Effect of cropland ecological conditions on soil nutrient and humic acid characteristics of gray desert soil

The experiment compared soil nutrients,pyrolytic and infrared ray spectra characteristics of humic acid of soil between un-cropped and cropped lands to determine the effects of cropland ecosystems on gray desert soil nutrients and humic acid characteristics.The results show increase in soil organic matter,total N,total P,total K,slowly-available K and available N;but decrease in available P and available K,while there is a slight decrease in soil pH after planting.The fatty lateral chain of humic acid in un-cropped land soil is much more than that in cropped land soil.The fat characteristics of the humic acid in un-cropped soil is stronger than that in cropped land soil.Soil humic acid is older under cropland ecosystem conditions.