A Problem-Solving Case Study

A system dominated by chemical solutions that treat symptoms rather than address root causes is destined to falter at some point. We are seeing this fatal flaw in the current health care crisis. More drugs are prescribed each year, yet degenerative disease continues to grow and our bulging hospitals are struggling to cope with the flood. The pharmaceutical “solution” is anything but – last year, prescription drugs became our fourth largest killers.

There is a similar bankruptcy in the management of plant and animal health. Every year since the “chemical experiment” in agriculture began, there has been an increase in the number of chemicals applied to our soils and food, yet every year the amount of pest pressure (on a global scale) has increased. In some cases, the chemical bombardment appears to be successfully keeping the foe at bay, but in many instances the weapons fail and the win/loss ratio can only worsen as climate change unfolds.

What happens when a finely tuned chemical management strategy is disrupted with a completely different set of environmental circumstances? The wheels fall off, and we are seeing such management crises develop in all of the forty countries in which we work. Environmental uncertainty demands a more holistic approach, where root causes are finally addressed. The self-priming, symptom treating, pseudo-science that is modern agribusiness will no longer be acceptable in this brave new world.

When the Wheels Fall Off

The NTS head offices are situated in the midst of one of the world’s largest ginger producing regions, at Yandina in SE Qld, Australia. We have worked with ginger growers in the region for years, so I was particularly concerned to hear of a pest management crisis that has developed in recent months. Ginger growers have been so hard hit by a Pythium plague that it may even threaten the viability of the industry. The local processing plant is expecting to run out of ginger mid-season and the shortage will push up the price of planting the crop. If the cost of seed ginger rises to $5+ per kilo, the bill for seed ginger may as high as $30,000 per hectare. The standard chemical regime to control Pythium has been costly and largely ineffective, so many growers are looking to buy new land rather than risking that kind of investment to plant in diseased soil.

I was keen to look more closely at the root cause of this disease, so we called several growers and set up field visits. It soon became apparent that the organic growers did not suffer the problem, so the disease pressure was obviously linked to some aspect of conventional growing. Environmental conditions were obviously playing a role because we have had one of the wettest seasons on record on the Sunshine Coast and Pythium loves damp conditions. There were also other possible players like the compromising of protective beneficials when gassing for nematodes. However, we suspected that nitrogen mismanagement could be a prime suspect and the field visits confirmed that suspicion.

Many industries follow a timetable where nitrogen is applied regularly without monitoring the actual need for the N. We analyse thousands of tissue tests from around the globe and it is very common to see excess nitrogen present in intensive horticulture, yet nitrogen still goes on every week like clockwork. Excess nitrate nitrogen has been shown to favour Pythium. The ginger growers we visited that were worst affected by this disease had all moved from urea to a blend popular for increasing N levels but containing high levels of nitrate nitrogen. Many growers are using 40 litres of this product every two weeks, regardless of their need for nitrogen.

There were several field tests that could confirm or refute this nitrate theory, so we monitored the crops on the farms we visited. For the purposes of this article, I will use the data from just one of the farms to demonstrate how the overuse of nitrate nitrogen can be counterproductive.

Too Much of a Good Thing

A local grower has worked with NTS for several years and has enjoyed enhanced crop quality and production using biological principles. He was recently involved with a research project involving the Sunshine Coast University, where researchers studied the potential of bio-control techniques in the management of Fusarium. They looked at the use of a beneficial microbial inoculum, and found impressive increases in the disease resistance, and the amount and quality of the seed ginger treated with this microbe blend.

This grower uses the NTS Soil Therapy™ service each year and corrects any mineral imbalances – however, he has not been using the Plant Therapy™ service of late. We have suggested that this is an important management tool during the season, as it provides an insight into what the plant is accessing and allows for much more precision in the nutrition program. He suffered significant crop losses due to Pythium this year and planned to scale back on his plantings until he had successfully mastered the problem.

Here is a snapshot of his nutrition program for last season – one thing to note is the amount of nitrogen the crop has received. Each season he applies 50 cubic metres of uncomposted chook manure (as do most of the ginger growers). Depending on the analysis of the manure, this is introducing between 400 and 600 units of nitrogen, most of which will become nitrate nitrogen, as it has not been stabilised via composting. The chook manure often goes in immediately after a legume cover crop, which has also supplied nitrogen. 2.5 tonnes of Nutri-Store 180®, a high-carbon, composted fertiliser from NTS, is also applied before planting. This product also contains another 50 units of stabilised nitrogen and a suite of trace minerals. The ginger seed is then planted with 300 kg of an NPK starter fertiliser. Throughout the season the nitrate nitrogen product is used every two weeks at 40 litres per hectare via fertigation and there is also some nitrogen in the foliars used in the program.

We are only talking about applied N at this point. The biological inputs, including the manure and the Nutri-Store 180®, contain nitrogen-fixing organisms and also activate these creatures, so there is an ongoing supply of free nitrogen from the atmosphere. Ginger is a heavy feeder, but it is highly likely that there was too much nitrogen in the equation and much of it entered the plant in the nitrate form.

Testing Our Hypothesis

Nitrate nitrogen is taken into the plant with water, so there is an inevitable nutrient dilution factor when nitrates are overused. This creates a minerally deficient plant that is much more susceptible to disease. There are four meters, which can be used to check for excess nitrates and to monitor the consequences of the excess. These include the Refractometer, the Nitrate Meter, the Sap pH Meter and the Conductivity Meter. If our nitrate hypothesis is correct, we would expect to see lower brix levels, higher nitrate levels, lower sap pH levels and higher conductivity levels in a Pythium affected crop compared to a healthy crop. In the current plague, it has often become a case of comparing different degrees of Pythium infection rather than looking at a Pythium-free option. I will explain the use of these meters in a little more detail for those unfamiliar with this technology.

The Refractometer and Disease Resistance

The refractometer measures dissolved solids in units called brix. It is a measure of nutrient density and one would expect to see low nutrient density when nitrates are oversupplied, due to the nutrient dilution factor. A vibrant, disease-resistant ginger plant should have a brix level of at least 8, but we would not expect to see those figures at the tail end of the season when the plant is pumping everything down to the roots. Rather, we are looking for a difference between diseased and healthy plants.

Nitrates impact the availability of three minerals more readily than others and these “victims” are calcium, potassium and silicon. The levels of calcium and silicon in a plant can be roughly determined by checking with a refractometer. When holding a refractometer up to the light, the line that separates the two visible hemispheres (white and blue) is used to determine brix. If this line is a clean, stark contrast between the two colours, then there is usually a deficiency of calcium and silicon in the plant. It is actually an indication of poor mineralisation in general, but calcium and silicon are key players in the delivery of minerals into the plant. Calcium and silicon are also the two minerals involved in cell strength and if they are deficient the plant will always be less resistant to fungal diseases.

Digital Diagnosis

While the refractometer refracts light through dissolved solids in the plant sap and the image is captured when looking through the lens, the other tools deliver a digital reading. The Nitrate Meter, produced by Japanese company, Horiba, accurately measures the presence of nitrate nitrogen in the plant sap. If our hypothesis is to stand up we would need to see higher nitrate levels in diseased crops.

Measurements from the Sap pH Meter are analysed in accordance with the findings of brilliant American researcher, Bruce Tainio. Bruce determined that a healthy, disease-resistant plant has a sap pH of 6.4. If the plant was lower than 6.4, it was more susceptible to fungal diseases – this was usually linked to a deficiency of one of the alkalising minerals. The Conductivity Meter measures the presence or lack of ions within the plant. High conductivity is most commonly linked to an excess of nitrate nitrogen. So, you understand the rules, now let’s look at the results.

The Tale the Meters Told

Good Ginger Brix: 2.5° (with blurry line)
Sap pH: 6
Nitrates: 640 ppm
Conductivity: 4.6 mS/cm

Pythium Ginger Brix: 2° (with clear line)
Sap pH: 5.7
Nitrates: 850 ppm
Conductivity: 5.7 mS/cm

As you can see, the hypothesis stood strong. The nitrates were significantly higher in the diseased plants and the consequences of the excess were also apparent. i.e. The low brix levels reflect a lack of calcium and silica, while the low sap pH reflects the likely calcium deficit. The nitrates were 30% higher in the diseased plant and the higher conductivity also reflected the excess. I was so confident of the findings that I offered odds on the outcome before we started using the meters. Luckily, the grower didn’t take my generous odds and so avoided any further losses.

The Recovery Strategy

In my opinion, there is no need to buy new land, as this problem is eminently solvable. It requires a four-pronged strategy.

  1. Nitrogen needs to be monitored more closely and the current nitrate emphasis should be dropped. It would be preferable to use urea with humic acid rather than the current nitrate-based input.

  2. Calcium and silica should be used as foliars throughout the season. These are the cell-strengtheners that can turn the cell wall into an impenetrable barrier to ward off fungal invaders. It is now understood that silica also triggers the plant's defence system, so you get two-for-one with this input.

  3. Beneficial microbial inoculums should be introduced for the myriad of benefits they provide. Trichoderma are well researched in relation to the many benefits they provide and they can be brewed to dramatically increase the players in the numbers game, without breaking the bank. The grower invested $1000 and purchased his own microbe brewing kit.

  4. The new microbe workforce that is to be introduced should be sent off to work with a lunchbox. There is tremendous benefit in including recognised biostimulants with inoculums, as it will increase the colonisation rate. The proven biostimulants that are applicable here are humic acid, kelp and amino acids. There will be a double whammy if the amino acids are combined with soluble silica, as new research reveals a powerful synergistic effect, which multiplies the protective effect of silica.

The Grower’s Game Plan

1) The 50 cubic metres of chicken manure should be applied in conjunction with Nutri-life 4/20™. This product can be brewed with a bacterial or fungal dominance with the addition of an NTS product called Dominate-B™, or Dominate-F™. In this case, the fungal version would be best, as it features cellulose-digesting organisms that will compost the manure in the paddock and thereby complex the nitrogen to reduce the nitrate conversion. 50 cubic meters of food is one hell of a lunchbox!

2) The planting blend should be combined with NTS Soluble Humate Granules™ at 5% (15 kg per hectare) to complex the nitrogen involved and slow its conversion to nitrates. This concentrate is equivalent to about 90 litres of liquid humic acid, so it will provide major activation to beneficial organisms around the roots.

3) Ideally, it would be a good strategy to treat the seed with Trichoderma before planting but it is usually soaked in fungicide that will knock them around. It is better to fertigate Trichoderma a few days after planting. Always include the lunchbox. In this case, Tri-Kelp™ and humic acid would serve as productive tucker for the new workforce.

4) There should be a strong silica emphasis throughout the season. Dia-Life™ could be fertigated regularly, while Photo-Finish™ could be foliar sprayed, if that is an option. Amino-Tech™ should be combined with Photo-Finish™ to increase the silica efficiency.

5) Leaf analysis should be conducted regularly to improve nutrition precision. Ideally, an NTS Agronomist could visit and monitor the crop with field instruments every month.

6) Calcium should be applied in foliar form. The cheapest option is calcium nitrate chelated with fulvic acid. Don’t worry about the small amount of nitrates involved, as we are only talking about 10 kg of calcium nitrate per hectare with 300 grams of NTS Fulvic Acid Powder™. Boron should always be combined with the calcium as Solubor at 500 grams per hectare. Boron is a calcium synergist and it also helps to solubilise silica.

7) Triple Ten™ and Shuttle Seven™ should be used very 2 weeks during the season and any trace mineral deficiencies, determined with leaf analysis, should be addressed with chelated inputs.

8) Finally, there should ideally be a saturation program with beneficial microbes. 100 litres per hectare of fungi-dominated Nutri-life 4/20™ should be brewed and applied every two weeks through the irrigation. This costs less than $30 per hectare and can offer multiple benefits.

In Conclusion

This Pythium plague is a precursor to increasing problems linked to changes in climate. Adaptability is the key word in this changing landscape. As this unfolds there will be less and less place for predetermined, timetable-based fertiliser applications, which can generate disease-sponsoring imbalances. We must now work with Nature rather than against her, as there will be fewer margins for error in the future. Nature likes a living, mineral rich soil that is self-protective. A fungal disease does not reflect a deficiency of fungicide, it reflects how you have nurtured your soil and plants. Key minerals, microbes and biostimulants are the answer!

Disclaimer: Prices noted are estimates only and in AUD.

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