Tag Archives: corn

Ploughshares into spray nozzles–the California Tour

6 Sep
English: Wild elephants in Munnar, Kerala

English: Wild elephants in Munnar, Kerala (Photo credit: Wikipedia)

How will farmers feed 9 billion people by the close of this century? That is the question posed to six renowned leaders in the field of conservation farming during the Conservation Ag Systems Innovation conference tour (CASI)
On August 28th, 29th and 30th,
Jeff Mitchell, University of California Cooperative Extension Specialist,  gathered together some of the world’s great visionaries to sell conservation farming practices to California farmers, students, and agency staffpeople. Conservation farming, a term used to refer to no-till, minimum tillage and controlled traffic farming practices, is popular in the midwestern US because it saves water and cuts fuel costs while preserving soil organic matter, which has many benefits to soil fertility. No-till is also popular in South America, particularly in Brazil, while controlled traffic farming (with conventional tillage) is practiced in Tasmania, an island off the coast of Australia, for the purpose of reducing soil compaction on the cropped rows while improving traction on the trafficked rows.

Don Reicosky from Morris, MN, a retired USDA ARS employee, explained the nuts and bolts of tillage and likened it to natural disasters for soil microorganisms. The best tillage is no-till, he explained.
Rolf Derpsch from Paraguay, who has worked in Brasil, Argentina, Somalia and Germany, explained why conservation tillage not only saves water but also reduces the need for fertilizer because soil microbes and organic matter act as a slow release fertilizer, protecting ground and surface water from contamination. He said that early adoption of no-till in South America was easier to support than here in the US because there was no initial attachment to what we call conventional tillage, and the yield increases with less gas and less fertilizer inspired the spread of conservation farming there.

Clay Mitchell from Geneseo, IA grows corn and soybeans alternating in a north-south direction to maximize profitability based on market prices for those two commodities, but that is not all. This farmer has combined controlled traffic farming with satellite GPS (Global Positioning System) technology, and an awe inspiring data collection protocol which allows him to micromanage the fertilizer application based on things like prior yield in a particluar square foot of field. Tillage has long been considered the primary way to get rid of weeds and make the fertilizer applications and rooting depth more uniform. With no-till, surface application of soil ammendments like lime (calcium or calcium-magnesium carbonates) could be inconsistent and will only reach a depth of a few centimeters during a growing season, so Mr. C. Mitchell advises crop rotations rather than tillage to incorporate surface applied lime at depth, and he relies on satellites to position his fertilizers exactly where they are most needed rather than tilling for greater uniformity. This is a real engineering problem solving strategy, but weed control

Jerry Hatfield spoke about what the EPA and the California Air Quality Control Board want from soil, and how much more food we will need to produce on the same land. These two ideas do not conflict–by keeping more carbon on the ground, soil water holding capacity goes up, meaning that less irrigation water is needed and droughts are less severe. Water use efficiency increases as does productivity per unit fertilizer, giving us some hope for the future, when worldwide land area will decrease while demand will be as high in the next 10 years as in the previous 100 years.

John McPhee of Burney, Tasmania explained how GPS technology can aid in controlled traffic farming which reduces erosion and compaction, improving drainage and allowing cultivation and planting sooner after rain events. He said that tillage was an integral part of his operation and it was not popular to consider no-till systems in Tasmania. He likened the soil microbes to an elephant per acre, and the residue left in the field as food for the elephant -FEED the Elephant!

I would like to suggest that there was another elephant in that room. Herbicides. There is no such thing as organic no-till. Tillage is a wonderful alternative to herbicides and with all the hype about overuse of Roundup and other easily available potent herbicides, which results in herbicide resistance in common weed species such as Palmer Amaranth. Mr. Clay Mitchell of Iowa explained that he rotated his herbicides by rotating his GMO corn and soybeans from Roundup Ready varieties to Liberty Link varieties (the first can tolerate lots of the herbicide Roundup, or Glyphosate, and the second can handle a lot of Glufosinate, an herbicide with a different mode of action. Rotating modes of action is smart to prevent resistance in weed species, but mechanical control is the only option for organic growers, so if we stop plowing, we protect the environemnt from carbon dioxide and particulate matter but this system depends on constant innovation of herbicide chemistries to keep up with herbicide resistance, and constant new developments in the world of GMO’s to allow excessive herbicide applications. The herbicide question looms large in my mind, particularly for the developing world, where transportation infrastructure increases the cost of everything from fertilizer to herbicide to parts for fancy GPS directed no-till equipment. So feed the soil microbial elephant, and give that herbicide elephant a few peanuts too, while you’re at it–the future of humanity and food security depend on it!

Aside

Sweetcorn: A chemical war zone. We are not just spectators any more.

28 Aug
Fusarium ear rot on maize

Fusarium ear rot on maize (Photo credit: CIMMYT)

It”s sweet corn season, and farm stands are popping up all over the country to feed the need. So where do you go for your sweet corn? Organic or conventional? Do you grow your own corn?

This time of year brings back memories of my days working on an organic farm and roadside stand where customers could pull in and yell out the window ” got any corn?”, and I would run out into the field and snap off a ripe ear, opening the husk and cracking off the top inch or so of cob to get rid of the earworm and damaged kernels at the top of nearly every ear that I picked. We told customers that ‘if they were handy with a knife’, a little pest damage was easy to remedy and that organic produce was bound to have some pest damage. In particular, we believed that a damaged organic ear of corn was safer to eat than a conventional ear harboring pesticide residue.

I took this experience to my next job interview, another seasonal farm labor job in Wisconsin at a ‘you-pick’ vegetable operation, where the owner scoffed at my experience on an organic farm, saying that pesticides were far less toxic than naturally occurring fungal toxins, and that production in organic systems would never be enough to ensure food security due to high losses from pest damage. Needless to say, I did not work for this farmer, and I paid no attention to his words because he had lectured me, a complete stranger, for several hours in a manic monologue and I thought he was a fanatic. That summer I worked as a cashier instead and forgot all about him until I took a field plant pathology class this year. Incredibly, this ‘fanatic’ who did not hire me was right, at least in the case of sweet corn.

Truths about natural fungal toxins on sweet corn that can kill you:

1. Since the 70’s, we have known that a fungus called Fusarium ear rot produces a toxin called Fumonisin that is directly linked to pancreatic cancer in humans and various other cancers in livestock. This is a fact that is poorly publicized and is more of a problem in humid environments that favor fungal growth, and the toxin is found in apparently healthy kernels as well as obviously infected kernels (Wild and Gong, 2010)

2. The fungus produces more of this potent carcinogen as the season goes on, with the highest concentrations near the end of the season (Picot-et-al. 2011)

3. Controlling caterpillar pests such as corn earworm or army worm provide some measure of control against Fusarium ear rot because the fungus is a secondary invader whose spores gain access to the ear by means of the bore hole made by the caterpillar. There are many ways to control caterpillars, and one of the most controversial is genetically modified (GMO) Bacillis Thurnigensis (BT) corn, which makes a bacterial toxin that kills caterpillars, turning them from healthy hungry larvae to stretchy black lines of tar(Wu, 2007). The main objection to this corn is that it contains bacterial genes. Organic corn growers can also utilize this wonderful chemical which is nontoxic to humans by spraying the actual bacterium on non-genetically modified corn varieties. Other options include spooning oil onto the silks of each unripe corn ear, a practice common before world war II, and spraying organophosphate, a chemical that is more toxic than either BT or oil and which is being phased out here in California due to its toxicity to aquatic insects. Of these options, oil and BT spray are options available to both organic and conventional growers. Whether produced by bacteria or by genetically modified corn, BT is much less toxic than Fumonisin toxin produced by ‘all natural’ Fusarium ear rot, and very likely stops Fusarium from entering the ear by killing the borer caterpillars before they can make the ear vulnerable to Fusarium attack.

Pesticide residues are higher in conventionally grown produce than in organically grown produce (Spangler et al 2012), but ignoring pests and pest damage entirely in an organic or a conventional system has the potential to invite natural toxins in which could pose a greater health threat.

Take home message: Organic pest damage isn’t always safe. Nature has had chemical warfare much longer than humans have been breeding crops and cultivating the land! An organic or conventional grower should stay on top of  insect pests in corn in particular because Fusarium head rot is much more frightening for human health than the pesticides used to kill the worms.

References

Picot et-al. 2011 The Dent Stage of Maize Kernels Is the Most Conducive for Fumonisin Biosynthesis under Field Conditions

Wild and Gong 2010 Mycotoxins and Human Disease-a largely ignored human health concern

Wu, F. 2007 BT corn shows less fungal infection

Spangler, C. S. et al (2012) Are Organic Foods Safer or Healthier Than Conventional Alternatives?: A Systematic Review. Annals of Internal Medicine 157:348-366