By Erica Faber – Technical Manager
Optimum plant growth, performance and production, depends on the balance, combination and concentration of mineral nutrients available in the soil. Plants often face significant challenges in obtaining an adequate supply of these nutrients to meet the demands of general metabolism, growth and production due to the many soil nutrient constraints I will explain in the following. If your soil and leaf analysis is not reflecting adequate, balanced levels of all the nutrients, it means that plant health, production and profits will be affected.
For a fertiliser programme to be successful it needs to be cost effective, able to keep up with the crop demand and be flexible in order to overcome soil and root constraints or plant nutrient deficiencies. Regular leaf sampling is an important management tool enabling us as growers to be more aware of the nutrient status of our crop and giving us an opportunity to address any problems before they have an effect on tree performance, production and our pockets!
IMPORTANCE AND BENEFITS OF SOIL AND LEAF ANALYSIS
- Allows us to monitor the pH of the soil and the nutritional status of the soil and crop.
- Enables us to adjust our fertiliser programs and address any nutritional deficiencies, excesses and imbalances before they adversely affect production.
- Allows us to meet the crops nutritional requirements at critical phenological times in order to support optimal tree performance and maximise yield.
- Gives us an opportunity to determine and address soil nutrient constraints to ensure a balanced supply of essential nutrients for optimum yields.
- Enables us to evaluate the effectiveness of our fertilizer programs. Has our fertilizer program yielded results physically? Can we see a difference in tree health, performance and yield? Is the leaf analysis showing improvements? If not, we need to evaluate why, reassess our program and make the necessary adjustments for an improved outcome for next season. If you are not seeing results or positive changes, your program is not effective and both time and money have been wasted not to mention the lost production potential and income.
- Always remember … input dollars should be spent where there is the greatest chance for the largest return on investments.
- If done properly, tissue and soil analysis will lead to more efficient and economical use of fertilisers. Excessive or inefficient applications, that drives costs up and profits down, can be avoided.
- Plants may not show any visible symptoms, but the nutrient content maybe insufficient enough to reduce the yields. Leaf analysis alerts us to this. If the deficiency can already be observed on the tree, the crop has already lost some potential yield.
- Leaf nutrient concentrations are the most accurate indicator of crop status AND there is often not a strong relationship between the nutrient levels in the soil and in the plant tissue. It highlights all the factors that might influence, limit or restrict nutrient availability and uptake, as well as nutrient antagonisms that may be occurring. This is the reason why our soil and leaf results don’t correlate.
- Allows us to make quick, in-season corrections to nutrient deficiencies through foliar applications of specific deficient nutrients.
- It highlights the nutrient retention capacity of the soil and whether we need to improve this to improve the effectiveness of our fertiliser applications?
- Enables the correction of problems BEFORE establishing an orchard. Trying to do corrections after planting is far costlier and time consuming and also affects overall tree establishment, performance and initial yield.
In order for analytical results to be meaningful, sampling guidelines should be followed. The information is meaningless if the sample has not been taken correctly. One of the basic principle of sampling is to return to the same sampling trees or sites from year-to-year. These trees or sites must be representative of the entire orchard or major portion of the block based on tree observation, past experience, crop yield, soil type etc.
Using sampling trees or sites eliminates year on year variability and results in more accurate analysis. This then gives us more clarity on the effectiveness of our fertiliser programs and the nutritional status of the soil and crop and what adjustments need to be made.
IDENTIFYING YOUR SOIL NUTRIENT CONSTRAINTS