**6. Nanofertilizers advantages over conventional mineral fertilizers**

Mineral nutrients if applied to crops in the form of nanofertilizers hold potential to offer numerous benefits for making the crop production more sustainable and eco-friendly [21]. Some of salient advantages are;


#### **7. Field evidences of nanofertilizers use for sustainable crops production**

The research findings of a field investigation proved in line with the postulated hypothesis where nano nitrogen fertilizers proved instrumental in boosting the productivity of rice. It was inferred that nano nitrogen fertilizer hold potential to be used in place of mineral urea and it can also reduce environmental pollution caused by leaching, de-nitrification and volatilization of chemical fertilizers [22]. Similarly, exogenously applied nutrients as nanomaterials increased the vegetative growth of cereals including barley [23] (man), while in contrast, nanofertilizers applied in conjunction with reduced doses of mineral fertilizers were found to be instrumental in boosting yield attributes and grain yield of cereals [24]. Nanofertilizer of zinc applied as ZnO was found to be instrumental in boosting peanut yield due to robust plant growth, increased chlorophyll content of leaves and significantly better root growth [25]. The growth and yield boosting impact of different nanomaterials is depicted in **Table 1**.

*Sustainable Crop Production*

ways;

which may increase nutrients uptake and reduce losses as well as nutrient toxicity. Nano-sized particles have been prepared from urea, ammonia, peat and other synthetic fertilizers as well as plant wastes. A formulation process involving urea deposition on calcium cyanamide resulted in nano-sized N fertilizer [11]. In another formulation, grinded urea was mixed with different biofertilizers to prepare an effective nanofertilizer to supply nutrients slowly and gradually for a longer period of time [12]. In similar way, ammonium humate, peat and other synthetic materials were mixed to prepare nanosized fertilizers. Mechanical cum biochemical approach is being employed to prepare such nanofertizers where materials are grinded to nanosized particles through mechanical means and then biochemical techniques are put in action to prepare effective nanoscale formulations. In addition, nano-emulsions are also being prepared by adding nanosized colloids to emulsions [13]. In short, fertilizers encapsulation with nanoparticles offers wide perspective for developing plant nutrient sources with greater absorption and nutrient use efficiency. The encapsulation of nutrients with nanomaterials can be performed in three distinct

1.Plant nutrients can be encapsulated within the nanomaterials of varying

2.Nutrient particles may be coated with a thin layer of nanomaterials such as

3.Nutrients may also be delivered in the form of emulsions and particles having

Nanofertilizers have been advocated owing to higher NUE as plants cell walls have small pore sizes (up to 20 nm) which result in higher nutrient uptake [14]. Plant roots which act as the gateways for nutrients, have been reported to be significantly porous to nanomaterials compared to conventional manuring materials. The uptake of nanofertilizers can be improved by utilizing root exudates and molecular transporters through the ionic channels and creation of new micro-pores [15]. Nano-pores and stomatal openings in leaves have also been reported to felicitate nanomaterials uptake and their penetration deep inside leaves. It was concluded that in broad/faba bean (*Vicia faba*), nano-sized particles (43 nm) were instrumental in penetrating deep to leaf interior in large number compared to larger particles of more than 1.0 micrometer size [16]. Similarly, the leaf stomatal radii of Arabian coffee (*C. arabica*) was below 2.5 nm, while that of sour cherry (*P. cerasus*) were also below 100 nm [17] and thus effectiveness of nanofertilizers in enhancing nutrient

Nanofertilizers have also been supported to have higher NUE owing to higher transport and delivery of nutrients through plasmodesmata which are nanosized (50–60 nm) channels for transportation of ions between cells [18]. Carbon nanotubes transported fluorescent dyes to tobacco cells through enhanced penetration of cell membranes and effectively played the role of molecular transporters [19]. The nanoparticles of silica were also instrumental in transporting and delivering

nature and chemical composition.

dimension in the range of nanoparticles.

**5. Biological mechanisms of nanofertilizers action**

different cargoes to target sites in different plants [20].

polymer film.

uptake was suggested.

**296**


#### **Table 1.**

*Impact of nanofertilizers on productivity of different crops under varying pedo-climatic conditions [32–40].*

In agreement to these findings, it was also reported that nanofertilizers of zinc improved the seed production of vegetables [26]. Similarly, nano carbon incorporated fertilizers effectively reduced the days to germination and promoted root development of rice seedling. It was inferred that nano-composites have the potential to promote vital processes such as germination, radicle and plumule growth and development [27]. Another aspect of nanofertilizers was explored regarding crop cycle as nanoparticles which were loaded with NPK, reduced the crop cycle of wheat up to 40 days, while grain yield was also increased in comparison to mineral fertilizers applied at recommended rates [28]. Slow release fertilizer coated with nanoparticles boosted the productivity of wheat-maize cropping system [29]. In addition to soil applied nanofertilizers, foliar application of chitosan was reported to be instrumental in boosting tomato yield by 20%, while it remained non-significant as far as carrot yield was concerned [30]. However, growth promoting effect of foliar applied chitosan was

**299**

been described in **Table 2**.

Nanocarbon + rare earth metals + N

Stevia extract + nanoparticles of Se + organo-Ca + rare-earth elements +

fertilizers

chitosan

**Table 2.**

production are enlisted below.

sustainable crop production.

**8. Limitations of nano fertilizers**

*Nano-Fertilizers for Sustainable Crop Production under Changing Climate: A Global Perspective*

**Nanofertilizers Crops Imparted characteristics**

Nano silicon dioxide Maize Increased leaf chlorophyll.

Nanoparticles of ZnO Chickpea Increased germination, better root

Nano silicon dioxide Maize Drought resistance, increment in lateral root

Nano silicon dioxide Tomato Taller plants and increased tuber diameter.

Nano-TiO2 Spinach Improved vigor indices and 28% increased

Gold nanoparticles + sulfur Grapes Antioxidants and other human health

Bentonite + N-fixing bacteria inoculation Legumes Improved soil fertility and resistance to

Nano-iron slag powder Maize Reduced incidence of insect-pest Nano-iron + organic manures Cotton Controlled release of nutrients acts as an

*Impact of nanofertilizers on different crops under varying pedo-climatic conditions [34–46].*

Colloidal silica + NPK fertilizers Tomato Increased resistance to pathogens.

Polyethylene + indium oxide Vegetables Increased sunlight absorption Polypropylene + indium–tin oxide Vegetables Increased sunlight utilization

Kaolin + SiO2 Vegetables Improved water retention.

development, higher indoleacetic acid

roots number along with and shoot length.

synthesis.

chlorophyll.

benefits.

insect-pest.

status.

Cereals Improved nitrogen use efficiency

Vegetables Enhanced root networking and root diameter.

effective insecticide and improves soil fertility

also recorded for horticultural crops such as cucumber, beet-root etc. The significantly higher selenium uptake by many crops including green tea was observed when it was applied as nanosized particles [31]. There are various other impacts that can be imparted by nanomaterials in different crops and some of these have

Despite offering numerous benefits pertaining to sustainable crop production, nanofertilizers have some limitations regarding research gaps, absence of rigorous monitoring and lack of legislation which are currently hampering the rapid development and adoption of nanoparticles as a source of plant nutrients [47]. A few of the limitations and drawbacks associated to nanofertilizers use for sustainable crop

1.Nano fertilizers related legislation and associated risk management continue to remain the prime limitation in advocating and promoting nano fertilizers for

*DOI: http://dx.doi.org/10.5772/intechopen.89089*

*Nano-Fertilizers for Sustainable Crop Production under Changing Climate: A Global Perspective DOI: http://dx.doi.org/10.5772/intechopen.89089*


#### **Table 2.**

*Sustainable Crop Production*

**298**

peat

**Table 1.**

fertilizer

In agreement to these findings, it was also reported that nanofertilizers of zinc improved the seed production of vegetables [26]. Similarly, nano carbon incorporated fertilizers effectively reduced the days to germination and promoted root development of rice seedling. It was inferred that nano-composites have the potential to promote vital processes such as germination, radicle and plumule growth and development [27]. Another aspect of nanofertilizers was explored regarding crop cycle as nanoparticles which were loaded with NPK, reduced the crop cycle of wheat up to 40 days, while grain yield was also increased in comparison to mineral fertilizers applied at recommended rates [28]. Slow release fertilizer coated with nanoparticles boosted the productivity of wheat-maize cropping system [29]. In addition to soil applied nanofertilizers, foliar application of chitosan was reported to be instrumental in boosting tomato yield by 20%, while it remained non-significant as far as carrot yield was concerned [30]. However, growth promoting effect of foliar applied chitosan was

*Impact of nanofertilizers on productivity of different crops under varying pedo-climatic conditions [32–40].*

**Nanofertilizers Crops Yield increment (%)**

potato

16

Cereals 14.8–23.1

Cereals 3.4–45%

Nanofertilizer + urea Rice 10.2 Nanofertilizer + urea Rice 8.5 Nanofertilizer + urea Wheat 6.5 Nanofertilizer + urea Wheat 7.3 Nano-encapsulated phosphorous Maize 10.9 Nano-encapsulated phosphorous Soybean 16.7 Nano-encapsulated phosphorous Wheat 28.8 Nano-encapsulated phosphorous Vegetables 12.0–19.7 Nano chitosan-NPK fertilizers Wheat 14.6 Nano chitosan Tomato 20.0 Nano chitosan Cucumber 9.3 Nano chitosan Capsicum 11.5 Nano chitosan Beet-root 8.4 Nano chitosan Pea 20

Nanopowder of cotton seed and ammonium fertilizer Sweet

Iron oxide nanoparticles + calcium carbonate nanoparticles +

Sulfur nanoparticles + silicon dioxide nanoparticles + synthetic

Aqueous solution on nanoiron Cereals 8–17 Nanoparticles of ZnO Cucumber 6.3 Nanoparticles of ZnO Peanut 4.8 Nanoparticles of ZnO Cabbage 9.1 Nanoparticles of ZnO Cauliflower 8.3 Nanoparticles of ZnO Chickpea 14.9 Rare earth oxides nanoparticles Vegetables 7–45 Nanosilver + allicin Cereals 4–8.5

*Impact of nanofertilizers on different crops under varying pedo-climatic conditions [34–46].*

also recorded for horticultural crops such as cucumber, beet-root etc. The significantly higher selenium uptake by many crops including green tea was observed when it was applied as nanosized particles [31]. There are various other impacts that can be imparted by nanomaterials in different crops and some of these have been described in **Table 2**.
