No-till can be practical for vegetables
No-till helps farmers work with nature, with massive benefits in the quality and health of soils and water use, sustainability and economics. And Bill Kerr speaks from first-hand experience.
No-till Production is sweeping the world, converting formerly uneconomic areas into viable units, and bringing environmental benefits too. No-till should hold a special appeal to organic producers. It’s also a huge opportunity for emerging farmers who don’t have the equipment, money or fertilisation knowledge for conventional farming. When the soil becomes enriched with organic matter, no-till and the balance of organisms take care of most problems. Tilling throws this balance out.
To start – know your soil
To start no-till off on the right foot, you need to know what’s in the soil. Each soil type has a distinctive mineral content, and soil condition can vary greatly. You have to start by addressing any large deficiencies or imbalances, and breaking up any hardpan. Increasing humus content will eliminate many of these problems over time, but addressing major problems in the beginning will provide benefits sooner.
To do this you may need to add lime and phosphate, if indicated by a soil test. You can add compost or manure if available. Chicken manure contains a fair quantity of phosphorus and kraal manure is rich in potassium. Going no-till, you’ll have to include tracks for tractors and walkways for workers. The most practical way is to make raised beds, leaving the sections in between for traffic. Raised beds also improve drainage and concentrate more topsoil at the root zone.
It isn’t always essential to cultivate the soil before making raised beds. Fertiliser can be broadcast before the beds are formed. Small-scale farmers can hire a contractor, or form beds manually by demarcating the pathways with a line and moving soil to either side with a hand hoe.
Tillage damage and microorganisms
When tilling the soil, you physically damage its structure by mixing the soil particles. You also over-aerate, stimulating bacterial activity which stops the rapid breaking down of crop residue, in return reducing humus. Equally bad, we create an imbalance between soil organisms, with excessive bacteria and less fungi. A fungus called mycorrhiza increases the plant’s effective root system by 10 to 1 000 times, and is readily destroyed by tilling.
In untilled soil with a healthy humus content, soil organisms thrive. A teaspoon of humus-rich soil may contain 1 billion bacteria of 30 000 different species, each playing a different role. Many make formerly unavailable minerals available to the plant. Many free-living bacteria and other soil organisms can extract nitrogen from the air, saving on fertiliser. About 6t of these beneficial organisms work underground in every hectare of good soil.
While I did started off with virgin veld for my vegetables, my severe eelworm damage and fungus problems disappeared after a few years of no-till and humus build-up. A seedling grower recently told me about a farmer who’d planned to plant only lettuce and use earthworm compost as a fertiliser with no-till. The grower had named a list of soil-borne diseases he thought would put the farmer out of business.
But eight years later, the farmer is still at it with superb results and no problems. He cuts his lettuce and replants the new seedlings between the old plants. In his area he can plant 12 months a year. The lettuce cycle is two months, which gives him six crops a year from the same untilled soil.
Chemical fertilisers interact and are greatly affected by soil pH, making soil fertility tricky. Most applied fertilisers contain a positive charge and adhere to negatively charged soil particles. Nitrogen comes in two basic forms – the positively charged ammonia that sticks to soil particles, and the negatively charged nitrates that are free to move in the soil water and are easily leached. We’re never certain how much leaching happens after rain, and often only find out when the damage is done.
But humus has positively charged areas to safely hold the nitrate, saving a lot of expensive nitrogen. My soil is at the point where there’s no nutrient leaching at all. The humus also acts as a buffer, reducing the adverse effects of mineral interaction. We’ve become used to the negative period of crop growth crop residue causes, as bacteria take up nitrogen from the soil to break the residue down. Bacteria have a carbon:nitrogen ratio of 5:1, and only release nitrogen back into the soil when the residue is used up and they die off.
But with no-till, the residue stays on the soil surface, and is slowly broken down by fungi and actinomycetes with no negative period. As the crop is harvested, the residue is slashed, herbicided or uprooted, depending on the crop, scale of production, conditions and following crop. If fertilisation is needed, whether chemical or organic, it is broadcast on the beds before planting, without working it in
For seeded crops on a larger scale, some form of light cultivation will be needed to loosen the soil to a few centimetres deep in the area to be planted. No-till is impractical where carrot lifters are used, but can be adopted until carrot lifting, then started again. In almost all cases, tillage benefits neither the soil nor the following crop, and should be minimised. No-till crops will have fewer pests and diseases, but you need to be practical and use products that don’t damage soil life, always maintaining a population of natural enemies. Costs will decline, and crops will be more productive. Farming becomes more exciting and pleasurable.
Benefits of no-till – Bill Kerr’s first-hand report
- Substantial savings in fuel and in capital invested in implements.
- One can re-plant immediately after harvest – no need to wait weeks before cultivation, which results in soil drying out.
- The increased humus associated with no-till creates an environment where soil diseases and eelworm eventually disappear.
- Better water penetration and retention.
- Lower soil temperature.
- Far healthier crops.
- No negative period from crop residues.
- After a lifetime of large-scale vegetable production, I only learnt about no-till near my retirement. When I look at my production and how little effort it requires, I wish I had this information many years ago. I last fertilised two years ago, spreading cattle manure on the surface of the soil. Subsequent crops haven’t had even a gram of nitrogen topdressing and are extremely lush and healthy.
- The soil is full of earthworms, and darker with more humus and a lovely earthly smell. This summer, Phytopthera destroyed all my clients’ peppers wherever the lands flooded. But frequent flooding on the bottom section of my peppers didn’t affect a single plant. For over 10 years I’ve planted tomatoes, often two crops a summer in the same soil, without problems, soil fumigation or chemicals.
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