Growing Root Crops in Red Soil

red-soilQueensland’s red volcanic soils are some of the most fertile in the world, and they are well suited to the growing of root crops. Root crops, like potatoes and ginger, are demanding feeders that respond well to this superior fertility. However, there are still some common problems associated with these soils, and the most notable of these is related to phosphorus availability. The negatively charged phosphate ion is notoriously unstable. It will readily form insoluble compounds with calcium (tri-calcium phosphate), iron, aluminium and manganese. In red soils, the problem is iron. These soils are coloured red because of an abundance of iron. Phosphate and iron rapidly form the insoluble iron phosphate, and it becomes a constant battle managing phosphorus for high-production fertility. A visit to some Nutri-Tech ginger growers highlights the pain and pleasure of growing root crops in the red zone.

Success in the Cold

Ken Dellit is a second-generation ginger grower, working 60 acres of prime red soil just West of Eumundi in SE Queensland. He has worked with NTS, via ginger consultant Melvan Johannesen, for the past ten years. Our visit was in response to reports of an excellent ginger crop produced in a difficult season, with the aid of Nutri-Tech products. This season, the wettest winter on record has been followed by the coolest summer in decades. This freak summer, which has to date only delivered two hot days, has produced cool soil temperatures, and the resulting slow growth has plagued growers from SE Queensland to Northern NSW and the West of both states. Cotton growers in Gunnedah, for example, are currently battling to overcome growth retardation based on low soil temperatures.

Ken’s Ginger Program

Ken Dellit’s ginger crop was produced with a fairly typical program for the region. Nematode control is central to good ginger production, but, as a good grower like Ken, develops a deeper understanding of the benefits of the biological approach, it becomes a difficult decision to sacrifice the entire soil biology in pursuit of this single pest. Last season, Ken trialed Nutri-Tech’s Nutri-Neem Granular Fertiliser, which is used for optimal plant health in Asia and India, and he reported both a great crop response and healthy plants. However, there was a problem with the supply of neem cake, due to harsh, import restrictions (Neem cake was part of the NTS range next season), and Ken was obliged to return to the poisons for control. Begrudgingly he decided to hedge his bets, choosing a 40% reduction in his Methane application, which would be buffered with biological alternatives. The pre-plant program included 2.5 tonnes of Grow-Mag per hectare and 3.5 tonnes of Nutri-Store 180® High Carbon Fertiliser per hectare. Nutri-Store 180® replaced the conventional application of 15 tonnes of chook manure per hectare.

The crop was then planted on August 16, on 3 bags of a ginger planting-mix containing 8-9-14 plus sulphur and trace elements. Just prior to emergence a blanket spray of the herbicide Diuron was applied at 2 kg per hectare. At the end of October the crop was side-dressed with 4 bags of Nitrophoska Blue per hectare. Nitrogen and potassium fertigation began in mid November and continued every fortnight, with 25 kg of urea and 25 kg of sulphate of potash per application. Humic acid was included at a rate of 1 litre per 20 kg with every urea application. Ken has been particularly impressed with this combination. He feels that there is improved and sustained nitrogen response as a result of the humic acid inclusion. 60 kg of calcium nitrate per hectare was also applied through the irrigation in January to provide a little soluble calcium energy.

A foliar program included two applications of Root-Tech Triple Ten™ at 5 litres per hectare. Ken reports a marked growth response following each of these foliar applications. Tri-Kelp Soluble Seaweed Powder™ was applied at 1 kg per hectare through the irrigation every four weeks. Again, Ken reported what he called a “terrific response” in terms of a noticeable greening and plant health response following each fertigation of kelp.

Benefits of the Program:

  1. There was no hint of unhealthy plants, despite the 40% reduction in Methane. Note: Nutri-Kelp™ has been widely used in Europe, the USA and Australia to enhance nematode resistance.

  2. Ken reported markedly thicker stalks than normal – Stalk caliber determines the bulb size with ginger.

  3. The crop, which was due to be harvested within 10 days, had achieved an average of 98% above the minimum size requirement for harvesting. A 65% average is the lowest size allowed, but 82 to 84% is considered normal.

  4. This crop bordered a second crop that had been planted with a similar program, except the 3.5 tonnes of Nutri-Store 180® per hectare had been reduced to 2.5 tonnes, and 15 tonnes of foul manure had been added instead. The block with the extra Nutri-Store 180® was quite obviously outperforming the block with the extra chook manure, even allowing for a four-week difference in planting times. Nutri-Store 180® is a patented, composed fertiliser with high organic carbon levels. The product contains 3 billion beneficial microorganisms in each teaspoon. Nutri-Store 180® has proven particularly effective in red volcanic soils, and part of the reason for this may relate to American scientist, Dr Phil Callahan’s findings regarding the relationship between compost and paramagnetism. Professor Callahan was the researcher who discovered that volcanic soils outperform soils of non-volcanic origin, as these soils contain high levels of an electromagnetic energy, which increases root cell division and dramatically boosts microbial subdivision in the root-zone. Callahan has termed this energy paramagnetism, and he has patented a meter that tests paramagnetic levels in the soil (The PCSM-Meter is marketed in Australia by NTS). Recently, utilising the laboratory and specialised equipment of German researcher Professor Popp, Callahan was able to show that, when a composted fertiliser is combined with highly paramagnetic soil, then the paramagnetic energy in that soil is magnified up to 100-fold. Ken Dellit and numerous other ginger and potato growers have experienced such a positive response with Nutri-Store 180, because, as Callahan suggests, the compost is magnifying the paramagnetic effect, ie increasing root cell division and stimulating the microbial workforce.

  5. The yield expectation for Ken Dellit’s block was around 45 tonnes per hectare, which is exceptional in a year where unseasonable climatic factors have reduced yields in many crops.

Managing Phosphate in Red Soils

Ken Dellit was impressed with his results this season, but in-field monitoring during our visit suggested that he could have further improved his yield, had he been aware of his classic red soil phosphate lockup, which seriously affected brix levels and yield potential. Brix levels in Ken’s block were only 1.5. The ideal minimum reading for ginger is 8. High-brix crops are high-yielding crops. Brix is governed by calcium and phosphate levels in the soil. In this case, calcium had been addressed with Gro-Mag, so plant-available phosphate was the likely culprit. Leaf analysis data from a neighbouring ginger farm confirmed repeated low phosphate readings in the leaf, despite reasonable soil levels of phosphorus. When iron in constantly tying up phosphate, then foliar fertilising becomes the best option to get phosphate into the plant, as this approach bypasses soil-based lockups.

There is also considerable merit in using NTS Soft Rock™ rather than acid-treated phosphates, which are far more prone to lockups. The exciting, new NTS product, Nutri-Life Bio-P™ also has a role to play in these situations, as this blend of phosphate-solubilising soil microbes can break the iron / phosphate bond, ingesting the phosphate ion and recycling it as a biologically active P source for utilisation by the plant.

The strategy to ensure maximum P response in red, volcanic soils is as follows:

  1. Broadcast NTS Soft Rock™ prior to planting to supply a steady P release throughout the season.

  2. Treat seed pieces with Nutri-Life Bio-P™, at 400 mL per hectare. There is an advantage in also including a little molasses and Tri-Kelp™ with this seed treatment.

  3. When there is sufficient leaf to justify the practice, consider a foliar program. Phos-Force Liquid Calcium Phosphate should be foliar-sprayed every two weeks at 5 litres per hectare. Phos-Force is one of the most powerful brix-builders on the market. There is no coincidence that a recent survey of ginger growers revealed that a grower using Phos-Force™ had achieved the highest brix levels measured in the area.

  4. Root-Tech Triple Ten™ contains very good phosphate levels. It also contains all of the other nutrients required to feed and promote the phosphorus solubilisers in Nutri-Life Bio-P™.

  5. Molasses and humic acid both help to reduce phosphate lockups. Molasses should be included with other fertilisers, at a rate of 3 to 5 litres per hectare. Huma-Life™ should be included with all other liquid fertilisers (particularly urea), at a rate of 5 L /ha. Remember that phosphate utilisation is a biological process. Phosphate, more than any other element, depends on soil microbes to build the path from soil to plant. In red soils, that path is strewn with obstacles, and increasing biological inputs becomes the imperative.