Explanations to the meaning of the different Parameters
Temperature:
Normally microorganisms only work well at a temperature higher than 12° C. So it is possible that you cannot see a difference between the different plots during the winter.
The different nitrogen states:
The normal level in summer for NO3 is 0 -100 ppm but in good soil you can only find very low levels to a max of about 20 ppm because all nitrogen is fixed by the microorganisms. In winter you cannot find NO3 in a good soil because the microorganisms fix all nitrogen before they finish their work by the end of the year.
NO2 shouldn't be found in the soil. If it does show you have a compaction in the soil (to little oxygen in the soil).
NH4 levels shouldn't be higher than 0,5 ppm. But after turning fresh organic matter into the soil (hay) it is normal that you can find a higher level of NH4 for some weeks in the soil (a max of about 2 to 3 ppm). The higher NH4 level results from the break down and build up work of the microorganisms in four different steps:
1. Changing protein to NH4
2. Changing NH4 to NO2
3. Changing NO2 to NO3 (a very short phase)
4. Fixation of NO3 in the protein of the microorganisms.
High levels of NH4 in the soil for several weeks are the result of to less oxygen in the soil, few microorganisms or to little microorganism activity caused by low temperatures. You also always have the danger of putrefication!
pH act/pot:
To measure pH act you have to mix the soil sample with distilled water. For pH pot you have to mix it with the KCL-solution you also use for the determination of the different nitrogen states (see: preparation of the extraction solution). The results of pH act are normally higher than those from pH pot. Distilled water loosens only easily connected
H+ ions from the soil instead of KCL-solution which loosens nearly all H+ions from the soil. That is why pH pot levels are usually lower than the levels from pH act. But if you have soil which is build up well, which means all organic matter is broken down and built up by the microorganisms, than you can nearly loosen all H+ ions with distilled water. In good soil the difference between both levels should not be higher than 0,5. The closer the levels the better (the more microorganisms) the soil, the wider the levels the less alive, the poorer the soil. This is also in connection with fertility and structure.
Air:
The pore space in average soil is about 50%. In this pore space you have also water. The bigger the pore space the better are the conditions for all life in the soil and the growing of plants. In humus rich soil you can find more pore space than in humus poor soil so we should find more pore space at the end of the test period. To have the pore space add the results from the air test with the results from the water test.
Water:
A good humus rich soil has more waterholding capacity (a humus particle can take in water four time grwater than its own weight). So perhaps we can see a difference between the test plot with hay and microorganisms and the test plot with no treatment just after six weeks!
Total organic matter:
We measure all carbon links in the soil with the Kjeldahl method. ( Send really dry soil samples to a lab but don't heat the soil samples over 60° C). In good soil where you want to use in a biological method you should have at least 5 % organic matter [O.M.](carbon links). The minimum for microorganisms to be alive is a limit of 2 %. Humus rich soil has to about 20% (the Lübke farm has about 16 % O.M.) but many farmers in Austria and all over the world have less than 2 or 1%.
Humusvalue:
The Humusvalue you can measure with the Lübke Humustest which shows you a connection between the humified and the non-humified organic matter. The best Humusvalue you can find in compost is a little over 70. The humusvalue is in correlation with total organic matter and should be three times higher than organic matter levels. If you have, for example, a soil sample with 5 % O.M. the Humusvalue should be 15 to 20, a soil with 16 % O.M. about 45 to 50.
If you have a soil sample with 5 % O.M. and only a Humusvalue of 7 this shows you that you have none or very few workers (microorganisms) who break down and build up the raw organic matter. (Hay you put into the soil will be in the same state after one year if there aren't any microorganisms. In these conditions you also have the danger of putrefication).
If you have a soil sample with 2% O.M. and a Humusvalue of 20 this means that you have a good build up of soil and still a lot of microorganisms but you haven't done something for your Humuslevel in your soil and if you don't add compost or green manure to the soil your still alive microorganisms will die and also the fertility and good soil structure will disappear.
It is essential to differentiate between humus and organic matter. Organic matter tests, like the Walkly-Black method or loss on ignition, are based on an extraction of all organic compounds in the soil or compost, but does not differentiate between raw and humified matter. Organic matter which has been humified has been biologically transformed into a stable form which is not as susceptible to leaching as non-humified organic matter. The humus figure determined by this method is not given in percentage, but is a relative number on a scale from 1 to 100. The portion of humus or humic substances in soil or compost which are soluble by the screening agent is extracted carefully and then compared against the standardized colorimetric scale.
