A Study on the Effect of Phosphate, Molybdate and Humic acid Application on the Availability of Iron Manganese and Molybdenum in Laterite Soil

Department of Agricultural Chemistry & Soil Science, Bidhan Chandra Krishi Viswavidyalaya, Kalyani-741 235 Manuscript received 17 January 1982, revised 10 February 1986, accepted 8 May 1986 A typical laterite soil of West Bengal was treated with phosphate, molybdate and humic acid singly as well as in combination and incubated at moisture saturation. Both phosphate and humic acid application showed considerable increase in Mo availability. Mo application decreased the DTPA-extractable Fe but increased the available Mn content of the soil. Phosphate application decreased both available Fe and Ma. Humic acid did not change the available Fe content but available Mn content was increased. Combined application of HA —Mo, P—Mo and HA — P as well as P —HA —Mo enhanced availability of Mo and Mn in the soil but available Fe content was found to be depressed. With the increase in incubation period, amount of available Mo and Fe gradually increased but Mn content showed a decreasing trend after initial increase