Economic and energy assessment of the efficiency of fertilizer application

How fertilizers affect yield and farm economics

Applying fertilizers "at random" is too expensive today. The efficiency of plant nutrition must be evaluated from three perspectives: agronomic (yield increase and soil fertility maintenance), economic (profit and return on investment), and energy-related. This allows not only for recording the result but also for adjusting technologies to specific soil and climatic conditions.

The influence of fertilizers on harvesting strongly depends on the cultivation zone. In the Chernozem (black soil) region, their contribution to growth formation is lower, while in the Non-Chernozem zone with less fertile soils, it is critically high. On average, the indicators are distributed as follows:

According to numerous research data, the increase in the volume of fertilizer application and yield are directly linked. However, it is impossible to uncontrollably increase nutrition doses. This leads to wasted resources and a drop in return on investment.

Expenses for the purchase and application of chemical agents today constitute a significant part of the budget for any crop farm. That is why the assessment of economic efficiency must be carried out annually. This helps to adjust nutrition rates in time and choose the most rational field work practices.

• Share of costs for chemicalization in crop production — more than 20%
• Correlation coefficient between dose and yield — 0.8
• Number of crops evaluated in the regional methodology — 25

Methodology for calculating economic efficiency

The assessment of the feasibility of fertilizer application begins with an analysis of technological maps and the results of field experiments. The main principle of such calculations is the observance of a single difference. This means that all indicators on fertilized plots are compared with a control variant where no fertilizers were applied.

For accurate calculations, specialists will need actual production data and the annual report. Based on these, they estimate net income, return on investment, profit, and the rate of profitability. The value of the obtained production is expressed in current market or purchase prices.

If it is not possible to establish your own control strips on the farm, data from experimental institutions for similar conditions are used. In this case, the increase is determined by calculation, although the accuracy of the assessment decreases. For example, based on multi-year production experiments, scales have been developed that allow for determining the share of mineral fertilizers in the harvest of 25 agricultural crops.

1. Establish a control unfertilized strip in the field or take the average data from scientific institutions for similar conditions as a basis.
2. Calculate the physical yield increase as the difference between the indicators on the fertilized and control plots.
3. Collect initial data: actual doses applied to the crop (kg/ha of active ingredient), obtained yield (c/ha), and current product prices (rub.).
4. Compare the cost of fertilizer with the profit obtained to assess return on investment, net income, and profitability.

Based on these steps, a system of efficiency indicators is calculated. It includes the value of the yield increase per 1 hectare, conditional net income per unit area, and the profitability of fertilizer application. The obtained data also show how much the cost of production of the finished product has decreased.

All costs (Z) for obtaining the yield increase from mineral fertilizers are taken into account. Total costs consist of:

• cost of fertilizers (Zud);
• expenses for unloading, storage, preparation, transport to the field, and application of mineral fertilizers (Zvn);
• expenses for harvesting, transporting the yield increase from the field, and its processing (Zub);
• expenses for selling the yield increase or placing it into storage (Zr);
• general production, general farm, and other expenses attributed to the cost of production of agricultural products according to accounting (Zn).

If the calculation is conducted for the future as a prognostic option, then instead of actual costs, standard costs adopted on the farm or actually developed over a number of years are used (Table 220; Mineev V.G., 1990).

 Grains 72 102 60 234 4.3 Cotton 136 92 39 267 3.7 Sugar beet 11 12 11 34 29.2 Flax (fiber) 176 314 320 810 1.2 Sunflower 148 226 48 422 2.4 Potato 13 13 12 38 26.6 Vegetables 8 8 8 24 42.6 Silage crops 10 9 8 27 37.2 Fodder root crops 8 8 8 24 42.9 Perennial and annual grasses (hay) 21 32 33 86 11.6 Meadows and pastures (hay) 31 23 77 13.0 Perennial plantations and berry bushes 27 23 71 14.1

Determination of net income (NI) from fertilizer application. It is determined by the formula

NI=(P+b)–C, where: P is the cost of the main product obtained as a result of fertilizer application, rub.; b is the cost of by-products, rub.;

C is the total amount of costs associated with fertilizer application to obtain the yield increase, rub.

Profitability (P) of fertilizer application is the ratio of net income to costs, calculated for 1 year or for the entire period of fertilizer activity, taking into account the residual effect:

P%   100.

The profitability of fertilizer application in crop rotation over their entire duration can be calculated using the formula:

 NI  100.

The payback of additional costs in monetary terms is determined by dividing the value of the obtained yield increase by the amount of additional costs. The payback of fertilizers in physical terms is determined by the formula:

E where: E is the amount of additional product in physical terms per unit of nutrient of fertilizer, centners;

Y is the yield increase in physical terms, centners;

N is the amount of nutrients applied for the given crop, centners.

This indicator makes it possible to choose correct, economically sound methods and timing for fertilizer application in various zones, depending on the type of soil, predecessor, level of farming culture, as well as to take into account the efficiency of fertilizer system in crop rotation.

The assessment of the economic efficiency of fertilizer application, especially at the stage of developing agricultural practices, is significantly difficult. This is mainly due to the volatility of prices for material and labor resources. However, new fertilizers and methods of use require an objective assessment of their advantages or disadvantages. Such an objective assessment can be the determination of the energy efficiency of crop cultivation, the application of a technological method, a new type of fertilizer, etc. To do this, it is necessary to take into account all energy costs for cultivating a crop or using a technological method and the energy content of the harvest, and to identify the degree of energy cost payback by the energy content of the harvest. The energy assessment, if necessary, can be converted into any monetary units if the cost of one gigajoule is known, i.e., an economic assessment can be provided. At the same time, it is necessary to remember that this is not a direct analogue of the assessment of the economic efficiency of an agricultural practice.

The intensification of agricultural production and the increase in crop yield are accompanied by an increase in the consumption of non-renewable energy, including due to the increasing use of fertilizers. Therefore, all over the world and in our country, in particular, energy-saving technologies are being developed, under which agricultural products are produced with lower costs.

The energy expenditure for the production of agricultural products consists of energy costs for fertilizers, pesticides, fuels and lubricants, depreciation charges for tractors, agricultural machinery, and motor transport; costs for electricity and costs of manual labor. Similarly, costs for an individual agricultural practice are taken into account. Each type of cost is specific to the particular production conditions and varies within a wide range. The objectivity of the assessment depends on the accuracy of their accounting, which, however, is not always possible, and therefore one has to use average indicators (Table 221; Mineev V.G., 1990).

Table 221 – Energy costs for the production of energy carriers Energy- Item of expenditure Energy carriers intensity, MJ

 Fertilizers, 1 kg a.i. nitrogen 86.8 phosphorus 12.6 potassium 10 complex (nitroammophoska, etc.) 51.5 liming 8.5 boron and molybdenum 180 bacterial (per 1 ha) 15 manure (80% humidity) 0.42 peat-manure composts (60% 1.70 humidity) lime fertilizers 3.80 local mineral fertilizers 2.90 Growth regulators retardants 264 Fuels and lubricants diesel fuel 42.7 gasoline 44.1 diesel oil 41.4 Electricity* 3.8 Manual labor*, per 1 hour of work: 1.3 light medium 1.9 heavy 2.5 Agricultural machinery, equipment, 5600 1 ton of mass * – Energy content.

The determination of energy costs is based on the technological map, which is the main document for planning technological processes and operations during the cultivation of agricultural crops. To determine the energy efficiency of individual agricultural practices, the costs for all types of work are taken from the technological map, the consumption of diesel fuel, gasoline, lubricants, electricity is determined, as well as the species composition and amount of fertilizers and pesticides, manual labor costs by complexity categories, energy intensity of equipment, and energy charges per hectare of arable land and per unit of product. The calculation of energy costs for liming, as well as the application of organic fertilizers, is carried out taking into account their residual effect.

Costs for energy carriers increase due to the need for additional work before their intended use – storage, packaging, etc. Costs for crushing caked fertilizers, their loading, delivery and unloading, delivery of fuels and lubricants and other cargo to the farm are not included in the energy costs for energy carriers, but are taken into account in the technological map as independent operations. The complexity category of manual labor is determined according to the reference book.

When applying fertilizers, it is necessary to take into account the energy expenditure for tractors and agricultural machinery. To determine the energy intensity of equipment, it is necessary to know the mass of each machine, the energy expenditure for its production, depreciation rates, annual output rate, the depreciation rate per 1 ha of standard ploughing (s.p.), and costs for current repairs and technical maintenance per 1 ha of s.p. (Table 222; Mineev V.G., 1990; Posypanov G.S., 1997). This information for each machine is taken from a reference book. To calculate the energy expenditure for a specific technological operation, it is necessary to calculate the actual output of the machine in hectares of s.p., using a process chart.

Table 222 – Energy intensity of equipment and energy deductions Machine Make Mass, kg Energy expenditure, MJ/ha s.p. Annual output, ha s.p./year Depreciation rate, MJ/ha s.p. Current repair and maintenance, MJ/ha s.p.

 T–150K 7535 42196 18.5 7806 1585 4.92 2.76 DT–75 5800 32450 18.5 6009 1375 4.37 1.90 MTZ–80 3000 16800 17.5 2940 724 4.06 2.33 MTZ–82 3200 17920 17.5 3119 756 4.12 2.36 LDG–150 1600 8960 14.2 1272 325 0.39 0.23 PLN–5–35 1500 8400 12.5 1050 185 5.68 4.22 ZKKSh–6 1410 7896 14.2 1121 350 3.20 2.37 SZ–3.6 1450 8120 14.2 1153 130 8.87 4.88 BZTS–1 140 784 14.2 111 70 1.43 1.40 BZSS 100 560 14.2 80 70 1.14 1.12 BDT 1600 8400 12.5 1050 800 0.86 0.45 KPS–4 1600 8400 16.6 1394 520 2.68 2.22 RVK–3.6 2000 11200 14.2 1590 520 3.06 2.54 SK–6 "Kolos" 9750 54600 16.0 8736 140 62.4 49.1 RMG–4 800 4480 20.0 896 432 2.07 0.99 OPSH–15 1000 5600 20.6 1120 1400 0.80 0.72

Energy costs for transporting fertilizers, yield increases, and other transport expenses are accounted for by fuel consumption, depreciation charges for vehicles, and direct labor costs, or by average energy costs per 1 ton-kilometer, which can be taken as 40 MJ on average.

After calculating individual energy cost items, the total energy costs for production are determined.

The next stage is determining the energy content in the harvest of primary and secondary products. Energy content depends on the size of the harvest and its chemical composition – the amount of fats, proteins, and carbohydrates.

The energy intensity of organic substances is as follows: carbohydrates 16.72 MJ/kg (4000 kcal), proteins 22.99 (5500), fats 37.62 MJ/kg (9000 kcal) (1 cal=4.18 J). Since the ratio of carbohydrates, proteins, and fats in grain, seeds, and vegetative mass of various crops is different, their energy content also differs significantly (Tables 223–225; Posypanov G.S., 1997).

Table 223 – Content of organic substances and energy in the harvest of field crops Carbohydrates, % Proteins, % Fats, % Energy content, GJ/t in carbs in proteins in fats total total dry matter

 Grain of cereals and buckwheat Wheat 84 14 2.0 14.1 3.2 0.8 18.1 Rye 85 13 2.0 14.2 3.0 0.8 18.0 Barley 85.6 12 2.4 14.3 2.8 0.9 18.0 Oats 82 12 6.0 13.7 2.8 2.3 18.7 Maize 84 11 5.0 14.0 2.5 2.0 18.5 Millet 83.5 12 4.5 14.0 2.8 1.7 18.5 Sorghum 88 10 2.0 14.7 2.3 0.8 17.8 Rice 91 7 2.0 15.1 1.8 0.8 17.7 Buckwheat 84 13 3.0 14.0 3.0 1.1 18.1 Seeds of grain legumes Field pea 74 24 2.0 12.4 5.5 0.8 18.7 Garden pea 77 21 2.0 12.9 4.8 0.8 18.5 Soybean 42 40 18.0 7.0 9.2 6.8 23.0 Bean 67 30 3.0 11.2 6.9 1.1 19.2 Lentil 65 30 5.0 10.9 6.9 1.2 19.0 Field bean 70 28 2.0 11.7 6.4 0.8 18.9 Chickpea 75 23 5.0 12.0 5.3 1.9 19.2 Grass pea 70 28 2.0 11.7 6.4 0.8 18.9 Common vetch 67 31 2.0 11.2 7.1 0.8 19.1 White lupin 52 38 10.0 8.7 8.7 3.8 21.2 Yellow lupin 51 42 7.0 8.5 9.7 2.6 20.8 Narrow-leaf lupin 58 36 6.0 9.7 8.3 2.3 20.3 Secondary products, natural humidity Grass straw 82 1 — 13.7 0.2 — 13.9 Buckwheat straw 81 2 — 13.5 0.5 — 14.0 Grain legume stalks 77 5 — 12.9 1.2 — 14.1 Root crop leaves 21 2 — 3.5 0.5 — 4.0 Chaff, husks 80 3 — 13.3 0.7 — 14.0 Root crops and tubers, raw mass Sugar beet 25 2 0.1 4.2 0.5 0.1 4.8 Fodder beet 23 1.5 0.1 3.9 0.4 0.1 4.4 Rutabaga 25 2 0.1 4.2 0.5 0.1 4.8 Turnip 22 1.5 0.1 3.7 0.4 0.1 4.2 Carrot 23 2 0.2 3.9 0.5 0.2 4.6 Potato 24 2 0.3 4.0 0.5 0.2 4.7 Jerusalem artichoke 25 2 0.3 4.2 0.5 0.2 4.9

Perennial legume grasses in the beginning of flowering phase Meadow clover 82.5 16 1.5 13.8 3.7 0.6 18.1 White clover 78.5 20 1.5 13.1 4.6 0.6 18.3 Alfalfa 79.5 19 1.5 13.3 4.4 0.6 18.3 Eastern goat's rue

80.5 18 1.5 13.5 4.1 0.6 18.2 Bird's-foot trefoil 78.5 20 1.5 13.1 4.6 0.6 18.3 White sweetclover 79.5 19 1.5 13.3 4.4 0.6 18.3 Sainfoin 80.5 18 1.5 13.5 4.1 0.6 18.2

Perennial grass species in flowering phase Timothy grass 92 7 1 15.4 1.6 0.4 17.4 Smooth brome 89 10 1 14.9 2.3 0.4 17.6 Meadow fescue 90 9 1 15.0 2.1 0.4 17.5 Cocksfoot 87 12 1 14.6 2.8 0.4 17.8 Crested wheatgrass 90 8 2 15.0 1.8 0.4 17.2 Siberian wildrye 84 14 2 14.0 3.2 0.8 18.0

Green mass of annual legumes in seed filling phase Common vetch 77 21 2 12.9 4.8 0.8 18.5 Hairy vetch 79 19 2 13.2 4.4 0.8 18.4 Grass pea 75 23 2 12.5 5.3 0.8 18.6 Field pea 79 19 2 13.2 4.4 0.8 18.4 Garden pea 79 19 2 13.2 4.4 0.8 18.4 Fodder bean 81 17 2 13.6 3.9 0.8 18.3 Soybean 76 22 2 12.7 5.1 0.8 18.6 Yellow lupin 77 21 2 12.9 4.8 0.8 18.5 White lupin 77 21 2 12.9 4.8 0.8 18.5 Narrow-leaf lupin 82 17 2 13.7 3.9 0.8 18.2

Green mass of cereal crops in milk stage of grain and sunflower in flowering phase Rye 87 12 1 14.6 2.8 0.4 17.8 Oats 88 11 1 14.7 2.5 0.4 17.6 Maize 90 9 1 15.1 2.1 0.4 17.6 Sorghum 88 10 2 14.7 2.3 0.4 17.4 Sunflower 88 10 2 14.7 2.3 0.4 17.4

Green mass of mixed crops Vetch + oats 81 17 2 13.6 3.9 0.8 18.3 Grass pea + oats 82 17 1 13.7 3.9 0.4 18.0 Pea + oats 83 15 2 13.9 3.5 0.8 18.2 Winter vetch + rye 83 16 2 13.9 3.7 0.8 18.4 Soybean + maize 83 15 2 13.9 3.5 0.8 18.2

Table 225 – Energy content (L) and conversion coefficient of products to dry matter, units (Ri) Crop Conversion coefficient of product to dry matter Total energy content in 1 kg of dry matter, MJ

 Winter wheat (grain) 0.86 19.13 16.45 Spring soft wheat (grain) 0.86 19.31 16.61 Spring hard wheat (grain) 0.86 19.49 16.76 Rye (grain) 0.86 19.49 16.76 Barley (grain) 0.86 19.13 16.45 Oats (grain) 0.86 18.80 16.17 Millet (grain) 0.86 19.70 16.94 Buckwheat (grain) 0.86 19.38 16.67 Rice (grain) 0.86 18.59 15.99 Bean (grain) 0.86 20.68 17.78 Pea (grain) 0.86 20.57 17.69 Sorghum (grain) 0.86 18.34 15.77 Maize (grain) 0.86 17.60 15.14 Maize (green mass) 0.25 16.39 4.10 Cotton (fiber) 0.76 19.81 15.06 Cotton (seeds) 0.86 21.00 18.06 Flax (fiber) 0.89 20.24 18.01 Flax (seeds) 0.88 23.50 20.68 Sugar beet 0.14 18.26 2.56 Sunflower (seeds) 0.92 19.38 17.83 Sunflower (green mass) 0.25 16.80 4.20 Soybean (grain) 0.88 20.57 18.10 Potato 0.20 18.29 3.66 Melons 0.11 14.90 1.64 Vegetables 0.10 14.36 1.44 Fodder root crops 0.25 16.39 4.10 Perennial grasses (hay) 0.20 18.91 3.78 Alfalfa for hay 0.25 21.83 5.46 Annual grasses for hay 0.20 16.39 3.28 Meadow-pasture grasses (converted to hay) 0.20 16.19 3.24 Forage grain crops for green feed (converted to hay) 0.30 15.40 4.62 Tobacco (shag) 0.45 20.20 9.09 Hemp (fiber) 0.90 19.60 17.64 Hemp (seeds) 0.88 21.00 18.48

* Provided at conventional standard humidity based on state standards for product quality (technical requirements).

The harvest size is the result of all agrotechnical measures. This resultant trait reflects the influence of all external factors on the agrocenosis. This influence extends not only to the harvest size but also to its chemical composition, and, consequently, to the energy content in the main and by-products. Knowing the harvest and the energy intensity of the main and by-products, the total energy content of the harvest is calculated.

Energy assessment of the efficiency of a technological method. Knowing the energy expenditures for crop cultivation and the energy content in the harvest of the main and by-products, an energy assessment of the efficiency of crop cultivation or the applied agricultural method is carried out.

The main criteria for assessing energy efficiency are:

– net energy income, defined as the difference between the energy content in the harvest and the total costs for crop cultivation;

– energy efficiency coefficient – the ratio of net income to energy expenditures;

– bioenergetic coefficient (efficiency) of sowing – the ratio of energy obtained with the harvest to the energy expended;

– energy cost of production – energy expenditures per unit of harvest.

The amount of energy accumulated in the main agricultural product obtained from the application of mineral fertilizers is determined by the formula:

Vlo  Уп 100, where: Vlo – energy content in the main (economically valuable) product, MJ;

Уп – yield of the main product from the application of fertilizers, MJ;

Ri – conversion coefficient of a unit of agricultural product into dry matter;

L – total energy content in 1 kg of dry matter of the main product, MJ;

100 – conversion coefficient from centners to kg.

In the total energy expenditures for the implementation of the technological process, mineral fertilizers per 1 kg of active ingredient are estimated by the following amount of energy (MJ): nitrogen – 86.6 (аN), phosphorus (аР) – 12.6, potassium (аК) – 8.3; manure (80% humidity) – 0.42 (table 226; Mineev V.G., 1990).

The lowest energy value is observed in nitrogen fertilizers, which is associated with higher energy expenditures for their production compared to phosphorus and potassium fertilizers.

Energy expenditures (А0) for the application of mineral fertilizers are determined by the formula:

А0 = (Н НР·аР) + (НК·аК), where: HN, НР, НК – respectively, the actual application rate of nitrogen, phosphorus, and potassium fertilizers, kg/ha of active ingredient; аN, аР, аК – energy expenditures per 1 kg of active ingredient of nitrogen, phosphorus, and potassium fertilizers. Energy efficiency (energy output or bioenergetic efficiency) of mineral fertilizer application (η) is determined by the formula:

How to calculate the energy balance and why an accurate experiment is important

To evaluate the real return from the application of fertilizers, it is not enough to calculate only financial costs. It is important to compare the energy that the farm spends on working with fertilizers with the energy obtained from the harvest increase. Such a comparison allows one to see the net efficiency of the technology, which does not depend on market price fluctuations.

• Energy in the harvest increase (Vf) — the amount of additional energy obtained with the main product due to the application of fertilizers, MJ
• Costs for fertilizers (A0) — total energy expenditures for the application of mineral fertilizers, MJ

The assessment of these indicators requires a strict approach to the methodology of field research. Practical experience always remains the main criterion of truth in agronomy. Only real field trials allow confirming calculations and protecting the farm from errors.

Statistical methods and special terms are necessary to reveal real economic trends and confirm the reliability of the experiment. However, statistics can confuse or create a false sensation if applied incorrectly. It is important for an agronomist to understand the exact meaning of each term so that the results of the calculations have practical meaning.