Long term effect of cropping systems on the chemical fractions of zinc and copper in alluvial soils of north-west India

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1 An Asian Journal of Soil Science Volume 7 Issue June, 202 Research Article Long term effect of cropping systems on the chemical fractions of zinc and copper in alluvial soils of north-west India MEMBERS OF RESEARCH FORUM : Corresponding author : S.S. DHALIWAL, Department of Soil Science, Punjab Agricultural University, LUDHIANA (PUNJAB) INDIA ssdhaliwal@pau.edu Co-authors : GURPREET SINGH AND U.S. SADANA, Department of Soil Science, Punjab Agricultural University, LUDHIANA (PUNJAB) INDIA BALKARAN SINGH, Department of Agronomy, Punjab Agricultural University, LUDHIANA (PUNJAB) INDIA Received : ; Revised : ; Accepted : Summary The present research study has been conducted with prime objective to investigate the chemical fractions of Zn and Cu under 0 cropping systems in alluvial soils. Surface (0-5 cm) soil samples were collected from an ongoing field experiment (in progress since 2000) with 0 cropping systems at research farm of Department of Agronomy, PAU, Ludhiana. These soil samples were analyzed for total Zn and Cu and their chemical fractions using atomic absorption spectrophotometer (Varion AAS-FS Model). Among chemical fractions, higher levels of Zn (WSEX, SpAd, MnOX and CFeOX) and Cu (WSEX and OM bound) were reported under maize-potato-mungbean and cotton-gobhi sarson cropping systems respectively. Among fractions, SpAd, held on organic sites, oxide bound and amorphous fractions of Zn and Cu contributed towards plant available (water soluble and exchangeable) fractions. Key words : Cropping systems, Micronutrients (Zn and Cu), Chemical fractions How to cite this article : Singh, Gurpreet, Dhaliwal, S.S., Sadana, U.S. and Singh, Balkaran (202). Long term effect of cropping systems on the chemical fractions of zinc and copper in alluvial soils of north-west India. Asian J. Soil Sci., 7():. Introduction The study of various fractions of Zn and Cu present in soil and conditions under which they become available to plants is pre-requisite in assessing their availability to plants. It is important to know the relationship between chemical fractions of micronutrients in the soil and their uptake by the crop. Under continuous cropping system, micronutrients are generally considered to be present in association with soil solution, organic and inorganic solid phases and this association is often referred to as speciation (Behera et al., 2009), thus, forming their various chemical fractions such as water soluble plus exchangeable, specifically absorbed and those associated with free calcium carbonate, oxide surfaces, soil organic matter and minerals. The alternate flooding (reduced stage) in rice and upland (oxidized stage) conditions in wheat effects transformation of Zn and Cu from one chemical form to another (Manchanda et al., 2003). Sekhon et al. (2006) reported that cultivation of rice-wheat continuously for 7 years without any Zn and Cu fertilization did not deplete the amount of micronutrient in various fractions from their original levels. Dhaliwal (2008) reported that green manure and soil applied Mn to rice wheat system increased the DTPA-extractable, water soluble plus exchangeable and Mn specifically adsorbed on the inorganic sites whereas, Mn held on organic sites and oxide bound surfaces decreased. Nayyar and Chhibba (2000) reported the transformation of Zn and Cu under rice-wheat cropping system, they founded that the prevalence of alternative oxidized and reduced condition cause decline in the content of crystalline oxide and reducible amorphous forms of Zn and Cu leading to their increased availability. According to Han and Banin (2000) saturation moisture regimes, results in Zn and Cu transformation from reducible oxide form into exchangeable and carbonate fraction. Distribution of Zn fractions and their contribution towards HIND AGRICULTURAL RESEARCH AND TRAINING INSTITUTE

2 availability and plant uptake of Zn under long term maizewheat cropping system indicated residual Zn as the dominant portion of total Zn (Behera et al., 2008). The results indicate that crop legume rotation can help in amelioration of the problem of Zn and Cu deficiency in soils (Wei et al., 2006). The inclusion of leguminous crop like cowpea increased the levels of Zn and Cu in the soil under different cropping systems (Patel et al., 2009). FYM proved to be the most efficient in enhancing availability of Zn and Cu as compared to GM and leguminous crops used under different cropping systems (Thind et al., 2002). Saha et al. (2000) reported more than 85 per cent of applied Cu was distributed in water soluble plus exchangeable, organic matter and amorphous iron oxide bound fractions and it was due to application of organic matter in soil which mobilized applied Cu from organic matter to amorphous bound fraction and reduced net transformation into residual fraction. Keeping these points in view the present study was planned with the objectives to study the chemical pools of Zn and Cu in the surface soils under different cropping sequences. Resources and Research Methods The experiment was conducted in a fixed layout since its beginning with treatments (cropping systems) combinations mentioned in Table A. Nitrogen (N), phosphorus (P) and potassium (K) fertilizers were applied to different crops as per recommendations given by Punjab Agricultural University, Ludhiana (Package of Practices for Rabi and Kharif crops) (Anonymous., 2009/0). The soil is slightly alkaline in reaction (ph 7.2), normal in soluble salt concentration (EC 0.40 dsm - ), low in OC (0.38 %), low in available nitrogen, medium in available phosphorus and low in available potassium. Sequential extraction procedure to determine chemical pools (fractions) of Zn and Cu in soil samples : The processed surface (0-5 cm) soil samples were taken before sowing Kharif crops used to fractionation of Zn and Cu into following chemical forms as per sequential procedure described below: Water soluble plus exchangeable fraction (WSEX) : Five grams of soil was shaken with 20 ml of M Pb(NO 3 in 00 ml centrifuge tubes for fifteen minutes at 25 0 C in Orbital shaker and mixture was centrifuged for ten minutes at 6000 rpm the supernatant filtered, separated and stored for analysis (Manchanda et al., 2006). The reagent M Pb(NO 3 is prepared by dissolving.65 gm of lead nitrate in one litre adjusting the ph of solution to 6.8 by 0.5M ammonium acetate (NH 4 AC) which is prepared by dissolving 38.5 g of ammonium acetate in litre. Specifically adsorbed (SpAd) : The soil residue from water soluble plus exchangeable fraction was shaken with 20 ml of 0.05M Pb(NO 3 for 2 hours at 25 0 C in orbital shaker and ; the sample was, thereafter, centrifuged ten minutes at 6000 rpm and the supernatant filtered (Iwaski et al., 993). The sequential extraction continued in the remaining of the soil sample. The reagent 0.05 M Pb(NO 3 is prepared by dissolving 6.56 g lead nitrate in one litre adjusting the ph of solution to 6.0 by 0.5M ammonium acetate. Mn-Oxide bound fraction (MnOX) : To the remaining soil sample 20.0 ml of NH 2 OH.HCl (hydroxylamine hydrochloride) 0. mol l -, at ph 2.0 were added, and the mixture was shaken for 30 min, centrifuged and filtered, the separated supernatant was stored for analysis (Chao, 972). The reagent 0. M NH 2 OH.HCl in 0.0M HNO 3 is TableA: Different crops and cropping systems followed in long term experiment Treatments Cropping systems Seasons Kharif Rabi Summer T Rice-Wheat Rice Wheat - T 2 Maize-Wheat Maize Wheat - T 3 Maize-Wheat-Mungbean Maize Wheat Mungbean T 4 Maize-Potato-Mungbean Maize Potato Mungbean T 5 Maize-Potato-Onion Maize Potato Onion T 6 Cotton-Wheat (late sown) Cotton Wheat - T 7 Cotton-African Sarson Cotton African sarson - T 8 Cotton-Gobhi Sarson Cotton Gobhi sarson - T 9 Groundnut-Toria+Gobhi sarson Groundnut Toria+Gobhi sarson - T 0 Groundnut-Potato-Bajra fodder Groundnut Potato Bajra fodder HIND AGRICULTURAL RESEARCH AND TRAINING INSTITUTE 44 Asian J. Soil Sci., (June, 202) 7 () :

3 LONG TERM EFFECT OF CROPPING SYSTEMS ON THE CHEMICAL FRACTIONS OF ZINC & COPPER IN ALLUVIAL SOILS OF NORTH-WEST INDIA prepared by dissolving g of ((hydroxylamine hydrochloride) NH 2 OH.HCl and nitric acid (HNO 3 ) in water and make the volume to one litre. Amorphous Fe-oxides bound (AFeOX ): To the Mn-oxide bound fraction free soil sample 20.0 ml of NH 2 OH.HCl (hydroxylamine hydrochloride) 0. mol L - plus HCl 0.25 mol l -, at ph.3 were added, and the mixture was shaken for 30 min at 25 0 C in orbital shaker, centrifuged and filtered, the separated supernatant was stored for analysis (Chao and Zhau, 983). The reagent 0.25 M NH 2 OH.HCl+0.25 M HCl is prepared by dissolving 7.37 gm of hydroxyl amino chloride (NH 2 OH.HCl) in water and pour 2 ml of hydrochloric acid (HCl) in it and make the volume of solution to one liter. Crystalline Fe-oxides bound (CFeOX) : To the AFeOX free soil sample 20.0 ml of 0.25 M NH 2 OH.HCl M HCl + ascorbic acid 0.0 mol l -, at ph.2 were added, the mixture was heated with boiling water (00 C) in a beaker placed on hot plate for 30 minutes, shaking from time to time; thereafter centrifuged and filtered; the separated supernatant was stored for analysis (Manchanda et al., 2006). The sequential extraction continued in the remaining of the soil sample. The reagent 0.25 M NH 2 OH.HCl M HCl +0. M ascorbic acid is prepared by dissolving 7.37 gm of hydroxyl amino chloride (NH 2 OH.HCl) in water, pour 2 ml of hydrochloric acid (HCl) and 7.6g of ascorbic acid in it and make the volume of solution to one litre. Organically bound fraction (OM) : To the CFeOX free soil sample was shaken with 20 ml of % Na 4 P 2 O 7 for one hour at 25 C in orbital shaker and mixture was centrifuged for ten minutes at 6000 rpm the supernatant filtered, separated and stored for analysis (Raja and Iyengar, 986). The reagent prepared by dissolving 4.46 g of Sodiumpyrophosphate in one liter. Residual fraction (RES) : Residual fraction (cation) = Total content (cation) - sum of all fractions (cation) The amount of Zn and Cu in different fractions was estimated using atomic absorption spectrophotometer. Total Zn and Cu : For total elemental analysis of Zn and Cu a 0.5 gm sample of soil was digested with 5 ml of hydrofluoric acid (HF), ml of perchloric acid (HClO 4 ) and 5-6 drops of nitric acid (HNO 3 ) in a 30 ml capacity platinum crucibles (Page et al., 982). When the soil became completely dry in the crucible the residue in the crucible was completely dissolved in 6 N HCl. The contents of the crucible were transferred to 00 ml volumetric flask with double distilled water. The digests were analyzed for total Zn and Cu after appropriate dilutions with atomic absorption spectrophotometer. The results of the elemental analysis were reported on an oven-dry weight basis. Statistical analysis : Micronutrient cations were subjected to Randomized Complete Block Design analysis of variance. Critical difference (CD) was used to compare the treatments effects at P<0.05.The statistical analysis was done with the help of method described by Panse and Sukhatme (985). Research Findings and Discussion The findings of the present study well as relevant discussions have been presented under following heads: Chemical fractions of Zn : The data presented in Table showed the various Table : Fertilizer application to different crops as per recommendation of package and practices of Kharif and Rabi crops, PAU, Luhiana Crop Variety Recommended dose of fertilizer (kg ha - ) FYM (t ha - ) N P 2O 5 K 2O - Rice PR Wheat PBW Wheat (late sown) PBW Maize Paras Cotton LH Groundnut M Potato Kufri Chandermukhi Gobhi sarson GSL African sarson PC Toria+Gobhi sarson TL-5 + GSL Onion Punjab Naroya Mungbean SML Bajra fodder PCB HIND AGRICULTURAL RESEARCH AND TRAINING INSTITUTE 45 Asian J. Soil Sci., (June, 202) 7 () :

4 chemical fractions of Zn in surface soil samples collected before sowing of Kharif crops in month of May In cotton-wheat cropping system, significantly higher concentration of Zn as 9.2, 4.45, 4.83, 0.6 and 5.2 mg kg - respectively, was observed in the case of WSEX, SpAd, MnOX, AFeOX and CFeOX fractions, respectively, as compared to other cropping systems. On the other hand, significantly higher Zn concentrations were associated with OM (9.92 mg kg - ) under maize-potato-mungbean cropping system. Residual (RES) (79.6 mg kg - ) and total (227.2 mg kg - ) fractions were higher under rice-wheat cropping system as compared to maize-wheat (44.8 and 86.3 mg kg -, respectively) and cotton-wheat (59.7 and 22. mg kg -, respectively) cropping systems. The significantly higher level of Zn in all fractions except WSEX-Zn fraction was observed under rice-wheat cropping system as compared to maize-wheat cropping system. Similar results were observed by Chandi and Takkar (982), who reported that 70 per cent of the total labile Zn remained in the weakly adsorbed Zn and OM-Zn. Cultivation of rice-wheat cropping system continuously for 7 years without any fertilization did not deplete the amount of Zn in various fractions from their original levels (Sekhon et al., 2006). However, application of organic manures resulted in redistribution of Zn from non-available forms (carbonates and CFeOX) to readily available (WSEX) and potentially available (OM, MnOX and AFeOX) forms in soil. In maize based cropping systems, significantly higher level of Zn in WSEX (8.5 mg kg - ), MnOX (4.64 mg kg - ) and AFeOX (0.0 mg kg - ) fractions were observed in maizepotato-mungbean cropping system as compared to maizewheat (5.9, 4.26 and 7.84 mg kg -, respectively) and maizewheat-mungbean (7., 4.3 and 7.84 mg kg -, respectively) cropping system. On the other hand in maize-wheat cropping system, significantly higher levels of Zn were shown by RES (44.8 mg kg - ) and total (86.3 mg kg - ) fractions as compared to other maize based cropping systems (Table 2-5). Interestingly, among maize-wheat (0.2 mg kg - ), maize-wheatmungbean (0.8 mg kg - ) and maize-potato-mungbean (2.4 mg kg - ) systems, maize-potato-onion cropping system reported significantly higher level of CFeOX-Zn (3.6 mg kg - ) fraction. Similar results were observed by Maskina et al. (998), who reported that the increase in WSEX fraction of Zn with FYM amended plots at the end of 5 cycle of rice-wheat rotation. Similarly, Behera et al. (2008) reported that among the various fractions of Zn, RES-Zn was the dominant fraction of total Zn in soil under maize-wheat cropping system. Among Cotton based cropping systems, cotton-wheat showed significantly higher concentration of Zn in all fractions except OM fraction as compared to other cotton based cropping systems. Cotton-gobhi sarson cropping system showed an edge of Zn in WSEX (9.0 mg kg - ), SpAd (4.32 mg kg - ), CFeOX (4.4 mg kg - ) and OM (9.70 mg kg - ) fractions as compared to cotton-african sarson (8.0, 4.04, 4.2 and 9.42 mg kg -, respectively) system. On the other hand higher concentrations of Zn in MnOX (4.55 mg kg - ), AFeOX (9.44 mg kg - ), RES (35.5 mg kg - ) and total (85.7 mg kg - ) fractions were observed in cotton-african sarson cropping system as compared to cotton-gobhi sarson (4.42, 9.20, 5.8 and 66.9 mg kg - respectively) cropping system. Among groundnut based cropping systems, significantly higher levels of Zn were reported in WSEX (5.8 mg kg - ) and SpAd (2.80 mg kg - ) fractions under groundnut-toria+gobhi sarson cropping system as compared to groundnut-potato-bajra (fodder) (5.2 and 2.0 mg kg -, respectively) cropping system. On the other hand significantly higher level of AFeOX-Zn (6.44 mg kg - ) fraction was observed under groundnut-toria+gobhi sarson cropping system as compared to groundnut-potato-bajra (fodder) cropping system. The inclusion of short duration Table 2: Different chemical fractions of Zn in surface soils (0-5cm) under different cropping systems Fractions Treatments WSEX SpAd MnOX AFeOX CFeOX OM RES Total Concentration of Zn (mg kg - ) T T T T T T T T T T Mean C.D. (P=0.05) HIND AGRICULTURAL RESEARCH AND TRAINING INSTITUTE 46 Asian J. Soil Sci., (June, 202) 7 () :

5 LONG TERM EFFECT OF CROPPING SYSTEMS ON THE CHEMICAL FRACTIONS OF ZINC & COPPER IN ALLUVIAL SOILS OF NORTH-WEST INDIA Table 3: Basic properties of experimental soil under different cropping systems Treatments Texture ph EC dsm - OC (%) N P K (kg ha - ) T LS T 2 LS T 3 LS T 4 LS T 5 LS T 6 LS T 7 LS T 8 LS T 9 LS T 0 LS Initial LS Table 4: Different chemical fractions of Cu in surface soils (0-5cm) under different cropping systems Treatments Fractions WSEX SpAd MnOX AFeOX CFeOX OM Residual Total Concentration of Cu (mg kg - ) T T T T T T T T T T Mean C.D. (P=0.05 ) Table 5: Correlation matrix between different chemical fractions of Zn and Cu Zn fractions Different fractions WSEX SpAd MnOX AFeOX CFeOX OM Res. Total SpAd 0.84** MnOX 0.76** 0.89** AFeOX 0.87** 0.84** 0.86** CFeOX 0.90** 0.92** 0.88** 0.89** OM 0.65* 0.83** 0.82** 0.67* 0.79** RES Total * 0.72* 0.69* * 0.97** SpAd -0.2 MnOX ** Cu fractions WSEX SpAd MnOX AFeOX CFeOX OM Res. Total AFeOX CFeOX OM RES * Total * Correlation coefficient significant at 5% = 0.63*, Correlation coefficient significant at % = 0.76** HIND AGRICULTURAL RESEARCH AND TRAINING INSTITUTE 47 Asian J. Soil Sci., (June, 202) 7 () :

6 crops like mungbean, toria and gobhi sarson in main cropping systems helped to increase the levels of Zn in all chemical fractions. Similar results were observed by Chandi and Takkar (982). Chemical fractions of Cu : In rice-wheat cropping system, significantly higher concentration of Cu was observed in WSEX (0.46 mg kg - ), SpAd (0.43 mg kg - ), MnOX (0.57 mg kg - ), AFeOX (0.22 mg kg - ), CFeOX (2.22 mg kg - ) fractions as compared to maizewheat (0.45, 0.22, 0.34, 0.20 and.74 mg kg -, respectively) and cotton-wheat (0.4, 0.5, 0.6, 0.5 and 2.4 mg kg -, respectively) cropping systems (Table 2). Higher content of Cu was reported in these fractions under rice-wheat cropping system which may be due to effect of submergence. On the other hand, the level of OM-Cu (. mg kg - ) fraction was significantly higher in cotton-wheat cropping system as compared to rice-wheat (0.86 mg kg - ) and maize-wheat (0.82 mg kg - ) cropping systems. Significantly higher concentration of Cu as 78.5 and 83.3 mg kg -, respectively,was present in RES and total fractions, respectively, under rice-wheat cropping system as compared to maize-wheat (67.2 and 7.0 mg kg -, respectively) and cotton-wheat (6.7 and 20.9 mg kg -, respectively) cropping systems. The levels of Cu in all fractions except CFeOX and OM fraction were significantly higher in maize-wheat cropping system as compared to cottonwheat cropping system. Similar results were observed by Sekhon et al. (2006), who reported that the cultivation of ricewheat cropping system continuously for 7 years without any fertilization stabilized the amounts of Cu in various fractions from their original levels. Similarly, Saha et al. (2000) and Manchanda et al. (2002) observed that higher content of Cu in AFeOX fraction in soil under rice-wheat cropping system. The significantly higher levels of Cu in WSEX (0.55 mg kg - ), AFeOX (0.24 mg kg - ), CFeOX (2.7 mg kg - ) and OM (.5 mg kg - ) fractions were observed in soil under maizepotato-mungbean cropping system as compared to maizepotato-onion (0.53, 0.3,.90 and.2 mg kg -, respectively), maize-wheat (0.45, 0.20,.74 and 0.82 mg kg -, respectively) and maize-wheat-mungbean (0.40, 0.6,.93 and 0.92 mg kg -, respectively)cropping systems. The higher concentrations of Cu fractions were observed in maize-potato-mungbean cropping system which may be attributed to addition of FYM in soil before sowing of maize and potato crops. Behera et al. (2009) reported that the water soluble Cu was present in surface soil whereas a major portion of Cu was present in the RES form. Among cotton based cropping systems, significantly higher concentration of Cu as 0.62, 0.24, 0.24, 0.2 and.34 mg kg -, respectively, was observed in WSEX, SpAd, MnOX, AFeOX and OM fractions, respectively, under in cotton-gobhi sarson cropping system as compared to cotton-wheat (0.4, 0.5, 0.6, 0.5 and. mg kg -, respectively) and cottonafrican sarson (0.50, 0.20, 0.20, 0.20 and.24 mg kg -, respectively) cropping systems. On the other hand CFeOX- Cu (2.4 mg kg - ) fraction was significantly higher in cottonwheat cropping system as compared to cotton-african sarson (.84 mg kg - ) and cotton-gobhi sarson (.77 mg kg - ) cropping systems. The RES-Cu (38.4 mg kg - ) and total-cu (42.7 mg kg - ) was significantly higher in cotton-gobhi sarson cropping system followed by cotton-wheat (6.7 and 20.9 mg kg -, respectively) and cotton-african sarson (32.0 and 36.3 mg kg -, respectively) cropping systems. Similar results were observed by Agbenin and Henningsen (2004). The levels of RES-Cu (49.9 mg kg - ) and total-cu (42.7 mg kg - ) fractions were significantly higher in groundnut-toria+gobhi sarson cropping system as compared to groundnut-potato-bajra (fodder) (33.0 and 36.2 mg kg -, respectively) cropping system. Similar results were obtained by Maskina et al. (998). Interactions among micronutrient fractions : Results for the relationships between different fractions of Zn and Cu have been presented in Table 6. Significant and positive correlation was observed between WSEX-Zn fraction and SpAd (r = 0.84**), MnOX (r = 0.76**), AFeOX (r = 0.87**), CFeOX (r = 0.90**) and OM (r = 0.65*) fractions of Zn. Similarly, SpAd-Zn fraction was significantly and positively correlated with MnOX (r = 0.89**), AFeOX (r = 0.84**), CFeOX (r = 0.92**), OM (r = 0.83**) and total (r = 0.65*) fractions of Zn, whereas the AFeOX, CFeOX, OM and total fractions of Zn showed positive and significant correlations (r = 0.86**, 0.88**, 0.82** and 0.72*, respectively) with MnOX-Zn fraction. Significant and positive correlations were observed between CFeOX-Zn fraction and OM (r = 0.79**) fraction of Zn. Similarly, significant and positive correlations were also observed between OM-Zn and total (r = 0.75*) fraction of Zn. The SpAd-Cu fraction was significantly and positively correlated with MnOX-Cu (r = 0.95**) fraction. Significant and positive correlation was observed between MnOX-Cu fraction and RES (r = 0.65*) and total (r = 0.66*) fractions of Cu. Conclusion : In cotton-wheat cropping system, significantly higher level of Zn and Cu was observed in WSEX, SpAd, MnOX, AFeOX and CFeOX fractions as compared to other cropping systems. Minimum level of WSEX-Zn was observed in ricewheat cropping system as compared to maize-wheat and cotton-wheat cropping systems. Significantly higher levels of Zn and Cu in WSEX, SpAd, MnOX, AFeOX and OM fractions were reported under maize-potato-mungbean cropping system. Among cotton based cropping systems, significantly higher concentrations of Cu in WSEX, SpAd, MnOX, AFeOX and OM fractions were observed under cotton-gobhi sarson cropping system. Levels of Cu in WSEX, SpAd, MnOX and OM fraction were significantly higher in groundnut-potato-bajra (fodder) cropping system. HIND AGRICULTURAL RESEARCH AND TRAINING INSTITUTE 48 Asian J. Soil Sci., (June, 202) 7 () :

7 LONG TERM EFFECT OF CROPPING SYSTEMS ON THE CHEMICAL FRACTIONS OF ZINC & COPPER IN ALLUVIAL SOILS OF NORTH-WEST INDIA Literature Cited Anonymous (2009/0). Package of Practices for Kharif and Rabi Crops. Punjab Agricultural University, LUDHIANA, PUNJAB (India). Behera, S.K., Singh, D. and Dwivedi, B.S. (2009). Changes in fractions of iron, manganese, copper and zinc in soil under continuous cropping for more than three decades. Commun. Soil Sci. Plant Anal., 40: Behera, S.K., Singh, D., Dwivedi, B.S., Singh, S., Kumar, K. and Rana, D.S. (2008). Distribution of fraction of zinc and their contribution towards availability and plant uptake of zinc under long-term maize (Zea mays L.) - wheat (Triticum astivum L.) cropping on an Inceptisol. Aus. J. Soil Res., 46: Chandi, K.S. and Takkar, P.N. (982). Effects of agricultural cropping systems on micronutrients transformation. Plant Soil, 69: Chao, T.T. (972). Selective dissolution of manganese oxide form soil and sediments with acidified hydroxyl chloride. Soil Sci. Soc. Am. J., 36: Chao, T.T. and Zhau, I. (983). Extraction techniques for selective dissolution of amorphous iron oxide form soils and sediments. Soil Sci. Soc. Am. J., 47: Dhaliwal, S.S. (2008). Different chemical pools of manganese as influenced by submergence, green manure and soil applied manganese under rice wheat system. An. Asian J. Soil Sci., 3: Han, F.X. and Banin, A. (2000). Long-term transformation of Cd, Co, Cu, Ni, Zn, V, Mn and Fe in the native arid-zone soils under saturated condition. Comm. Soil Sci. Plant Anal., 3: Iwaski, K., Yoshikawa, G. and Sakurai, K. (993). Fractionation of zinc in greenhouse soils. Soil Sci. Plant Nutri., 39: Manchanda, J.S., Chhibba, I.M. and Nayyar, V.K. (2003). Transformation of micronutrients under rice-wheat system. In: Singh, Y., Singh, B., Nayyar, V.K., Singh, J., (Ed.). Nutrient management for sustainable rice-wheat cropping system. New Dehli: NATP, ICAR and Punjab, Punjab Agricultural University, LUDHIANA (PUNJAB) India. pp Manchanda, J.S., Nayyar, V.K. and Chhibba, I.M. (2006). Speciation of exchangeable and crystalline of oxide bound Zn, Cu, Fe and Mn ions form calcareous soils during sequential fractionation. Chem. Spec. Bioavail., 8: Manchanda, J.S., Nayyar, V.K. and Chhibba, I.M. (2002). Chemical pools of copper and their availability to rice and wheat as influenced by sodic irrigation. In: National seminar on developments in soil science Indian Soc. Soil Sci., NEW DEHLI, India, pp.33. Maskina M.S., Singh, B., Singh, Y., Baddesha, H.S. and Meelu, O.P. (998). Fertilizer requirement of rice wheat and maize wheat rotation on coarse-textured soils amended with farm yard manure. Fert. Res., 7: Nayyar, V.K. and Chhibba, I.M. (2000). Effect of green manuring on micronutrient availability in rice-wheat cropping system in northwest India in: Long term soil fertility experiments in rice wheat cropping system. Abrol, I.P., Bronson, K.F., Duxbury, J.M. and Gupta, R.K., (Eds) Rice-wheat consortium paper series 6. Ricewheat consortium for indo-gagnetic plains, New Delhi, India, pp Panse, V.G., Sukhatme, P.V. (985). Statistical methods for agricultural workers 4 th Ed. ICAR, NEW DELHI, India. pp Patel, K.P., Swarnkar, P.K. and Singh, M. (2009). Effect of continuous cropping on change in crop productivity, nutrient budgets and soil properties with and without FYM under pearl milletmustard-cowpea cropping system. The nutrition colloquion XVI UC Davis. Raja, M.E. and Iyengar, B.R.V. (986). Chemical pools of zinc in some soils as influenced by sources of applied zinc. J. Indian Soc. Soil Sci., 34: Saha, J.K., Mandal, B. and Mandal, B. (2000). Redistribution of copper in alfisols under submergence. Commun. Soil Sci. Plant Anal., 3: -9. Sekhon, K.S., Singh, J.P. and Mehla, D.S. (2006). Long-term effect of varying nutrient management practices on the distribution of native iron and manganese in various chemical pools under a ricewheat cropping system. Arch. Agron. Soil Sci., 53: Thind, S.S., Singh, M., Sidhu, A.S. and Chhibba, I.M. (2002). Influence of continuous application of organic manures and nitrogen fertilizer on crop yield, N-uptake and nutrient status under maizewheat rotation. J. Res. Punjab Agric. Univ., 39: Wei, X., Hao, M., Shao, M. and Gale, W.J. (2006). Changes in soil properties and the availability of soil micronutrients after 8 years of cropping and fertilization. Soil Tillage Res., 9: ******** ****** **** HIND AGRICULTURAL RESEARCH AND TRAINING INSTITUTE 49 Asian J. Soil Sci., (June, 202) 7 () :