Graeme's Q & A – Sharing the Solutions

I regularly receive email queries and I do my best to personally respond to every question. It occurred to me that some of these responses may be of interest to others, so this week’s blog will feature a few of those detailed responses. I have not included the names of the growers involved due to privacy reasons.

Hi Graeme,

I am always interested in your blog articles, they are very interesting and always make me think about our system and how we can improve it by moving away from chemicals and inorganic fertilisers. I have a continuous cropping farm near Clare in SA where we predominantly grow bread wheat, durum wheat and lentils. In relation to your last 2 blogs, I was wondering if you would mind commenting on the following points:

Question 1

Monopotassium Phosphate (MKP) – I found your comments on this very interesting. I find that our potassium levels in the wheat crops fall prior to flowering and I feel this is having a detrimental effect on our seed weight and therefore our test weight. To me seed weight is very important, as the plant will set the seed number, but the weight of each seed can have a large influence on final yield. I believe this is an area that has been overlooked in the past. I believe that the potassium uptake is low at this stage of the crop development as, in recent years, our soil water levels at this time in the season have been low and potassium moves via the soil water. I always wonder if, in the higher rainfall areas of south east SA, they get better test weights because it is generally wetter during grain fill and therefore the plant can extract more K.

In relation to MKP, what rate would you be applying prior to flowering in wheat crops? Would an application of MKP on lentils prior to flowering also be beneficial?

Graeme's Response

The Potential for Foliar Potassium to Boost Grain Yield – When monitoring with a potassium meter, it can be quite amazing to witness the dramatic potassium drawdown from flowering onwards. I have seen leaf levels drop by 50%, as soon as the plant moves into reproductive mode. There can be some really good gains in applying some foliar potassium at this time. Potassium is the second most prevalent mineral within the plant. It is most required during the reproductive period, where it increases the translocation and utilisation of the plant sugars required to increase the size and weight of grains and fruit. The question would be, "which potassium input would be most effective?"

MKP should be diluted at 2 – 3 kg to 50 – 100 litres of water, which means it can be difficult to get much on in broadacre situations. You should always include 120 grams of NTS Fulvic Acid Powder™ with the MKP to increase the uptake and buffer the burning potential. The other option is to foliar spray potassium sulfate (with fulvic acid). This may be a more productive option because you can apply more potassium, and the sulfur should prove a helpful protein-builder. Typically, you would apply around 3 – 5 kg per hectare of potassium sulfate dissolved in a minimum of 100 litres of water. 120 grams of NTS Fulvic Acid Powder™ will chelate the potassium and increase the uptake by as much as 30%. This increased performance relates to a phenomenon called cell sensitisation, where the permeability of the cell membrane increases to sponsor this improved nutrient uptake. Your lentils would also benefit from either potassium option.

Question 2

Interplanting Cereal Crops with Legumes – I also found your comments interesting in relation to this. Utilising our disc seeder, we are able to sow wheat on 12 inch spacings and, in between these rows, sow something else. We usually sow our wheat on 6-inch row spacings. I think it would be interesting to intersow legumes, but I am concerned about the amount of light they may receive between the wheat rows and therefore they may not do so well. I am also concerned that we spray a broadleaf spray usually around 6 weeks post-emergence and obviously this will kill any interplanted legumes. I’m not sure that we can do away with this broadleaf spray. What are your thoughts on these aspects of interplanting? What species would you recommend to interplant in wheat? We might give it a go this coming season.

Thank you for your time in advance.

Graeme's Response:

Interplanting with Clover – I think it would be great to interplant with a blend of these legumes. The mineral benefits here are three-way. The clovers provide some nitrogen to the cash crop. However, more importantly, these legumes release acid exudates from their roots, which sever the bond between calcium and phosphate. These two minerals are magnetically drawn to each other and form an insoluble compound (the phenomenon of "locked up phosphate'). Biological acids can break this bond and render both minerals available in soil solution for the benefit of the cash crop. Calcium and phosphate are the two of the most important minerals for photosynthesis, the single most important process in crop production.

The shade may be a bit of a problem, but there will still be considerable benefits. I would consider a mix of crimson, red, yellow and white clover, but the majority of the seed should be red clover. Part of the aim here is to out-compete weeds with the clover, so it would be a shame to see the clover killed at six weeks. I guess you know your situation, so it will be your call. I wish you every success.

Hi Graeme,

Thanks for your weekly articles. I really look forward to them. I print them off and collect them in a folder for later reference.

I have a question about the efficacy of foliar sprays on fruit trees with a glossy or waxy surface. I grow avocados in Northern NSW. Recently I attended a talk where a well-known avocado consultant suggested that it was a waste of time foliar spraying this crop, as the nutrients are so poorly absorbed. What are your feelings about this advice?

Thanks for your help.

Graeme’s Response

This is a common misunderstanding in your industry and I suspect it relates back to some trial work from several years ago, involving the Queensland DPI. In that study, they sprayed calcium nitrate on avocados to determine if this technique would help satisfy calcium requirements for avocado crops grown in calcium deficient soils. They concluded that the foliar nutrition was poorly uptaken and hence, foliar nutrition was not recommended for avocados.

In my opinion, there were three key oversights in this study, including: the lack of a sticker/spreader to compensate for the waxy surface of this leaf; the need for a tool to increase nutrient uptake; and a faulty assumption that requirements of a major nutrient can be addressed through the leaf. I will discuss each of these separately.

  1. It is essential to stick and spread foliar nutrition on orchard crops – a good sticker and penetrant will overcome the resistance of a shiny leaf surface. I can’t help but mention our Cloak™ Spray Oil in this context. We offer a money-back guarantee that this spray oil will outperform any similar input, and we have never needed to refund a single grower in 55 countries. Cloak™ contains a super-penetrating omega-3 fish oil and organic, cold-pressed canola oil, but the secret to this input is the emulsification. We spent many months of research to develop a superior emulsifier that can be visibly witnessed with something called the "bloom effect". Here, you drop a teaspoon of spray oil into a glass bowl full of water. There is a quite spectacular effect underwater that looks like an exploding atomic bomb. The aim is that, when this bloom has completed, there should be absolutely zero signs of oil droplets on the surface. The water should be milky white with no visible oil droplets. Obviously, this means that the spray oil will perform at its best. It will deliver minerals more efficiently, while also creating a rainfast effect and improving target penetration.

  2. The uptake enhancer that works exceptionally well on this crop is fulvic acid. This natural substance has been shown to create ‘cell sensitisation’, a phenomenon where the cell membrane becomes more permeable and allows about one third more of the foliar ingredient to enter the leaf. This is a huge benefit for all crops but it is an essential additive with more difficult leaf surfaces, like that of the avocado tree.

  3. The trial, which was eventually used to question the efficacy of foliar fertilising avocados, involved calcium. This is one of the most abundant nutrients in the plant and the majority of this mineral should be sourced from the soil. Foliar nutrition is about supplying the triggering power of trace minerals or for topping up major minerals. However, calcium is an immobile mineral and there can be a sluggish delivery into the fruit, where it has a major impact on crop quality. The foliar application of chelated calcium can actually deliver calcium directly into the fruit to significantly improve quality. In the original trial the calcium was not even chelated. They just used calcium nitrate and measured leaf levels rather than fruit levels to determine uptake.

I hope some of you have found this information useful. If you have a question, please feel free to email me and I will do my best (within my crazy schedule) to provide a helpful response.

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