[Effects of farmland use type and winter irrigation on nitrate accumulation in sandy farmland soil].
With the sandy farmland in the marginal oasis in middle reaches of Heihe River Basin, Northwest China as test object, this paper studied soil NO3- -N accumulation and leaching under effects of different farmland use type and winter irrigation. The results showed that the mean NO3- -N concentration in 0-300 cm soil profile in different farmlands ranged from 1.27 mg x kg(-1) to 83.60 mg x kg(-1) Soil NO3- -N concentration was higher in 0-40 cm and 135-300 cm layers, but lower in 40-135 cm layer. Greenhouse vegetable field had a significantly higher soil NO3- -N concentration than the other farmland use types. The accumulated amount of soil NO3- -N decreased in the order of greenhouse vegetable field > tomato field > cotton field > seed maize field > maize-wheat rotation field > maize-wheat stripe intercropping field > alfalfa field > jujube plantation. The NO3- -N accumulation in 0-300 cm soil profile in greenhouse vegetable filed reached 2171.45 kg x hm(-2), which would be a serious menace to groundwater quality, followed by tomato field and cotton field. Lesser accumulation of soil NO3- -N was found in seed maize field, maize-wheat intercropping field, maize-wheat rotation field, alfalfa field, and jujube plantation, but its pollution potential would not be neglected. After winter irrigation, soil NO3- -N concentration decreased in 0-80 cm layer but increased in 80-300 cm layer, indicating that winter irrigation caused NO3- -N leaching into deeper soil depth. The leached amount of soil NO3- -N to deeper layers increased with increasing amount of winter irrigation. To mitigate soil NO3- -N leaching and groundwater contamination, a comprehensive consideration should be made on the rational arrangement of farmland use type, proper decrease of planting N-accumulated crops, and reasonable winter irrigation.
Yang
Rong
R
Linze Inland River Basin Comprehensive Research Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China. yangrong@lzb.ac.cn
Su
Yong-zhong
YZ
D000383:Agriculture / Q000379:methods; D002681:China; D002523:Edible Grain / Q000254:growth & development*; D003368:Gossypium / Q000254:growth & development; D009566:Nitrates / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis; D012621:Seasons; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis*; D014675:Vegetables / Q000254:growth & development*; D014874:Water Pollutants, Chemical / Q000032:analysis
D009566:Nitrates; D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D009584:Nitrogen