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As an alternative water sources, piggery wastewater has attracted more and more attention. Study on piggery wastewater irrigation technology is essential for alleviating agricultural water resource deficit, reducing nitrogen fertilization and protecting eco-environment. Based on a field irrigation experiment in reinforced concrete lysimeters, the effects of piggery wastewater and clean water (equal nitrogen inputs) irrigation on soil NH+4-N and NO-3-N variations in time and profiles were studied. The inputs and outputs of nitrogen and the amount of nitrogen mineralization of different treatments were analyzed according to the principle of nitrogen balance. The results showed that the changes of soil ammonium nitrogen with time showed a similar trend to nitrate nitrogen, which had a peak in top-dressing stage at first, and then decreased. Ammonium nitrogen content was decreased with the increase of soil depth, but there was no significant difference in nitrate nitrogen. It can be easily leached and accumulated. Ammonium nitrogen and nitrate nitrogen were slightly decreased in PWH (piggery wastewater with high nitrogen) treatment after top-dressing stage, while the decrease range was more sharply in CKH (clean water and high nitrogen) treatment. PWH treatment was beneficial to the mineralization of organic nitrogen, and crop nitrogen uptake, nitrogen mineralization and nitrate nitrogen leaching amount in PWH treatment were higher than those in CKH treatment with values of 6.91%, 21.29% and 11.82%, respectively.