|کد مقاله||کد نشریه||سال انتشار||مقاله انگلیسی||ترجمه فارسی||نسخه تمام متن|
|4927442||1431828||2018||5 صفحه PDF||12 صفحه WORD||دانلود کنید|
2. مواد و روشها
2.1. منبع داده ها
2.2. ایجاد مدلهای تحلیل مسیر
2.3. سهم بالقوه هر فرم فسفر در بافر کردن فسفر رزین
3. نتایج و بحث
3.1. ایجاد مدلهای تحلیل مسیر
3.2. تاثیر شخم خاک بر شاخص فسفر فراهم خاک برای گیاه
3.3. پتانسیل فرمهای مختلف فسفر برای بافر کردن فسفر رزین
4. نتیجه گیری
جدول 1. سهم مستقیم بالقوه فرمهای فسفر خاک در بافر کردن فسفر رزین پس از 23 سال سیستمهای بدون شخم
شکل 1. روابط بین فرمهای فسفر خاک در مخازن آلی و غیر آلی در خاک تحت 23 سال سیستم بدون شخم (a) و شخم متداول (b) با خیش زنی و چنگک کشی با دیسک هارو. حبابها نشان دهنده اندازه مخزن فسفر هستند. فلشهای سیاه مسیرهای مهم را نشان می دهند.
- Path analysis improve the understanding of soil P forms and availability in NT and CT.
- CT increase moderate labile organic P contribution to Resin-P due to mineralization.
- Moderate inorganic P was directly linked to Resin-P in NT.
- Resin-P was explained by P that comes from a weak HCl-P extraction, mainly in NT.
- Residual organic and inorganic P fraction were not related to any fraction of P.
Path analysis applied to sequential chemical fractionation of Hedley may improve our understanding on the linkage between P forms and its availability in soils. In this work, we assessed the role of Hedley-P fractions in buffering Resin-P (a plant-available soil P index) in a very clayey Oxisol (720Â gÂ kgâ1 clay) and the validity of the postulated causal models for two long-term (23-yr) tillage systems (conventional-CT and no-till-NT) by path analysis. The model that accounted for the path from the less labile organic and inorganic P fractions to more labile ones, and from these fractions to the Resin-P showed the highest p value in NT (pÂ =Â 0.36) and CT (pÂ =Â 0.05), showing that the proposed models are a plausible representation of the tested causal relationships. These models explained 75 and 93% of Resin-P (UÂ =Â 0.25 and 0.07) in CT and NT systems, respectively. The buffering flux of organic fractions was more pronounced in NT. However, the organic P pool has a higher direct contribution to buffer Resin-P in CT (94%) than in NT (35%), due to higher mineralization of organic P forms with moderate lability caused by soil disturbance. On the other hand, in the long-term NT, moderate inorganic P showed a high contribution to directly buffer Resin-P (40%). Although inorganic P associated with Ca is a very small fraction of P in strongly weathered soils, the path analysis showed that this fraction was a direct source of P in both soil tillage systems, but it was more important source to buffer Resin-P in NT (16.7%) than in CT (1.9%) due to the higher P content and path coefficient of this fraction in NT. Residual organic and inorganic P fraction were not related to any fraction of P, indicating that these fractions were neither a sink nor a source of P in both tillage systems, or that they become a temporary source and sink at the same time in the long-term experiment. The path analysis showed to be an important tool to interpret the results obtained in sequential chemical fractionation of P, improving our understanding of the soil P dynamics in contrasting tillage systems.
Journal: Soil and Tillage Research - Volume 175, January 2018, Pages 276-280