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
Justification
Agricultural productivity depends largely on the uppermost layer of soil which is generally 15 to 20 cm deep for most soils. This soil layer stores and releases water for plant use, provides a rooting zone for plants, and supplies plant nutrients. It also enhances seed germination and root penetration, and supports a complex community of microorganisms and fauna that decompose organic materials and recycle nutrients (Parr et al., 1992). A productive soil needs a favorable structure and an efficient nutrient cycling system. Management practices which simultaneously enhance these functions can lead to sustainable land use.
In general, more attention has been given to increasing crop production on soil compared to the development of the soil itself. This is summarized in the following question: Should one feed the plant or should one feed the soil?” The answer depends on the time scale. In the short-term, one has to feed the plant but in the long-term one has to feed the soil by improving its structure, increasing the organic matter content and water holding capacity, and by ensuring that it contains a wide array of microorganisms and fauna. In the long-term, the structure of surface horizon of soils has to be improved so that it can support healthy crops. Therefore, it is necessary to assess the physical, chemical and biological indices of soil quality rather than plant productivity as an indicator of soil productivity.
The Tillage-straw-nitrogen (TSN) plots were set up at the Ellerslie and Breton Research sites of the University of Alberta in 1979. The tillage treatments were till and no till; the straw treatments were no straw (i.e., straw was removed and not returned to the plots) and straw (i.e., straw returned to the plots); and nitrogen fertilizer was applied at rates of 0, 50 or 100 kg/ha). 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. Therefore, there is a great opportunity to assess plant and soil productivity of these plots as well soil quality parameters. A holistic approach would yield insights of management on the improvement of the whole soil rather than just plant productivity.
From a practical pint of view two questions need to be answered; (1) What makes these trials different than other long-term trials?; and (2) Why should something be done now?
The TSN (Tillage-straw-nitrogen) plots were set up at the Ellerslie and Breton research sites in 1979. This experiment at Ellerslie and Breton are unique from other tillage, straw, nitrogen experiments because of the soil type (Black Chernozem and Gray Luvisol, respectively), as well as their climatic zones. The experimental 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. We already have a wealth of knowledge about the aboveground productivity and some soil measurements. However a holistic approach is needed to assess changes in fundamental soil properties due to key management practices, i.e., tillage, straw management and fertilizer application.
The lease for the Ellerslie Research station expires in 2011. Therefore, the TSN plots are being prepared for a reverse tillage experiment i.e., the serotill plots will be tilled and the tilled plots will be converted to zero till. It is critical to sample the plots thoroughly this year to access the cumulative effect of consistent management over a period of 28 years. The reverse tillage experiment will be conducted in 2008.