3. Nano-fertilizers for Balanced Crop Nutrition

Fertilizers play a pivotal role in improving the productivity across the spectrum of crops. The nutrient use efficiencies of conventional fertilizers hardly exceed 30–35 %, 18–20 %, and 35–40 % for N, P, and K which remained constant for the past several decades. Nano-fertilizers intended to improve the nutrient use efficiencies by exploiting unique properties of nanoparticles. The nano-fertilizers are synthesized by fortifying nutrients singly or in combinations onto the adsorbents with nano-dimension. Both physical (top-down) and chemical (bottom-up) approaches are used to produce nanomaterials, and the targeted nutrients are loaded as it is for cationic nutrients (NH₄ ⁺, K⁺, Ca²⁺, Mg²⁺) and after surface modification for anionic nutrients (NO₃ ⁻, PO₄ ²⁻, SO₄ ²⁻). Nano-fertilizers are known to release nutrients slowly and steadily for more than 30 days which may assist in improving the nutrient use efficiency without any associated ill-effects. Since the nano-fertilizers are designed to deliver slowly over a long period of time, the loss of nutrients is substantially reduced vis-a-vis environmental safety. The work done on nano-fertilizers is very limited across the globe, but the reported literature clearly demonstrated that these customized fertilizers have a potential role to play in sustaining farm productivity. This chapter focuses on synthesis and characteristics of macro- and micronutrient carrying nano-fertilizers and their application in achieving balanced crop nutrition.