The study of Humus levels within soil and it's use as a stabilizer of soil fertility is one of the major concerns of soil science. The Results of this expeditionary study have shown that the humus levels of the Zarafshan Valley has decreased significantly. The data collected showed that rapid and repetitive cultivation of crop fields, especially monoculture crop fields, and applying high amounts of nitrogen fertilizers significantly impacts the humus levels of the soil. It was also shown that planting certain crops (cotton, tobacco, corn for grain, wheat) reduced the humus levels of the soil. However, alfalfa significantly increased the humus levels even in deeper soil depths. In our specific field experiment with carbon-14, it was discovered that with nitrogen fertilizers in doses of 220 kg/ha, the degeneration of alfalfa root into humic acid and fulvoacid decreased. It was also shown that the use of organic fertilizers raised the humus levels in the soil, especially in areas of high elevation. In the very first years of cultivating previously untouched land, the humus levels of these lands significantly decreased. This was due to the increased mineralization of organic matter in this soil. Therefore it should be noted that with respect to cultivation, humus levels of newly cultivated virgin lands will be much lower compared to land that has been cultivated for some time. In a separate study, the mechanical composition of meadow ground changed drastically compared to serozem. It was also seen here that deeper soil depths yielded lower concentration of humus. But it was also seen that rising water tables transformed land into meadowland, and this caused humus levels to be increased in shallow soil depths. Lastly it was noted that the humus levels were greater in soils that were repeatedly cultivated than those that were cultivated less often.