It was exciting to see all the interest in indicator issues. Some
folks wanted comments back, then I got carried away.
Excerpts from Jim Meade (firstname.lastname@example.org) 06Nov94:
> In some cases,
> there are more yield differences within soil types in the same field as
> there are across soil types.
> Initial discussions I've heard, indicate that drainage has a large
> function in yield. Fertilizer does, but only to a point and not directly
> related to input quantity. Variety can make a difference, but it is not
> the major factor. Therefore, all the variable rate technology (VRT)
> needs to be investigated very carefully before buying into that. Some
> farmers are saying that temporal factors are more important than spatial
I agree, Jim, those _are_ unsettling ideas. I consider the "big four"
to be weather, inputs, soil, and genetics, not necessarily in that
order. Do you (or others in the list) know of any studies
regarding either the soil or the fertilizer situations mentioned?
I would particularly be interested in seeing the statistics. A large
sampling variation within a soil map unit, let's say, might not
take away the fact that there is greater variability among fields
with different soils than among fields with the same soil. Maybe a
statistician can comment. Of course, as you say, fields
can have many soil map units, and there can also be inclusions of
unlike soils within map units.
Exerpts from Dick Richardson (d.richardson@MAIL.UTEXAS.EDU) 06Nov94:
Referring to Jim Meade's comments ...
> I'd like to add that organic matter, coupled with soil organismal
> activities seems to be closely tied to this difference. In rangeland, for
> example, we can see this by the onset of stress in dry times if we have
> remotely senses spectral data (near IR reflectance). The same holds for
> crops. I depend on the dung beetles in the summer, but ants and termites
> are helpful. They can be indicators as well. Earthworms in the winter are
> important indicators of processes needed, but it depends on how cold the
> ground is. It's these critters that get dung and litter in the ground, and
> at the same time open up the avenues for rapid infiltration and aeration.
> They are indicators of more than simply OM.
Food for thought here. Certainly it's reasonable that pore-building,
aeration, and organic matter incorporation are key processes in
soils for maintenance of plant growth. But then you have to
decide if the indicators should be chosen from among the results of
those processes (soil infitration, porosity, soil organic matter) or
from among the causal agents (beetles, ants, earthworms)? Which is
cheaper? Which is more reliable or universally applicable? Do the
critters give us extra info that the soil physical properties do not?
> On a more baseline field- or regional-level note, I don't believe ANY index
> of sustainability is meaningful if it doesn't have an indicator of
> lessening the dependency on fossil fuel and related outside inputs. No
> matter what the practice, if it isn't moving in this direction in a
> recognizable way, it's almost surely moving toward un-sustainability.
That would be the prudent approach, since we cannot bet our future on
the discovery of a cheap, clean substitute for fossil fuels.
Which is one reason that I like nitrogen use efficiency as
an indicator, especially if you also report an estimate of
the fraction of total applied nitrogen that comes from commercial
fertilizer vs. from manure. Which we do.
> In a
> larger scale, I think the same is true if it isn't addressing other
> consumer related issues of the Northern Hemisphere, and populational issues
> of the Southern Hemisphere. This is my greatest complaint about many of
> the indicators we see discussed in the conferences.
It certainly is a big picture, and I know that each of us only
deals with a certain part of it. One of the scariest things
is that we might think we've got the bases covered and then get
blindsided. The comment was made at the August SANREM indicators
meeting that the country of Rwanda was looking good in terms of
agricultural sustainability and food security, before the civil war
brought them unbelievable misery. (Am I stating that
correctly, Chuck B.?). Maybe we need a "political stability" and
a "respect for human life" indicator.
Exerpts from Greg McIsaac (GRM@age2.age.uiuc.edu) 06Nov94
> It seems to me that an approriate combination of indicators will
> depend upon the particular region and predominant farming system and
> what people are committed to sustaining. In many cases it may be wise
> not to combine indicators but to monitor variables and pay attention
> to whether and where they are approaching some critical level. This
> may sound like a daunting task but I think new software tools in
> presenting spatial data may be heplful in sumarizing such information.
Certainly we will be reporting on a series of indicators. Our low
sample density over large regions is a limitation to doing maps, but
maybe you could say more about those software tools.
Brings up something that I didn't emphasize: the principal
audience for EMAP is policy-makers who will be thinking in terms of
fairly large regions ... groups of states.
> Perhaps a software environment
> that allows users to manipulate the data may be more appropriate than
> boiling the data down to one or a few numbers.
Believe it or not, that is one of the plans for EMAP's
information managment system. I don't know how far down the
road that is, but mostly they're testing things with data from
the bigger groups (forests and estuaries).
> You mentioned farmer interviews in collecting data on soils and
> cropping systems. Is there any effort to include other
> constituencies in developing appropriate indicators?
Not within our Agro group.
> I'm supprised that you did not raise the issue
> of temporal variation as one of the major challenges. What kind of
> time scales do we need in order to define sustainable systems, or to
> more simply seperate out temporal variation due to "regular"
> cycles from unusual variations due to some change in management
Maybe I should clarify that we're not trying to define sustainable
systems as much as trying to measure what proportion of U.S.
agricultural lands are in good condition, and how that is changing
over time. If a trend shows up, then hopefully we'll be able to
give some suggestions as to why it happened. Then you've got the issue
of "Is it too late to do anything about it?" That's pretty serious.
I certainly hope that some of our indicators will be anticipatory, that
they'll point toward future sustainability or lack of it. See comments
on nitrogen use efficiency above. A question for Greg: what would
be a regular cycle in an agroecosystem, not including weather? Certain
insect pests? How do you know if a pest outbreak is because of a
natural cycle vs. insecticide resistance vs. loss of beneficials vs.
excessive monoculture? Seems these could get very intertwined.
Don't underestimate my ignorance of entomology, however.
To Dominique Charron (email@example.com) 07Nov94
I also got a message from Ellen Wall there at Guelph. Do you
work together? Have either of you had contact with Anne
Hellkamp from our EMAP-Agro group? Anne has been in touch with two
different Canadian efforts at monitoring the health of agriculture.
Ellen asked for some EMAP publications, which I will send after
next week's meetings.
Once again, speaking for myself and not the program...
| MIKE MUNSTER |
<> EMAP-Agricultural Lands phone 919-515-3311 <>
| 1509 Varsity Dr. fax 919-515-3593 |
<> Raleigh, NC 27606 email firstname.lastname@example.org <>
| USA |