| Aiming at the problems of excessive application of organic fertilizer and chemical fertilizer and unreasonable ratio of organic and inorganic in open field of Ningxia Yellow River irrigation District,taking open field vegetable heart as the test crop,using the method of field infiltration pool in-situ monitoring test and indoor analysis and statistics,under the condition of micro-spraying,the total amount of conventional fertilizer（CON）,Fertilizer reduction 20 full amount of organic fertilizer（RN）and fertilizer reduction 30 increase 1/3 organic fertilizer（MRN）three kinds of fertilization measures for open field vegetable soil nitrogen leaching,inorganic nitrogen accumulation and the influence of vegetable heart yield,make clear open field vegetable nitrogen leaching and inorganic nitrogen migration law,put forward based on the yield,environment and economic benefits of open field vegetable heart organic fertilizer replacement fertilizer ratio,provide theoretical support for the green production of yellow vegetable heart in Ningxia irrigation area.The main results are as follows:（1）There is a significant positive correlation between the amount of sprinkler irrigation and the amount of leaching water of 0-90 cm soil（P<0.05）.the higher the amount of sprinkler irrigation,the higher the amount of leaching water.Different fertilization measures had no significant effect on the leaching water of vegetable fields under sprinkler irrigation.when the amount of sprinkler irrigation accumulated more than 71.73 mm after planting,the soil water was leached to the soil layer below 90 cm,resulting in soil nitrogen leaching.（2）the nitrogen application amount was significantly positively correlated with the nitrogen concentration in 0-90 cm soil leaching water（P<0.05）,and the higher the nitrogen application amount was,the higher the nitrogen concentration in leaching water was.Different fertilization measures had a significant effect on nitrogen leaching,RN and MRN treatment significantly reduced the annual soil total nitrogen,nitrate nitrogen and ammonium nitrogen leaching,the average decreased 36.87%,23.68%and 59.26%,respectively.The soil nitrate nitrogen and ammonium nitrogen leaching amount accounted for 23.03%～65.51%and 0.12%～0.42%of total nitrogen leaching respectively under the annual 3 season open field vegetable core planting,indicating that nitrate nitrogen was the main form of nitrogen leaching in micro-sprayed open field vegetable core soil.（3）During the annual period,the total nitrogen and nitrate nitrogen leaching loss was the highest after 15-20 days of open field planting,and the ammonium nitrogen leaching process was slow and hysteresis.The soil total nitrogen and nitrate nitrogen leaching loss were both in the second quarter>the third quarter>the first quarter,and the total nitrogen leaching loss in the second quarter accounted for 35.6938.04 of the total annual nitrogen leaching loss.Ammonium nitrogen leaching loss was in the third quarter>the first quarter>the second quarter.（4）RN and MRN treatment significantly reduced the accumulation of inorganic nitrogen in 0-120 cm soil layer of open field,with an average decrease of 28.45%and 37.98%respectively.The total amount of inorganic nitrogen accumulated in 0-120 cm soil treated in 3 seasons was the same as that in total nitrogen leaching.The higher the accumulation of inorganic nitrogen in soil,the greater the risk of nitrogen leaching.The accumulation of inorganic nitrogen in 0-120 cm soil showed a trend of first decreasing and then increasing,and gradually moved to deep soil.the peak of nitrate nitrogen accumulation in 0-20 cm soil reached 198.16 kg·hm-2.（5）Different fertilization measures had no significant impact on the yield of open field vegetable heart.RN and MRN treatment could promote the absorption and utilization of nitrogen,phosphorus and potassium nutrients in vegetable heart,which was conducive to the formation of economic yield of vegetable heart.compared with the average yield of 8.84%,the average cost saving and efficiency of 0.62 million yuan·hm-2 were increased respectively.To sum up,the total amount of nitrogen,phosphorus,potassium and organic fertilizer applied to maximize the yield,environment and economic benefits of vegetable heart in 3 seasons is N 268.5 kg·hm-2,P2O5 99.5 kg·hm-2,K2O 157.5 kg·hm-2 and 12,000 kg·hm-2 respectively. |
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