Assessment of Soil Quality on TSN Plots at Ellerslie and Breton Utilizing Physical, Chemical, and Biological Properties
Assess the impact of consistent management, tilled vs no-till, straw removed or not, and N application rate on soil quality using physical, chemical and biological properties at Ellerslie and Breton, AB.
IPNI-2007-CAN-AB25
21 Dec 2007
Methodology
Experimental Design: The TSN (Tillage-straw-nitrogen) plots were set up at the Ellerslie and Breton Research sites in 1979. The experiential design for these sites was a randomized block consisting of 10 treatments x 4 replicates as shown on Table 1. These plots have been in consistent management for 28 years and are being prepared for a reverse tillage experiment which will be conducted in 2008.
Table 1. Experimental design for the TSN Plots at Ellerslie and Breton
Treatment | Tillage | Straw | N rate | Placement |
1 | No till | No Straw | 0 | |
2 | Tilled | No Straw | 0 | |
3 | No till | Straw | 50 | Banded |
4 | No till | Straw | 0 | |
5 | Tilled | Straw | 0 | |
6 | No till | Straw | 100 | Banded |
7 | Tilled | Straw | 100 | Banded |
8 | Tilled | Straw | 50 | Banded |
9 | Tilled | No Straw | 50 | Broadcast & Incorp. |
10 | Tilled | No Straw | 50 | Banded |
These plots have been sampled in May 2007 to assess the carbon sequestration, N pools, dry aggregate size distribution, N mineralization potential, etc. In order to assess changes in soil quality over a period of 28 years, a list of potential soil parameters to assess (i) soil structure and soil-air-water relations; (ii) biological indicators; (iii) macronutrient supply indicators; and (iv) salinity indicators has been drawn up (Table 2).
Table 2. List of potential soil parameters
(i) Soil Structure and Soil-Air-Water Relations
Indicator | Soil quality information |
Dry- and wet-aggregation indices and water stability index | The water stability index is a ratio of wet/dry aggregate indices and can provide information of stability of soil structure |
Bulk density/ penetration resistance | Soil compaction, physical environment for roots and soil organisms. Bulk density is needed to calculate volumetric moisture content |
Texture | This is a master variable and needs to be measured |
Aeration porosity to a specified tension, e.g. 50 cm of water | This class of porosity controls infiltration, drainage and aeration and is most affected by soil disturbance |
Available soil moisture | This is an important parameter for assessing vegetation growth potential |
Effective rooting depth | Plant roots provide a visual evidence of the degree of soil disturbance |
(ii) Biological Parameters
Indicator | Soil quality information |
Total Organic C | Organic matter reserves, biological resources |
Total Organic N | Organic N reserves, organic matter quality |
Microbial biomass C and N | Size of microbiological population, rapidly cycling, organic matter, and nutrients. |
Microbial C/ Total organic C ratio | Ecosystem stability; C cycling ratios; soil organic matter quality |
CO2 production | Availability of organic matter reserve, microbial activity. |
Respired C/ microbial C ratio | Respiratory quotient. |
Microbial N/ Total organic N ratio | Ecosystem stability; N cycling ratios; soil organic matter quality |
Mineralized N/ microbial N ratio | Specific N mineralization rate. |
Soil meso- and macro-fauna | Indicator of a healthy food web |
(iii) Macronutrient Supply Parameters
Indicator | Soil quality information |
Potentially-mineralizable N | Potential of a soil to supply plant-available N |
Kelowna P | Plant-available phosphate. |
Available K | Plant-available potassium. |
Available S | Plant-available sulfur. |
pH | |
in-situ nutrient supply | Plant Root Simulator (PRS) Probes |
(iv) Salinity Parameters
Indicator | Soil quality information |
Reaction (pH) | Acidity or alkalinity of soil. |
Salinity (EC) (dS/m) | Degree of salinity |
Sodicity (SAR) | Degree of sodicity |
Caption-exchange capacity | Buffering capacity and ability to retain nutrients. Derived measurements provide the sum of cations, base saturation and ESP |
Saturation (%) | Moisture saturation |
Stoniness Class | Degree of stoniness |
Texture | Mater variable |
Moist Consistency | Soil structure parameter |
CaC03 Equivalent (%) | Affects SAR and ESP calculations |
Gypsum (%) | Affects SAR and ESP calculations |
Timelines
Ellerslie site (if funding is approved for 2007)
Select and sample the Ellerslie site in the week of June 25 to June 30, 2007
Order supplies and start incubation experiments and measurement of microbial C and N (July and August, 2007)
Determine moisture retention curves, wet and dry aggregate size distribution and texture (Aug./Sept, 2007)
Fit in other items listed in Table 1 in between the above measurements (July to September)
Compile data and conduct statistical analysis
Breton site (If funding is approved for 2008)
Select and sample the Breton site in the week of July 9 to July 13, 2007.
Order supplies and start incubation experiments and measurement of microbial C and N
(August to September, 2007)
Determine moisture retention curves, wet and dry aggregate size distribution and texture (Oct./Nov., 2007)
Fit in other items listed in Table 1 in between the above measurements (August to December, 2007)
Compile data and conduct statistical analysis
Sampling and Methods of Analysis
For soil moisture retention curve and macroporosity:
Install and remove metal rings (5 cm OD x 3 cm deep) with undisturbed soil at 4 depths: 1-4; 6-9; 11-14; 16-19 cm; 5 rings per depth so we do not have to re-saturate cores for the different pressures. Samples are to be refrigerated, not dried.
For wet and dry aggregation:
(sample will be divided into half, where half will be used for wet aggregation, half for dry aggregation).
To complement what Dr Malhi has sampled already for dry aggregation; excavate a slice of soil (approx 20 x 30 cm) with flat spade; 4 depths 0-5; 5-10; 10-15; 15-20 cm
For microbial C and N, C and Net mineralization, specific C and N mineralization and mineralizable N; texture;
Three composite core samples per treatment: 0-5; 5-10; 10-15, 15-20 cm depths. Samples are to be refrigerated immediately after sampling.
For infiltration: in situ measurements using the Guelph permeameter.