Abstract: The effect of outersource phosphorus usage and the application ways of humic acid on the content of available phosphorus in gray desert soil were studied in a laboratory. The results show that the content of soil available phosphorus was increased at first and then decreased with the increase of outersource phosphorus usage, and the soil phosphorus fixation rate was increased at first, and then decreased, but increased again with the increase of outersource phosphorus usage. There was a maximum balance point of available phosphorus in soil. The effect of application ways of outersource phosphorus and humic acid on soil available phosphorus content was significant. Soil available phosphorus content could be significantly increased by applying humic acid or outersource phosphorus. The effect of rational application of combining humic acid and outersource phosphorus on soil available phosphorus content was more significant than that by applying outersource phosphorus or humic acid only. Soil available phosphorus content could be increased most effectively by applying outersource phosphorus at first and then humic acid.

Key words: outersource phosphorus, humic acid, application way, gray desert soil, available phosphorus, Manas, Xinjiang