Manuring and fertilization of mandarins

Manuring and fertilization

        Mandarins, like other citrus fruits also require judicious application of mineral nutrients for proper growth, development and sustained production of high-quality fruits. Mandarins also require micro-nutrients—zinc, copper, manganese, iron, boron and molybdenum—in ample quantities but not sodium and chlorine, which are rather harmful for mandarins. Improper supply of nutrients may cause serious disorders which may lead to orchard decline.

  

         It is very difficult to recommend any single fertilizer schedule for mandarins as fertilizer requirement is guided by soil fertility, previous fertilizer use, nutrients removed by crop, leaching losses and scion cultivar which is further modified by rainfall, temperature, stock-scion combination and age of the tree. There are no scientific recommendations on manuring of young mandarin plants in India. However, application of 20–25kg farmyard manure together with 0.4kg calcium ammonium nitrate is recommended at the time of planting. A mixture of 90g each of N, P, K/tree may be applied in first year after planting. This dose may be gradually increased to 450g each of N and P, and 900g of K/tree in the seventh year and kept constant thereafter.

          Though the nutrient requirement of major elements is met by supplementing N, P, K fertilizers but farmers usually forget about micronutrients, which are the most essential part of citrus nutrition. Although each micronutrient has its typical deficiency symptoms but these are so complicated that it becomes very difficult for an orchardist to identify and correct these. Hence farmers are advised to follow the schedule given in Table 1. The micronutrients should be supplied through foliar spraying. This mixture should be sprayed on major flush of the leaves expanded to at least two-thirds of their normal size.

Nutrient supplement	Quantity (kg)
Zinc sulphate	2.5
Copper sulphate	1.5
Magnesium sulphate	1.0
Manganese sulphate	1.0
Ferrous sulphate	1.0
Boric acid	1.0
Slaked lime	1.0
Urea	4.5
Water	450 litres

(Table . Combined nutritional spray schedule for mandarins)

           Normally young plants are manured once a year, while bearing plants more than once. Total amount of P and K fertilizers is applied at one time, while N fertilizers are applied in 2 or 3 split doses. In north-western India, manures are added twice a year, once during June and another after harvesting in December– January. In central India, mandarins are manured during December for ambe bahar and in May for mrig bahar. However, for Coorg mandarin, manuring thrice (March–April, June–July and September–October) is highly beneficial.

       For soil application, first 30–40cm area around the tree trunk should be given hoeing and fertilizers should be applied in the form of ring. They should be mixed thoroughly. The trees should be irrigated immediately.

           Application of fertilizers with drip irrigation is also beneficial.