Strategies to Increase Nitrogen and Zinc Use Efficiency for Climate Smart Coastal Soil Nutrient Management

Abstract

India has an 8,129 km long coastline. A vast coastal tract faces a serious problem of soil salinity over an area of 3.1 m ha. Most of the coastal salt-affected soils were deficient in nitrogen (N) and zinc (Zn). N availability in coastal soil was lesser associated with poor mineralization by microbes with an increase in soil salinity. Low organic matter, CEC, and light texture encourage the leaching loss of applied nutrients in these soils. It is generally observed that Zn content in soil decreases with an increase in pH. The uptake of N and Zn by plants in saline soils is also affected by the presence of a high concentration of Cl -1 ions. A sustainable strategy to increase nutrient use efficiency in coastal salt-affected soils includes the addition of amendments and balanced use of organic, inorganic, and biological sources of nutrients. Experiments conducted in coastal saline soils which had pH 8.06, EC 2.48 dS/m, and low status of N and Zn, proved the efficacious nature of INM strategy namely 75% NPK + Azospirillum + Phosphobacterium + Zn enriched humic acid @ 20 kg/ha in significantly increasing the availability of Alkaline KMnO 4 -N, DTPA-Zn and improving the N and Zn use efficiency. Another experiment conducted in coastal sodic soil revealed the usefulness of NPK along with 75% ZnSO 4 fortified coir pith/green leaf manure application in increasing Zn use efficiency. A study conducted in coastal sandy on nitrate leaching and its control showed that the application of NPK along with 40 t clay/ ha + 20 kg/ha of humic acid was efficient in increasing the NH 4 -N and NO 3 -N (Nitrate nitrogen) content in soil and improving the N use efficiency.