From benbrook@hillnet.comSat Mar 23 12:03:17 1996
Date: Sat, 23 Mar 1996 11:10:22 -0500
From: Charles Benbrook <benbrook@hillnet.com>
To: sanet-mg@amani.ces.ncsu.edu
Subject: Weed Suppressive Soils Research Opportunity

To:  SANET-mg

        Try number 2, I did the address wrong the first time.  Sorry.  chuck

>Cc: dave@mortsun.unl.edu, BUHLER@NSTL.GOV, drkeeney@iastate.edu, ken@ewg.org,
>        bake@ccof.org, hansmi@consumer.org, goodmanR@macc.wis.edu,
>        hoppin+r%WWFUS@mcimail.com, RRJANKE@KSUVM.KSU.EDU,
>        76372.2132@compuserve.com, wcliebhardt@ucdavis.edu, mdlip@aol.com,
>        asorensen@niu.edu, werner@zzyx.ucsc.edu, liebman@maine.maine.edu,
>        jddoll@facstaff.wisc.edu, bjacobsen@reeusda.gov,
>        merrigan@access.digex.com, benbrook@hillnet.com,ccox@sies.wsc.ag.gov
>
>To:  Students/faculty, Dept. Heads in soils, biology/ecology, microbiology,
>agronomy, plant path. and relate disciplines:
>
>Re: Research Opportunity to Explore Biological Basis of Weed Suppressive Soils
>
>        There is growing evidence that weed-seed viability and survival is
>influenced by a range of biological processes including predation by a wide
>range of beetle species, microbial breakdown of the seed as it rests in the
>soil profile, and upon germination, attack by indigenous organisms that
>prefer foxtail (or whatever weed species) roots to anything else around.
>Together, these processes can create what some people refer to as "weed
>suppressive soils".  There is intriguing evidence from some recent Practical
>Farmers of Iowa trials that these mechanisms can play a powerful role in
>lessening weed management problems in fields and management systems where
>conventional "wisdom" would predict a very tough and ongoing battle with weeds.
>        Over the next couple of years the nation has a unique opportunity to
>test the boundaries of bioligcal/microbial weed management, as some 15 plus
>million acres return from the CRP to crop production.  Such land will be
>loaded with weed seeds, high in organic matter, and if managed correctly,
>will be exceptionally high in arthropod and microbial activity.  
>        Most of the land coming out of the CRP will unfortunately be managed
>in ways that will greatly reduce beetle and microbial acitivity, since
>conventional wisdom will say the ground has to be either heavily tilled or
>sprayed with burn-down herbicides plus heavy doses of grass/broadleaf
>products.  Already, farm magazines are scaring farmers about the high
>populations of insects that will be living in all the trash, and urging a
>preventive application of some soil insecticides.  And of course, to break
>down all that organic matter, farmers will need to apply susbtantial
>quantities of N, which if applied in common hot fertilize forms, will
>dramatically skew microbial populations in the soil, and reduce the chances
>that there will be sufficient microbial biodiversity in the soil profile in
>the key 4-8 week period in the spring and early summer when microbial
>biocontrol processes must either be in full-gear, or not happen.  These
>management -- herbicides, soil insecticides, heavy fertilizer applications,
>tilage --are likely to all work contrary to the biological processes that
>create weed suppressive soils.
>        So, the research opportunity is to work with some farmers converting
>CRP ground back to crops, develop a set of alternative management systems on
>a portion of fields, using combinations of reduced tillage, manure,
>cultivation, planting patterns/methods to control weeds with no herbicides
>and/or reduced rates.  In each of the reduced or no herbicide plots, a 100
>foot section of a couple of rows should then be fumigated or treated with
>some pesticide material that will knock back soil microbial activity and
>arthropods, but leave weed seeds unharmed.  The hypothesis would be that
>weed germination, survival, and growth would be significantly greater in the
>pesticide treated section of the rows than the untreated.  If this
>experiment, and variations on the theme, were run in several states over the
>next few years as more CRP gound returns to production, the collective
>results could markedly influence thinking about future directions in weed
>management research and management.  It will also lend key insights into the
>role of predation and microbial control of weeds in adjusting economic
>thresholds for weeds in the context of IPM systems. 
>        I would appreciate periodic updates from anyone carrying out such
>work in the next couple of years.  I am sure others on SANET would also like
>to be kept appraised of developments.  
>
>