Tissue testing is one of the most valuable tools for proactive crop management and yet many growers ignore or under utilise this technology.
A simple leaf test before flowering can make a huge difference to profitability.
Here are 10 reasons why every grower should leaf test on a regular basis.
1 To identify soil-based lock-ups
Even if you have provided all of the relevant minerals and boosted the biology that delivers these minerals, it is still likely that excesses will influence mineral delivery to the plant.
Many minerals are antagonistic to others if they are over supplied. Calcium for example, directly limits the delivery of seven minerals if it is under supplied, as it stimulates the uptake of these minerals.
However, if it is over supplied via too much lime in a soil lacking the storage capacity for that amount of added calcium, then those same seven minerals are also shut down. This phenomenon is often called “The Goldilocks Effect” because it’s all about supplying just the right amount of this important nutrient.
Leaf tests provide an insight into these mineral dynamics and offer the opportunity to develop a strategy to counter these effects, usually through direct supply of relevant minerals into the plant using foliar fertilising.
2 To ensure everything is right at the business end of the season
Things change when the plant enters the reproductive mode.
There is a dramatic increase in the need for sugar production (and delivery) to fuel the formation of seed or fruit and this requires chlorophyll management.
It is the chlorophyll-based sugar factories that determine the production of this extra glucose and the efficiency of these sugar factories is determined by the minerals that govern chlorophyll density.
We need to test for the presence of the minerals that can create the undesirable stripes, blotches and pale colours at this critical time so we can deliver the missing minerals and reclaim chlorophyll density.
This is the part of the season where profitability is determined and it is a brave or foolhardy soul who enters the business end of the season driving blind.
It amazes me that any business person could rely on guess work at this crucial time. However, I acknowledge that there are the more enlightened amongst us who understand the requirements of their plants at any given time through a combination of observation, experience and intuition. The rest of us need leaf tests before flowering, for every crop, so we are not driving blind!
3 To determine the need for liming in your soil
The Albrecht-based, cation balancing philosophy has been oversold in relation to its relevance in every soil type.
It is claimed that all soils require a base saturation of 68% calcium and in some cases this is simply not true. Some soils give up their calcium more easily than others and if your soil is one of these, then you may be wasting large sums of money on liming.
Leaf tests tell you how much calcium your plant is accessing. If the leaf test shortages mirror the soil test shortages then it is time to lime.
There is another strategy which can help you decide about the merits of any dry mineral application. Micronised Mineral Suspensions (MMS products) can be used to evaluate the field response of any dry mineral fertiliser.
We often hear the comment “I didn’t get as much benefit as I hoped from that liming”. While it is much more common to hear positive responses to liming, it is becoming increasingly unacceptable that some growers are investing in calcium and not seeing the anticipated returns on their investment.
Don’t gamble
Here’s what you can do to take the gamble out of this type of fertilising.
If you are contemplating liming for example, then apply 20 litres of Lime-Life™ to a single hectare along with a kilo of Solubor to ensure that there is enough boron for a good calcium response.
The 20 litres of Lime-Life will give a rapid response if you need calcium and then you will know that it is worth liming the rest of the farm.
Always remember that “Calcium is the trucker of all minerals and boron is the steering wheel”.
During my recent seminar tour of New Zealand it was common to see incredibly boron deficient farms where dairy farmers complained about their lack of response from liming. There is no point in addressing your calcium shortage in soils that contain just 0.2 ppm of boron unless you are also going to address the boron deficiency.
4 To avoid over supply of nitrogen
When a fertiliser gives a big response it is human nature to apply a little more to test the boundaries of the benefit.
This is often unkindly called the moron approach but it is a major problem in horticulture, particularly in relation to nitrogen.
It is more common to see nitrogen ‘over done’ than any other mineral because it is a mineral required in large amounts for healthy plant growth and consequently it can give a big response if it is lacking.
The secret is to know when enough is enough and this is when leaf analysis is essential.
This might involve conventional leaf testing or D.I.Y. sap analysis using a Horiba Nitrate Meter. Either way, the guiding maxim should always be “How low can I go?”.
There are two key benefits in adopting this minimalist strategy. The cost of nitrogen is destined to rise and rise, in line with oil, so only applying what is needed, and no more, has obvious economic appeal.
Secondly, high nitrate levels in the plant reflect more than wasted nitrogen. They point to a plant that has become a calling card for insect attack due to the nutrient dilution factor associated with nitrate nitrogen.
A chief role of insects in the great scheme of things is garbage disposal. They are able to tune in to infra-red radiation from plants. A healthy, minerally balanced plant emits a steady flow of infra-red while a nitrate-packed plant sends out a staccato stream of infra- red radiation. The insect responds, as it is programmed to do, and attacks the ‘sick’ plant.
When nitrates enter the plant they are always carried in by water. If nitrates are over supplied then we have a watery plant where other nutrients have been diluted. Modern agriculture need not be at constant war with nature. It’s just that we keep on firing the first shot!
Regular leaf tests ensure that we don’t shoot ourselves in the foot through over doing nitrogen.
5 To monitor levels of ‘the big four’
Continued next issue
Contact Nutri-Tech Solutions phone 07 5472 9900
See this article in Tree Fruit December 2013
