Department of Plant Sciences

Mango is the one of the least profitable crop in India. Micronutrient disorders are important causes of low productivity of Mango in India (6.5 t/ha). The semi arid climate and the high soil pH, free CaCO3, low soil organic matter are some of the causes for these disorders. Zinc, manganese, iron deficiencies have been recorded in Mango in various agro ecological zones. Due to the huge tree, size and 2 –3 vegetative flushes in a year and the immobile nature of nutrients, foliar spray is not very effective. Soil application by conventional methods has not proved effective due to the reaction of the applied micronutrient fertilizers with soil of high pH or free CaCO3 and due to the low efficiency of applied Zn, Fe and Mn (Morvedt,1980). Hence an innovative method using the rhizosphere acidifying nature of neem cake a product from neem (Azadiracta indica) available in India was used a decoction of neem cake 5% with 1% ammonium sulphate had the potential to release NH+4 – 10nos due to nitrification inhibiting property of neem cake. This resulted in localized acidity and released the Zn, Fe and Mn available in the alfisols in which Mango is grown in the semi arid tropics. Continuous application of. of micronutrients soil results in heavy metal enrichment and costly. Hence a LEISA initiative (Low external input for sustainable agriculture was attempted). A field experiment conducted in Cv. Alphonso (Age 15 years) grown in a soil of pH 7.2 indicated spot drenching of neem cake decoction in the active root zone (3 metre from trunk in 25 cm band) once in 15 days for three times resulted in reduction of pH to 5 .8 doubling the Zn, Fe and B from the 0.72 ppm, 2.8 and 6.2 and 0.43 mg/kg in the untreated control to 0.84,7.2, and 0.68 mg/kg in treated spots. This increased the leaf Zn,Fe,B from 12,30, and 14 mg/kg in untreated control to 26, 58 and 62 mg/kg in treated trees within year of treatment.