Nitrate-N leaching occurs at significantly higher pace in sandy soils, and it can drain out of the root zone in a matter of days. This leached nitrate-N can even reach the aquifer within months, which can be seriously detrimental to ground water quality. 

In a study published in Agricultural Water Management, ZENG Fanjiang's team from Xinjiang Institute of Ecology and Geography of the Chinese Academy of Sciences invented an efficient fertilizer application method: urea side drilling in mud (SDM).

SDM is a simple modification of the conventional top dressing (CTD) technique in which urea is side-drilled in a sludge of sand soon after the infiltration of applied water, rather than applying prior irrigation, because, in muddy condition, still an ample quantity of water remains available to dissolve the applied urea. Thus, SDM can enhance nitrate-N availability in cotton root zone by reducing leaching loss, and maximizes uptake and nitrogen use efficiency in sandy soils. 

Cotton (Gossypium hirsutum L.) is an important oilseed and fiber crop which grows well in well-drained soil. In Xinjiang Uygur Autonomous Region, cotton is widespreadly cultivated. However, most of them grows in coarse textured aeolian sandy soils with high water infiltration potential around the Taklamakan Desert. 

This study sorted out the best possible nitrogen application method for cotton that would reduce leaching and improve nitrogen recovery efficiency in sandy soils under flood/furrow irrigated conditions through evaluating the growth and yield attributes of cotton on sandy soil. It could be beneficial to the study of nitrogen leaching losses management in cotton and other crops grown on sandy soils under conventional flood or furrow irrigated conditions.