A simulative analysis of influence of precipitation on water leakage and nitrogen leaching in irregated farmland;

In net room,pot experiments were conducted to study the effects of different proportions of organic and inorganic nitrogen(0∶4,1∶3,1∶1,3∶1 and 4∶0) on growth of leaf-used lettuce and soil nitrogen leaching under the same nitrogen application rate.

In the net room,pot experiments were conducted to study the effects of different nitrogen fer- tilizers(urea,ammonium nitrate,ammoumium bicarbonate)on the growth of leaf-used lettuce and the soil nitrogen leaching.

Nitrate leaching in deep unsaturated zone was studied by getting 18 meters soil samples.

Experiment on the nitrogen leaching in the drainage condition of rice field in Ningxia Yinnan irrigation region;

In an undisturbed column experiment,the nitrogen leaching losses in the powder soil and blue clayey paddy soil was studied by applied urea with new nitrification inhibitor 3,4-dimethyl pyrazole phosphate(DMPP).

The advances in the researches on nitrogen leaching from vegetable soils, and effects of the leaching on underground water are reviewed in this paper.

The result shows that the change of nitrogen leaching loss was in the form of wave,and presented 4 times washing peaks on the 10th day,40 days,90 days and about 110 days after transplanting during rape growing season.

The water and nitrogen applications are the two main factors that affect the nitrate leaching on farmland.

Nitrate leaching from ago-ecosystem is an important contributor of nitrate contamination of water resources,which has been extensively concerned by researchers of home and abroad for the recent decade.