**2.1 Nutrient management basics**

Nutrient management involves managing the amount, source, placement, form, and timing of the application of plant nutrients and soil amendments to optimize plant growth and yield while minimizing environmental impact. Integrated nutrient management (INM) is a recommended practice that involves using both organic and inorganic fertilizers to improve soil productivity and crop productivity. This approach, along with the integrated use of major plant nutrients (nitrogen, phosphorus, and potash), organic carbon sources (animal manures and plant residues), and bio-fertilizers (beneficial microbes), has been shown to significantly enhance maize growth, yield, and yield components, as well as grower's income. Conservation agriculture (CA) practices, including zero-till flatbed (ZTFB), permanent beds (PNB), and conventional systems (CT), have also been found to increase farm profits and improve soil properties. Nutrient expert-based application (NE), recommended fertilization (RDF), and farmers' fertilizer practice (FFP) are recommended CA-based nutrient management practices that can further enhance productivity and profitability [2, 6, 16]. Maize production heavily relies on adequate nutrient management, with nitrogen, phosphorus, and potassium being the most critical nutrients. Nitrogen is vital for vegetative growth and grain yield, but its mismanagement can cause environmental problems such as nitrate leaching and greenhouse gas emissions. Various nitrogen management practices, including split applications during planting and vegetative stages, have been found effective in improving maize yields and nitrogen use efficiency. Similarly, phosphorus plays a critical role in root growth, flowering, and grain filling, and its deficiency can result in poor crop quality and reduced yield [17–19]. Phosphorus management practices, such as soil testing and banding phosphorus fertilizers, have been found to enhance phosphorus availability in the soil and improve maize productivity. Additionally, potassium is essential for osmoregulation, enzyme activation, and photosynthesis, and its deficiency can lead to reduced yield and increased susceptibility to biotic and abiotic stresses. Effective potassium management practices include soil testing, potassium fertilizer application, and applying potassium fertilizer at planting and during the vegetative stage. Research has shown that these practices can improve maize yield and potassium use efficiency [4, 20, 21]. Understanding the nutrient requirements of maize, as well as the nutrient content of the soil, is essential to develop a nutrient management plan that balances these needs with available resources.
