Posts Tagged: environmental quality

CAST issue paper on the threat of herbicide-resistant weeds on soil conservation efforts

I wanted to share a link today to a paper published by CAST, the Council for Agricultural Science and Technology.  This paper, entitled "Herbicide-resistant weeds threaten soil conservation gains: finding a balance for soil and farm sustainablity", was released about a year ago and addresses one of the less obvious issues resistance imposes - soil erosion.  This paper can be viewed or downloaded (free!) at the link above.

The development and adoption of effective postemergence herbicides, both conventional and GMO-linked, has resulted in tremendous gains in soil conservation for much of the country due to the reduction in "clean" tillage, in-season cultivation to control weeds, and tillage operations to incorporate soil-applied herbicides.  This is of particular benefit in regions with summer rain, intense winds, and varied topography (like much of the Midwest where I'm from) but it benefits California growers and citizens too.

I won't attempt (in a Friday afternoon blog post) to repackage the careful assessment and explanation written by Shaw, Culpepper, Owen, Price, and Wilson.  I'd encourage you to read through the article for a slightly different view of the complex issues and cost/benefit considerations made by weed managers.  In the CAST paper, the issue is largely soil erosion from water but here in California, you might be more likely to consider dust (PM10).  I'd offer the point that weed management considerations are full of trade offs - economics, time, environmental;  non-chemical weed control efforts are not without problem. 

Brad

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Herbicide-resistant weeds threaten soil conservation gains: finding a balance for soil and farm sustainablity

CAST Abstract.  (Shaw et al. 2012)

Tillage has been an integral part of crop production since crops were first cultivated. Growers and scientists have long recognized both beneficial and detrimental aspects of tillage. There is no question that most tillage operations promote soil loss, adversely affect (lower) surface water quality, and negatively impact soil productivity. Weed management is a primary reason for tillage, and until the development of highly effective herbicides, conservation tillage was not feasible. Furthermore, with the development of herbicide-resistant (HR) crops, particularly glyphosate-resistant (GR) crops, herbicides such as glyphosate minimized the need for tillage as a weed control tactic; the resulting crop production systems have been primary enablers for the success of U.S. Department of Agriculture Natural Resource Soil Conservation programs.

Outreach on methyl bromide alternatives for the Pacific West region

One of my research focus areas over the past few years has been related to soil fumigation issues, specifically focused on methyl bromide alternatives for the tree and vine nursery industry.  I described some of this nursery work in a post late last year.  Today I wanted to share a brief description and links containing a more overarching view of methyl bromide alternatives related research in California, Oregon, and Washington.

With the support of USDA-ARS, a five-year program was initiated in 2006 to support research, demonstration, and extension projects in western cropping systems heavily reliant on preplant soil fumigation with methyl bromide.   These included several nursery systems (decideous tree and vine, sweet potato slips, cut flowers and bulbs, forest seedlings) production systems (orchard and vineyard  replanting, strawberry, etc) as well as controlling atmospheric emissions of fumigants.

As these projects reach the end of the five-year horizan, we started building a website to serve as a bit of a clearinghouse for information on the issues and research results.  Last week in Orlando, FL at the Annual Research Conference on Integrated Methyl Bromide Alternatives and Emission Reductions (who names these things anyway?), I coauthored a paper and poster with one of my USDA-ARS collegeues on our extension website and related outreach efforts.  A pdf copy of the poster is attached at the bottom of this post or can be found here. 

Better yet, you can visit the USDA-ARS Pacific Area-Wide Methyl Bromide Alternatives Program website (ok, I take the blame for the website name).  There are about 100 pages of information and links to a lot of more in-depth information by several multidisciplinary research teams.  Some of these pages are still being developed or finalized but I think this site is good start to explaining the methyl bromide issues, research successes, and continuting challenges in California and other western states.

Take care,

Brad

 

soil fumigation extension Hanson UCD

Impact of herbicidal weed control on soil, water, and energy

I recently received a copy of a paper published by CropLife Foundation entitled "The Importance of Herbicides for Natural Resource Conservation in the U.S.".   Publication date: January 2012.

I thought the paper had some interesting data on how herbicidal weed control has reduced the amount of tillage-based weed control and contributes to reductions in soil erosion, water concervation, and energy use in agriculture. 

The article is available along with a number of other publications at the CropLife Foundation home page (here), direct link to the pdf (here), or attached below with permission of the authors.

Take care,
Brad

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From the introduction of the paper:
Herbicides are used to reduce weed populations on approximately 220 million acres of U.S.
cropland [1]. More than 90% of the acreage of most field crops as well as vegetable, fruit, nut, and specialty crops are treated with herbicides annually. Herbicides were first introduced in the 1940s and by the 1970s had achieved a dominant role in managing weeds in crop fields. Prior to the introduction of herbicides, the dominant methods of weed control were cultivation and hand weeding. Although still practiced, cultivation and hand weeding have been greatly reduced in U. S. crop production.

The use of herbicides has had major impacts on the conservation of soil, water and energy
resources in the U.S. These impacts occurred largely due to the replacement of tillage with
herbicides for weed control. Weed control methods used by organic growers also impact natural resource, even though they do not include herbicides, which furthers our understanding of the role of herbicides in conservation.

Can GE and non-GE alfalfa coexist?

Article originally posted on the UC ANR Green Blog on October 11, 2011.  Written by Danial Putnam and reposted with permission.  Brad

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Those of us who work with alfalfa have seen our much-loved Queen of Forages relegated to poster child of all things evil about genetic engineering (GE) and the supposed damage it may wreak. While hay growers have always felt alfalfa has received insufficient attention – this was probably not what they had in mind! 

Those of us who work with alfalfa have seen our much-loved Queen of Forages relegated to poster child of all things evil about genetic engineering (GE) and the supposed damage it may wreak. While hay growers have always felt alfalfa has received insufficient attention – this was probably not what they had in mind!

 I’m referring, of course, to the release of Roundup Ready alfalfa (RRA) in 2005 and the subsequent lawsuit that stopped its planting from 2007 until 2011 – a case that went all the way to the Supreme Court!

The drama continues today with newly minted lawsuits, as farmers once again plant RRA and conventional alfalfa throughout the U.S. But what does this ballyhoo mean for those who actually grow alfalfa?

At the heart of the controversy is co-existence: whether cross-pollination from GE alfalfa would completely prevent organic or other growers who didn’t want GE alfalfa from practicing agriculture as they see fit. Or, alternatively, whether farmers can adopt methods to avoid undue neighbor influence or contamination.

Successful coexistence can be defined as the ability of diverse production systems (organic, GE-adopting, conventional) to thrive without excessive neighbor influence, or resorting to extraordinary protection measures.

Is co-existence possible? The answer is a definitive “yes” based on both history and principle.  Agriculture is replete with examples of farmers adjusting and cooperating to make diverse systems work. In principle, there is no technical reason that diverse farming practices cannot co-exist.

So if you produce alfalfa for organic, export or other markets that don’t want GE crops, what is required? The answer is very different for those who grow alfalfa for hay vs. those who produce seed. Seed requires considerable isolation distances to prevent contamination – and always has.

For hay, a series of steps can reduce this risk to very low levels.

The first, and most important step is to plant seed tested and determined as non-GE. Plenty of conventional seed is available, as are inexpensive testing methods to assure that the seed is non-GE. Seed companies have committed to produce conventional seed in the future, including seed destined for GE-sensitive markets.

The next step is to assure that contamination doesn’t happen during harvest – through partial bales moving in balers from field to field or accidental misidentification of hay lots. This is likely the second-highest risk of contamination.

The lowest – but not zero – risk of contamination in hay: inadvertent gene flow from hayfield to hayfield.

Neighbors can reduce this risk further by: 1) Controlling unharvested plants on field edges and feral alfalfa along roadsides to prevent seed production; 2) Routinely harvesting hay to prevent excessive flowering; and 3) Completely removing crop before excessive flowering or seed production. Crop removal prevents permanent contamination, since seed must fall to the ground and grow into new plants to contaminate hayfields.

Lastly, it is important to understand thresholds or market tolerance.

Does a single RRA stem, accidently baled in a 200-ton lot of conventional hay (containing billions of stems), constitute contamination? This will be market-determined. Commercially available test strips will likely satisfy most if not all sensitive markets of a hay product’s non-GE status.  All markets have thresholds for contaminants, and there is no reason to believe this to be an exception.

In short, methods are readily available to assure an alfalfa crop’s non-GE status, even as neighbors start growing GE alfalfa. These require a higher awareness of gene flow and other avenues of contamination, but do not appear to be onerous or difficult.

We also should not underestimate the importance of mutual respect and willingness to cooperate among parties as keys to a co-existence strategy. It is axiomatic that coexistence is impossible if parties are unwilling to listen to each other, allow a diversity of viewpoints or develop a way to resolve disputes.

The alfalfa industry has largely stepped forward to support diverse systems within the agricultural landscape and needs to continue to do so. This has been the case with National Alfalfa & Forage Alliance efforts to promote coexistence over the past 5 years, which continue today (see their website).  Seed companies and growers continue to negotiate isolation distances for production of GE and non-GE seed. Likewise, hay farmers have demonstrated co-existence by growing RRA and organic alfalfa successfully on the same farms.

This year in California’s Imperial Valley, seed, hay and organic growers, exporters and seed companies have met extensively and decided to prohibit RRA in their region due to the close proximity of seed, hay, biological factors and the importance of seed and hay exports.

These are examples of “bottom-up” co-existence approaches led largely by farmers and companies – in contrast to regulations decided in Washington or through the courts.

The concept of right-to-farm and co-existence between neighbors and diverse industries is not new to agriculture. Yet the introduction of GE alfalfa and its potential influence on neighboring farmers requires improved co-existence strategies for alfalfa.

(This article was first printed in Hay and Forage Grower magazine.)

New film traps fumigants and increases strawberry yields

Producing 85 percent of the nation’s strawberries, California growers urgently need alternatives to methyl bromide fumigation if they are to maintain yields. Methyl bromide has been phased out for all but critical uses because it depletes ozone in the upper atmosphere.

UC scientists now report that use of totally impermeable film in strawberry fields can improve the effectiveness of a widely-used MB alternative known as 1,3-D (1,3, dichloropropene). Use of the film reduces the amount of 1,3-D needed to maintain yields, while lowering field emissions overall.

The strawberry industry is highly dependent on soil fumigation to control pests and maintain high yields. The methyl bromide alternative, 1,3-D, can be used only in certain quantities, due to air quality concerns.

In a recent trial, totally impermeable film (TIF) was laid out over Salinas fields to prevent the fumigant from leaking. The new film was compared with the standard film used by growers. Fumigant concentrations under TIF were 46 percent to 54 percent higher than under standard film, and the higher concentrations were correlated with higher strawberry yields and better weed control. Scientists report these findings in detail in the October–December 2011 electronic edition of the University of California’s California Agriculture journal.

Impermeable films have three benefits, according to lead author Steven Fennimore, UC Cooperative Extension specialist and weed scientist in UC Davis Department of Plant Sciences. The films trap the fumigant in the soil for a longer time and thereby increase its effectiveness; they reduce fumigant emissions, which after reacting with nitrogen oxides, can convert to ground-level ozone; and they reduce the amount of fumigant needed for effective pest control.

Emissions are a chief concern. Methyl bromide, a widely used fumigant in combination with chloropicrin, has been phased out since 2005 because it is an ozone-depleting substance targeted by the Montreal Protocol (a global treaty to control ozone depletion) and the U.S. Clean Air Act. However, it is still being used in some California strawberry fields under a critical-use exemption. Restrictions on the use of 1,3-D to 90,250 pounds per 36-square-mile township (called the township cap) leave few other options for growers in key strawberry production areas near densely populated areas.

Comparing TIF with standard film, and methyl bromide plus chloropicrin with varying amounts of 1,3-D plus chloropicrin, the scientists rated the effectiveness of TIF. The results, writes Fennimore, suggest that to achieve fruit yield and weed control similar to methyl bromide and chloropicrin, 33 percent less 1,3-D plus chloropicrin is needed under TIF than standard films.

TIF may ease some of the burdens of fumigant regulations on end-users, as well as ease concerns of the general public about exposure to fumigants, he concludes.

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The research article “Totally impermeable film retains fumigants, allowing lower application rates in strawberry” can be viewed and downloaded at http://californiaagriculture.ucanr.org/landingpage.cfm?article=ca.E.v065n04p211&fulltext=yes.

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