The accumulation of ten nutrient ele-ments of RA system at tree layer was 2214. 22 kg/hm2, which was 1. 46 times of PP system.是什么意思_The accumulation of ten nutrient ele-ments of RA system at tree layer was 2214. 22 kg/hm2, which was 1. 46 times of PP system.在线翻译_英语_读音_用法_例句