“FRACTIONS OF MICRONUTRIENTS IN THE SOILS OF SAURASHTRA REGION OF GUJARAT” 2535
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Date
2018-03
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JAU,JUNAGADH
Abstract
Micronutrients play a vital role in enhancing crop productivity and improving quality of crops. Almost 10 agro-ecological situations of Saurashtra region have been identified which vary in soil resource. Among them, Junagadh is one of the centers representing medium black calcareous soil (Vertic Haplustepts). Therefore, the research work on “Fractions of Micronutrients in the soils of Saurashtra Region of Gujarat” at Department of Agril. Chem. and Soil Science, JAU, Junagadh. To achieve the forgoing objectives whole work is divided in two parts.
The part one (I) comprised regular monitoring of the fertility since 1990. Sampling was made from the soils of predetermined survey number at ten years intervals. The samples of 1990 and 2010 were analysed for fractionation of micronutrients viz., Fe, Mn, Zn and Cu as well as soil pH, soil EC, soil CaCO3, soil CEC, soil Ex.Ca, soil OC, soil clay, soil ESP, soil available nitrogen, soil available phosphorus, soil available potash and soil-heat soluble sulphur for long term changes.
Second part (II) of investigation comprised the samples derived from long term fertilizer experiment initiated 16 years back on (Vertic Haplustepts) medium black calcareous clayey soils of Junagadh. The samples were analysed for fractionation of micronutrients viz., Fe, Mn, Zn and Cu as well as soil properties.
I. SOIL GROUP ANALYSIS :
Status and Depletion :
The status of ferrous was highest in soil group MBLS in year 2010, manganese in soil group CD and DBBT in both years, zinc in soil group SBLS and RAD in both years while copper was highest in soil group RAD and DBBT in 1990 and 2010, respectively. So far as depletion is concerned soil group SBBT registered maximum depletion in iron and manganese, copper in soil group CD and RAD, while zinc displayed a variegated picture.
Correlations :
The DTPA available micronutrients showed strong positive relationship with percent availability thereby rendering its predominance in most of the soil groups with some exceptions. Soil properties showed a variegated picture and different relationships were found to vary in direction and magnitude in various soil groups.
Regressions :
The prediction models were worked out for DTPA available forms as influenced by the other representative forms in the years 1990, 2010 and pooled utilizing the multiple correlation and regression analysis. As in forms, the DTPA available micronutrients as influenced by various soil properties were also subjected to multiple correlation analysis in the year 1990, 2010 and pooled and prediction models were derived. So far as stepwise regression analysis of pooled data is concerned, soil properties could explain the behaviour of DTPA available micronutrients viz., Fe, Mn, Zn and Cu to little extent.
Path Co-efficients :
The path co-efficient analysis of DTPA available micronutrients as influenced by various soil properties revealed that the values of total component were very high in most of soil groups and soil property could explain only a little of the behaviour of DTPA available micronutrients.
II. LONG TERM FERTILIZER EXPERIMENT:
The experimentation on various soil groups of Saurashtra region as well as Long Term Fertilizer Experiment (LTFE) in Junagadh constituting soil group MBBT (Medium black, Trap basalt) clearly indicated that the predominant form of available total iron, zinc and copper was DTPA available form, while in case of manganese it was reducible form. All the four micronutrients viz., iron, manganese, zinc and copper exhibited increase over time in a long run viz., 16 years, especially available ferrous reached below critical levels. Although ferrous is the most abundant element in the earth crust but its’ availability requires suitable management at the earliest in the soils of Saurashtra region. The chemical fertilizers appeared to supplement as well as trigger the utilization of micronutrients. The dynamics of micronutrients alongwith its forms, in general, exhibited gross negative trend with varying magnitude according to soil, climate, agronomy and cropping pattern followed in the region. The combined application of organic and inorganic fertilizers in continuous manner, might have sustain the crop yield.
In light of high residual values in multiple correlation and regression analysis, the soil properties had little influence on DTPA available micronutrients. Based on multiple correlation and regression analysis the prediction model for DTPA available micronutrients are presented. The exchangeable form in case of zinc, manganese and ferrous had the maximum impact on DTPA available form of micronutrients. On the contrary in case of copper total form had the maximum influence on DTPA available ferrous. The picture may slightly vary with the soil groups. The path co-efficient analysis of DTPA available micronutrients as influenced by various forms revealed that total content of micronutrients had a direct positive effect. While residual forms had a direct negative effect which was because of its strong indirect negative effect through total micronutrient content.