ORCHARD MANAGEMENT: AVOCADO SOIL AND LEAF ANALYSIS – DIGGING DEEPER

Has your avocado fertiliser programme yielded physical results? Can you see a difference in tree health, performance and yield?  Is the leaf analysis showing improvements? If your answer to these questions is “No” then you need to evaluate why, reassess your programme, and make the necessary adjustments for an improved outcome for next season. If done properly, soil and leaf analysis will lead to more efficient and economical use of fertilisers and excessive or inefficient applications, that drive costs up and profits down, can be avoided.

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.

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.

Taking the time to dig deeper into your soil and leaf test results will allow you to…

  • Evaluate the effectiveness of your fertiliser programmes.
  • Monitor the pH of the soil and the nutritional status of the soil and crop.
  • Adjust your fertiliser programmes and address any nutritional deficiencies, excesses and imbalances before they adversely affect production.
  • Meet the crop’s nutritional requirements at critical phenological times in order to support optimal tree performance and maximise yield.
  • Determine and address soil nutrient constraints to ensure a balanced supply of essential nutrients for optimum yields.
  • Make quick, in-season corrections to nutrient deficiencies through foliar applications of specific deficient nutrients.
  • Evaluate the nutrient retention capacity of the soil and whether you need to improve this to improve the effectiveness of your fertiliser applications.
  • Correct 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.

Sampling accuracy
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 principles 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. This must be 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 you more clarity on the effectiveness of your fertiliser programmes and the nutritional status of the soil and crop and what adjustments need to be made.

Soil and leaf result correlation
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.

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.

The leaf test highlights all the factors that might influence, limit or restrict nutrient availability and uptake, as well as nutrient antagonisms that may be occurring.

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!

Decoding Soil and leaf test results and having a better understanding of soil nutrient constraints, crop nutrient status and adjusting fertiliser programmes accordingly, will not only improve tree performance and production but also improve profitability by avoiding fertiliser applications that are ineffective.

Always remember; input dollars should be spent where there is the greatest chance for the largest return on investments.

If you need assistance with understanding what your soil and leaf tests results are telling you please contact the Just Avocados Grower services team info@justavocados.co.nz.

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