Biological Fertiliser Use

Over the past decade or so farmer interest in non-conventional fertilisers has steadily increased. Reasons include the growth in organic dairying, pressure to reduce nutrient runoff and concerns about the effects of soluble fertilisers on soil and stock health leading to increased interest in “biological” approaches. Conventional fertiliser companies are now offering some products to meet this market niche.

This item looks briefly at two dairy farmers who have been using alternative fertilisers successfully for ten and four years respectively. They have seen improvements in soil and plant condition and stock health, and have used little or no urea and only modest amounts of P in a biological form. Production levels are similar to surrounding farms.

Pacific Biofert Ltd has been in the alternative fertiliser business for 25 years and confirms that sales have recently taken off. Clive Sinclair became interested in biological fertilisers almost by accident. He has learnt a great deal about enhancing biological activity in soils and has developed a range of microbially activated mineral products that can be tailored to suit each farm’s requirements.

It seems like there have always been alternative fertilisers available to farmers – liquid seaweed and fish products, specialty mineral mixes, new forms of old products and so on. However, the mainstays of pastoral farming for the past 50 years have been superphosphate, often combined with muriate of potash and agricultural lime. The rule of thumb was 3 – 5 cwt of super per acre plus a ton of lime every three years. From the 80’s onwards, strategic applications of urea were increasingly added to the mix on dairy farms in the drive for greater production.

In recent years warning bells have been sounded about the wisdom of applying so much soluble fertiliser. Runoff into waterways and contamination of groundwater have become important issues, clovers have become weaker, scarce and even disappeared from some pastures and many farmers have become concerned about the lack of balance in feeding their stock a monoculture of ryegrass. Animal health has become a major cost centre.

Those farmers who have taken a close interest in their soils have watched as worm numbers have dwindled and soil condition has deteriorated. Regrassing that at one time was a once-a-decade activity is now accepted as being necessary every 5 – 7 years as the pastures “run out”.

Recent research has indicated a fall in carbon (organic matter) levels in some dairying soils, probably the result of high urea applications and greater grazing intensity.

In the past decade or so organic dairying has been encouraged by Fonterra and this has led to increased interest in fertilisers compatible with the various organic certification regimes. Some conventional farmers have also become concerned about the use of urea because of soil and animal health concerns and have sought alternatives. At first the major fertiliser companies resisted stocking such products, but in recent times they have changed to meet the demands of a growing market. Ballance recently acquired all the shares in the niche market supplier Summit-Quinphos and has rebranded it as “Altum”.

Matt Ward, Altum’s sales manager for the Waikato region, says that while RPR-based products still form an important part of the company’s offering, they have been supplemented with novel fertilisers and regionally optimised animal nutrition products.

“Our emphasis is on complete nutrient management rather than just on fertiliser, and we cover everything from fertilisers and trace elements to soils, plants and animal nutrition to farm mapping,” says Matt. “We try to match people with products that suit their needs, and if farmers are looking for something that acts faster than RPR but is not acidic like super and DAP, then we go to the Pacific Biofert range.”

John van der Goes is in his 12th season with a herd of 160 cows on a 57ha milking platform of rolling country near Morrinsville. He has used alternative fertilisers for six years.

“It all started from getting stuck in the trap of needing to put on more and more nitrogen and I thought that we were becoming far too reliant on it. A fertiliser rep recommended Pacific Biofert products, so I talked to Managing Director Clive Sinclair who explained that it was just a matter of making soil conditions favourable for clover to harvest nitrogen out of the air,” says John.

“What I liked about it was that he was not trying to reinvent the wheel. The fertiliser is still RPR rock but it is broken down through composting rather than using sulphuric acid. It made sense to me so I thought I would try it for four years and see how it went.”

Initially his farm’s phosphate levels were high, so John put on only “Biolime” to help adjust the soil pH. Now he is only applying Biophos at about 250kg/ha, which he says represents a saving in both quantity and cost.

“What has surprised me is that our Olsen P levels haven’t dropped much even though we didn’t put any P on at all for four years. It seems there is a fair bit of P locked up in the soil that we have been able to unlock,” he says.

“We’ve still been growing the same amount of feed as farms around us, and there is much more clover now and lots of earthworms so the soil is looking friable and healthy. We’re purposely milking fewer cows now but getting the same production.”

“Basically we are just trying to farm in a way that is fairly straightforward and sustainable. And I guess with a greater emphasis on the environment, we felt a fair bit of push to lower nitrogen application. Also I was getting sick of having to put it on all the time – we would have been putting 30 tonnes of urea on our 57 ha and now we’re down to about 75 units of N for the whole season.”

Stuart Morley milks 220 cows on 80ha at Kerepehi. He sharemilked there for two seasons in 2001, then went to another farm for six years but has been back at Kerepehi for the past four years. He has used Pacific Biofert products for many years.

“Before we came here the first time we used Biophos on my parents’ farm, and I did field trials with it. It worked out that it was a lot better in terms of dry matter production and pasture quality,” says Stuart.

“When we started here the farm was typical of the area with variation between paddocks and not much worm activity. We put on Biophos and minerals and the feed improved, and we got production up to 80,000kg MS from 230 cows.”

When Stuart moved his herd to the second farm he was amazed to find that the cows were very reluctant to eat the grass there. It looked lush and had plenty of clover, he says, but he if he didn’t shut them in the area to be grazed they would come back to the cowshed.

Coming back to the Kerepehi property after six years he found that while the use of Biophos had continued, the application of minerals hadn’t, and the sharemilker had applied gibberellic acid to the pasture. “It was really peculiar looking grass we grew in the first six months we were back. The bases of the plants were dead, the grass had yellow stalks about 3” long and only the top was green. It took about two years for the pastures to come right, and that just shows me that forcing the system doesn’t work,” says Stuart.

“We’re now back up to 70,000kgMS, pastures are in good condition, biological activity as seen in worm casts are everywhere and this has been increasing every year. If we can get cow numbers back up to 230 this place has got the potential to reach the previous production level.”

Tests have shown that soil P levels are high enough not to have to apply phosphate. However, plant analyses indicate high levels of potash and molybdenum, despite the fact that none has been applied since 2001, and Stuart says they are monitoring this closely. Lime increases the availability of K and Mo, so he is using liquid forms of Ca and Mg.

One of the constants since he started to use Biofert products is a generally high level of animal health. Apart from a season where some stock contracted neosporosis he has had few reasons to call his vet – he doesn’t drench or inject his herd. In fact, he says, the vet rang him recently to see if he was still a client or was using someone else!

Clive Sinclair got into the fertiliser business almost by accident. Back in the 80’s he was feeding fish waste to pigs and ended up with far more fish than he could use, so he started making liquid fertiliser. One Friday after a hectic week fulfilling a large export order, he left the factory without cleaning up. When he returned after the weekend he found that fungi had grown all over the fish waste and had etched the concrete floor. Figuring that if the fish/fungi mix could digest concrete it could do the same for rock phosphate he mixed the two and found that it worked. With further experimentation he found that leaving the mix in a heap led to its composting and resulted in a dry, granular product that was highly effective in stimulating plant growth.

“RPR is relatively insoluble and is only slowly available to plants. Treating it with sulphuric acid to product superphosphate makes it readily available but only through the soil solution, so it can be leached away easily,” says Clive.

“Moreover, much of the phosphate in this form becomes bound up in soil colloids and so is locked away from soil organisms and plants. Composting it with fish waste allows bacteria and fungi to multiply and incorporate the phosphate into their cells, and in this form it doesn’t leach into waterways or ground water but is readily available to soil organisms and plant roots.”

Clive explains that plant roots get most of their nutrients not from the soil solution but indirectly from bacteria and other soil organisms. In return the plants pass on energy in the form of carbohydrates that are made through photosynthesis in the leaves. This exchange of mineral nutrients for energy takes place via a “microbial bridge” comprising fungi which have hyphae (threadlike filaments) permeating throughout the healthy soil and are in intimate contact with both plant roots and soil organisms.

“Maintaining the integrity of the microbial bridge is absolutely essential to having healthy and vigorous biological activity in the soil and hence vigorous and nutrient dense pasture growth. Unfortunately it seems that extensive use of high analysis soluble fertilisers can reduce microbial activity and lead to loss of soil carbon and reduced dry matter production,” he says.

“A growing number of farmers are becoming concerned about this, and we have had a much higher level of enquiry in the last few years. I have seen many instances where, like John and Stuart, farmers have applied phosphate, lime and trace nutrients in a biologically activated form and the soils have improved greatly without any loss in production. Animal health has also improved.”

Pacific Biofert now has a manufacturing facility near Pokeno where it produces a wide range of biological fertilisers including Biophos, Biolime and products incorporating many of the major and minor trace elements. Their process is IFOAM and BioGro certified and so compatible with both organic and biological farming systems.

BioPhos – RPR is inoculated with phosphate-fixing fungi and bacteria that multiply in a controlled composting process and convert the rock phosphate to highly plant available polyphosphate that is very resistant to leaching. Polyphosphate is released into the microbial network and thus made available to plants. Biophos also stimulates beneficial fungi and bacteria including nitrogen fixing Rhizobia on clover roots.

Biolime is a blend of lime, fish nutrient and a small amount of composted sawdust that is inoculated with a formulation of bacteria and fungi. During processing the calcium carbonate is digested into a form that is much more available than straight lime, has a shorter release period and greater absorption so that less needs to be used to get the desired effect.

BioMag is made in a similar fashion to Biolime but with Serpentine rock. It is 22% Mg, and uses fish nutrient to feed the microbes that incorporate Mg into their cellular structure making it readily available to plants.

Moana chelates are plant foods in which the desired mineral is processed into a stable organic form that allows it to be absorbed by plants and thus correct deficiencies. The chelated minerals include zinc, selenium, molybdenum, manganese, magnesium, iron, iodine, copper, cobalt, calcium and boron. The chelates are non toxic and feed soil microorganisms.

In addition, the company produces animal tonics and a product containing the soil-enhancing fungus Trichoderma.

Product mixes are tailored to an individual farm’s requirements based on soil and foliage tests.