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Farming and Agriculture

Zero result – a waste of time and money

In the previous issue of my articles -12 December, 2023, I wrote how after twenty years or so, we, as farmers, were beginning to doubt the effectiveness of more and more super phosphate.  
 |  Malcolm Campbell  | 

For a time, we reverted to using the waste from the broiler chicken sheds. This worked fairly well. However, when employing milkers and other people on the farm, it is important to have them put their views forward and to take their views into consideration. At this time, we were constantly reminded in farming journals to get your Olsen P levels up to produce optimum pasture. Generally, any people employed wanted to see more and more phosphate poured on. 


As a result, it was decided in 1991 to run yet another extensive experiment. One ton of super phosphate was collected in the Transit Van from Kiwl Fertiliser in Morrinsville. Once loaded into the spreader, it was spread at a rate of about 300kgs a hectare from one end of the farm to the other, in one strip just over one kilometre long. There was one exception.  In the last paddock, the spreader was put in the wrong gear and the phosphate went on at well over 300kgs sowing rate more like 900kgs a hectare. Having learned to fly, it was easy to observe this trial. From the air, the slightest variation of anything at all can be seen. For example, where farmers spread nitrogen, any variation in the pattern caused by say a chain or rope hanging from the tractor can be seen and uneven spread even more so. The result of our experiment was absolutely zero. Nothing at all. Obviously more phosphate was simply a waste of time and money. That ton of phosphate bought in 1991 was the last ton of phosphate ever purchased for use on our land.


Now how could this be? Our view of what was happening was reinforced by a number of overseas people who did not agree with the soil husbandry in New Zealand. One Australian lady, Christine Jones, on a visit to New Zealand said, “If you have been applying phosphate for ten years you have enough in the soil for the next one hundred years.”  That observation by Christine drew a barrage from advisers and consultants. She was not at all popular. So how much of the various elements are in your garden soil or farm soil or any soil? It is necessary to do a ‘Total Test’ and this will reveal what your soil contains. But what the soil contains may not be what you need to grow what you want to grow. By using these ‘Total Tests’, we have been able to establish that most farms have between four and twelve tonnes of phosphate per hectare in the top 150 millimetres (six inches) of soil. Indeed, a writer in a December Issue of another paper states, and I quote, “Within six weeks of application, 75 percent of soluble phosphate is inactivated.” (end of quote). Hence, we have the heavy loading of unavailable phosphate in the soils. There are some anomalies. Here we are with literally an over-abundance of phosphate in the soil and still pouring more on. It is like chasing your tail and again pouring on expensively man-made nitrogen, when the atmosphere in contact with the soil contains close to 80% free nitrogen, but like the phosphate unavailable, unless the biology in the soil is activated to take in that free nitrogen. In all of this, that silica that was delivered from the Taupo eruption 1800 years ago has a big role to play. Here again is another anomaly. Silica is the most common element on earth, but to get your soil alive, it has to be the correct form of silica!

 NEXT ISSUE. Don’t assume soil needs more phosphate.