اثر حذف ماده آلي بر قابليت دسترسي و رهاسازي پتاسيم غيرتبادلي در خا كهاي لسي استان گلستان

The impact of soil organic matter (SOM) removal on availability and release of non-exchangeable potassium (NEK) in loessial soils of Golestan province)

چكيده 1 همانند اجزاي معدني خاك، مواد آلي خاك 1 2 نيز نقش مهمي را در شيمي خاك ايفا مي كند . رفتار خاك ها تحت تاثير نوع و ميزان ماده آلي موجود در آ ن هاست، تجزيه مواد آلي موجود در خاك ها مهم ترين عامل توليد اسيدهاي آلي در خاك، كه باعث هوازدگي كاني هاي رسي (منبع عمده پتاسيم غيرتبادلي) و رهاسازي پتاسيم غيرتبادلي مي شوند، مي باشد. علاوه بر مقدار پتاسيم غيرتبادلي ، سرعت رهاسازي و در دسترس قرار گرفتن اين جز از پتاسيم در طول دوره رشد گياه نيز از اهميت ويژه اي برخوردار مي باشد. اين آزمايش به صورت فاكتوريل با طرح پايه كاملا تصادفي در 3 تكرار انجام شد . فاكتور اول شامل 4 سري خاك غالب استان گلستان و فاكتور دوم شامل تيمار شاهد، حذف ماده آلي با ماده آلي (NaOCl) آب اكس يژنه و هيپوكلريت سديم بود . نتايج نشان داد كه هيپو كلريت سديم بيش تري را نسبت به آب اكسيژنه حذف كرد، كه بيانگر توانايي كم تر آب اكسيژنه در حذف ماده آلي مي باشد. ميزان رها سازي پتاسيم غيرتبادلي از خاك ها، در حضور و بدون حضور ماده آلي تعيين شد . نتايج آزمايش هاي سينتيكي نشان د اد كه ميزان كل پتاسيم غيرتبادلي رها شده از خاك ها در هر سه تيمار پس از پايان زمان عصاره گيري در سري علي آباد بيش ترين بود . كم ترين ميزان رهاسازي پتاسيم غيرتبادلي در تيمار شاهد مربوط به سري كردكوي و در دو تيمار حذف ماده آلي مربوط به سري دلند بود. در تيمار حذف ماده آلي با آب اكسيژنه در مقايسه با تيمار شاهد ، پتاسيم بيش تري از همه خاك ها رها شد ، برعكس در تيمار حذف با هيپوكلريت سديم نسبت به شاهد ، پتاسيم كم تري رها سازي شد . بنابراين ماده آلي اثرات مستقيم و غير مستقيمي بر ميزان شكل هاي شيميايي پتاسيم و همچنين سينتيك رهاسازي آن دارد. واژ ههاي كليدي: پتاسيم، ماده آلي، اسيدهاي آلي، سينتيك رهاسازي

Abstract1 Soil organic matters (SOM) like soil mineral components also play an important role in soil chemistry. Soils responses are affected by the type and quantity of SOM. Decomposition of SOM is the most important factor in the production of acids in soil, which cause weathering of clay minerals (main resource of NEK) and releasing NEK. Besides the NEK quantity, the rate of potassium release and its availability in plant growth period are significantly important. The experiment was carried out as a factorial in completely randomized design including two factors, with three replications. First factor included four dominant soil series of Golestan province and the second factor contained blank, removal of SOM through H2O2 and NaOCl treatments. The results showed that NaOCl removed more SOM than H2O2. This means that H2O2 has less ability in the removal of SOM. The rate of NEK release was determined in soils with and without SOM. Kinetic experiments results indicated that total quantity of NEK from the soils in all treatments was maximum in Aliabad series at the end of extraction. The rates of NEK release were minimum at blank in Kordkoy series and in both SOM removed treatments in Daland series. More K was released in all soils in H2O2 removed treatment; whereas less K was released in NaOCl treatment. Consequently, SOM has direct and indirect effects on the chemical forms of K quantity and its kinetic release. Keywords: Potassium, SOM, Organic acids, Kinetic releaseAbstract1 Soil organic matters (SOM) like soil mineral components also play an important role in soil chemistry. Soils responses are affected by the type and quantity of SOM. Decomposition of SOM is the most important factor in the production of acids in soil, which cause weathering of clay minerals (main resource of NEK) and releasing NEK. Besides the NEK quantity, the rate of potassium release and its availability in plant growth period are significantly important. The experiment was carried out as a factorial in completely randomized design including two factors, with three replications. First factor included four dominant soil series of Golestan province and the second factor contained blank, removal of SOM through H2O2 and NaOCl treatments. The results showed that NaOCl removed more SOM than H2O2. This means that H2O2 has less ability in the removal of SOM. The rate of NEK release was determined in soils with and without SOM. Kinetic experiments results indicated that total quantity of NEK from the soils in all treatments was maximum in Aliabad series at the end of extraction. The rates of NEK release were minimum at blank in Kordkoy series and in both SOM removed treatments in Daland series. More K was released in all soils in H2O2 removed treatment; whereas less K was released in NaOCl treatment. Consequently, SOM has direct and indirect effects on the chemical forms of K quantity and its kinetic release. Keywords: Potassium, SOM, Organic acids, Kinetic release