Orbiba Robotics

07 Mayıs 2023 21:01

Plant Analysis Methods

Plant analysis is done in addition to soil analysis to help determine the nutrient supply capacity of soils.

It is a guide to determine the availability of plant nutrients and the nutrient uptake capacity of plants and to examine the relationships between nutrient status and plant performance. Samples of the analyzes to be made should be taken according to the procedures.

Leaf Analysis

Leaf analysis is of great importance for farmers. Leaf analysis gives producers a lot of unknown information about the plant. A few of them are as follows; Determining which nutrient deficiencies occur in plants and related to nutritional deficiency or excess, and making necessary applications to eliminate this deficiency,

To determine the fertilizer requirement of the plant based on the analysis results before nutrient deficiencies occur.

It is checked whether the given nutrients are taken by the plants.

Sometimes a plant in the soil may not take the nutrients into the plant. The reason for this is; Which element is not taken, the presence of some ions that cause the deficiency of that element causes a deficiency in the plant.

By making these analyzes, it prevents timely fertilization, getting enough information about the deficiencies and excess nutrients in the plant, and applying extra fertilizer, thus reducing its costs.

Rules to be Considered While Taking Leaf Samples

First of all, the species and variety characteristics of the leaf samples taken should be the same. Mixed samples should not be taken. Especially fruit trees can be found in gardens at different ages. For example, leaves of 5-25 year old trees should not be mixed. However, the leaves of those aged 15-20-30 years can be mixed. Diseased leaves showing extreme nutritional deficiency should be selected and this should be stated in the garden information sheet. There is no need to separate leaves that are extremely nutrient deficient in the entire garden. One part of the garden may be completely different from the other part in terms of soil type. Considering the obvious differences, sampling should be separate for each different soil type. The leaves can be taken at any time of the day. However, the leaves should not be wet.

For each plant, leaf samples are taken at different times and in different ways.

For example; In the vineyard, when flowering or moles fall, the leaf opposite the first cluster is taken. 100 leaf samples should be taken from 25 vines from 4 sides of a vine.

In tomato; When the fruit in the first generation reaches the size of a walnut, a leaf sample is taken. The leaves that have completed their development closest to the growth apex are suitable for sampling, and a total of 30 leaves should be taken, 1-2 leaves from a plant.

The leaf samples we take should be placed in a bag and labeled. When the fruit in the first generation reaches the size of a walnut, the leaf sample is taken. The leaves that have completed their development closest to the growth apex are suitable for sampling, and a total of 30 leaves should be taken, 1-2 leaves from a plant.

Preparing the Leaf Sample for Analysis

The information about the leaf samples coming to the laboratory is first recorded in the registry and the laboratory sequence number is given to the sample. The samples are taken out of their bags and checked to see if they are suitable. Not sufficient in quantity; any deterioration, rot, etc. If there are samples, new ones are requested. After the recording and examinations are completed, the preparation of the samples for analysis begins.

First, the washing process is done. Generally, if analysis is to be made for macronutrients, washing is not necessary. However, there should be no soil particles on the leaf sample. If there are pieces of soil stuck on the leaf, it is sufficient to clean it with a brush or similar tool. However, it should be noted that leaf samples taken from soils with high calcium carbonate and gypsum contents are not contaminated with soil. In micro element analysis, it is very important that there are no dust, soil, fertilizer and pesticide residues on the leaves. For this reason, green plant samples brought to the laboratory must be washed as soon as possible. Washing should only be applied to leaves that have not lost their freshness and turgor.

The second process is the drying process. Samples should be dried as soon as possible after collection in order to stop chemical and biological changes and enzymatic reactions. Since the leaves will continue to breathe after they are collected, a delay in the drying process will cause dry weight loss. In addition, delayed drying may lead to the breakdown of proteins in the sample into simple nitrogenous compounds and loss of some nutrients such as nitrogen and sulphur. Green leaves containing approximately 90% water should be dried in well-ventilated drying cabinets. Samples should be placed in the drying cabinet as loosely as possible. Otherwise, some organic compounds may decompose.

Another process that needs to be done is the grinding process.

Leaf samples, whose washing and drying processes are completed, are ground in the mill or crushed in a mortar. It is more suitable to grind the samples in a mill for macro element analysis, and to crush in a mortar for micro element analysis. Grinding or crushing the samples is very important in terms of providing homogeneity, preparation of high representative analysis samples and increasing the efficiency of chemical processes as the particle size will be reduced. Leaf samples are usually ground with Wiley mills fitted with a 20-mesh sieve. The grinding fineness of the samples varies depending on the sample amount to be used in the analysis.

The last process is the storage process. Leaf samples, whose washing and drying processes are completed, are ground in the mill or crushed in a mortar. It is more suitable to grind the samples in a mill for macro element analysis, and to crush in a mortar for micro element analysis. Grinding or crushing the samples is very important in terms of providing homogeneity, preparation of high representative analysis samples and increasing the efficiency of chemical processes as the particle size will be reduced. Leaf samples are usually ground with Wiley mills fitted with a 20-mesh sieve. The grinding fineness of the samples varies depending on the sample amount to be used in the analysis.

Burning of Plant Specimens

Mineral substances found in plant samples can usually be determined after the organic matter has been burned in the plant. The methods used in burning organic matter are generally divided into two as dry burning method and wet burning method. The method of burning the plant samples is decided under the influence of various factors.

The element to be determined is one of the most effective and important factors at this point.

Many elements with volatile properties are lost in the dry burning method. Therefore, the dry burning method is not a very preferred method.

For this, after the plant samples are ground, they are usually processed by a wet burning method for elemental analysis.

This burning process is done by two methods. These:

Wet Burning: It is the most useful method of wet burning method. Many elements other than nitrogen can be analyzed by wet burning. It is not possible to determine micronutrients such as Zn, Fe, Mn and Cu by dry burning in plants containing large amounts of silica such as Triticum aestivum (wheat) and oryza sativa (paddy). For this reason, the HNO3-HClO4 wet burning process is applied in this type of plants.
Dry Burning: Nutrient analysis with dry-burning is a simple, safe and cost-effective method compared to the wet-burning method with HNO3-HCIO4. Dry firing is suitable for macro elements such as P, K, C, Na and Mg and micro elements such as Fe, Zn, Cu, and Mn. Wet burning is more suitable for tissues with a high-silica content.

Nitrogen analysis is done as follows; nitrogen in the plant with concentrated sulfuric acid (H2SO4).

It is the titrimetric determination of ammonia (NH3), which is formed as a result of distillation of ammonium in alkaline medium.

1 g of ground plant sample. transferred to the Kjeldahl tube.

Add 1 spoon of mixing salt or 1-2 pieces of copper.

15 ml. Sulfuric Acid is added and placed in the incinerator.

It is burned for 2-2.5 hours at a temperature not exceeding 400˚C.

Initially, the mixture of plant, salt and acid is almost black in color.

The burning process ends when the color of the mixture in the tube turns light gray or off-white as a result of burning.

The sample in the Kjeldahl tube is allowed to cool until it turns warm.

50 ml of pure water is added on it and 50 ml of 2% boric acid is put into the ml erlenmeyer as an apron.

NaOH is absorbed enough to make the environment alkaline.

Distillation continues until ml extraction is accumulated in the Erlenmeyer flask.

The apron, which is initially red in color, turns light green with the formation of ammonium borate.

It is titrated with sulfuric acid of certain normality.

The titration is stopped when the light green color changes to the original red color.

Calculate the % total nitrogen from the formula.

In other nutritional elements; Flame photometer

Determination of other elements (Cu, Zn, Mg, Mn, K, Na) in plant samples is also based on measurement with flame photometer or atomic absorption spectrophotometer after wet burning or dry burning.

Agricultural Analyst / Plant Ecosystem Engineer

DİLEK KOKUŞ

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