Thursday, February 18, 2016

Weed Blasting

Organic growers now have a new tool to control weeds: abrasive weeding, or “weed blasting,” which uses an air compressor to blast organic grit at weed seedlings during vulnerable growth stages.

Weed blasting can reduce weed biomass in organic tomato and pepper crops by up to 97 percent, while maintaining crop yields similar to hand-weeded control plots.

Organic fertilizers, such as soybean meal, can be used as abrasive grit, which could mean farmers could control weeds and fertilize their crop in a single pass.

The method, recently field-tested at the University of Illinois, has been proven effective. In conjunction with plastic mulch, abrasive weeding reduced final weed biomass by 69 to 97 percent compared to non-weeded control plots.

During the study, grit was applied through a hand-held siphon-fed sand-blasting unit connected to a gas-powered air compressor, which was hauled down crop rows with a walk-behind tractor. A number of grit sources were tested: walnut shells, granulated maize cob, greensand, and soybean meal. If applied at the right plant growth stage, the force of the abrasive grit severely damages stems and leaves of weed seedlings.

No significant differences were fund between the grit types in terms of  efficacy.

Plots with plastic mulch and one or more blasting treatment achieved the same fruit yields seen in hand-weeded plots, and 33 to 44 percent greater yields than in non-weeded control plots.

According to the study, weed blasting does affect some weeds more than others. Essentially, the smaller the seedling, the better. Also, seedlings whose growing points are aboveground (annual broadleaf species) are more susceptible to blasting than seedlings whose growing tips are located below ground (grasses and broadleaf perennials).

Source: Samuel Wortman, University of Illinois.

Organics
Farm Supply
Artwork: Portable Air Compressor


Wednesday, November 4, 2015

Maple Syrup Migrating

As the climate warms this century, maple syrup production in the Northeast is expected to decline by 2100, and the window for tapping trees will move earlier by about a month, according to a Cornell University study.

Currently, the best times to tap maple trees are within an eight-week window from late winter to early spring when temperatures cause freezing at night and thawing by day. By 2100, Northeast producers can expect to begin tapping maples closer to Christmas.

Sap flow is related to pressure changes in the trees' xylem, which are tubes beneath the bark that carry sap from the maple's roots up to the leaves. As maple trees freeze in winter, gases are pushed out of the xylem into surrounding tissues, and negative pressure is created within the xylem compared with atmospheric pressure. When the trees thaw, the gases expand and dissolve back into the sap, creating positive pressure. When tapped, the sap flows out because the pressure inside the xylem is greater than outside.

Based on this principle, researchers identified that the best days for sap flow are when diurnal temperatures swing at least a few degrees below freezing at night to a few degrees above freezing by day.

They scaled down global climate computer models to regional scales to determine daily temperatures for 10,000 locations across the sugar maple's range -- from North Carolina to Quebec to Minnesota, with optimal production areas in the Northeast and Quebec -- from 1970 to 2100. In this way, the researchers could identify daily minimum and maximum temperatures during optimal eight-week windows for tapping sugar maples.

By "backcasting," they validated their models with temperature data, which revealed that start dates for tapping maples in the Northeast are about a week earlier than in 1970.

Under a high carbon dioxide emissions computer model scenario, syrup production will decline slightly in the Northeast, mostly after 2030. According to the study, by 2100, the average number of flow days will stay constant in Saranac, N.Y.; decline by about two days in State College, Pa.; five days in Montpelier, Vt.; and by 10 days in Jackman, Maine. In a more moderate emissions scenario, producers will lose about half as many days in each location. Similarly, in the high emissions scenario, start dates for tapping maples will be earlier by about a month between now and 2100: In Jackman, the current optimal start date of March 11 shifted to early February; in Saranac and Montpelier, the current start date of March 1 moved ahead to Feb. 1; and in State College and Ithaca, N.Y., start dates advanced to mid-January from mid-February.

Maple syrup production south of Pennsylvania will likely be lost by 2100 due to lack of freezing, while production in Quebec may benefit from climate changes.

Sources:
Brian Chabot, professor of ecology and evolutionary biology, Cornell University

Outgoing: Tapping at Kripplebush
Syrup
Out There: Serious Climate Changes Looming Closer
Artwork: Collecting Of Sap From Maple Trees


Thursday, October 1, 2015

Tar Spot Appears in the Midwest

Tar Spot, a fungal disease in corn typically found in Mexico, South America and the Caribbean has been spotted in fields near the Indiana-Ohio border. While no threat for growers this year, it could cause problems in next year's crop if the fungus survives the winter.

This corn disease is not only new to Indiana and Illinois, where it was first reported, but its appearance is a first in the U.S., according to Pierce Paul, a corn and small grain Extension specialist with the College of Food, Agricultural, and Environmental Sciences at The Ohio State University. It may have been transported to the Midwest earlier this season by Tropical Storm Bill.

“We don’t want to cause a panic, but we do want to raise awareness of the issue and let growers know that this disease is out there,” Paul said.

Tar spot begins as oval to irregular bleached to brown lesions on leaves in which black spore-producing structures are formed. Affected areas of the leaf will have a rough or bumpy feel to the touch. Signs of tar spot can also appear on leaf sheaths and husks.

“Because tar spot is generally considered a tropical disease, it’s unlikely that the fungus will survive the harsh Midwest winter to become established here,” Paul said. “We’ll just have to wait and see and do more research on the disease in the Midwest.”

While most corn growers are either harvesting corn now or their crops are in the drying down stage, the disease is still detectable on dry, senescent leaves, he said. Growers who suspect they’ve found it in their fields can send samples to Pierce Paul at OARDC, 1680 Madison Ave., Wooster, OH 44691, to have the samples lab tested to determine which fungus — Phyllachora maydis or Monographella maydis — may be present.

“At this point, only P. maydis-infected plants have been found,” he said. “Both fungi would have to be found before substantial yield loss occurs.

“Growers who find tar spot in their fields may want to take note of the hybrid they’ve used this year and avoid using that same hybrid next year just in case the fungus survives the winter.”

Source: Ohio State University Extension

Plants and Seeds
Farm Supply
Covert Art: Compendium of Corn Diseases


Monday, February 16, 2015

Cover Crop Grazing No Problem.

Cover crops reduce soil erosion, boost organic matter, keep moisture in soil and sequester carbon in the soil so less of it is released as a greenhouse gas.

Conventional wisdom holds that if cattle were allowed to graze on cover crops they would eat up and remove the nitrogen and carbon otherwise left on the soil in the cover crop plant residue. Allowing cattle to tread on the soil also could compact it, preventing air and water from passing through the soil to reach plant roots.

Now, a 7-year study by Agricultural Research Service (ARS) ecologists has demonstrated that relatively low levels of grazing do not significantly affect the amount of organic matter in soil and do not compact the soil. It also showed that cover crops provided high quality forage and that the organic matter lost by allowing cattle to graze on cover crops was likely made up in the organic material supplied as manure. As in previous studies, they also found that no-till soils generally contained more carbon and nitrogen than conventional till soils.

The researchers grew winter or summer grains and used cover crops for both in the off-season. They also compared no-till versus tilling, and grazing versus no grazing. Cow/calf pairs were allowed to graze at a rate of one pair per 4 acres.

Husbandry
Plants and Seeds
Farm Supply
Artwork: Cattle Grazing


Monday, December 8, 2014

Memory in Plants

"In the mimosa we find memory, but no consciousness. Memory of course involves no image in the plant... Memory has nothing to do with nerves or brain. It is a primal quality."
 ~ Friedrich Nietzsche

When we say that plants have memory it means that they have a past, "which they bear in their extended being and which they may access at any given moment," writes Michael Marder in Plant-Thinking. He gives two examples:

Barley leaves will unfurl if they are exposed to red light, so long as they contain calcium. If calcium is removed from the plant, the leaves will not unfurl. Yet, if the calcium is added a couple hours later, the plant will unfurl without the red light shining, "remembering" how it had shone earlier.

Plantlets of flax, likewise, respond to the stress of drought or wind by depleting calcium from their cells in a process that takes about a day, and yet they will continue to remember the traumatic event for up to a week as evidenced by their calcium depletion.

"These examples demonstrae that what Nietsche chanced upon in his reflection on the mimose is in fact a more general tendency of vegetal beings to store imageless and non-representational material memories in their cells, and so to retain a trace of the remembered thing iteslef, in place of its idealized projection," Marder concludes.

A Philosophy of Vegetal Life
by Michael Marder
Columbia University Press, 2013
Plants and Seeds
Plant Roots: Growth, Function and Interactions with the Soil
Artwork: Magical Mimosa by Jessica Jenney


Monday, December 1, 2014

Less Fertilizer, More Nutrition.


Giving too much phosphorus to wheat and barley plants has been shown to raise the amount stored as phytate, rather than as more digestible forms of phosphorus. This finding is important for two reasons:

    * Livestock that are fed high-phytate grains excrete more phosphorus in their manure, which can pollute water.
    * Phosphorus is a finite resource that could be irreplaceable once it has been thoroughly mined -- which could happen in the next 25 years.

The researchers found that soil phosphorus levels may affect grain phytate levels as much as plant breeding can, offering two complementary solutions to the nutritional and environmental problems caused by high phytate levels in grains. Besides being more environmentally sound, getting the application rate for phosphorus fertilizers just right might improve the nutrients delivered by grain crops such as wheat and barley.

Not only is the phosphorus in low-phytate grain crops more digestible by people, but low-phytate grains free up minerals essential to human nutrition: zinc, manganese and iron.

Source: Agricultural Research Service

Fertilizer
Farm Supply
Growing Guides

Tuesday, September 30, 2014

Down South, Apply Poultry Litter in Spring.

Poultry litter is a popular fertilizer in many southern states because that is where most of the U.S. broiler chickens are produced. The litter's nitrogen content boosts crop yields and saves on the expense of commercial fertilizers.

But farmers in Mississippi and other southern states are applying  litter at the wrong time of time, according to a U.S. Department of Agriculture (USDA) agronomist.

Farmers in Mississippi often apply poultry litter in the fall, months before planting cash crops in the spring, because it's cheaper then and they have more time than in the spring, but Haile Tewolde at Mississippi State has found that spring is the optimal season for applying litter in the South and Southeast.

Tewolde and his colleagues applied poultry litter in the spring and fall to test plots of corn planted each April for three years. They applied the litter at two rates - four tons per acre and eight tons per acre - and incorporated it into the soil by "disking," a process that turns the soil and pulverizes it so that the litter blends in with the soil. For comparison, the researchers applied nitrogen fertilizer to other test plots in the spring and fall.

The results showed that over three years, yields were cumulatively higher in plots with litter applied in the spring than in the fall, regardless of the application rate. At the four-ton rate, spring-application yields were 16.7 percent higher, and at the eight-ton rate, they were 12.8 percent higher.

The results also showed that while using litter produced less corn than using fertilizer in the first year, those results were reversed in the second and third years. Higher yields in the second and third years were likely because nitrogen in the litter applied during the first year stayed in the soil and benefited crops in subsequent years.

Plants and Seeds
Farm Supply
Growing Guides
Artwork: Manure Spreading