اثر مواد آلي و شوري بر توزيع شكل هاي شيميايي روي در يك خاك آهكي پس از كشت ذرت

Effect of Salinity and Organic Matter on Distribution of Zinc Chemical Forms in a Calcareous Soil after Maize Cultivation

اطلاع از توزيع شكل­ هاي شيميايي روي در خاك­ هاي آهكي جهت شناخت زيست­ فراهمي و تحرك آن ضروري است.ﺑﻪ ﻣﻨﻈﻮر ﺑﺮرﺳﯽ اﺛﺮات ﺷﻮري و ﻣﺎده آﻟﯽ ﺑﺮ ﺷﮑﻞﻫﺎي ﺷﯿﻤﯿﺎﯾﯽ روي در ﯾﮏ ﺧﺎك آﻫﮑﯽ ﺗﺤﺖ ﮐﺸﺖ ذرت، آزﻣﺎﯾﺸﯽ ﻓﺎﮐﺘﻮرﯾﻞ در ﻗﺎﻟﺐ ﻃﺮح ﮐﺎﻣﻼً ﺗﺼﺎدﻓﯽ در ﺳﻪ ﺗﮑﺮار در ﺷﺮاﯾﻂ ﮔﻠﺨﺎﻧﻪ اﻧﺠﺎم ﺷﺪ. ﻓﺎﮐﺘﻮرﻫﺎ ﺷﺎﻣﻞ ﺳﻪ ﺳﻄﻮح ﺷﻮري )0، 15 و 30 ﻣﯿﻠﯽاﮐﯽ واﻻن ﻧﻤﮏ در ﮐﯿﻠﻮﮔﺮم ﺧﺎك( و دو ﻧﻮع ﻣﺎده آﻟﯽ ) ﮐﻮد ﮔﺎوي و ﮐﺎه-ﮐﻠﺶ ﮔﻨﺪم( ﻫﺮ ﮐﺪام در دو ﺳﻄﺢ ) 0 و 2 درﺻﺪ وزﻧﯽ( ﺑﻮد. اﻧﺪازهﮔﯿﺮي ﺷﮑﻞﻫﺎي ﺷﯿﻤﯿﺎﯾﯽ روي از ﻃﺮﯾﻖ روش ﻋﺼﺎرهﮔﯿﺮي دﻧﺒﺎﻟﻪاي ﺳﯿﻨﮓ و ﻫﻤﮑﺎران اﻧﺠﺎم ﺷﺪ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ ﺑﺎ اﻓﺰاﯾﺶ ﺳﻄﻮح ﺷﻮري، ﻏﻠﻈﺖ ﺷﮑﻞﻫﺎي ﻣﺤﻠﻮل+ ﺗﺒﺎدﻟﯽ، ﮐﺮﺑﻨﺎﺗﯽ و اﮐﺴﯿﺪﻣﻨﮕﻨﺰ روي اﻓﺰاﯾﺶ و ﺷﮑﻞ آﻟﯽ ﮐﺎﻫﺶ ﯾﺎﻓﺖ. ﮐﺎرﺑﺮد ﻣﻮاد آﻟﯽ ﺳﺒﺐ اﻓﺰاﯾﺶ ﻏﻠﻈﺖ ﺷﮑﻞﻫﺎي ﻣﺤﻠﻮل+ ﺗﺒﺎدﻟﯽ، ﮐﺮﺑﻨﺎﺗﯽ، آﻟﯽ، ﭘﯿﻮﺳﺘﻪ ﺑﻪ اﮐﺴﯿﺪ ﻣﻨﮕﻨﺰ و اﮐﺴﯿﺪ آﻫﻦ ﺑﻠﻮرﯾﻦ ﺷﺪ. ﮐﺎرﺑﺮد ﺗﯿﻤﺎرﻫﺎي آﻟﯽ درﺻﺪ ﻧﺴﺒﯽ ﺷﮑﻞﻫﺎي ﻣﺤﻠﻮل+ ﺗﺒﺎدﻟﯽ، آﻟﯽ، ﮐﺮﺑﻨﺎﺗﯽ، اﮐﺴﯿﺪ ﻣﻨﮕﻨﺰ و اﮐﺴﯿﺪي آﻫﻦ را اﻓﺰاﯾﺶ و درﺻﺪ ﻧﺴﺒﯽ ﺷﮑﻞ ﺗﺘﻤﻪ را ﮐﺎﻫﺶ داد. ﺗﯿﻤﺎر ﺷﻮري درﺻﺪ ﻧﺴﺒﯽ ﺷﮑﻞﻫﺎي ﻣﺤﻠﻮل+ ﺗﺒﺎدﻟﯽ، ﮐﺮﺑﻨﺎﺗﯽ و اﮐﺴﯿﺪ ﻣﻨﮕﻨﺰ را اﻓﺰاﯾﺶ، و ﺷﮑﻞ ﻫﺎي آﻟﯽ و اﮐﺴﯿﺪ آﻫﻦ ﺑﻠﻮرﯾﻦ را ﮐﺎﻫﺶ داد. ﺑﻨﺎﺑﺮاﯾﻦ ﮐﺎرﺑﺮد ﻣﺎده آﻟﯽ و ﺷﻮري ﺳﺒﺐ ﺗﻮزﯾﻊ ﻣﺠﺪد ﺷﮑﻞﻫﺎي ﺷﯿﻤﯿﺎﯾﯽ روي ﺷﺪ. ﻫﻤﭽﻨﯿﻦ، ﻫﻤﺒﺴﺘﮕﯽ ﻣﺜﺒﺖ و ﻣﻌﻨﯽداري ﺑﯿﻦ ﺷﮑﻞﻫﺎي ﻣﺤﻠﻮل+ ﺗﺒﺎدﻟﯽ، ﮐﺮﺑﻨﺎﺗﯽ، اﮐﺴﯿﺪ ﻣﻨﮕﻨﺰ و اﮐﺴﯿﺪ آﻫﻦ ﺑﺎ روي ﻗﺎﺑﻞ ﺟﺬب در ﺧﺎك وﺟﻮد داﺷﺖ.

Information about forms of zinc (Zn) in calcareous soils is essential for understanding its bioavailability and mobility. To investigate the effects of salinity and organic matter on the chemical forms of Zn in a calcareous soil under maize cultivation, a factorial experiment as completely randomized design with three replications was conducted in greenhouse conditions. Factors included three salinity levels (0, 15 and 30 meq salt kg-1 soil) and two types of organic matter (manure and wheat straw), each of them at two levels (0 and 2 percent). Sequential extraction procedure of Singh et al. was used to measure Zn chemical forms. Results showed that the Zn concentrations of soluble+ exchangeable, carbonatic, mn-oxide fractions were increased and Organic fraction was decresed by increasing of salinity levels. Application of the all organic treatments caused to increase the Zn concentrations of soluble+ exchangeable, carbonatic, organic, mn-oxide and fe-oxide fractions. The Zn concentration of residual fraction in wheat straw treatment was reduced. The relative percentage of soluble + exchangeable, organic, carbonatic, mn-oxide and fe-oxide fractions were increased and residual fraction was decreased by application of all organic treatments. Salinity caused to increase the relative percentage of soluble+exchangeable, carbonatic and mn-oxide fractions and to reduce the organic and crystalline fe-oxide fractions. Therefore, application of salinity and organic matter caused to redistribution of Zn chemical fractions. Also, the available Zn in soil had a positive and significant correlation with soluble+exchangeable, carbonatic, mn-oxide and fe-oxide fractions.