Weeds tell farmers the kind of soils they have and crops to grow on them
Farmers can easily tell the type of soils in their farms by simply observing the type of weeds that grow in it.
This is a cost -free and accurate method of soil sampling that can save farmers from hefty laboratory test costs, while still allowing them to determine the kinds of crops to grow.
According to several studies conducted by reputable farming agencies including the Garderner and ICRAF, weeds indicate the acidity or alkalinity of soils hence making it easier for a farmer to identify the kinds of crops that can be grown on them. Weeds can also give a hint on soil fertility, soil drainage and moisture levels in the soils.
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A study conducted by Diana Barker, a soil sampling expert and published in the Gardener, shows that most prevalent types of weeds that grow in an area for a long time, tell the soil composition with an accuracy of 8 out of 10. The study, for instance, reveals that the Dandelion and Common Mullein weeds both indicate an acidic soil, but Common Mullein can also mean a low fertility soil. So, if you see the weed growing alone, it could mean a number of things, but when it grows along dandelions, this is a likely indication of an acidic soil.
The researcher also advices farmers to pay attention to the health of the weed while studying their soils. For example, a healthy stand of clover weed can be an indication of nitrogen deficiency in soil, while the same weed will grow in soil that had sufficient nitrogen, but will appear much less vigorous. The study, however, explains that some weeds like Purple Nettle and Shepherd’s purse can grow in most soil types and so are not reliable indicators.
Soils with a PH value of below 7 are deemed acidic. According to the study, weeds like Eastern Bracken, English Daisy, Ox-eye Daisy, Hawk Weed, Pineapple Weed, Wild Strawberries, Mayweed, Dandelion, Knapweeds, Pinks, plantains and Wild Radish are an indication of acidic soils. This means that if a farmer spots any of these weeds he can plant crops that do well in acidic soils including blueberries, endive, hydrangeas, rhododendrons, rhubarb, potatoes, shallots, sweet potatoes, and watermelons. In case the soils have high acid levels, the researcher recommends the addition of wood ash.
Those with a PH value above the neutral 7 are alkaline in nature hence support crops like beets, lettuce, muskmelons, onions, and spinach. The kinds of common weeds likely to grow in alkaline soils, according to the study, include Black Henbane, Nodding Thistle, Goosefoot, Wild Carrot, Field Peppergrass, White Mustard, Bladder Campion and Bellflower. To lower high alkalinity in soils, the expert explains that Sulfur can be added to the soils.
Fertile soils according to the research have a PH value ranging from 6.2 to 7. This, therefore, means that when weeds like Burdock, Butter Print, Fat Hen, Pokeweed, Pigweed, Queen Anne's Lace (Daucus carota) and Chickweed (Stellaria media) are spotted on a farm, soils there are fertile and a good for growing maize, lettuce, melons, peppers, squash, and tomatoes. Consequently, when weeds like Dog fennel, Biennial Wormwood, Broom sedge, Wild Radish, Sheep Sorrel and Yellow Toadflax grow in an area, this can can be an indication of poor or depleted soil. Beans, beets, carrots, legumes, parsnips, peas, radishes, sage, and thyme have tendency to tolerate poor soil conditions.
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Weeds like Ox-Eye, Docks, , Goldenrods, Groundnut, Poison Hemlock, Horsetail, Jewelweed, Joe-pye weed, Lady’s thumb, Marsh Mallow, May apple, Meadow pink ,Meadow Sweet, Mosses,Stinging Nettles,Pennsylvania smartweed, Ragwort, Tansy, Sheep sorrel, Silvery cinquefoil, Sweet flag and Tall buttercup grow in wet soils while Arrow-leafed Wild, Field Bindweed, White Cockle, Cornflower, Dog Fennel, Goldenrods, Maltese Thistle, Sandbur, Small Nettle, and Yellow Toadflax grow in sand soils.
The observation of weeds as means to determine soil type is good news to millions of farmers across the world who cannot afford the high costs attached to professional soil sampling. It is expected to go a long way helping farmers identify suitable crops to grow in their farms especially at a time when a lack of key farming knowledge is blamed for poor produce, especially by small holder farmers who make up to 70 per cent of farmers in the world, according to a 2013 FAO report.
Write comment (0 Comments)By George Munene
Based in Mwea, Safi Organics turns rice husks into organic fertiliser that is two to three times cheaper than store-bought fertilisers but gives up to 30 per cent more yield.
“A bag of DAP fertiliser currently retails at Sh7,000 and is predicted to rise even higher by the end of the month, a price unaffordable to most small-scale farmers. This is a perilous place for Kenya’s agricultural sector where smallholder production accounts for 78 percent of total production.
We guarantee our farmers a 3:5:3 NPK macronutrient distribution from our fertilisers. 90 percent of them rely solely on Safi products and attest to seeing a 30 per cent rise in their output.
Being made up of 70 per cent organic matter, our fertilisers have the advantage of improving soil health, helping it retain moisture which we've proven saves farmers 15 per cent of their irrigation costs, ”said Safi’s co-founder and CEO Samuel Rigu.
Farmers using their fertilisers in rice fields in Mwea for at least three years have seen their soil pH rise from 4.7 to 6.8--the ideal soil pH for rice cultivation.
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Founded in 2015, Safi Organics started out providing farmers with an acidic soil ammender (SAFI Biochar) that is sold for Sh1,700. This adds organic material to the soil improving its physical properties,i.e, water retention, infiltration, permeability, aeration, and its structure.
With increased farmer demand the company has expanded its range of products to cover the entire planting process: SAFI Savi, a carbon-negative organic fertilizer that increases farmer yields while reducing soil acidity retailing for Sh2,400. Top-dressing fertilizer (SAFI Sarvi Topper fertilizers) priced at Sh2,400 and SAFI foliar fertilizer costing Sh600.
Setting up the company in the country's rice basket means they are never short of their main raw material –rice chaff. They utilise 15 tons of rice hulls daily which would otherwise have been burnt contributing to greenhouse gases (GHG) build up in the atmosphere. This is then mixed in with what Samuel describes as ‘a secret source’ of organic waste making six tons of fertiliser every day.
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Safi works with over 1,000 farmers across the country majority of whom are rice growers. Other crops growers have had success with the organic fertiliser include maize, french beans, green grams, bananas, fruits trees, and tomatoes.
“Crops that are heavy feeders such as tomatoes require four bags of our fertiliser per acre, while light feeders like maize require two bags.
The company employs 18 full-time workers, who are supplemented by 50 casuals, and has received grants and recognition from international bodies like USAID, USADF, and Citi Foundation.
Safi Organics: +254 (0) 725-778-829
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