Thanks, Nick. The background story may be funny. I was leaving home to meet my brother and grandpa for dinner. I was going to throw away a cardboard box into the bin, but it was too big to fit in. I was a bit in a rush. So I decided to leave it next to the bin instead of smashing it. This made me wonder about what would be the impact on soil animals of not having put the box into the bin, neglecting effects on my time (which was the real driver of my decision). I realised the people taking care of the garbage would probably do it, and therefore spend a tiny bit more of energy. This got me into very roughly calculating how many nematode-years are affected by increasing food consumption by 1 kcal. If I recall correctly, here is how I did the Fermi estimate in my drive to my grandpa’s house (do try this at home, not driving!). 1 g of rice has 4 kcal. So 1 kg of rice has 4 k kcal (= 10^3*4). I assumed rice has yields of 3 t/​ha/​year (5 t/​ha/​year would have been better), 0.3 kg/​m^2/​year (= 3*10^3/​10^4). So I got an energy production for rice of 1.2 k kcal/​m^2/​year (= 4*10^3*0.3), which I think I wrongly converted to 10^-4 instead of 10^-3 m^2-year/​kcal (= 1/​(1.2*10^3)). I supposed increasing the area of rice fields by 1 m^2-year increased or decreased 3 M nematode-years. So I got a change in the living time of nematodes per kcal of 300 nematode-years (= 3*10^6*10^-4). Using the correct past result would have led to 3 k nematode-years (= 3*10^6*10^-3), which is inside the range of 640 to 13.1 k which I obtained above.
Thanks, Nick. The background story may be funny. I was leaving home to meet my brother and grandpa for dinner. I was going to throw away a cardboard box into the bin, but it was too big to fit in. I was a bit in a rush. So I decided to leave it next to the bin instead of smashing it. This made me wonder about what would be the impact on soil animals of not having put the box into the bin, neglecting effects on my time (which was the real driver of my decision). I realised the people taking care of the garbage would probably do it, and therefore spend a tiny bit more of energy. This got me into very roughly calculating how many nematode-years are affected by increasing food consumption by 1 kcal. If I recall correctly, here is how I did the Fermi estimate in my drive to my grandpa’s house (do try this at home, not driving!). 1 g of rice has 4 kcal. So 1 kg of rice has 4 k kcal (= 10^3*4). I assumed rice has yields of 3 t/​ha/​year (5 t/​ha/​year would have been better), 0.3 kg/​m^2/​year (= 3*10^3/​10^4). So I got an energy production for rice of 1.2 k kcal/​m^2/​year (= 4*10^3*0.3), which I think I wrongly converted to 10^-4 instead of 10^-3 m^2-year/​kcal (= 1/​(1.2*10^3)). I supposed increasing the area of rice fields by 1 m^2-year increased or decreased 3 M nematode-years. So I got a change in the living time of nematodes per kcal of 300 nematode-years (= 3*10^6*10^-4). Using the correct past result would have led to 3 k nematode-years (= 3*10^6*10^-3), which is inside the range of 640 to 13.1 k which I obtained above.