Occlusive effect of soil aggregates on increased soil DTPA-extractable zinc under low soil pH caused by long-term fertilization
2013
Guo, Z., Anhui Academy of Agricultural Sciences, Hefei (China). Soil and Fertilizer Research Inst. | Guo, X., Key Laboratory of Nutrient Cycling and Resources Environment, Hefei (China) | Wang, J., Anhui Academy of Agricultural Sciences, Hefei (China). Soil and Fertilizer Research Inst. | Wang, D.Z., Key Laboratory of Nutrient Cycling and Resources Environment, Hefei (China)
To investigate the effect of low soil pH caused by fertilization on soil available zinc in calcareous soil, this study was conducted based on a long-term experiment consisting of: (a) no fertilization (CT); (b) mineral fertilizer application coupled with 7500 kg/ha of wheat straw (WS-NPK); (c) mineral fertilizer application coupled with 3750 kg/ha of wheat straw (1/2WS-NPK); (d) mineral fertilizer application alone (NPK). Long-term fertilization results in a significant increase in soil DTPA-extractable zinc. However, the increased soil DTPA-extractable zinc is unavailable to crops and mainly confined to greater than 0.25 mm and 0.25 mm to 1 mm aggregates. Compared to CT, soil DTPA-extractable zinc under fertilization is more than 9.67% and 122.36% higher in greater than 0.25 mm and 0.25 mm to 1 mm aggregates, respectively. Furthermore, plant-available zinc in the 015 cm soil layer and wheat grain zinc are both significantly positive related to soil DTPA-extractable zinc in greater than 2 mm aggregates. Therefore, plant-available zinc in the 015 cm layer is closely associated with DTPA-extractable zinc in greater than 2 mm aggregates, and the low soil pH caused by long-term fertilization could not enhance plant-available zinc in the surface soil layer nor elevate wheat grain zinc concentration because of the occlusive effect of soil aggregates.
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