Citrus nutrition research in India: Current status and future strategies

Abstract

Diagnosis of nutrient constraints and their management are the two pillars of citrus nutrition programme with ultimate objective of fertilizer use efficiency. Leaf analysis-based diagnostic norms emerging through researches on different commercial citrus cultivars have revealed 1.52-2.80% N, 0.09-0.17% P, 0.96-2.59%K, 1.73-3.43% Ca, 0.24-0.69% Mg, 69.5-249.0 ppm Fe, 21.0-87.6 ppm Mn, 2.1-17.6 ppm Cu, and 11.6-62.0 ppm Zn as optimum values. Using diagnosis and recommendation integrated system, nutrient constraint diagnosis can further be made possible at any stage of crop development without loosing the precision of application. The occurrence of cultivarlregion specific multiple nutrient deficiencies in citrus orchards is a common sight depending upon cultivar adopted to specific soil and climate. The fertilizer management of citrus orchards in recent past has found a new look in terms of automated fertigation (fertilizer requirement of 600 g N - 200 g P - 100 g Wtree with basin irrigation reduced to 400 g N - 140 g P - 70 g Wtree through irrigation) organic cultivation through microbially enriched organic manuring, site specific nutrient management (1200 g N - 600 g P - 600 g K-75 g Zn - 30 g B - 75 g Fe - 75 g Mnltreelyear on Typic Ustorthent and 600 g N - 400 g P - 300 g K-75 g Zn - 30 g B - 75 g Fe - 75 g Mnltreelyear on Typic Haplustert) using geostatistically defined soil variability within an orchard and variable rate application technology, all to be integrated to develop a precision-based citriculture, in addition to conventional integrated nutrient management.