Liquid fertilizers, part 3 (Starter liquid complex fertilizers)

In Ukraine, the modern global technology of applying starter fertilizers along with sowing directly to the seeding zone (POP-UP or IN-FURROW technology) is gaining popularity, which provides young plants with available nutrients in the initial stages of growth. Fertilization during sowing is recommended for all crops and is mandatory for corn. This agricultural practice allows to increase the yield of winter wheat by an average of 2.5-3.0 dt / ha, spring cereals — by 2-4 dt / ha, sugar beet — by 2-3 mt / ha, sunflower — by 0, 2-0.3 mt / ha, cabbage — by 4-6 mt / ha.

Types of starter fertilizers

Both dry and liquid forms of fertilizers are used as starter fertilizers. Sometimes, standard nitrogen-phosphorus granular fertilizers are used along with seeding, such as: Monoammonium phosphate or Diammonium phosphate. Although these fertilizers contain a high concentration of nutrients, but have a low solubility and a high salt index.
However, only specialized fertilizers, in form of micro-granules in particular, are suitable for the safe application in the seedbed.

Local application of micro-granular fertilizers ensures accurate dosing and even distribution of micro-granules for full and rapid uptake of nutrients by plants. Micro-granules, the size of which is only 0.5-1.5 mm, provide a significantly larger area of fertilizer contact with the soil and an accelerated diffusion of nutrients, as a result, contributes to (resulting in) a faster and more efficient absorption (uptake) by plants. One gram of a classic mineral fertilizer contains 15-40 granules, and the same amount of micro-granular fertilizer contains 1000 — 3500 pcs. and even more depending on the manufacturer. At the same application rate as regular fertilizers, you get ten times better distribution of nutrients in the soil.

Liquid forms of starter fertilizers have many advantages over classic dry granular fertilizers, especially under insufficient soil moisture conditions. The uniform application, rapid penetration into the root system, high utilization rate of nutrients by plants ensures their almost complete absorption.

Only pure ballast formulas based on 100% orthophosphates can be used, when applying starter fertilizers on POP-UP technology. Although such fertilizers contain a low concentration of phosphorus, they have a number of advantages:

• low application rates (10-40 kg / ha);
• minimum of harmful impurities and ballast salts (chlorides, sulfates)
• low salt index and neutral pH
• unlimited shelf life without the risk of precipitation;
• a balanced amount of nitrogen and potassium is available for relevant needs;
• a joint application of biologically active substances, pesticides and micronutrients necessary for an effective start, primarily zinc is admitted.

Today, the concept of starter nutrition of crops has undergone significant changes: it includes not only providing plants with the necessary nutrients at the beginning of growth, but also creating favorable conditions for the undergoing processes in the rhizosphere. This approach is called rhizosphere management.

Today, numerous publications are devoted to the issue of rhizosphere management, which state that in order to achieve high fertilizer efficiency, it is necessary to increase the absorption of nutrients and reduce their losses by root fertilization rather than soil fertilization.

Traditionally, the concentration of nutrients in the soil solution has been increased by over-fertilization, based on the assumption that high application rates mean high yield. However, the plants’ root ability to mobilize nutrients from the soil by increasing the penetration of organic acids and enzymes into the rhizosphere was neglected.

Application of excess fertilizers results in reduced response to them, often even a total loss of response. Recent studies have shown that crop yields can be maintained at good level or even increased, if fertilizer application rates are reduced. This is achieved by regulating the supply of nutrients to the root zone in sufficient quantity and by stimulating rhizosphere processes that improve the efficiency of fertilizers applied and mobilization of elements in the soil.

Special attention should be paid to phosphorus nutrition, since phosphorus is a slow-moving element and is absorbed several millimeters away from the root — that is, in the rhizosphere. From a scientific point of view (theoretically), phosphate fertilizers should be applied to the rhizosphere rather than to the entire soil profile, but this is technically difficult to achieve. However, it is quite possible in relation to the starter nutrition, and precise control of root / rhizosphere processes and interactions can play an important role in developing effective solutions for the sustainable use of phosphorus.

The main idea of such technologies is that the focus is shifting from providing nutrients to the plant only from the fertilizers, to managing the processes in the soil in such a way that the nutrients from both fertilizers and soil become the most efficient.

Production

RKDs based on thermal orthophosphoric acid are almost transparent liquids based on extraction orthophosphoric acid — cloudy solutions (due to formation of aluminum and iron phosphates, silicon acid).

When using thermal orthophosphoric acid, RKDs are produced with nutrient ratio of 9:9:9, 27% N, P2O5 and K2O in total. Crystallization of the solution does not allow to increase the nutrient content. The typical composition of 9: 9: 9 grade is presented by: (NH4) 2HPO4 — 12-15%, NH4P2O4 — 2-4%, (NH2) 2CO — 12-13%, KCl — 13-14%. Amide nitrogen accounts for 61-66% of the total.

Advantages and disadvantages

The main advantages of RKDs are:

1) unlike liquid nitrogen fertilizers, RKDs do not contain free ammonia, therefore they can be transported and stored in an unpressurized container;

2) can be applied to the soil surface without immediate application;

3) More evenly distributed over the field than solid fertilizers;

4) uniform composition: each drop of liquid fertilizer has the same composition;

5) RKD operations are fully mechanized, the cost of storage, application to the soil and loading and unloading operations, as well as operations during transportation is lower;

6) The losses during transhipment and storage do not exceed 1%, whereas for solid fertilizers it is 10-15% or more;

7) Generally less likely to be stolen;

8) if necessary, they can be used with other preparations (micronutrients, growth regulators, pesticides), while additional preparations are distributed throughout the fertilizer, which allows to apply them more evenly;

9) RKDs are neither poisonous nor explosive;

10) Seed planters currently on the market are quite easily adapted to the application of liquid fertilizers during sowing;

11) The cost of RKDs is lower than that of solid fertilizers (energy-intensive and expendable technological stages of granulation, drying, dust collecting, etc. are excluded in the process of their production).

The effectiveness of liquid complex fertilizers on different soil types

The effect of RKDs on the basis of phosphoric acid, applied into acidic, phosphorus-fixing soil (for example, red soil, with a low phosphorus, as well as poor acidic soddy-podzolic soils) is weaker than that of granular forms. This is observed when applying a complete RKDs with a ratio of 1: 1: 1 and an additional nitrogen component (ammonium nitrate). There is no decrease in the effect of the phosphate component on acidic sod-podzolic soil, when applying an unbalanced solution with a ratio of N: P2O5 1: 4.5 or 1: 3.

RKDs and granular fertilizers applied on limed sod-podzolic soils and chernozems are equivalent.

The agrochemical value of liquid fertilizers applied on calcareous soils with an alkaline reaction (for example, on carbonate chernozems, chestnut soils, gray soils) is higher than that of granular forms.

In acidic soddy-podzolic soil, there is a short-term decrease in mobile phosphorus when the solution is applied, which is associated with the phosphate fixation by sesquioxides. This process is not observed in chernozems. After applying RKDs in gray soils, the amount of mobile phosphorus increases compared to the application of granular fertilizer.

The efficiency of RKDs is determined by the phosphorus and nitrogen components. For example, RKDs with ammonium nitrate applied on acidic soddy-podzolic soil and red soil are less efficient than solid granular fertilizers, but RKDs with urea are equivalent to granular forms. As for typical chernozem with a slightly acidic reaction and gray soils, the form of nitrogen component does not affect the fertilizer: the efficiency of solutions and granular fertilizers is equivalent. The effect of RKDs on the product quality (grain, potatoes, hay) is also equivalent to solid fertilizers.

Liquid Fertilizer Application

One of the problems that farmers face is the lack of knowledge about the application of Liquid Fertilizers.
That is why In-FURROW technology is increasingly popular among farmers for the effective application of RKDs — it means the application of any preparations (fertilizers, plant protection products, microbial preparations, growth regulators, etc.) in the seed furrow or as close to seeds as possible during sowing. This method guarantees maximum effect as a starter feeding and minimizes the negative effects of stress at the beginning of plant development.

When it comes to fertilization, the term POP-UP technology is used, that is, application of fertilizers in direct contact with the seeds during sowing. The use of this technology by farmers only confirms the fact that it is possible to invest in a plant in the most efficient way applying optimal amount of fertilizers into the root zone.

This method is often very effective, since the localization of fertilizers can significantly increase the utilization rate of nutrients, which makes it possible to reduce the application rates and save money. However, it must be borne in mind that the risk of damage to sprouts as a result of creating high salt concentration area nearby, as well as the release of toxic ammonia by some fertilizers (for example, urea or DAP). Of course, you can predict the risk of damage by looking at the salt index. It is impossible to predict the safety of fertilizer for sprouts in a certain area by calculating the salt index, however, it is possible to compare fertilizers with their ability to create high osmotic pressure in the application zone. For example, fertilizers with a salt index of 20 or less can be considered relatively safe. Liquid complex fertilizers specially designed for application to the seed bed usually meet these conditions. It is also important to take into account the tolerance of crops to salt effect. Cereals and pulses are considered the most tolerant, but for oilseeds, salt effect is an important factor.

The risk of sprout damage increases under the following conditions:

• In the soils with a low organic matter. Because more fertilizer elements remain in the soil solution and are not absorbed by the soil;
• In dry soil, that can be explained by the concentration near the seeds, which remains high for a long time;
• In cold soil, because the roots grow and develop more slowly, thus, they are negatively affected by a high fertilizer concentration for a long time;
• In light-textured soils (or, in other words, when the exchange capacity of soils is low);
• For row crops with wide row-spacings (the higher the row-spacing, the higher the fertilizer concentration in the row);
• Using a rising dose of fertilizers.

The design of the applicator for the application of starter fertilizers, the width of the fertilizer band in particular, affects its safety for sprouts, the wider the band, the lower the risk.

The latest applicators allow fertilizers to be applied close to the seeds, with a slight shift to the side, which can also be considered a POP-UP application (if the distance is less than 1.5 cm), but slightly reduces the risk of damage.

Application Method of starter RKDs

Starters are applied during sowing by special applicators which are mounted on seeders. The recommended method of application is ultra-local application with seeds (POP-UP placement). In general, both dry and liquid fertilizers may be applied according to the standard «2 × 2» model (at a distance of 5 cm to the side and 5 cm down from the seeds), but the maximum benefits of starter fertilizers are revealed precisely when applied directly with the seeds.

Starter fertilizers are applied when sowing cereals and industrial crops, and along with soy and vegetable seeds in open and protected field. The application rate of starter fertilizers is 10-50 l / ha, depending upon the fertilizer’s formula, crop, particle size distribution, soil moisture and other indicators. World experience has shown that corn and sunflower react best to this fertilization method, when sowing, an average of 20 kg / ha of microgranules or 20-30 l / ha of liquid orthophosphate fertilizers are applied.

Practical recommendations on the use of RKDs

Before proceeding, be sure to consult an agronomist or manager who specializes in RKDs (before ordering RKDs, you must take into account plant nutrition programs, precursor crop, targeted crop yield, technical and financial capabilities of the farm, etc.);

Make a soil analysis in the area where you plan to apply RKDs;

Use RKDs at all stages of plant nutrition, most appropriately as starter feeding;

Select a supplier in advance, schedule a shipment date. This will help to maximize budget savings and prevent problems with time constraints in the field;

Working out the logistics, application and storage in your household;

Prepare the equipment and plan your budget. Consider the household necessities in the equipment modification for application of RKDs.

RKD application instructions

Mixing instructions

Liquid fertilizers can be mixed with many crop products.

Some non-100% Ethylenediaminetetraacetic acid (EDTA) chelates may not be compatible.

In a small container prior to full scale mixing, proportionally mix all the components to confirm compatibility.

Thorough mixing of all blends is important.

Temperature and storage time can influence the degree of success.

Mix only the amount that will be immediately used.

Long-term storage is not suggested.

Mixing procedure

Add ½ of total water to spray tank

Start recirculation in the tank

Add micronutrients and /or any other flowable material

Add any soluble powder first pre-mixing with water

Add the recommended amount of liquid fertilizer

Add remaining water volume and continue recirculation prior to spraying

Precautions

RKDs are categorized as 3rd class of hazard — moderately hazardous (limiting indicator is inhalation toxicity), irritant of the eye mucous membranes. Fertilizer should be kept away from children and stored in a dry place in the original sealed package.

If swallowed, seek immediate medical attention and show the label; if in eyes, rinse immediately with plenty of water and seek immediate medical attention.

If spilled, collect the spilled substances and wash off the rest with water.

Transportation and storage

Liquid fertilizers are recommended to be stored in poly, fiberglass, stainless, or coated steel tanks to prevent possible product discoloration.

Storage in flat bottom tanks is recommended during winter months. Bubble and recirculate material before usage. Material stored in cone bottom tanks (although not recommended) will require longer recirculation after inter to regain product consistency.

It is not recommended to store and transport the product in aluminum or galvanized steel tanks.

Packaging

In Ukraine, Liquid starter fertilizers are available in 1l, 20l and 1000l containers.