Aging effect of organic and inorganic fertilizers on phosphorus fractionation in a calcareous sandy loam soil
Journal Article
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المجلة \ الصحيفة:
Pedosphere
مستخلص المنشور:
In most arid and semiarid soils, naturally occurring phosphorus (P) is a major yield limiting plant nutrient. In this study, a calcareous sandy loam alkaline soil was fertilized with organic (OP) and inorganic (IP) P sources at low (80 mg P kg−1 soil) and high (160 mg P kg−1 soil) application rates. Three combinations of OP and IP (i.e. 75% OP+25% IP, 50% OP+50% IP and 25% OP+75% IP) at low and high rates were applied followed by soil aging for 21 days. Soil samples were collected after 1, 2, 3, 7 and 21 days, and subjected to sequential extraction to analyze soluble and exchangeable, Fe- and Al-bound, Ca-bound and residual P fractions. Results indicated that soluble and exchangeable P fraction significantly increased up to 24.3%, while Ca-bound fraction decreased up to 40.7% in soils receiving 75% OP+25% IP and 50% OP+50% IP, respectively, compared to control (receiving no P fertilizer source). However, the transformation of P fractions was influenced by aging time. Addition of P sources caused instant changes in different P fractions, which then tended to decline with aging time. Change in soil pH was the limiting factor in controlling P availability. Organic P source at high application rate significantly increased soil P availability as compared to IP source with soil aging. Depending on the P fractionation, a proper combination of OP and IP sources of fertilizers, as long-term slow P releasing and instant P releasing sources for plant uptake respectively, may be a sustainable strategy for meeting the crop P requirements in arid and semiarid soils.