties (pH, infiltration rate, LOC and OM) in the data from 2016. Correlations are weak, with few exceptions (for these exceptions the sample size is small and thus with no statistical meaning).
- AMP no-till correlations with VSA indicators are moderate to strong, statistically significant, with VSA indicators related to soil structure (VSA structure, porosity and stability) and VSA susceptibility to erosion, which is in line with known features of these cropping systems, and weak correlations with all other VSA indicators.
- AMP minimum tillage show only a weak positive, statistically significant correlation with VSA soil colour, and very weak or no correlation with other VSA indicators.
- AMP groups that increase soil cover (AMP Permanent soil cover/removing less vegetation cover and AMP Residue maintenance/mulching) have moderate, positive and statistically significant correlations with VSA porosity. All other correlations with VSA indicators are either moderate but not statistically significant, weak or non-existing. These AMP groups show a weak positive correlation with LOC, but not statistically significant.
- AMP leguminous crops correlations with VSA indicators are moderate positive, statistically significant, with VSA indicators related to soil structure (VSA structure, porosity and stability). Correlations with other VSA indicators are weak or inexistent. Correlations with measured properties are weak and positive with infiltration rate and LOC, but not statistically significant.
- AMP manuring/composting has positive moderate correlations with VSA structure and porosity. Correlations with other VSA indicators are either weak (inc. with VSA stability) or non-existing. Manuring and composting have no effect on OM content (rs=0.00), and only show a weak positive correlation with LOC, not statistically significant.
- AMP crop rotation only has a weak positive, statistically significant correlation with VSA porosity. Other correlations with VSA indicators and measured properties are either weak, not statistically significant, or non-existing.
- AMP measures against compaction has no statistically significant correlation with VSA indicators and measured soil properties. The higher correlations, moderate and weak, are structure related (VSA structure and porosity) but not statistically significant. Correlation with VSA tillage pan is weak and not statistically significant, which stresses the need to prevent soils from becoming compacted.
- AMP integrated pest management (including organic farming) has positive moderate, statistically significant correlations with VSA structure and porosity. Other correlations with VSA indicators and measured properties are either weak, not statistically significant, or non-existing.
- AMP irrigation management has positive moderate, statistically significant correlation with VSA structure. Other moderate correlations with VSA indicators exist with VSA porosity, tillage pan and soil colour, but not statistically significant. Other correlations are either weak or non-existing.
- AMP change of land use practices / intensity level, has a definition too broad to allow any correlation to rise amid all the noise generated by so different management practices.
Note: For full references to papers quoted in this article see