اﺛﺮ ﺑﻘﺎﯾﺎي ﭘﻨﺒﻪ، ذرت، ﮔﻨﺪم و ﯾﻮﻧﺠﻪ ﺑﺮ ﻏﻠﻈﺖ آﻣﻮﻧﯿﻮم و ﻧﯿﺘﺮات ﺧﺎك

The effect of cotton, maize, wheat and alfalfa residues on soil ammonium and nitrate concentrations

اﯾﻦ ﺗﺤﻘﯿﻖ ﺑﻪ ﻣﻨﻈﻮر ﺗﻌﯿﯿﻦ اﺛﺮ ﺑﻘﺎﯾﺎي ﮔﯿﺎﻫﯽ ﭼﻨﺪ ﮔﯿﺎه زراﻋﯽ ﺑﺮ ﻣﯿﺰان ﻧﯿﺘﺮوژن ﻣﻌﺪﻧﯽ ﺧﺎك، در ﻗﺎﻟﺐ ﻃﺮح ﺑﻠﻮكﻫﺎي ﮐﺎﻣﻞ ﺗﺼﺎدﻓﯽ در ﭼﻬﺎر ﺗﮑﺮار و ﺷﺶ ﺗﯿﻤﺎر ﺷﺎﻣﻞ ﭼﻬﺎر ﻧﻮع ﺑﻘﺎﯾﺎي ﮔﯿﺎﻫﺎن ﭘﻨﺒﻪ، ذرت، ﮔﻨﺪم و ﯾﻮﻧﺠﻪ، ﮐﻮد اوره ﺑﻪ ﻣﯿﺰان 90 ﮐﯿﻠﻮﮔﺮم در ﻫﮑﺘﺎر و ﺷﺎﻫﺪ اﺟﺮا ﺷﺪ. در ﻣﺮاﺣﻞ ﻣﺨﺘﻠﻒ ﻧﻤﻮ ﺷﺎﻣﻞ ﭘﻨﺠﻪزﻧﯽ، ﺳﺎﻗﻪروي، آﺑﺴﺘﻨﯽ، ﮔﺮدهاﻓﺸﺎﻧﯽ و رﺳﯿﺪﮔﯽ ﻓﯿﺰﯾﻮﻟﻮژﯾﮏ، ﻣﯿﺰان ﻧﯿﺘﺮات و آﻣﻮﻧﯿﻮم ﺧﺎك اﻧﺪازهﮔﯿﺮي ﺷﺪ. ﻣﯿﺰان ﻧﯿﺘﺮات + آﻣﻮﻧﯿﻮم آزاد ﺷﺪه از ﺑﻘﺎﯾﺎي ﯾﻮﻧﺠﻪ و ﮔﻨﺪم ﺑﺎ اﺧﺘﻼف ﻓﺎﺣﺶ در ﻧﺴﺒﺖ ﮐﺮﺑﻦ ﺑﻪ ﻧﯿﺘﺮوژن ﺑﻪ ﺗﺮﺗﯿﺐ ﺑﺮاﺑﺮ 74/7 و 68/2 ﮐﯿﻠﻮﮔﺮم در ﻫﮑﺘﺎر ﺑﻮد. اﺧﺘﻼف ﻧﯿﺘﺮات + آﻣﻮﻧﯿﻮم آزاد ﺷﺪه از ﺑﻘﺎﯾﺎي ﮔﯿﺎﻫﯽ در ﻣﻘﺎﯾﺴﻪ ﺑﺎ ﺗﯿﻤﺎر ﮐﻮد اوره ﻣﻌﻨﯽدار ﻧﺒﻮد. در اﻧﺪازهﮔﯿﺮيﻫﺎي ﻣﺮﺣﻠﻪاي ﮐﻤﺘﺮﯾﻦ ﻣﯿﺰان ﻧﯿﺘﺮات + آﻣﻮﻧﯿﻮم ﺧﺎك در ﻣﺮﺣﻠﻪ ﮔﺮدهاﻓﺸﺎﻧﯽ و ﺑﯿﺸﺘﺮﯾﻦ آن در ﻣﺮﺣﻠﻪي رﺳﯿﺪﮔﯽ ﻓﯿﺰﯾﻮﻟﻮژﯾﮏ ﺑﻪدﺳﺖ آﻣﺪ. ﻧﯿﺘﺮات + آﻣﻮﻧﯿﻮم آزاد ﺷﺪه از ﺑﻘﺎﯾﺎي ﮔﯿﺎﻫﯽ و ﮐﻮد اوره در ﻣﻘﺎﯾﺴﻪ ﺑﺎ ﺗﯿﻤﺎر ﺷﺎﻫﺪ ﻣﻌﻨﯽدار ﻧﺒﻮد. ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻧﺘﺎﯾﺞ، ﻣﻌﺪﻧﯽﺷﺪن ﻧﯿﺘﺮوژن ﺑﻘﺎﯾﺎي ﮔﯿﺎﻫﯽ راﺑﻄﻪي ﻧﺰدﯾﮑﯽ ﺑﺎ اﻓﺰاﯾﺶ دﻣﺎ ﻧﺸﺎن داد. ﺑﻪ ﻃﻮر ﮐﻠﯽ، در ﺻﻮرت ﺗﻮﺟﻪ ﺑﻪ اﻧﻄﺒﺎق زﻣﺎن ﻣﻌﺪﻧﯽ ﺷﺪن ﻧﯿﺘﺮوژن ﺑﺎ ﻣﺮﺣﻠﻪي ﻧﯿﺎز ﮔﯿﺎه، ﺑﻘﺎﯾﺎي ﮔﯿﺎﻫﯽ ﻣﯽﺗﻮاﻧﺪ ﺟﺎﯾﮕﺰﯾﻦ ﻣﻨﺎﺳﺒﯽ ﺑﺮاي ﺑﺨﺸﯽ از ﮐﻮد ﺑﻪ ﻋﻨﻮان ﻣﻨﺒﻊ ﺗﺄﻣﯿﻦﮐﻨﻨﺪهي ﻧﯿﺘﺮوژن ﺑﺎﺷﺪ.

This study was conducted to investigate the effects of crop residues on mineral nitrogen rates of soil using four crop residues of cotton, maize, wheat and alfalfa, urea treatment (90 kg/ha) and control based on completely randomized block design with four replications. N fertilizer (urea) was added to residues, in terms of C/N ratio and calculation of nitrogen factor, before incorporating them into the soil to eliminate immobilization. Values of nitrate and ammonium were measured in different stages including tillering, stem elongation, booting, anthesis and physiological ripening. Total N released from alfalfa and wheat residues were 74.66 and 68.23 kg/ha, respectively. Total N mineralized from crop residues was not significant compared with urea treatment. In stage by stage analyses, the lowest and the highest values of total N were obtained in anthesis and booting stages, respectively. Total mineralized N released from crop residues and urea treatment was not significant. Totally, results revealed that if the trend of N releasing time from residues was matched with crop demand pattern, crop residues could be considered as an appropriate source for providing nitrogen.