“You got it plum backwards: You’re supposed to KILL the weeds and GROW the crops”. Contrarian that I am, I plant weeds and let the crops fend for themselves.
My neighbors call it weed farming or trash farming. (Less charitable folks say I’m lazy or just plain mental). I call what I do common sense agronomy. Planting in weeds saves lots of money. You should try it.
Most farmers think weeds are enemies that should be exterminated by any means possible. I take a more balanced view: Weeds are valuable agricultural resources if properly managed = you have to get off your tractor long enough to think of weeds as an ally. My spray-by-the-calendar neighbors don’t agree with me but my weedy fields are highly profitable. Their farms are up for auction.
A weed is a plant growing where it is not wanted. The key to intelligent agriculture is to grow weeds where they are needed. Here are some ways that weeds can help fill your bank account:
–> WEEDS ARE GOOD ORGANIC FERTILIZER. I ran a lawnmower across a typical meadow (8 grasses + 23 broad leaf weeds = 31 species) and sent the clippings off for analysis: 1.00% Nitrogen : 0.27% Phosphorous : 1.10% Potassium by weight = 20 pounds Nitrogen + 5.4 pounds Phosphorous + 22 pounds Potassium per ton.
Compare this with cow manure from my neighbor’s dairy: 0.5% Nitrogen : 0.15% Phosphorous : 0.40% Potassium by weight = 10 pounds Nitrogen + 3 pounds Phosphorous + 8 pounds Potassium per ton.
Fresh green weeds contain approximately double the nutrients of dairy cow manure. A dense field of weeds 3 feet high yields about 2.5 tons of green manure (stems and leaves) ~ 50 pounds Nitrogen + 13.5 pounds Phosphorous + 55 pounds Potassium per acre. Green weeds rot fast so most of these nutrients are quickly available to crop plants.
How to Green Manure a Field: First, cut weeds with a flail, rotary, or sickle bar mower, or use a forage chopper. Next, use a rear-mounted rototiller, moldboard or disk plow to till the chopped foliage into the soil. RULE: Always mow before plowing! Chopped plants rot faster so crop roots absorb nutrients sooner. Last, seed or plant field immediately = the same day. Never leave the soil bare, not even for a single day. Naked soil is wasted dirt. Keep the ground covered with growing plants at all times.
Chop-And-Drop: How do you “green manure” a no-till field? Answer: Mow the cover crop as close to the soil surface as possible and leave the chopped vegetation where it falls. Use a rotary mower, flail mower, forage chopper, or common lawnmower if you want the cover crop to decompose quickly (to feed a following crop or clear a field for planting). Use a sickle bar mower or roller-crimper for Mulch-In-Place planting. Timing is important: To kill a cover crop mow when plants start flowering or begin setting seeds. Late planted annual cover crops can be left standing until killed by frost; standing vegetation traps snow over winter. Fall oats are a good crop for this purpose. Winter killed oats protect soil but do not obstruct spring planting with conventional equipment.
To green manure a field without machinery, use animals to stomp the cover crop. Erect temporary fencing and “Mob Graze” the field. Animals should be “well crowded” together. Ideal stocking density = 680 to 1,210 Animal Units per acre. (1 Animal Unit = 1,000 pounds live weight). For example: 680 beef cattle per acre = 1 cow for every 8 x 8 feet = 64 square feet per animal. 1,210 beef cattle per acre = 1 cow for every 6 x 6 feet = 36 square feet per animal. Keep animals confined until they eat the top 1/3 of the foliage then move herd to fresh pasture. Plant stomped cover crop the same day with no=till equipment. Alternatively, broadcast grain into standing cover crop then immediately mob graze field. This is an old Roman agronomic practice called stomp seeding.
–> WEEDS ARE HIGH QUALITY MULCH. Fight fire with fire. Use weeds to smother weeds. An 8-inch blanket of cut weed mulch provides 95% or better weed control for 6 to 8 weeks during the growing season. That is all the time you need to get your crop up and growing. Once your plants are well established any weeds that poke above the crop canopy won’t matter. The crop itself suppresses most weeds. Peek under the leaves and you will see little weeds lurking in the shade. These tiny plants lost the competition for sunlight. As long as your crop continues to grow, your fields will remain mostly weed free.
Mulch-In-Place: Find the weediest field possible. Dense, luxuriant, rank growth 6 feet high is best = about 4 tons of biomass (stems and leaves) per acre. Cut weeds with a sickle bar mower or flatten with a roller-crimper. Seed or transplant directly through the mulch with no-till equipment, or sow by hand. If desired, you can immediately top seed field with a low growing nitrogen fixing legume like Dutch White Clover (Trifolium repens), Crimson Clover (Trifolium incarnatum), or Sub Clover (Trifolium subterraneum). The tiny clover seeds fill any holes in the mulch and provide useful biodiversity. (If you don’t have a weedy field, sow Winter Rye = Secale cereale at 3 bushels per acre then mow or roll when 6 feet high or when seeds reach the soft dough stage. Cereal rye grows fast like a weed and yields 4 to 5 tons = 8,000 to 10,000 pounds of long straw mulch per acre. Alternatively, seed a high biomass crop like Sudan Grass = Sorghum sudanense or Forage Maize = Zea mays).
Lawnmower Farming: You can run a 25 acre ~ 10 hectare commercial vegetable farm with nothing other than a common lawnmower. (For larger areas use a riding lawnmower = lawn tractor). Find the weediest field possible. Mow a strip where you want to plant your crop. Roll irrigation tape down the row. (The idea is to water the crop rather than the entire field). Set your transplants then mulch heavily with cut weeds. Apply a circle or collar of green mulch 1 foot = 12 inches thick around each plant. This is a form of sheet composting = the weeds rot and release nutrients to feed your crop. (It’s ok to use synthetic fertilizers but these are expensive. A 40 pound bag of 10-10-10 = 10% Nitrogen + 10% Phosphorous + 10% Potassium costs $17.12 at my local farm store. Why spend 43 cents per pound for chemical fertilizer when weeds cost nothing)?
Weed mulches protect and feed earthworms = Lumbricus terrestris. Earthworm casts = manure fertilize the soil. Weed fields fallowed = untilled for 7 years typically have 1 ton = 1 million earthworms per acre ~ 23 earthworms per cubic foot of topsoil. 1 million earthworms per acre produce 2,000 pounds = 1 ton of worm casts each DAY during the growing season. That is an enormous amount of free organic fertilizer ~ 150 to 180 TONS per acre of worm manure in a typical 5 to 6 month growing season ~ 6 to 8 pounds of worm casts per square foot (distributed from the surface through the entire soil column about 6 feet deep).
Earthworms also biologically till the soil so air and water penetrate deep into the subsoil. Plant roots follow worm borrows 5 to 6 feet underground where the soil stays moist = crops are nearly drought proof. (My weed fields average 902 MILES of vertical earthworm burrows per acre). A hundred-year rainstorm (2-inches per hour) falling on a fallow weed field has almost no runoff = zero soil erosion. Rain sinks into the land like water through a colander. Underground water keeps my crops growing while my neighbors’ fields wilt.
Earthworm populations are directly proportional to the amount of available food = organic matter. Apply more mulch and more worms will come. Space rows widely so you have sufficient weeds to cut for mulch. (On very large farms use a forage chopper to deposit chopped weeds into convenient windrows. Set transplants down the windrows). RULE: Cut weeds only to clear rows for planting or to harvest for mulch. Leave remaining weeds standing to maintain wide environmental diversity.
If you don’t have any weedy fields, plant mixed species cover crops. The goal is to imitate the broad ecological diversity of a naturally weedy field. Include 50% legume seed in the mix because earthworms need protein in their diet. Earthworm populations double on fields of clover versus fields of grass. More legumes = more earthworms = more free fertilizer = more money in your bank account.
If you can’t afford cover crop seed go to the nearest grain elevator and ask for elevator screenings. These are usually free or cheap and contain many weed seeds. Haul as many tons as practical; you will need every pound of weed seed obtainable. Sow weeds generously = with wild abandon. Your neighbors will think you daft, but it really does pay to plant weeds (especially on poor, eroded, or barren fields). Run the remaining elevator screenings through a roller mill to make weed seed meal. Weed meal is high quality organic fertilizer; use it just like cottonseed meal or other expensive soil amendment. Apply weed seed meal liberally because it won’t burn plant roots.
Once weed fields are planted they require little or no attention = the crops grow themselves. Mulch protects young transplants for the first 3 to 6 weeks until they put down roots. Once crops are well established they will outgrow or overwhelm most weeds. This is especially true for vigorous plants like tomatoes, peppers, and vine crops: Pumpkins, squash, gourds, sweet potatoes, cucumbers, and melons. Vine crops tolerate light shade and easily climb over weeds 5 to 6 feet tall. I always get my best melons from the weediest fields. On rare occasions weeds may grow too densely around a pepper or tomato plant. Thin offending weeds with pruning shears.
Weed Seed Meal: Seeds of most plants make good fertilizer. The trick is to mill = grind seeds into a coarse meal or flour so they do not sprout. If weed seeds are not available, substitute any type of waste or spoiled grain, for example, wet or dry brewer’s grains. There is no standard analysis for weed seed meal; nutrient content varies depending on species and proportion which change by locality and season. It is good practice to test weed seed samples yearly so fertilizer application rates can be adjusted as needed. Below are some average nitrogen (N), phosphorous (P), and potassium (K) values for rough calculations. Note: lb = pound. 1 pound = 0.454 kilogram. 1 American ton = 2,000 pounds = 908 kilograms = 0.908 metric ton. 1 metric ton = 1 megagram = 1,000 kilograms = 1,000,000 grams = 2,200 pounds = 1.1 American tons.
Wheat, Broken (Kansas 2011): 2.00% N : 0.85% P : 0.50% K = 40 lb N + 17 lb P + 10 lb K per ton
Weed Seed Meal (Saskatchewan 2015): 3.02% N : 0.56% P : 0.77% K = 60 lb N + 11 lb P + 15 lb K per ton
Weed Seed Meal (Hungary 2013): 2.7% N : 0.90% P : 0.90% K = 54 lb N + 18 lb P + 18 lb K per ton
Rice, White Broken (California 2016): 1.00% N : 0.21% P : 0.27% K = 20 lb N + 4 lb P + 0 lb K per ton
Rice Hulls = Husks (Philippines 2014): 1.9% N : 0.48% P : 0.81% K = 38 lb N + 9 lb P + 18 lb K per ton
Rice, Brown (California 2016): 1% N : 0.48% P : 0.32% K = 20 lb N + 9 lb P + 6 lb K per ton
Rice Bran (India 2015): 4.00% N : 3.00% P : 1.00% K = 80 lb N + 60 lb P + 20 lb K per ton
Oats, Broken (New York 2010): 2.00% N : 0.80% P : 0.60% K = 40 lb N + 16 lb P + 12 lb K per ton
Flaxseed = Linseed Meal (Manitoba 2008): 5.66% N : 0.87% P : 1.24% K = 113 lb N + 17 lb P + 24 lb K per ton
Dent Corn, Spoiled (Maryland 2014): 1.65% N : 0.65% P : 0.40% K = 33 lb N + 13 lb P + 8 lb K per ton
Cowpeas, Broken (California 2014): 3.10% N : 1.00% P : 1.20% K = 62 lb N + 20 lb P + 24 lb K per ton
Cotton Seed, Whole (USDA 2015): 3.14% N : 1.25% P : 1.15% K = 63 lb N + 25 lb P + 23 lb K per ton
Cotton Seed, Pressed (USDA 2015): 4.51% N : 0.64% P : 1.25% K = 90 lb N + 12 lb P + 2b lb K per ton
Cotton Seed Meal (Egypt 2012): 6.6% N : 1.67% P : 1.55% K = 132 lb N + 33 lb P +31 lb K per ton
Castor Beans, Pressed (Egypt 2012): 5.5% N : 2.25% P : 1.125% K = 110 lb N + 45 lb P + 22 lb K per ton
Brewer’s Grain, Wet (Pennsylvania 2012): 0.90% N : 0.50% P : 0.05% K = 18 lb N + 10 lb P + 1 lb K per ton
Brewer’s Grain Dry (Pennsylvania 2012): 4.53% N : 0.47% P 0.24% K = 90 lb N + 9 lb P + 4 lb K per ton
Beans, Soup Broken (New York 1988): 4.0% N : 1.20% P : 1.30% K = 80 lb N + 24 lb P +26 lb K per ton
Barley, Spoiled (Manitoba 2011): 1.75% N : 0.75% P : 0.50% K = 35 lb N + 15 lb P + 10 lb K per ton
For slow release fertilizer mill weed seeds into coarse flakes or meal. Grind weed seeds into powder for fast acting fertilizer.
Calculate application rates according to soil test recommendation for desired crop. Minimum application rate is 1 ton = 2,000 pounds per acre ~ 5 pounds or 1 gallon per 100 square feet ~ 2 Tablespoons or 2/3 ounce per square foot. Apply 1 pound of weed seed meal for every 25 feet of row or trench. Mix 1/2 to 1 cup in each bushel (8 gallons) of potting soil. To fertilize trees and bushes, apply 1 pound or 1 1/4 quarts of weed seed meal for every inch of trunk or stem diameter. Spread meal from trunk or stem to drip line = farthest extent of branches.
Average density of weed seed meal = 0.3125 to 0.40 scale ounce per Tablespoon ~ 5 to 6.5 scale ounces per cup ~ 20 to 25.6 scale ounces per quart ~ 80 to 102.4 scale ounces per gallon ~ 5 pounds to 6 pounds 6.4 ounces per gallon ~ 40 to 51 pounds per bushel (8 gallons). 1 ton = 2,000 pounds weed seed meal = 40 to 50 bushels.
For example: 200 bushel per acre corn crop requires 200 pounds of nitrogen per acre. 200 pounds N divided by 54 pounds of nitrogen per ton of weed seed meal = 3.70 ~ 4 tons of weed seed meal needed per acre of corn. Weed seed meal can be tilled into the earth by conventional plowing, broadcast on soil surface, side banded down rows, or drilled into furrows or trenches.
For feeding earthworms broadcast weed seed meal (1 ton per acre or 2 Tablespoons per square foot) on soil surface. Reapply throughout the growing season when meal is no longer visible.
–> WEEDS PROVIDE FREE BIOLOGICAL INSECT CONTROL. I used to work for a cannery company. I have dreadful memories of being bombed by crop dusters. I would run for my truck, slam the door and stomp on the gas pedal. The toxic mist really was that lethal. Any human caught in the open would spend weeks in hospital and years twitching oddly. Of course, the cabbage loopers took only 2 or 3 seasons to develop immunity to the toxin. Then it was replaced with something even more poisonous. Never again! I refuse to become yet another ghastly statistic. Just as stubbornly, I won’t buy something I don’t need. Farming is all about cheap. Margins are slim (especially for commodity crops) so a jug of synthetic chemical per acre can make all the difference between hanging-on-by-our-fingernails profit and loss of the family homestead. Consequently, I cross all agricultural chemicals off my shopping list. I’m not a “tree hugger” just ruthlessly frugal. My family has farmed the same land for over 800 years. I’m not going to be the one who fails.
Pests Be Gone! Weeds are the poor man’s wildflowers. Sow weeds just as you would wildflowers to provide food, shelter, and alternate hosts for beneficial predatory and parasitic insects. For best results, reserve at least 5% of cropland for weeds. Seed every 20th row with weeds. Plant a strip of weeds around each field, vineyard, and orchard. The trick to biological insect control is to grow weeds in close proximity to crops needing protection. Serious insect problems usually mean a farm does not have enough wild plants. Spatial orientation is important: Weeds on one side of a farm will not protect tomatoes on the opposite side. Plant tomatoes and weeds together = few hornworms.
Strip Cropping: Plant crops in long narrow strips 4 to 16 rows wide (depending on the size of planting and harvesting equipment). Long fields increase mechanical efficiency = fewer turns. Try to keep strips as narrow as mechanically practical. Narrow strips maximize biological edge effects and increase light penetration into crop canopy. More edges = less pests. More sunlight = more photosynthesis = higher yields. Run strips across fields and farms following land contours. Plant adjacent strips with unrelated crops to increase biological diversity = more food and shelter for beneficial insects. If weed seed is unavailable or wildflowers too costly, plant mixed species cover crops to simulate weed populations. Thomas Jefferson used buckwheat (Fagopyrum esculentum), turnips (Brassica rapa subspecies rapa), and winter vetch (Vicia villosa) = small flowered plants ideal for predators and parasites with tiny mouth parts. A diligent program of crop rotation, strip planting, and weed farming usually keeps pest populations from rising to harmful levels.
–> WEEDS ARE POTENT INSECTICIDES. Over millions of years weeds have evolved elaborate chemical defenses against bugs. Most weeds have only 1 or 2 minor pests; many wild plants are immune to just about everything. When bugs get out of hand most infestations can be controlled by spraying with weed tea = a simple infusion of fresh weeds in hot water. Find any weeds not bothered by the pest needing control. Collect a large quantity of plants equal to the volume of water needed for spraying. Chop weeds with a shredder, hydro-mill, or household blender. Alternatively, crush weeds in a roller mill or laundry wringer. Soak milled weeds in boiling water until mixture cools to air temperature. Strain before use then add a commercial surfactant so insecticide spreads over and sticks to crop leaves.
If necessary, dilute weed tea concentrate with clear water to make up spray tank volume. One application is usually enough to control most pests. If infestation continues spray again or increase insecticide concentration by brewing equal weights of weeds and water (1 pound of weeds for each pint of water). The forests around me abound with wild plants, especially ferns. Nothing eats a fern. Fern tea will kill or deter any bug known to modern agriculture. Many common farm and garden weeds are equally distasteful or toxic.
–> WEEDS ARE GOOD NURSE CROPS. Weeds moderate farm microclimates by reducing wind speed, increasing humidity, shading soil, drawing water from subsoil depths and sharing moisture with shallow-rooted plants. In times of drought, crops grown in weeds often out yield plants in cultivated weed-free fields. Even dead weeds are useful; they protect topsoil from wind and water erosion, and their decomposing tissues feed soil organisms.
Sow-And-Go: Drill or broadcast small grains into standing vegetation. For best results sow tall varieties as these compete better against weeds. The best time to plant is in the dry or cold season when most weeds and grasses are dead, dormant, or growing slowly. Pelleted seed greatly increases germination and seedling survival. If desired, you can sow Dutch White Clover (Trifolium repens) along with the grain. With plentiful water, expect yields 60% to 70% of conventionally planted cereals. If rains are poor expect little or no harvest.
Sow-and-Go agronomy works best with winter cereals. Here in Butler County, Pennsylvania (40.8606 degrees North Latitude, 79.8947 degrees West Longitude) sow-and-go winter wheat yields 24 to 28 bushels = 1,440 to 1,680 pounds per acre. (Conventionally planted wheat yields 40 bushels = 2,400 pounds per acre). My fields look awful but they produce enough grain to feed my family and the entire parish. More importantly, out-of-pocket costs are minimal so profits are high. Sow-and-Go cereals reduce economic risk. Consequently, growing grain in weeds usually makes more money than planting cereal crops in cultivated or herbicide-sprayed fields.
–> WEEDS ARE GOOD BEE FORAGE. A jar labeled “wildflower honey” means “made from weeds”. Very few apiaries plant flowers for their bees. Most commercial honey in the United States comes from hives that are trucked across the country to pollinate almonds, blueberries, and oranges. These bees are fed sugar syrup to keep them alive so if you want “real” honey buy from small, local apiaries or keep your own bees.
Honeybees feed on small flowers because they have short tongues. Most weeds are ideal bee forage because they produce many small flowers throughout the growing season.
For a hungry bee the average plow-and-spray farm is a “green desert”. Vast monoculture fields of corn and wheat do not provide nectar = starving hives. To maintain healthy bee colonies plant weeds and wildflowers throughout the farm or sow small-flowered crops like Anise (Pimpinella anisum), Caraway (Carum carvi), Coriander (Coriandrum sativum), Dill (Anethum graveolens), and Fennel (Foeniculum vulgare). Seed every available space as honey production is directly dependent on flower numbers. More blossoms = more pollen and nectar = more bees = more honey. Alternatively, plant mixed species cover crops to replace the bountiful blossoms of naturally weedy fields. For example, seed orchards with buckwheat (Fagopyrum esculentum), hairy vetch (Vicia villosa), and turnips (Brassica rapa subspecies rapa) to feed bees and other beneficial insects.
Think before mowing! Do not clip entire hay fields at once. Leave 5% to 10% of each field un-harvested so bees have something to eat. Whenever practical, divide fields into blocks or strips then harvest sequentially so beneficial insects can move to undisturbed areas. Similarly, mow orchards only before harvest; let weeds, wildflowers, and cover crops grow without disturbance. More flowers = fewer insect pests.
Plant thoughtfully. Bees will fly 5 miles to gather nectar but long trips are inefficient = less honey. Would you like to walk 5 miles to get your dinner? Think like a bee and sow flowers as close to hives and crops as practical. Integrate crops and weeds whenever possible. For example, alternate strips of tomatoes and weeds. Result: Save $400 per acre for insecticides.
There is no such thing as a free lunch. Biology can replace synthetic chemicals but there is an economic trade-off: At least 5% of a farm must be covered in weeds. This is the same as losing 5% of your corn crop and that costs money. If this is not acceptable then plant wildflowers or any other small-flowered crop that you can harvest and sell the seed. You can have bees and a profitable farm at the same time.
“Weed Farming” is an essential part of the New Green Revolution where biology replaces what is normally done by diesel tractors and synthetic chemicals. This is leading edge agronomy = what our Great-Great-Grandfathers used to do. Every farmer should reserve a few acres to experiment with this rediscovered technology. Growing crops in weeds is profitable — provided farmers exercise careful stewardship. For best results manage weeds just like a living mulch or mixed species cover crop. Always remember that there are 2 crops growing on the same land at the same time — the weed crop and the cash crop. Each requires equal care or both crops may fail.
RELATED PUBLICATIONS: Managing Weeds as Cover Crops; Weed Seed Meal Fertilizer; No-Till Hungarian Stock Squash; Planting Maize with Living Mulches; Living Mulches for Weed Control; Organic Herbicides; Pelleted Seed Primer; Crops Among the Weeds; Forage Maize for Soil Improvement; Forage Radish Primer; and Rototiller Primer.
WOULD YOU LIKE TO KNOW MORE? Contact the Author directly if you have any questions or need additional information on growing crops and weeds together.
Please visit: http://www.worldagriculturesolutions.com — or — send your questions to: Eric Koperek, Editor, World Agriculture Solutions, 413 Cedar Drive, Moon Township, Pennsylvania, 15108 United States of America — or — send an e-mail to: Eric Koperek = firstname.lastname@example.org
ABOUT THE AUTHOR: Mr. Koperek is a plant breeder who farms in Pennsylvania during summer and Florida over winter. (Growing 2 generations each year speeds development of new crop varieties).