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Hello Jennifer. There is no purpose to the priming effect. It does have an effect though. An increase in microbial activity with addition of labile material results in release of extracellular enzymes by soil bacteria and fungi. These enzymes are released by microbes to depolymerize the labile carbon. However, the enzymes also encounter humus and work to depolymerize the humus. This is the priming effect, an increase in degradation of stabilized carbon as a result of addition of labile carbon materials to soil. I hope this helps understand the priming effect better. take care, Mario
Hi. I will start compiling those marks starting this Sunday.
Hi All. I keep to the same instructions about the exam as given in lectures. It will be emailed and posted online to the course homepage at the start of the exam period (1:30pm). It is open book and needs to be emailed back by 4:30pm. Exceptions being students registered with student support services that have time considerations to beyond 4:30pm. take care, Mario
yes, it is.
Hi Victoria. Of is the best designation. This way the horizon is not confused with the LFH surface layer of forest or shrub land.
Hi. Please see Lecture 5 slide 11. It shows the diagnostic horizon for each of the soil orders. A diagnostic horizon is what is key to placing a soil in a particular Order. You will see that the diagnostic horizons are not shared between Orders. Take care, Mario
yes for those who have the Monday session.
Hello, yes I made a mistake, it should be Great Groups. Page 23 of Soil Classification System of Canada linked on our website gives the Great Groups for all soil orders in Canada.
Hello All. I sorting out with the TA the marking of labs and their return to you. They will be emailed back to you so you can see how you did. take care, Mario
Hello All. As this is an open book exam you can and are encouraged to consult materials external to lectures and powerpoints. take care, Mario
Hi. We went over this in class. I was confused and thought this week was a break week. I said last week it was due next week because of the break. No one said “what do you mean, a break”. Recognizing the mistake I said you can send the assignment in before your session next week. take care, Mario
Hello. For starters, perennial vegetation such as forages and grasses are not disturbed by tillage. So larger aggregates can form without being broken by the impact of cultivation equipment in breaking them apart. However, we have cropped soils that are not tilled but don’t build as good soil structure as under perennials. Perennials invest more energy and resources into building root systems than annual crops. Perennials rely on roots to store energy and nutrients for growth in spring. Many perennials can grow sooner than annual in spring and continue to grow in the fall. Thus perennials for the most part, grow for a longer portion of the year than annual crops in our climate. This all results in more carbon input into soil with perennial via the root system. Further perennial roots are growing and dieing constantly, this adds carbon to soil and feeds microbes. The roots also encourage micorrhizal association (roots with a fungus, we will learn more on this later). The mycorrhizae have thin threads or filaments of cells. These excrete sticky glycoproteins to bind soil together. They also physically make a mesh around aggregates. Roots also can bind microaggregates together to make larger aggregates, partly because of excretion of sticky carbon substances and also because they push and pack soil as they grow and expand in pores. So you see its about carbon input for a longer period of time, roots, feeding soil microbes and lack of disturbance. Sorry for the long answer.
Hello Victoria. Good question. It should read
contains pores that are very narrow that allow for water storage and retention in soil
Yes, applies to both lab sections. Happy Thanks Giving, Mario
Lab 2 lab is due before your lab section time the week we come back from the break. take care, Mario