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Phytolith‐occluded carbon (PhytOC) has significant potential for long‐term biogeochemical carbon (C) sequestration because of its high resistance against decomposition. It may also play a crucial role in slowing the increase in global CO2 concentrations and mitigating climate warming. As phytolith C sequestration flux is usually correlated with phytolith content, C content of phytoliths and above‐ground net primary productivity in plants, we hypothesize that application of fertilizers may increase phytolith C sequestration in some degraded grasslands. In this study, we conducted a field experiment to investigate the effects of external application of nitrogen (N) at six levels (0, 10, 20, 30, 40, and 50 g N m−2 year−1) from 2011 to 2013 on the potential for phytolith C sequestration in degraded grasslands. Analysis showed that N application increased the PhytOC production flux in the extremely degraded grassland from 0.003 to 0.021 t CO2 ha−1 year−1 and the flux increased with the level of N fertilization peaking in the 20 g N m−2 year−1 treatment at 700 % of the control flux, but decreased at higher N doses. Assuming half of China's grasslands are fertilized with N to recover from degradation and the phytolith C sequestration flux of degraded grasslands amended with N is half of the 700 % increase, the potential of phytolith C sequestration in China's grasslands could be increased at least 60 %. This study demonstrates that optimization of nutritional supply is a promising approach to increase long‐term phytolith C sequestration in degraded grasslands.

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The amygdalin content of four species of stone fruit trees (apricot, peach, plum, and bitter apricot trees) during different stages was investigated by thin-layer chromatography. The results showed that the amygdalin content in the kernel was much higher than in pulps, roots, shoots, or leaves, and the highest amygdalin occurred in bitter apricot kernels. The patterns of amygdalin content in leaves of the four species consisted of a single peak curve, which increased from 30 April to 30 July, then started to decline reaching a lower level in October. In shoot and root, amygdalin decreased dramatically from 15 March to 15 May, then increased slightly until 15 December and maintained a relatively stable value. The tendency of amygdalin in xylem of stem and root was similarly a double peak curve, originally increasing from 15 March to 15 May, then decreasing to a low level, after that increasing slightly until December. However, the patterns of amygdalin content in shoots phloem was distinct from that of the xylem. The amygdalin decreased in shoot phloem whereas it increased in the stem xylem during the stage from 15 March to 15 July. The amygdalin content in root phloem and root xylem showed a similar trend with stem. Results demonstrated that amygdalin content in pulps and kernels was increased with the increasing in the leaves; the decrease in amygdalin in the phloem is connected with the increased in the xylem in early growth period.