تغییرات کیفیت خاک‌هایی با رژیم‌های رطوبتی مختلف در اثر کشت و کار: با تاکید بر کیفیت فیزیکی خاک

ﻋﻤﻠﯿﺎت ﮐﺸﺎورزی ﻣﯽﺗﻮاﻧﺪ ﭘﯿﺎﻣﺪﻫﺎﯾﯽ زﯾﺎن ﺑﺎر ﺑﺮ ﮐﯿﻔﯿﺖ ﺧﺎکﻫﺎ داﺷﺘﻪ ﺑﺎﺷﺪ. آﮔﺎﻫﯽ از ﺗﻐﯿﯿﺮات زﻣﺎﻧﯽ ﮐﯿﻔﯿﺖ ﺧﺎک در اراﺿﯽ ﮐﺸﺎورزی ﺑﺮای ﻣﺪﯾﺮﯾﺖ ﺑﻬﯿﻨﻪ زﻣﯿﻦﻫﺎ و رﺳﯿﺪن ﺑﻪ ﺑﯿﺸﯿﻨﻪ ﺑﻬﺮهوری اﻗﺘﺼﺎدی ﺿﺮوری اﺳﺖ. در اﯾﻦ ﭘﮋوﻫﺶ، ﺑﺮﺧﯽ وﯾﮋﮔﯽﻫﺎی ﻓﯿﺰﯾﮑﯽ ﭼﻬﺎر ﺧﺎک زراﻋﯽ ﺑﺎ ﺧﺎکﻫﺎی ﺷﺎﻫﺪ ﻏﯿﺮزراﻋﯽ ﻫﻤﺠﻮار آنﻫﺎ ﻣﻘﺎﯾﺴﻪ ﮔﺮدﯾﺪ. در ﻫﺮ ﻣﻨﻄﻘﻪ ﻣﻮرد ﻣﻄﺎﻟﻌﻪ، ﭼﻬﺎر ﻧﻤﻮﻧﻪ ﺧﺎک (ﺷﺎﻣﻞ دو ﻧﻤﻮﻧﻪ ﺧﺎک زراﻋﯽ و دو ﻧﻤﻮﻧﻪ ﺧﺎک ﻏﯿﺮزراﻋﯽ ﻣﺠﺎور آن) اﻧﺘﺨﺎب ﮔﺮدﯾﺪ. ﺣﺴﺎﺳﯿﺖ ﺑﻪ ﺗﺸﮑﯿﻞ ﺳﻠﻪ، ﻣﻨﺤﻨﯽ رﻃﻮﺑﺘﯽ ﺧﺎک، ﺗﻮزﯾﻊ اﻧﺪازه ذرات و ﻣﻨﺎﻓﺬ ﺧﺎک، ﻣﻘﺎوﻣﺖ ﻣﮑﺎﻧﯿﮑﯽ، ﻣﻘﺪار رﻃﻮﺑﺖ در دﺳﺘﺮس و ﻣﻘﺪار ﺗﺨﻠﺨﻞ ﺗﻬﻮﯾﻪای، ﻇﺮﻓﯿﺖ زراﻋﯽ ﻧﺴﺒﯽ، ﮔﻨﺠﺎﯾﺶ آب اﻧﺘﮕﺮاﻟﯽ اﻧﺪازهﮔﯿﺮی ﺷﺪﻧﺪ. ﺑﻪ ﻃﻮر ﮐﻠﯽ در اراﺿﯽ ﺗﺤﺖ ﮐﺸﺖ، ﻣﻘﺪار ﻣﻮاد آﻟﯽ ﺧﺎک (1/81 در ﺑﺮاﺑﺮ 2/70 درﺻﺪ)، ﭘﺎﯾﺪاری ﺳﺎﺧﺘﻤﺎن ﺧﺎﮐﺪاﻧﻪﻫﺎ (5/2 در ﺑﺮاﺑﺮ 7/4)، ﻣﻨﺎﻓﺬ رﯾﺰ (0/28 در ﺑﺮاﺑﺮ 0/39)، رﻃﻮﺑﺖ ﻇﺮﻓﯿﺖ زراﻋﯽ (0/27 در ﺑﺮاﺑﺮ 0/34) و ﻧﻘﻄﻪ ﭘﮋﻣﺮدﮔﯽ داﯾﻢ (0/15 در ﺑﺮاﺑﺮ 0/20) و آب ﻗﺎﺑﻞ دﺳﺘﺮس ﮔﯿﺎﻫﺎن (0/11 در ﺑﺮاﺑﺮ 0/15) ﻧﺴﺒﺖ ﺑﻪ اراﺿﯽ ﻏﯿﺮزراﻋﯽ ﮐﺎﻫﺶ ﯾﺎﻓﺖ (0/05≥ p). ﺑﺎاﯾﻦ ﺣﺎل، ﻓﺮاواﻧﯽ ﻣﻨﺎﻓﺬ درﺷﺖ (0/39 در ﺑﺮاﺑﺮ 0/23) و ﺣﺴﺎﺳﯿﺖ ﺑﻪ ﺗﺸﮑﯿﻞ ﺳﻠﻪ (0/70 در ﺑﺮاﺑﺮ 0/57) در اراﺿﯽ ﺗﺤﺖ ﮐﺸﺖ اﻓﺰاﯾﺶ ﻧﺸﺎن داد (0/05≥ p). ﻣﯽﺗﻮان ﻧﺘﯿﺠﻪ ﮔﺮﻓﺖ ﮐﻪ ﻋﻤﻠﯿﺎت ﮐﺸﺖ و ﮐﺎر، ﻣﻮﺟﺐ ﮐﺎﻫﺶ ﮐﯿﻔﯿﺖ و ﻓﺮوﺳﺎﯾﯽ ﺧﺎک ﻣﯽﮔﺮدد و ﺿﺮوری اﺳﺖ ﺑﺎ ﻣﺪﯾﺮﯾﺖ ﻣﻨﺎﺳﺐ از ﺗﺎﺛﯿﺮات ﻧﺎﻣﻄﻠﻮب آن ﺟﻠﻮﮔﯿﺮی ﺷﻮد.

Changes in quality of soils with contrasting moisture regimes as affected by cultivation: with an emphasis on soil physical quality

Agricultural practices may decline the quality of soils. Knowing the temporal changes of soil quality in the agriculture lands is crucial for optimal management of lands and to achieve the maximum economic efficiency. In this study, some physical characteristics of four cultivated soil were compared with neighboring noncultivated soils as control treatments. A given site, four soil samples (including two soil samples from cultivated lands and the two soil samples from adjacent noncultivated lands) were collected. Soil structural stability, soil moisture retention curves, particle size distribution and porosity of soil, mechanical strength, plant available water and aeration, relative field capacity, integral water capacity was measured. In the cultivated lands, soil structural stability, macroporosity and field capacity were decreased, while the microporosity and soil sensitivity to crusting were increased compared with the uncultivated lands. It could be concluded that agricultural practices decline the soil quality that should be avoided by proper soil management.