In this Soil Network of Knowledge webinar, Jason Condon presents a masterclass using ‘analog PowerPoint’ to explain soil testing basics including how to interpret soil laboratory test reports. To access the webinar, you need to tick a box and provide your name and email address. Jason recommends the booklet, Understanding your soil test, by Cath Botta. While this webinar was produced in NSW, it is relevant to all Australian regions [1:54:09]. #
Topics covered are:
[8:43] why test your soil
[11:24] the components of different clay particles and their response to pH change
[17:18] soil testing laboratory accreditation (ASPAC and NATA)
[18:48] the elements of laboratory soil test report
[19:10] the limitation of ‘traffic light’ gradings
[20:30] interpreting soil colour using the Munsell soil colour book
[21:20] soil texture (measure of clay content)
[22:17] visualising pH as the pH of soil drops
[25:20] electrical conductivity -(pH (1:5 water) vs pH (1:5 CaCl2)
[27:33] pH buffering measured using the negative charge of soils, cation exchange capacity (CEC) and the NH4Cl/BaCl2 test
[37:13] effective cation exchange capacity (ECEC)
[40:50] plant-available phosphorus (Colwell P or Olsen P), phosphorus buffering index (PBI)
[48:45] Better Fertiliser Decisions for Cropping tool (www.BFDC.com.au) – fertiliser trial data for Australian soils
[51:23] Ca:Mg ratio
[52:40] considering the soil sampling depth and tillage systems in trial results
[55:21] increasing organic matter
[57:19] taking soil samples from depths of at least 20 cm in 5 cm increments, see what the roots are doing
[59:36] soil carbon
Questions:
[61:32] Ammonium is a base cation. Why is it not included when calculating CEC?
[62:06] Can you comment on the role of animals or manure incorporating dung beetles in the system?
[63:15] If a nutrient response curve for 0-10 cm sample shows no response to nutrient addition above the critical value, can you find that there’s a nutrient deficiency caused by stratification?
[64:32] How often should we be soil testing our paddocks?
[68:38] To what extent does aeration influence elements in solution?
[72:17] If we have a Colwell P of 20 and the critical value to increase one Colwell P is 2.5, is it fair to say that there is 50 kg per hectare of P available to plants?
[75:08] Can you give us a scenario where measurements at deeper levels could indicate physical problems in contrast to chemical problems?