SEGH Articles

Enhancing Nutrient Use Efficiency: The Role of Specialty Fertilizers

13 March 2018
The International Fertilizer Association (IFA) held its Task Force and Strategic Forum Meeting in Zurich, Switzerland on Nov 13-15, 2017. The purpose of the meeting was to discuss and prepare the Fertilizer Industry for the challenges foreseen by 2030 along with a special focus on Enhancing Nutrient Use Efficiency: The Role of Specialty Fertilizers. Dr Munir Zia provides SEGH readers with a brief overview of this topic.

Nutrient Use Efficiency (NUE) is defined as yield per unit input. In agriculture this is usually related to the input of fertilizer, whereas in the scientific literature the NUE is often expressed as fresh weight or product yield per content of nutrient. Improvement of NUE is an essential pre-requisite for the expansion of crop production into marginal lands with low nutrient(s) availability. There are many forms of NUE. Four of them are commonly used (source: Hemantaranjan 2013):

1. Partial factor productivity -PFP (crop yield per unit of nutrient applied) tells us how productive the cropping system is in comparison to its nutrient input.

2. Partial nutrient budget –PNB (nutrient in harvested crop per unit of nutrient applied) tells us how much nutrient is taken out of the system in relation to the amount put in.

3. Agronomic efficiency –AE (yield increase per unit of nutrient applied) answers a more direct question: “How much productivity improvement was gained by the use of this nutrient?”

4. Recovery efficiency – RE (increase in above-ground crop uptake per unit of nutrient applied) tells us how much of the nutrient applied was taken up by the plant.

NUE in Pakistan: nitrogenous (N) and phosphatic (P) fertilizer use efficiency are only 30-60% and 15-20%, respectively. Pakistan is ranked lowest among neighboring countries for nitrogenous fertilizer use efficiency (Table 1):


Table 1: nitrogenous (N) fertilizers use efficiency



(million ha)


Mean Cereal Yield


Mean Nitrogen Rate



(kg grain/kg N)


(kg N grain/ kg fertilizer N)

















































Ref.: IPNI-2014

PFP = Partial Factor Productivity of nitrogenous fertilizer; PNB = Partial Nutrient Balance of nitrogenous fertilizer


Table 1 shows comparative nitrogenous fertilizer performance indicators. Pakistan has the lowest NUE computed as Partial Factor Productivity (PFP) - that is 21 kg of cereal grains/kg of N fertilizer. The second indicator (the Partial Nutrient Balance (PNB) - a ratio: kg N recovered/kg of N applied) is also the lowest (0.33%).

The N performance indicators for Pakistan are lowest among countries and even of world average, which suggests imbalanced application of nutrient N with special reference to phosphorus, potassium, and other micronutrient fertilizers. In case of phosphatic fertilizers, agronomic efficiency (AE) for wheat is about 9 kg /kg of applied phosphorus. Such low fertilizer use efficiencies are partially responsible for yield gaps in Pakistan.

Measures to Enhance NUE

i.        Specialty fertilizers – controlled release fertilizers

    ii.        Genetics and management practices assuring maximum economic yields

   iii.        Precision agriculture technologies to sense crop needs and improve application

   iv.        Increased use of on-farm measures evaluating nutrient use efficiency

    v.        Decision support tools applying science at the farm level


Specialty Fertilizers are customized and/or fortified fertilizers developed specifically to enhance NUE, e.g. granular fertilizer particles that help gradual release of fertilizer nutrients to match crop(s) requirements, usually over a few weeks/months (see Figure 1).

 Munir Fertilizer Granule

Figure. 1 Diffusion mechanism of controlled release of Nitrogen from fertilizer granule


Specialty fertilizers are intended to provide the following benefits:

  • INCREASE YIELD with same fertilizer dose
  • MAINTAIN YIELD with lower fertilizer dose
  • INCREASE YIELD with lower fertilizer dose


Specialty fertilizers can be grouped into three categories:

  • Slow and/or controlled release fertilizers (e.g. polymer coated urea)
  • Fortified secondary and micronutrients (e.g. chelated zinc)
  • Customized N-P-K grades; and fully water soluble grades etc. (e.g. N-P-K-S 15:15:15-10)


At present, major multinational fertilizer companies are focusing on development of controlled release fertilizers that can be subdivided into three categories:

  • Organic compounds (e.g., humate coated urea)
  • Water soluble fertilizers with a physical barrier to control the release of nutrients (e.g. polymer urea)
  • Inorganic low solubility compounds (e.g. partially acidulated rock phosphate)


Global Market of specialty fertilizers is projected to reach $20 billion by 2020. Major global players include:

Yara International (Norway)

Agrium Inc. (Canada)

The Mosaic Company (US)

Sinochem Group (China)

Sociedad Quimicay Minera S.A. (Chile)

Haifa Chemicals Ltd. (Israel)

In the US, a premium of 16-35% is charged over such specialty products. Below is a summary of coating materials used to produce Controlled Release Urea Fertilizer on a commercial scale. Until now, no breakthrough has been reported in the controlled release of phosphorus from MAP/DAP/TSP fertilizers.

Table 2: Commercial scale controlled release fertilizers and coating materials

Commercial name

Composition of coating material



Sulfur+wax + diatomaceous earth + coal tar

Tennessee Valley Authority, USA



Polyolefin + inorganic powder

Chisso Co. Kitakysya, Japan

LP30/LPS40/LPSS 100


Chisso-Asahi Fertilizer Corporation


Polymeric material

Agrium Inc. Canada


Polymeric material

Chisso-Asahi Fertilizer Corporation



Haifa Chemicals Ltd. Israel

Zn-coated urea

Zinc oxide

Indo-Gulf Fertilizers, India

Agrium PCU

Polymeric material

Agrium US Inc.

Kingenta PCU

Polymeric material

Shandong Kingenta Ecological Engineering Co. Ltd. China


In Pakistan other than Neem Coated Urea, only three commercial scale fertilizer products (Nurea - sulfur coated urea 36% N; calcium ammonium nitrate; and zinc-coated urea) fall under the category of specialty fertilizers.



Hemantaranjan. A, Physiology of Nutrition and Environmental Stresses on Crop Productivity, Scientific Publishers (2014).



Keep up to date

Submit Content

Members can keep in touch with their colleagues through short news and events articles of interest to the SEGH community.

Science in the News

Latest on-line papers from the SEGH journal: Environmental Geochemistry and Health

  • Geochemistry of uranium and thorium in phosphate deposits at the Syrian coastal area (Al-Haffah and Al-Qaradaha) and their environmental impacts 2019-03-16


    The aim of this research was to study the geochemistry of uranium and thorium in phosphate deposits in the upper Cretaceous phosphate deposits in the Syrian coastal area. The study covered three sites, namely Ain Al-Tenah, Ain Laylon, and Al-Mhalbeh. Petrographical study showed that phosphate deposits are of nodular type with micrit to microspaite cement, containing siliceous bone residues, and green grains of glauconite, which are increasing in abundance and volume in the south toward Al-Mhalbeh, reflecting the formation of phosphate in a shallow marine environment. In addition, uranium concentration varied between 3 and 112 ppm in Ain Laylon, 4.2–17 ppm in Ain Al-Tenah and 5–61 ppm in Al-Mhalbeh. Thorium concentration varied between 0.2 and 7.5 ppm in Ain Laylon, 0.3–1.4 ppm in Ain Al-Tenah and 0.3–4.4 ppm in Al-Mhalbeh. The average Th/U ratio in the collected samples was within the range 0.04–0.08 except for five samples which exceeded the value 0.1. Moreover, the 226Ra/238U ratios are lower than unity in all samples, while the 210Pb/238U ratios ranged between 0.4 and 1.2 and the 210Pb/226Ra ratios were found to be higher than unity. On the other hand, the impact of leaching and mobility of uranium and thorium from deposits to the surrounding agriculture fields in the area has been studied using the Radium Equivalent Activity Index (Raeq). The equivalent radium activity was 102 Bq kg−1 in Ain Al-Tenah, 403 Bq kg−1 in Ain Laylon, 407 Bq kg−1 in Al-Mhalbeh and 749 Bq kg−1 in agricultural soil samples. However, the data reported in this study can be considered as a baseline data for the phosphate deposits at the coastal area.

  • Measurement of radon, thoron and their daughters in the air of marble factories and resulting alpha-radiation doses to the lung of workers 2019-03-15


    Concentrations of radon (222Rn) and thoron (220Rn) were measured in the air of different marble factories by using a nuclear track technique. The influence of the marble dust nature and ventilation on radon and thoron concentrations was investigated. It was observed that measured radon and thoron concentration ranged from 310 to 903 Bq m−3 and 6 to 48 Bq m−3, respectively. In addition, alpha-activities due to the unattached and attached fractions of 218Po and 214Po radon short-lived progeny were evaluated in the marble factories studied. Committed equivalent doses due to the attached and unattached fractions of 218Po and 214Po nuclei were evaluated in the lung tissues of marble factory workers. The dependence of the resulting committed equivalent dose on the concentration of the attached and unattached fractions of the 218Po and 214Po radionuclides and mass of the tissue was investigated. The resulting annual committed effective doses to the lung of marble factory workers due to the attached and unattached fractions of the 218Po and 214Po radionuclides were calculated. The obtained results show that about 80% of the global committed effective doses received by workers in the studied marble factories are due to the attached fraction of the 218Po and 214Po radon short-lived daughters from the inhalation of polluted air. Male workers spending 8 h per day (2080 h per year) in a marble factory receive a maximum dose of 34.46 mSv y−1 which is higher than the (3–10 mSv y−1) dose limit interval given by the ICRP. Good agreement was found between data obtained for the average effective dose gotten by using this method and the UNSCEAR and ICRP conversion dose coefficients.

  • Quantitative health risk assessment of inhalation exposure to automobile foundry dust 2019-03-14


    With a growing awareness of environmental protection, the dust pollution caused by automobile foundry work has become a serious and urgent problem. This study aimed to explore contamination levels and health effects of automobile foundry dust. A total of 276 dust samples from six types of work in an automobile foundry factory were collected and analysed using the filter membrane method. Probabilistic risk assessment model was developed for evaluating the health risk of foundry dust on workers. The health risk and its influencing factors among workers were then assessed by applying the Monte Carlo method to identify the most significant parameters. Health damage assessment was conducted to translate health risk into disability-adjusted life year (DALY). The results revealed that the mean concentration of dust on six types of work ranged from 1.67 to 5.40 mg/m3. The highest health risks to be come from melting, cast shakeout and finishing, followed by pouring, sand preparation, moulding and core-making. The probability of the risk exceeding 10−6 was approximately 85%, 90%, 90%, 75%, 70% and 45%, respectively. The sensitivity analysis indicated that average time, exposure duration, inhalation rate and dust concentration (C) made great contribution to dust health risk. Workers exposed to cast shakeout and finishing had the largest DALY of 48.64a. These results can further help managers to fully understand the dust risks on various types of work in the automobile foundry factories and provide scientific basis for the management and decision-making related to health damage assessment.