To give the reader an idea of the energy intensiveness of modern agriculture, production of one kilogram of nitrogen for fertilizer requires the energy equivalent of from 1.4 to 1.8 liters of diesel fuel. This is not considering the natural gas feedstock.
In a very real sense, we are literally eating fossil fuels. However, due to the laws of thermodynamics, there is not a direct correspondence between energy inflow and outflow in agriculture.
Modern intensive agriculture is unsustainable. It is damaging the land, draining water supplies and polluting the environment. And all of this requires more and more fossil fuel input to pump irrigation water, to replace nutrients, to provide pest protection, to remediate the environment and simply to hold crop production at a constant. Yet this necessary fossil fuel input is going to crash headlong into declining fossil fuel production.
~ Eating Fossil Fuels, by Dale Allen Pfeiffer ~The related terms, "sustainable" and "sustainability" are popularly used to describe a wide variety of activities which are generally ecologically laudable but which may not be sustainable. An examination of major reports reveals contradictory uses of the terms. An attempt is made here to give a firm and unambiguous definition to the concept of sustainability and to translate the definition into a series of laws and hypotheses which, it is hoped, will clarify the implications of the use of the concept of sustainability. These are followed by a series of observations and predictions that relate to "sustainability." The laws should enable one to read the many publications on sustainability and help one to decide whether the publications are seeking to illuminate or to obfuscate.
~ Reflections on Sustainability, Population Growth, and the Environment: Carrying Capacity & Denial of Population Problem ~“Food has something in common with energy — they're both commodities that you use up. And they're both worth fighting over. Naturally, if food is a problem that could blow up in our faces, the smart thing to do would be to think strategically.”
~ AgriWarfare & Strategic Food: The Agriculture Ticking Time-Bomb: F-O-O-D, is a Fighting Word, like OIL ~
Organic windfall for bankrupt soil
Farmers Weekly
Farmers Weekly
The torrential rains of February and March 2000 drowned many fields north of the Soutpansberg in Limpopo Province. At the time, Bertus Otto noted that the crops in his conventionally fertilised lands were yellow and sickly – “really bankrupt”, even though he’d cultivated his lands for 33 years, ploughing, subsoiling, fertilising and practising good crop rotation. In stark contrast, the natural veld adjacent to his farm, Secrabje, was in full bloom. “So my neighbour, Nature, was a far better farmer than I was,” he admits.
Well-thought-out organic idealism
Bertus realised that for over three decades he’d been doing something wrong. Now, for the past seven years, Secrabje has been one of SA’s few totally organic commercial farms.
Bertus believes the first crucial question every farmer considering the switch to organic production needs to ask is: why do want to farm organically? Is it a conscience, financial or ideological issue? His main reasons for switching to organic were his passion for nature and the need for a sustainable market. “I never liked the idea of farming with chemicals,” he recalls.
“Today you’ll spray a crop, tomorrow you’ll find many friends – birds and even bats – lying dead all over the fields. It would be like entering a family graveyard.”
Since going organic he’s noticed a significant increase in wildlife on the farm.
“Nature is coming back. We’ve also embarked on a programme to identify bats, and to breed some species.”
Study your market place and secure it
Once Bertus decided to go organic, he discussed the way forward with his sons. “We wanted to make ourselves irreplaceable,” he recalls. Their first step, and the first thing farmers need to do before going organic, Bertus stresses, was finding a buyer for their produce. If they hadn’t, they might have wound up without one, especially while their farm was in the process of conversion.
The Ottos approached a few potential clients. None were interested, until they heard the word “organic”. Then they wanted to know how much space they had to allocate. But Bertus warns farmers not to believe organic farming opens up an “easy” new world. A lot of hard work lies ahead. There are also a few organic products, such as bananas, that no longer get a price premium as they’re so common on the market. On the other hand, products such as pumpkin, butternut and sweet potato are in high demand by baby food manufacturers.
“When you listen to the inner circle talk at one of our largest food stores, you hear they want a third of their company’s products to be organic by 2012,” says Bertus. Going organic is a great way to make yourself irreplaceable in the market, he stresses.
“You only have to look at whether there’s a market for your product. But the first thing all supermarkets want to know is whether your production is sustainable – whether you can deliver daily.”
Forget everything you know
Although it probably wouldn’t be tasty, Bertus is prepared to eat all the nutrients and inputs used on his farm, and is still looking for a chemical farmer that can say the same. “I don’t have the guts, but otherwise I’d even be prepared to eat the compost,” he jokes.
He had to discard everything he’d ever learned about chemical farming. “All plant nutrients come from nature. Who do you think you are to take them back to nature?” challenges Bertus. He believes all processes needed for good soil happen naturally.
But human help is sometimes needed, for example, to help return plant waste to impoverished soil, stimulating the natural processes that increase productivity. “Have you ever seen a fertiliser truck in the Knysna forest?” he asks. “How did that world become so fertile without it? And more importantly – how does it remain intact? Branches break, fall down and decompose to litter, then to compost, which is “mined” by microorganisms, bacteria and fungi. The digested compost is the perfect food for plants.
But these microorganisms die when synthetic chemicals such as herbicides and pesticides are applied.” Bertus believes this starts a cycle which disrupts nature.
“Do you realise chemical farming isn’t sustainable?” he asks. “You need to ask yourself why so many chemicals are being withdrawn from the market. They’re a risk to humans and the environment. Nature doesn’t tolerate bad genes. It all boils down to the proverbial survival of the fittest.”
Carbon, carbon, carbon
“Get your soil’s organic carbon level right and you’re halfway there,” says Bertus. Unfortunately this is easier said than done. Secrabje’s soil had been practically depleted of organic carbon from 1967 to 2000, while Bertus was farming chemically. “The soil’s carbon content needs to be around 3%,” he explains. “The higher the production you want from your soil, the higher it needs to be.”
Especially in the hotter parts of the country, crop residues should be worked as deeply into the soil as possible. “When the organic carbon levels are correct, re-evaluate irrigation. Water will be used more efficiently for plant production, and you might need to apply less of it.” Today Bertus no longer takes soil samples unless they’re required for EurepGAP or other certification.
Every now and again he’ll take leaf samples, and tries to do this in temperatures around 25ºC.
Finding compost near you
Organic farmers constantly need compost. Bertus recommends identifying suitable compost sources nearby, or the process won’t be sustainable, as transporting bulky raw material can be very expensive. “Look around your area and see what’s readily available,” he advises. “Urban areas always have a surplus of plant biomass. Animal waste and green manure are excellent, as they accelerate the process.”
He’s identified 80 sources of compostable material in the vicinity of his farm. As it contains no residue, packhouse waste is a very valuable compost component. As for compost processing, Bertus opts again for the natural solution. “You can’t manage compost as well as the land can,” he says. “Work it into the ground and let it ferment there.”
Contact Bertus Otto on (015) 575 9912 or 082 449 2434, or e-mail m.a.otto@lantic.net. |fw
Source: Farmers Weekly
Does compost tea work?
Farmers Weekly
Farmers Weekly
The use of compost tea in South Africa is a relatively new fertiliser innovation and has been met with huge scepticism by some agriculturists. Those who have incorporated it into their production cycles are convinced it really makes a difference. Glenneis Erasmus speaks to a few farmers and specialists.The pros and cons of compost tea is currently a hot topic among agriculturists. While some outright reject it as rubbish due to lack of scientific proof and standardised recipes, measurements and applications, there are those who swear by it. “It’s true that scientific proof helps to build confidence in a product, but anecdotal evidence abounds. One can’t discount some farmers’ experience or say that compost tea doesn’t work, just because the results aren’t scientifically substantiated,” says Jako Pieterse who has his own company, Ecosoil, that specialises in compost production.
A laboratory manager at the Soil Foodweb Institute of South Africa, Stephanus Malherbe agrees, “I’ve seen many farmers achieve improved yield and soil health with what I considered to be rather poor-quality compost tea. I’m not advocating the use of substandard compost tea, all I am saying is the cost of synthetic fertiliser is rising astronomically, making it increasingly difficult for farmers to remain profitable. Scientist would be much more useful if they followed up on the findings of farmers and helped them to identify what works.”
Duncan Dicey who farms at Nooitgedacht in Wolseley affirms that it definitely isn’t a quick fix or stand-alone solution to production problems. “Compost tea application should be incorporated into other sustainable production methods to enhance soil and plant health. We’ve been using it for two seasons and have seen significant improvements in our soil structure. We’re hoping that in the long run it will re-establish soil health and help us become less dependent on synthetic fertiliser that depletes the soil.” Obvious improvements This aspiration to reduce fertiliser costs doesn’t seem too far from being realised.
Before starting Ecosoil, Jako was a fruit-farm manager at Karweyderskraal near Hermanus for 15 years. During his last five years, the use of compost tea in a fertigation system helped reduce the amount of minerals being leached from the soil.
The average phosphorous levels in the orchard increased from 38,3 parts per million (ppm) in 2000 to 55,1ppm in 2004, while the manganese content went from 7ppm to 10ppm. Sulphur increased from 7,1ppm to 27,2ppm and carbon increased from 2,2ppm to 2,5ppm. Nitrogen applications were cut by 70%. Jako, along with Soils Alive that also specialises in compost production, have recently been involved in studies on potato production in the Sandveld.
So far the yield increase in the potato cultivar FL2006, treated with compost tea and other biological products, has been 11%. In a control cultivar the yield was 43,4t/ha, while the FL2006 achieved a yield of 48,2t/ ha, with a fertilisation reduction of 20%. The results are even more significant considering the potatoes were harvested three weeks earlier than usual due to a shortage of potatoes for the potato chip market.
The increased number of beneficial microorganisms in the soil has improved soil health and structure, making compost tea one of the most powerful tools organic farmers have to enhance production. Bruce Gilson, who farms fruit organically on his farm Tierhoek situated in the Breede River Valley, can’t imagine farming without it.
“Combining compost and mulches significantly improved our soil structure. The soil is softer and smells better. There’s an abundance of earthworms indicating healthy soil. Healthy soil results in fewer pest and disease-related problems.”
Ferdie Richter who farms just outside Keimoes agrees, “We have three blocks of sultana grapes right next to the Orange River. The two blocks treated with compost tea showed a higher resistance to downy mildew than the untreated block. The increased resistance reduced my disease-control costs.”
The most remarkable thing about compost tea is that it makes it relatively simple and inexpensive to achieve dramatic results. Bruce adds, “We make our own compost tea and use it on a regular basis as foliar feed through fertigation. Our tea consists of about 10ℓ of good quality compost, 2ℓ of fish emulsion and 2ℓ of kelp, all diluted in 1 000ℓ of water. The mixture is aerated and brewed for between 18 hours and 20 hours and is then ready to use.
Around 100ℓ of compost tea is applied to the orchards every week from July and August, until the first autumn rains the following year, at a cost of only R0,10/ℓ”. Even so, there is a lot of criticism of the use of compost tea. It’s difficult to distinguish beneficial from non-beneficial organisms or measure good quality.
Stephanus confirms this, “The most effective way to identify organisms is through DNA testing. Such tests are expensive and time- consuming – farmers can’t afford to wait months to get results.
Making use of the old, culture technique takes only two days. The problem is that microorganisms are volatile. If somebody posts the tea and it takes two days to get to us, the sample no longer reflects what the farmer has in his tank.” This, however, should not be seen as an obstacle, according to Stephanus. “We look at the sample through a microscope and identify the extent of the biodiversity, as different microorganisms have different functions. The more diverse the range of microorganisms, the healthier the soil is likely to be,” he says. He advises farmers to ensure that their compost is of good quality and to rather have it analysed.
Jako agrees. He believes compost used for compost tea should be purpose-made. “There’s not enough attention to detail in the making of ordinary compost. Controlling temperatures and ensuring aerobic conditions throughout the heap to prevent a build-up of pathogens are imperative,” he says, adding that the more diverse the starting material, the more diverse the finished product.
Contact Jako Pieterse on 072 906 1636.
Does Compost Tea or not?
Claims that there is no scientific evidence that compost tea actually works seem unfounded. A literary review by Dr Steve Scheuerell and Dr Walter Mahaffee published in Compost Science and Utilization, 2002, summarises findings by numerous scientists on the benefits of aerated and non-aerated compost teas. There is debate over whether it’s necessary to aerate compost tea or not. Jako feels that it’s necessary, as beneficial microorganisms need oxygen to multiply. Another advantage of aerated compost tea is that it’s quicker to produce – between 18 hours and a couple of days, depending on the organism diversity needed in the finished product.
Non-aerated compost tea can take up to 21 days before it is ready. A disadvantage of aerated compost tea is that it requires mechanisation for continuous air addition. Scheuerell and Mahaffee point out that non-aerated compost tea is associated with lower costs, low energy input and more documented reports of plant-disease control.
There have been reports that non-aerated compost tea could cause phytotoxicity and provide an optimal environment for human pathogen regrowth, but the two authors did not observe phytotoxic symptoms when they used non-aerated compost tea as foliar spray or potting-mix drench, nor have they come across any documented evidence to substantiate such claims. Low oxygen conditions are ideal for most human pathogen growth anyway.
The authors point out numerous reports by producers and the scientific community that reveal disease suppression in crops. For some plant diseases, the level of control is considered inadequate for conventional agriculture. However, organic producers with limited control options, consider even this partial disease control as a better option than no disease control. Much of the anecdotal evidence lacks sound experimental design, objective assessment strategies or supportive dates.
The article suggests the growing number of producers using compost tea is strong evidence of measurable benefits. A better understanding of compost tea and its uses is needed. Scientists are urged to follow up results of growers with replicated field trials to illuminate the extent that compost teas will provide a reliable disease-management tool in the future.
Source: Farmers Weekly
Soil health, from Compost – the bedrock of Thelema Vineyards success
Farmers Weekly
Farmers Weekly
Situated on the Helshoogte Pass outside Stellenbosch, Thelema Mountain Vineyards was nominated the second-best cellar in SA in a 2007 reader poll by Wine magazine. This internationally acclaimed cellar is one of Wine editor Christian Eedes’ top 10 favourites. Thelema’s owner and cellar master Webb seems unaffected by the hype. At the age of 28 he left his life as a charted accountant in Durban to study winemaking full-time at the University of Stellenbosch.
In 1983 Gyles bought a derelict plum, apple and pear farm, where today Thelema produces 25 000 cases of premium wine on 50ha of mainly decomposed granite high-potential soil. Cultivars include Sauvignon Blanc, Rhine Riesling, Chardonnay, Cabernet Sauvignon, Shiraz and Merlot.
Irrigation water is stored in a farm dam fed by winter rain draining off the Simonsberg Mountain. Growth precision G yles believes in combining natural balance and cutting-edge technology to produce excellent wines year after year. The vertical shoot positioning (VSP) system, which arranges shoots to grow upwards, is used to balance growth with grape production. Gyles says his perfect VSP vine has a 12cm spur spacing, and two buds left after pruning.
During spring, two shoots should grow with 17 or 18 leaves each. Two bunches will form on each shoot, and after vertical shoot growth of 1,2m, these bunches will ripen to suit requirements. “In practice, we manage each block according to its potential,” he says. “If growth is too vigorous, the fruit won’t ripen. As a corrective measure, we’ve experimented with the double Guyot pruning system, where instead of pruning the shoots, new leaders are developed each season.” Soil health the natural way n the vineyards, Gyles showed Farmer’s Weekly the friable soil structure and the abundance of living organisms present.
Sample holes were dug, and we were amazed at the depth of root penetration and the amount of hair root development. “That looks like healthy soil and vines to me, so I’m happy,” observed Gyles. He sees soil health as the foundation of quality wine and an intrinsic part of sustainable production. “About six years ago we noticed a decline in our production,” he recalls. “Plant vigour was going down, so we had soil samples analysed. The results showed an alarmingly high count of plant-parasitic nematodes, and very few other living organisms.”
“We were advised to use an extremely costly, intensive chemical programme, which would have set us back R30 000/ha, but nematologist and retired academic Professor Bertus Meyer suggested using ompost to restore soil balance naturally – a cheaper, and far more environmentally friendly solution.”
With the help of Barbara Von Wechmar, an expert on composting, Thelema set out to rebuild its soil. “At first we bought compost, which we placed on the bunkies and covered with straw,” explains Gyles.
“Buying these materials was expensive, but we had to start somewhere. In the meantime, Barbara taught us how to make our own compost with material available on the farm. “Cellar waste is notoriously difficult to decompose, but with the correct inoculants, which she supplied, even grape skins can make excellent compost. Thelema can now use all its cellar waste for composting.” Recently Thelema bought a mower with a side chute so that cover crops could be mulched, instead of buying in straw.
Barbara’s technique also doesn’t require the windrows to be continually turned by expensive machines. Today Thelema removes all pruning material from the vineyards, chips it and adds it to the compost mixture. This helps prevent disease, as the heat generated by the compost wind row kills the pathogens in the cuttings.
Compost extract is prepared with an aerator and applied through the dripper irrigation, according to Barbara’s prescriptions. “In 2005 the lab recommended we chemically treat 12 vineyard blocks,” says Gyles.
“This number came down to one block in 2007.” Cover crops Viticulturist Conrad Schutte explains Thelema’s cover crop strategy. “We use cover crops for weed control and to suppress vine vigour in some blocks. We use as little herbicide as possible, and our ryegrass has been manageable up to now. Blocks with very vigorous vine growth are planted to a permanent cover crop.
We use fescue (Festuca arundinacea), which the rep claimed is the same grass as on Newlands,” Conrad smiles. Pruning intensity and production is carefully monitored. If a decline is noticed, every alternate row is cleared of fescue and an annual crop such as triticale is established instead. Blocks with medium vigour are planted to triticale, and low-vigour is remedied with purple vetch, a natural nitrogen fixer, mixed with triticale. Irrigation management Irrigation is managed with the help of a pressure bomb and a continuous capacitance soil moisture probe.
As Conrad explains, “We used to use a conventional moisture measurement system until two years ago. But it was like taking a photo. It didn’t tell you what was happening in-between measurements. The new probe system takes electronic measurements every 30 minutes, which can then be downloaded onto a computer.”
This allows for far more accurate irrigation management. “For instance, during véraison (when the berries change colour), we don’t want undue moisture pressure on the vine and irrigate accordingly,” says Conrad. “Other stages require the vine to be stressed, so we limit water to achieve the exact amount of stress required. “The better our information, the better we can manage this process.
We also combine data from Aqua Check test strips with pressure bomb samples that measure leaf and stem water potential, because while the soil might be at the correct moisture level, the plant may not be functioning optimally due to root disease or some other factor. “Together with experimental plot data from sample vines, we get a clear picture of our vineyard’s condition.
This also helps us predict the crop size so the cellar can budget for the right number of barrels, and the marketing department can do strategic planning,” concludes Conrad.
Contact Thelema Mountain Vineyards on (021) 885 1924, e-mail wines@thelema.co.za or visit www.thelema.co.za. |fw
Source: Farmers Weekly
