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Clover is our one big advantage in the global market because of its nitrogen fixing capabilities. In the 1960s Sir Bruce Levy formulated a plan that would eventually cash up on that advantage. It involved applying large amounts of fertilisers onto virgin land to grow plenty of dry matter, which would ultimately allow more stock to be grazed. To achieve this, he believed every bit of research would have a prime objective of increasing clover response, with farmers eventually using clover as a simple yardstick to productivity. He also believed that an increase in clover, through the use of fertilisers, would stimulate the underground fertility reserve through the natural cycle, therefore produce a sustainable growth of clover that was well balanced, and capable of handling the high stocking rates. By attaining this biological outcome, he believed farmers would receive the majority of their fertiliser cost for free, instead of applying them from a bag. In his words:
“This composting ameliorates the land and provides for an army of worms and bacteria that play an important part in releasing soil fertility from dead and dying portions of plants on the surface and below ground.”
“The Crumbs that Fall”, N.Z. Fertiliser Journal, 1967
This made sense to a lot of people, especially to the Government and Hatuma. He was right in every aspect, and the plan was very much conceivable. Unfortunately though, it had one major flaw – it was assumed clover grown with acidic water-soluble fertilisers would lead to sufficient recycling of the nutrients by the soil life. But an army of earthworms and bacteria will not tolerate an acid environment in the litter layer (top 10-12mm of soil), and in time it became clear Sir Bruce Levy’s vision at a national scale was never going to be a sustainable one.
Now, in the space of only a few decades, clover management has evolved to where farmers are recommended to apply nitrogen from a bag so the clover plant does not have to fix its own free nitrogen; it can save all its energy for growing above ground instead and have its fertiliser requirements be satisfied synthetically from the farmer’s wallet. According to the 2005 Parliamentary Commissioner to the Environment’s report, Growing For Good, more than 770,000 tonnes of nitrogen fertiliser was applied for the year ending 2002 – more than ten times that used in 1983. And market trends are showing no reduction. This massive reliance on artificial nitrogen is coming at a national cost, both economically and environmentally, and it is certainly not what Sir Bruce Levy had in mind.
Clover stimulation is one of the main benefits of Hatuma dicalcic. It is overwhelmingly evident from farmers’ experiences, especially from first time users. Where they are concerned, clover seems to appear from nowhere, even on areas they had long time given up on. Then, through light annual dressings, it continues to flourish each year, allowing the natural nitrogen cycle to work, and ultimately producing strong, healthy stock. Just like Sir Bruce Levy intended.
How does Hatuma dicalcic succeed where others have not? Clover, being a legume, has a wonderful ability to fix its own nitrogen from the atmosphere. It manages to do this through beneficial soil bacteria called rhizobia. They enter the plant through its root hairs and cause growths, or clover nodules, and a symbiotic relationship is formed between the two. The rhizobium bacteria, while living in the nodules, can fix considerable amounts of nitrogen from the atmosphere and feed it to the clover, while the clover, through photosynthesis, feeds the bacteria carbohydrates to regulate its supply of nitrogen. It is a simple and very effective partnership - the more clover grows, the more nitrogen is fixed per hectare, which leads to more carbon ultimately added to the soil.
However, as acidifying products are applied to the soil, these essential forms of soil life can become restricted or even killed off, and the clover plant becomes reliant on being fed nitrogen from the back of a spreader, just like every other plant. As noted:
“. . . clover seeds also need to be inoculated. The bacteria in the culture are very sensitive to contact with water soluble fertilisers, to excess acidity and to excess alkalinity.”
“Superphosphate is very acid, close contact being lethal to nodule bacteria in cultures. Lime-reverted superphosphate 3:1 and serpentine superphosphate are not entirely safe . . . A good fertiliser is a lime:superphosphate 1:1 mix, prepared carefully and allowed to react for a week or so. Superphosphate has been reported to reduce the nodulation of clovers even if broadcast immediately after the inoculated clover seed was sown.”
C. During, Fertilisers and Soils in New Zealand Farming, Dept. of Ag. Bulletin No. 409, 1967
Properly made Hatuma dicalcic, with its pH of 6.5-7.0, does not have this lethal effect. In fact, tests results show soil containing Hatuma dicalcic phosphate had a higher number of rhizobia in all samplings than without (click here for a larger version of the graph): |
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Conducted by AgResearch, 2002
- Another trial conducted in 1974 by Vautier Enterprises concluded that twice as many rhizobium bacteria grew in Hatuma dicalcic than in straight lime.
Another symbiotic relationship formed – which can be just as beneficial as the rhizobia and clover alliance – is when mycorrhizal fungi help feed the plant a supply of phosphorous, nitrogen and other essential mineral nutrients. Again, with the plant giving carbohydrates in return. However, if the clover can source its own supply of phosphate or nitrogen from water-soluble fertilisers then that relationship struggles to form, and like the ending of the plant/rhizobia relationship, the soil loses an important supply of carbon.
Clovers are recognised for their high calcium content. For healthy clover nodules to form they too must have a good supply of calcium available; nodules can hold up to twice the amount of calcium as other parts of the clover plant. It is assumed this extra calcium creates a safe environment by acting as a buffer against any acidity affecting the work of the nitrogen producers. The simplest method of maintaining this calcium level is by creating a neutral pH in the litter layer (10-12mm). This allows the plant to have a constant supply to feed the nodules (calcium is most available between a pH of 7.0 - 8.5, (Truog)). This ideal neutral pH environment for the clover and rhizobium can be demonstrated by the standard industry practice of lime-coated/inoculated clover seed, which is seen as a form of protective maintenance for up to 18 months (it also proves how little lime is required to do the job provided it is focussed on the immediate pH environment).
This is why the majority of Hatuma dicalcic farmers do not feel a need to apply extra costly rates of synthetic nitrogen. After having established efficient nitrogen production through the natural cycle, they feel the extra addition of acid-forming nitrogen fertilisers will only jeopardise it. By creating the right environment their clover can now compete with other pasture species more easily, allowing for a balanced feed for the stock. Even dairy farmers have discovered they can wean themselves off applied nitrogen, to the point where they are still being highly productive without any extra inputs, or any major changes to their management. Farmers are even finding as their use of artificial nitrogen ceases so do certain stock health problems, which obviously helps their economic bottom line.
To show how clover-friendly Hatuma dicalcic phosphate is, clover seed (uncoated/un-inoculated) was sown in a container. No soil was present, only straight dicalcic. Within six months the dicalcic was growing an abundance of thick clover, despite minimum aeration, moisture and no help from soil life.
In a farming environment, this transmits to clover that can be grown on all paddock faces, including northerly ones. The testament to this is beyond dispute. Create the perfect environment in the soil for the clover and it will continue to thrive by making the most of climatic conditions. This will allow the clovers reputation as a premium stock feed to be utilised, especially for the important diet of growing young animals and their mothers. It will also allow the beneficial microbes, bacteria and fungi to protect, feed and nurture the plant, without relying on the farmer’s bank account. |