Comprehensive treating effect of gully reclamation project on the nitrogen and phosphorus non-point pollution control in small watersheds
[Background]The gully reclamation project has effectively solved the problems of farmland resource constraints and human-land conflicts on the Loess Plateau,but its interception effect and mechanism on erosion-based non-point source pollution are still unclear.[Methods]Water samples were collected from a typical untreated watershed(Shengli River)and a ditch-cultivated watershed(Gutun River)and an ecological interception ditch(Nangou),and soil samples were collected from typical newly-created lands and adjacent sloping lands,and the nitrogen(N)and phosphorus(P)contents were measured,and the data were processed using Origin and Excel software.[Results]1)The soilN andP content in the newly-created land with continuous cultivation increased,and the N and P content of itscultivated soil layer was significantly higher than that of the sloping land(P＜0.05),and the N infiltration rate of the newly-created land was higher than that of the sloping land.2)The total reduction rates of water total nitrogen(TN),total phosphorus(TP),nitrate nitrogen(NO3--N),and ammonia nitrogen(NH4+-N)by the three-stage ecological interception dam reached 44.3％,94.8％,91.2％,and 46.9％,respectively.3)The runoff in different periods of the sub-basin was ranked as Annual season＞Wet season＞Dry season,which was consistent with the pattern of regional precipitation,and the runoff of the untreated watershed was 29 times of the treated watershed.4)The changes in water TP,TN,NO3--N,and NH4+-N contents in different periods were all ranked as Dry season＞Annual season＞Wet season.5)Compared with the untreated watershed,the treated watershed intercepted the largest amount of TN,followed by NO3--N,and the smallest amount of TP.[Conclusions]The results of the study show that the gully reclamation projectmay intercept the agricultural N and Pnon-point pollution from the source and in the process,which is conducive to improving the efficiency of chemical fertilizer use.
nitrogen and phosphorus non-point pollutiongully reclamation projectsmall watershedecological interception damNangou model
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