I'll send the picture separately so its file size won't interfere with the
text files. When one looks at this root difference, one should remember
that root growth is promoted not just by soil and water conditions but also
by bacteria in the root zone. I suspect that the Cuban field where the SRI
was being used had a good endowment of bacillus, pseudomonas or
burkholderia that were greatly multiplied by the soil aeration, root
exudation, etc. that SRI practices provide. A colleague in South Africa has
recently done some controlled experiments that showed as much as a doubling
in root size attributable strictly to presence vs. absence of certain
bacteria. So keep always in mind the soil microbiological dimension of
plant growth and performance, not just the chemical or just the physical
aspects of soil quality.

Dr. Ana Primavesi is one of the most well known and respected tropical
soil/ecosystem specialists in Latin America. Unfortunately, she has
published little in English (most is in Portuguese as she lives in Brazil,
though some is translated into Spanish). I sent her a paper on SRI having
met her at a conference in Havana last May, asking for her thoughts on SRI.
Attached is her response, which I polished the English on a bit so it would
be easier for you to read. She tells us many things we already know about
SRI, but her confirming some of our conclusions is very welcome, and she
adds some depth and richness to our understanding. So, for whatever
stimulation of thinking and practice these ideas might be, here are Ana
Primavesi's perspectives on SRI.
Norman