LONG-TERM EFFECT OF ORGANICS AND FERTILIZERS ON PROPERTIES OF Typic Ustochrept SOIL UNDER BIDI TOBACCO (Nicotiana tabacum L.)
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Date
2002
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AAU, Anand
Abstract
Since last 38 years a long term manurial experiment to study the effect of bulky manures and manurial combinations on soil productivity of Typic Ustochrept is in progress at the Bidi Tobacco Research Station, GAU, Anand. The treatments comprised of bulky manures (No organic manure (N), Green manuring (G), FYM @ 12.5 t ha-1 every year (F1), FYM @ 12.5 t ha-1 in alternate year (F2) and manurial combinations as recommended dose of N (180 kg ha-1) through castor cake (C4), ammonium sulphate (A4), equal amount from both the source (C2A2), recommended dose of NPK (180 + 90 + 135 kg ha-1, respectively) as A4P2K3 and 135 kg N ha-1 through ammonium sulphate along with recommended dose of P2O5 and K2O as A3P2K3. PHYSICAL PROPERTIES The bulk density was significantly decreased, while the water holding capacity was increased due to the application of organic manures over no organic manures. The green manuring and FYM @ 12.5 t ha-1 every year were superior to others in the reduction of bulk density and increase in water holding capacity, respectively. Among manurial combinations A4P2K3 had profound effect over others in lowering the bulk density, while WHC was the highest under C4. The treatment combination F1 x A4P2K3 registered minimum BD. The bulk density and WHC increased with increase in the depth of soil profile. CHEMICAL PROPERTIES The pH was maintained near neutral due to green manuring and application of recommended dose of NPK. The interaction effect showed minimum pH under GM x A4 treatment combination. The EC and cation exchange capacity were increased significantly due to green manuring and application of FYM @ 12.5 t ha-1 every year. Maximum organic carbon content was noted under treatment combination of G X A4P2K3. The total-N content was significantly the highest under FYM @ 12.5 t ha-1 every year at 0-15 and 15-30 cm soil depth. Among manurial combination FYM @ 12.5 t ha-1 in alternate year registered the least total-N. It increased upto 30-60 cm depth of soil profile. The total-P content was the highest under green manuring followed by FYM @ 12.5 t ha-1 every year. Among manurial combinations, A4P2K3 registered the highest value of total-P. However, the interaction effect showed that F1 x A4P2K3 showed the highest total-P, while N x A4 combination recorded the lowest total-P. The different fractions of P were improved by addition of bulky manures. Ca-P fraction contributed more than 50 per cent of total-P. All the fractions of P were increased due to A4P2K3 followed by A3P2K3. The non-exchangeable and total-K were maximum under Fi, while exchangeable-K was maximum under F2. Among manurial combinations, A4P2K3 recorded the highest concentrations of all the fractions at all the depths. The total-K increased with the increase in the depth of soil profile. The total-S content was the highest under FYM @ 12.5 t ha-1 every at all the depths. The highest total-S was registered under A4P2K3 treatment under manurial combinations. It increased upto 15-30 cm and thereafter decreased. The maximum concentration of available and total Fe, Mn, Zn and Cu were noted under FYM @ 12.5 t ha-1 every year followed by its application in the alternate year. Among manurial combinations, A4P2K3 showed the highest available and total micronutrient cations at all the depths, except Zn, which was maximum under A3P2K3 at all the depths. Depth-wise distribution showed that availability of Fe, Mn and Cu was maximum at 15-30 cm and for Zn it was at 0-15 cm. Total-Zn and Mn decreased with the depth of soil profile, while total-Cu was almost the same at all the depths. Cadmium was detected (0.81-1.20 mg kg-1) in plot receiving single superphosphate @ 90 kg P2O5 ha-1 year-1. BIOLOGICAL PROPERTIES Total microbial biomass carbon was the highest in treatment involving green manuring every year followed by FYM @ 12.5 t ha-1 every year. The interaction effect indicated maximum microbial activity in G x A4P2K3 combination. CORRELATION COEFFICIENT The highly significant negative correlation was found between crop yield and bulk density, while WHC showed positive relationship. Similarly, CEC, organic carbon, total-S and microbial biomass carbon also showed positive relationship with crop yield. From the above results it can be concluded that for maintaining the optimum physico-chemical and biological properties of Typic Ustochrept (Inceptisols) soil of middle Gujarat under tobacco crop either it should be green manured or FYM @ 12.5 t ha-1 should be applied every year. Absence of organic manures (green manuring or FYM or Cake) and application of only nitrogen @ 180 kg N ha-1 is likely to deplete soil of micronutrients especially Zn. For monitoring of physico-chemical and biological properties of soil under bidi tobacco crop, samples should be drawn from 0-15 and 15-30 cm depths, as significant association with crop yield and some of the properties was obtained at these depths.
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Agricultural Chemistry and Soil Science, A Study