Beating the Chloroplast Count

graeme -

Biological farming is about sustainability, profitability and new-found enthusiasm, and it is based on working with nature rather than against her. The proactive bio-farmer drives the crop cycle with a confidence based on knowledge and understanding. The master of the growing craft appreciates the holistic essence of crop management. Often complex interrelationships can be better understood within a framework. Key concepts should be identified to develop an umbrella perspective. The key concepts in high-yielding agriculture are not calcium, humus management or soil balance, as we might suspect. The single most important determinants of yield are in fact **chlorophyll **and photosynthesis. These two features of plant biology are only ever given token coverage in crop management discussions, but good management of chlorophyll and photosynthesis will have more impact on your profitability than any other management approach.

THE MIRACLE SUGAR FACTORY

Chlorophyll is much more than the green material in the leaf. It is the bio-lab where sunlight, water and carbon dioxide are combined to produce a simple sugar called glucose. This sugar is the fuel for every plant process and also forms the basis of the plant compounds we are striving to produce. 95% of the weight of a crop is determined by photosynthesis, while just 5% involves soil minerals, i.e. if we were to burn 100 kg of plant material, the ash that remained would weigh just 5 kg and this residue would consist of potassium, calcium, phosphorus and other soil minerals.

The chemistry of glucose (C6H12O6) involves the key trio in all organic compounds – carbon, hydrogen and oxygen. Glucose, a simple six-carbon sugar, is the basis of starch, cellulose, oil, lignin, wax and protein. All of these valued compounds, with the exception of protein, contain varying amounts of carbon, hydrogen and oxygen, based on the glucose from which they are derived. Protein differs in that it also contains up to 16% nitrogen and a sulphur component along with the CHO trio. The major difference between these compounds is that they all contain more carbon than their glucose building blocks. For example, it takes numerous six-carbon glucose molecules to create a single molecule of high-carbon oil or cellulose.

THE LINK BETWEEN SOIL LIFE AND PHOTOSYNTHESIS

The carbon involved in all of these compounds, of course, comes from carbon dioxide (CO2), and a tremendous amount of CO2 is required to produce a good yield. It is important to understand that the atmosphere doesn’t contain sufficient CO2 to satisfy yield requirements. Supplementary CO2 must come from the soil. Plant roots metabolise oxygen during energy intensive processes like nutrient uptake, growth and respiration, and they release CO2 as a by-product. This CO2 diffuses out of the soil and is absorbed into the plant via the stomata on the underside of the leaf (see diagram). However, even this additional supply of CO2 is not enough here to ensure sufficient sugar production for maximum yields. The critically essential link here is biological. Aerobic micro-organisms also release CO2 as a by-product of oxygen metabolism, and it is this CO2 supply that can make the difference between ordinary and exceptional yields. This is undeniable testimony to the relevance of the biological farming approach in conventional agriculture. It is simply good business sense to adopt management practices that convert the below-ground environment into a carbon dioxide generator.

THE BIOLOGICAL SUPPLEMENTATION OF CO2

The more vigorous the root structure and the larger the number and diversity of aerobic micro-organisms living in and around those roots, the higher the production of CO2 for photosynthesis.

MANAGING CHLOROPHYLL

The key to managing photosynthesis is to maintain luxury levels of chlorophyll at all times. Photosynthesis takes place within individual chlorophyll units called chloroplasts. A loss of chloroplasts causes plants to become chlorotic (yellow). The more chloroplasts we can maintain in the plant, the higher the sugar production and the higher the yield potential. The chemistry of a molecule of chlorophyll is revealing.

A magnesium atom lies in the centre of the molecule, surrounded by four atoms of nitrogen plus the inevitable CHO (carbon, hydrogen and oxygen).

A chloroplast is nitrogen intensive and completely dependent upon magnesium, ie if the plant is not taking up luxury levels of magnesium into the leaf, then there will be some degree of chlorophyll deficiency. While the chemistry is remarkably simple, there is of course more to chlorophyll management than simply supplying enough magnesium and nitrogen. Sulphur is often tied to nitrogen performance, and a sulphur shortage will reduce the number of chloroplasts. The trace elements zinc, manganese and iron all play a role in the correct functioning of chloroplasts, and a shortage of any of these will create a corresponding drop in the number of chloroplasts.

Most growers are familiar with the chlorotic patterns associated with trace element deficiencies or the insipid pale of a crop running out of nitrogen puff, but the role of calcium in the supply of these chlorophyll builders to the leaf is often ignored. Calcium is the ‘trucker of all minerals’, and the presence of soluble calcium in the root-zone ensures the realisation of this transport potential.

THE PHOSPHATE FINANCIER

The point to understand, when considering crop production in terms of chlorophyll management, is that any chlorosis – any loss of green for any reason – will result in less production of glucose and lower yields. This is why we are so insistent upon the value of leaf analyses during the crop cycle to ensure that the ‘chlorophyll builders’, and their subcontractors, are always at optimum levels in the leaf. For example, we always insist on maintaining luxury levels of ‘The Big Four’ in the leaf. ‘The Big Four’ – calcium, phosphorus, magnesium and boron – are needed at good levels throughout the season. Why is this? Well, as explained, calcium is an important subcontractor ensuring the delivery of the builders to their chloroplast workplace. Boron is a calcium synergist – the steering wheel behind the trucker. Magnesium, as the cornerstone molecule in the chloroplast, may be the centrepiece for the sugar factory, but what about phosphorus? The fact is that phosphorus is the banker that funds the entire building project. The injection of funds in this context relates to a series of phosphate-based compounds, which provide the energy needed for every plant process. The most important of these compounds is adenosine-triphosphate (ATP), but there are no fewer than six phosphate compounds involved in the initial creation of glucose. You can supply all of the nitrogen, magnesium, sulphur and trace elements in the world, and the calcium to ensure their supply, but without phosphorus there is no sugar production and there is no conversion of simple sugars into the compounds like proteins, oils and starch, which provide the basis of the farmer’s income.

THE ‘STARTER’ PRIORITIES

If the management of photosynthesis is seen as a central goal in crop production, it is important to understand the relationship between the above-ground and below-ground portions of the plant. The plant roots and the micro-organisms, which live on or around them in the root-zone (or rhizosphere), are completely dependent on the above-ground plant to supply the sugar for their energy needs. There is no root growth without sugar, and there is no sugar production without the necessary minerals provided by the roots and nutrient-solubilising micro-organisms. In recognition of this synergy, the above ground plant translocates 60% of its total glucose production to the roots, and the roots release 50% of this sugar shipment into the surrounding soil to feed the root-zone microbes.

The mineral management priority involves the supply of the right starter nutrients to ensure the initial supply to the leaves of the minerals needed to build chlorophyll and produce sugar. Nitrogen and magnesium are essentials, as they are the core elements in each chloroplast. These major elements should be present in a planting blend or pre-plant mix if a soil test confirms their requirement. The trace elements, which are required in much smaller amounts initially, can be covered by a seed treatment or liquid injection at planting. Phosphate is the absolute priority at planting, because there is no sugar production and no associated early root growth without this element.

THE NTS PHOTOSYNTHESIS STARTER PLAN

At NTS we begin with a soil test. The Soil TherapyTM service can be an invaluable learning tool and programming guideline. If the soil test reveals a phosphate deficit, we will normally address the shortage with a combination of soluble and slow-release phosphate. Nutri-Phos Soft Rock™ is the slow-release option. This organically certified, natural phosphate becomes available far more rapidly than reactive rock phosphate (hard rock phosphate), but it releases the phosphate load over the entire cropping period. The soluble phosphate component is addressed with a multi-faceted game plan, because we are always aware of the supreme importance of this element. In both organic and conventional situations, we will suggest the use of Phos-LifeTM – a Micronised Mineral Suspension (MMS)TM, which supplies 10% organically buffered, plant-available phosphate and almost 30% soluble calcium in liquid form. Phos-LifeTM is boom-sprayed (broadacre) or fertigated (horticulture) immediately before planting.

Seed treatment or liquid injection will always involve a highly successful and inexpensive approach, which involves a combination of small amounts of four products, two of which are phosphate-based. The program includes the relevant crop-specific Triple Ten™ product, which contains 10% phosphorus in a pH-neutral, biologically balanced form. It also includes Nutri-Life Bio-P™, a microbial inoculum which is a proven phosphate solubiliser that can gradually solubilise the bank of ‘tied up’ phosphate found in most farmed soils. Nutri-Life Bio-P will also enhance the release of natural phosphate inputs like Nutri-Phos Soft Rock™.

Planting blends, using granular fertilisers, should always include some form of soluble phosphate, regardless of phosphate levels in the soil test, i.e. soil test data does not always guarantee the solubility of the soil phosphate measured, and we must have some soluble phosphate at germination to kick-start the photosynthesis process.

In conventional situations, we favour planting blends including either MAP or DAP, depending on the soil pH. The Americans favour MAP in all situations, but we have found that, if these materials are suitably complexed, then either input is valuable. Complexing the acid-treated phosphates is the key to stability. NTS Soluble Humate Granules™, a unique humic acid product in a 2-5 ml soluble granule, have revolutionised the use of MAP and DAP. Both MAP and DAP are notoriously unstable and liable to ‘lock-up’ and become insoluble anytime between six to sixty days after application. When these materials are combined with 5% soluble humic acid granules (5 kg per 100 kg of MAP or DAP), the phosphate is complexed by the humic acid as the respective granules dissolve together. The phosphate then becomes a phosphate humate, which prevents the phosphate from forming insoluble compounds with calcium in alkaline soils or iron and aluminium in acidic soils.

In organic situations, we suggest the use of NTS Guano Granules™, which contain 15% phosphate (a third of which is citrate-soluble). Like MAP, these granules can also be combined with NTS Soluble Humate Granules™ (now BFA certified) to improve phosphate performance.

If a soil test reveals a serious zinc deficiency, we may have to introduce our Micronised Mineral Suspension (MMS)TM – Zinc-LifeTM, which contains 65% zinc in a bio-available form. Zinc is particularly important from a photosynthesis perspective, because it plays a double role. Zinc is one of the important chlorophyll builders, but it also governs the production of the auxin growth promotant, which determines the size of the leaf. Leaf size magnifies the potential for effective photosynthesis, as the leaf is essentially a solar panel collecting sunlight, water and carbon dioxide to produce glucose in the chloroplasts. This is why zinc can provide a more pronounced response than any other trace element, if it is deficient.

CHLOROPHYLL MANAGEMENT IN PRACTICE – AN EXAMPLE

Essentially, yield building is about capturing and converting more sunlight and carbon dioxide into sugar. A lack of sugar can limit yield dramatically. Terminal dominance, for example, is a function of sugar rationing. Terminal dominance is about the top bud having more importance than the buds below. When a plant senses a chlorophyll shortage, it will favour the top bud.

The importance of maintaining maximum chloroplast counts cannot be overemphasised. Many plant species make decisions about the amount of seed or fruit they will attempt to produce early in the crop cycle. Reproduction is the plant’s sole purpose in life, and all decisions are based on seed viability in prevailing conditions. The corn plant is a perfect example of this phenomenon. At five weeks after spiking, the corn plant conducts a chlorophyll inventory. At this precise point, the number of chloroplasts present will determine the exact number of kernel rows that the plant will produce. The number of rows will always be even, so an increase of two rows can significantly increase yields. Nine weeks after spiking (emergence), the corn plant performs another chloroplast count. This time, the number of cobs per plant will be decided along with the length of those cobs. The plant is essentially making a reproductive decision based on the likelihood of good sugar supply, which is critical for fruit and seed development.

If we can ensure maximum chloroplast counts immediately, prior to week five or week nine, then we have every possibility of achieving excellent yields. A soil test or a timely leaf analysis will determine the exact composition of an appropriate foliar spray, but often (especially in broadacre situations) it will be nitrogen that will be most deficient (particularly in a nitrogen-hungry plant like corn).

Here it is important to understand the valuable role of foliar-applied urea to address this shortage. Many growers have yet to appreciate what can be achieved with foliar urea, particularly when it is buffered and magnified with humic acid (NTS Liquid Humus™). Urea supplies nitrogen in the amine form, which can be converted to amino acids and plant protein with a minimum of energy (glucose expenditure) when applied to the leaf. Traditional nitrogen management involves large nitrogen applications at pre-plant or planting. At the time when this nitrogen should be present in the reproductive-boosting ammonium form, it has converted to the undesirable, growth-producing nitrate form. Nitrate nitrogen requires heavy energy expenditure to convert it to amines and then to amino acids and protein. In fact, 10% of the entire glucose production of the plant is required to fuel the enzymatic reaction involved in this conversion. This is not only a total waste of precious sugar but, as nitrates accumulate in the leaf awaiting conversion to a useable form, they pose a serious health threat to animals and humans. Excess nitrates reduce the oxygen component in blood, contributing to a wide range of problems and they are also recognised carcinogens. Nitrate-packed plants also emit an infra-red calling signal to the insect clean-up squad. By contrast, urea as a foliar, virtually provides a direct injection of amines for easy protein conversion and a rapid chlorophyll response. Note: This is not the case with soil-applied urea, which is notoriously unstable and supplies most nitrogen in nitrate form (unless stabilised with humic acid).

In the case of the corn plant, nitrogen is often the key contributor to chlorosis. The game plan is to provide nitrogen and everything else that will ensure the maximum number of chloroplasts before the yield-determining chlorophyll audit. At four and a half weeks, nitrogen, humic acid and a blanket-coverage, total nutrient foliar can be applied to boost chlorophyll, to beat the chloroplast count and set the stage for good results. If we repeat this exercise again at eight and a half weeks, before the second audit, our rich-green chlorophyll complement would convince the plant to push for two ears of maximum length instead of a single ear (terminal dominance does not occur in the presence of adequate sugar). A likely spray program for conventional growers is as follows:

In 100 litres of water, blend:

  1. 20 kg of urea (only possible if buffered with humic acid).
  2. 1 litre of NTS Liquid Humus™ (humic acid).
  3. 2 litres of Corn-Tech Triple Ten™ (a broad-spectrum mineral and hormonal stimulant)
  4. 400 mL of CLOAK Spray Oil™.

An equivalent program for organic growers is as follows:

In 100 litres of water, blend:

  1. 3 litres of Nutri-Tech Black Gold™ (organic).
  2. 200 ml of Nutri-Life Bio-Plex™ (nitrogen-fixing bacteria which live and work on the leaf surface)
  3. 400 ml of CLOAK Spray Oil™.

Note: Organic growers would also benefit from a boom-sprayed side-dress of nitrogen-fixing bacteria (Nutri-Life Bio-N™) and molasses, applied to the soil at four weeks and again at eight weeks.