The amount of nutrients in the structure of animal manures is very low compared to chemical fertilizers. As can be seen from the chart below, the nitrogen amount of 1 ton of well-burned and very dry cattle manure is equal to the nitrogen amount of 10 kg of 33% N Ammonium Nitrate. However, there is not only nitrogen in the structure of animal manures, but also phosphorus, potassium, calcium, magnesium and micronutrients such as iron, copper, zinc, manganese and boron. In other words, animal manures are like multi-nutrient composite fertilizers, but the amount of nutrients is very less compared to chemical fertilizers.

It is best to use fertilizer according to soil analysis. However, an expert can understand which nutrient is low by looking at the development of the plant, the color and size of the leaves of the plant. For example, a weak (weak) development in annual plants, the leaves being smaller and thinner than normal, and yellowing, especially in the old lower leaves, indicate that the plant needs nitrogen fertilizer. In perennial fruit trees, if yellowed leaves are seen at the bottom of the shoot, it means that there is nitrogen deficiency. On the same leaves, especially if the undersides of the leaves are bluish-green or bluish-purple, this indicates a phosphorus deficiency. Whether it is an annual or perennial plant, if a yellowing that starts from the leaf tip and turns light green, then greenish-yellow on the leaf margins, progresses from the leaf margin to the middle vein of the leaf, this indicates potassium deficiency.

Nitrogen loss occurs in the form of ammonia gas from nitrogen fertilizers, especially Ammonium Sulphate and Urea fertilizers, which are applied without mixing into the soil. In addition, depending on soil conditions, nitrogen gases (N2O – NO – N2) may pass into the atmosphere as a result of enzymatic reaction by bacteria in the soil (denitrification bacteria), and nitrogen loss may occur.

Fertilizers containing plant nutrients not only have a decisive effect on the product amount and quality of the plant, but also play an important role by reducing the risk of disease and pests infecting the plant. In addition, there is a close relationship between various environmental factors such as fertilization, air temperature and drought, and the salt content of soil and water.

The sensitivity and resistance of the plant to environmental factors and pests is largely determined by its genetic structure. This situation is related to the anatomical structure of the plant and the development of physiological and biochemical metabolism within the plant. Plants respond to external factors by changing their anatomical structures. In addition to physical changes such as the formation of thick and durable epidermis cells in the leaves and high ligninization in the tissues, plants also show resistance against diseases and pests by secreting some toxic compounds such as phytoalexin as a result of biochemical reactions occurring in their bodies. Good nutrition of the plant and therefore the use of correct and balanced fertilizers play a very important role in the effective activation of these defense mechanisms.

Even if scientists and researchers produce new and resistant varieties with increased resistance to external factors in the laboratory environment, it is possible to use less but more effective pesticides with the use of correct and balanced fertilizers.

The resistance of plants to high or low temperatures and drought varies from species to species. There is a close relationship between plant nutrition and especially the plant's water consumption and cold resistance. The increase in the amount of dry matter in the plant, especially in the leaves, provides less damage to the plants from the cold. In addition, the use of correct and balanced fertilizers regulates the respiratory and transpiration functions of the plant, minimizes water loss and ensures that the plant is less damaged by drought.

What does Soil Conditioner mean? The materials that are used to correct some physical and chemical properties of the soil that are not suitable for growing plants are called soil conditioners. In the regulation of the Ministry of Agriculture and Rural Affairs dated 04.06.2010 and numbered 27601, it is clearly stated that soil conditioners are not fertilizers. In this regulation, soil conditioners are grouped under three main groups and their qualifications are stated:

- Mineral soil conditioners
- Organic soil conditioners
- Organic + Mineral soil conditioners

In this article, only some information about “Mineral Soil Modifiers” will be given.

Some of the agricultural lands have decreased or lost their productivity qualities due to faulty agricultural practices for various reasons. It is possible to improve the soils and make them productive by applying soil conditioners to such agricultural areas. However, these materials used to improve the soil are never chemical (mineral) fertilizers and cannot be marketed as fertilizers.

The reasons that require soil improvement can be summarized as follows:

- Soil salinity
- Soil alkalinity
- Soil acidity
- Water retention-Aeration quality of the soil
- Soil erosion
- Effects on soil nutrient availability and nutrient holding capacity

Mineral-based soil conditioners are generally used to correct the degraded soil properties mentioned above. Gypsum (Gypsum) CaSO4.2H2O is used in the improvement of soil salinity. Since this chemical substance contains Calcium (Ca) and Sulfur (SO4) as plant nutrients, it never replaces fertilizer. Producers who want to reduce soil salinity should consult an expert in this field for the amount of gypsum to be used per decare, according to the root depth of the plant to be grown, the quality of irrigation water to wash the salts, and the soil properties. The sodium (Na) element, which creates salinity in the soil and is retained by the clay mineral, is replaced by the calcium of the gypsum applied to the soil, and sodium passes into the soil water and Sodium Sulphate (Na2SO4.10H2O) is formed. Sodium sulfate is removed with irrigation water and soil salinity is reduced in this way.

Sulfur and sulfur-containing materials are generally used to reduce soil alkalinity (high pH). Elemental sulfur is one of these materials. In addition to elemental sulfur, some compounds containing sulfur can be used to reduce soil pH. However, its effectiveness is never as high as elemental sulfur. Elemental sulfur mixed into the soil produces Sulfuric acid (H2SO4) as a result of the enzymatic reaction of the sulfur bacteria in the soil. Sulfuric acid dissolved in soil water splits into hydrogen (H) and sulfate ions. Since plants cannot take hydrogen ions with their roots, the amount of hydrogen ions in the soil increases and the soil pH value is reduced in this way. If a soil has both salinity and alkalinity, the salinity must be reduced first.

To increase soil acidity (low pH), lime and lime-derived materials containing Calcium are used. Lime (CaCO3), burnt lime (CaO), slaked lime [Ca(OH)2] and Dolomite (CaCO3 + MgCO3 (Agricultural Lime) are the leading ones. The amounts to be given per decare, the thickness of the soil layer to be pH increased, the pH value of the soil and some soil properties should be taken into account and consulted with an expert. The pH of the soil prevents the pH of the soil to be strong acid (low pH) and the presence of other nutrients in the soil, especially the presence of high-value phosphorus in the soil. The amount of iron and manganese elements in soils can increase to toxic levels.For this, liming is required.

Materials such as vermiculite, zeolite, pumice, perlite, diatomite and volcanic tuff are used in order to improve the water holding and aeration capacity of the soil and to increase the nutrient holding capacity. The ratio of these materials to be used is determined as a result of soil analysis. These materials added to the soil in order to improve some physical properties of the soil also cause a decrease in soil erosion. By mixing these materials in certain proportions per decare, it enables the plant roots to develop better in soils with poor physical structure and allows plants to absorb water and nutrients from the soil more easily.

Soil conditioners, which have been tried to be briefly explained so far, do not become fertilizers because they contain nutrients or by adding chemical fertilizers to overcome difficulties in marketing. The Ministry of Agriculture and Rural Affairs accepts these materials as "Soil Conditioners" and gives production and marketing permissions as soil conditioners. Soil conditioners are never a substitute for fertilizer as previously stated.