S.D. More and H.K. Kausadikar
Department of Agricultural Chemistry and Soil Science, Marathwada Agricultural University, Parbhani - 431 402, Maharashtra State, India
Survey of the Sweet orange growing belt of Marathwada region (Parbhani and Nanded districts) was undertaken to assess the nutritional status of Sweet orange orchards (Cv. Nucellar) in relation to their declining status. Using Diagnosis and Recommendation integrated system (DRIS) norms for soil and leafs were developed for optimum Sweet orange production., Leaf nutrients norms to achieve a yield of 21.78 to 27.95 t ha-1 were, Nitrogen 1.89 to 2.58 per cent, Phosphorus 0.09 to 0.15 per cent and Potassium 1.71 to 2.45 per cent, Calcium 3.25 to 6.59 per cent, Magnesium 0.36 to 0.58 per cent and Sulphur 0.17 to 0.35 per cent. Among micronutrients, Iron 99.46 to 186.42 g g-1, Manganese 16.88 to 40.64 g g-1, Zinc 12.32 to 28.32 g g-1, Copper 3.40 to 7.42 g g-1, Boron 47.87 to 94.97 g g-1 and Molybdenum 0.74 to 1.62 g g-1. To achieve optimum yield of 21.78 to 27.95 t ha-1, DRIS norms for soil parameters viz. pH 7.83 to 8.38, EC 0.40 to 0.68 and organic carbon 5.74 to 8.30 g kg-1 were observed as optimum. DRIS for Soil nutrients were available Nitrogen 76.78 to 162.35 g g-1, available Phosphorus 6.05 to 13.86 g g-1 and available Potassium 230.06 to 447.06 g g-1. Among secondary nutrients, available Calcium 1576.38 to 3743.7 g g-1, available Magnesium 483.8 to 1157.6 g g-1 and available Sulphur 18.35 to 26.35 g g-1. Among micronutrients, DTPA extractable Iron 2.76 to 11.23 g g-1, Manganese 8.04 to 26.74 g g-1, Zinc 1.31 to 3.66 g g-1, Copper 1.78 to 4.49 g g-1, hot water soluble Boron 0.33 to 0.55 g g-1 and Molybdenum 0.19 to 0.42 g g-1. Study indicated low Iron, Zinc and Nitrogen in large number of orchard soils. Although, many orchards were low in soil nutrients, the status was expressed neither in leaf content nor in forms of deficiency symptoms due to hidden hunger.