| Protected vegetable area of China accounts for over 90%of protected vegetable area of the global.Compared to traditional vegetable cultivation,protected vegetable fertilizer input is greater and nutrient loss is more severe.Ammonia volatilization is one of the main pathways for nitrogen fertilizer loss,causing pollution to the atmosphere,soil,and water environment.Research had shown that replacing nitrogen fertilizer with organic fertilizer or reducing nitrogen fertilizer can reduce ammonia volatilization,and water-saving irrigation can also reduce soil ammonia volatilization.Therefore,on the basis of conventional water and fertilizer management,this article explores the impact of reducing irrigation volume and replacing nitrogen fertilizer with organic fertilizer on ammonia volatilization in protected vegetable fields.The field experiment was conducted in Bomao Tomato Picking Base,Caidian District,Wuhan City.Three irrigation volume gradients were set in the experiment:conventional irrigation volume（100%）,85%of conventional irrigation volume,70%of conventional irrigation volume,and four fertilization methods:no nitrogen fertilizer（CK）,chemical fertilizer（CF）,20%reduction of organic fertilizer（SF）,and organic fertilizer（OF）.There were 12 treatment groups,named CK70,CK85,CK100,CF70,CF85,CF100,SF70,SF85,SF100,OF70,OF85,OF100,respectively.The following results were obtained.（1）Compared with 70%and 85%irrigation,conventional irrigation was beneficial for the normal growth of tomato plants and ensures tomato yield.Under three irrigation levels,the plant length was the largest under conventional irrigation volume;At 70%and 85%irrigation rates,the highest yield of tomato was obtained by applying organic fertilizer（OF）,which was 21390.0 kg/hm2and 23878.5 kg/hm2;When the irrigation amount was 100%of the conventional irrigation amount,the tomato yield obtained by applying fertilizer was the highest,at 26581.5 kg/hm2。（2）As the irrigation amount decreased from 100%to 70%,the soil ammonia volatilization decreased;When applying organic fertilizers,reducing irrigation by 30%had a more significant effect on reducing ammonia emissions than applying chemical fertilizers.Compared with CK100,the cumulative ammonia volatilization of CK85and CK70 decreased by 4.2%and 18.5%,respectively;Compared with CF100,the accumulated ammonia volatilization of CF85 and CF70 decreased by 2.6%and 9.56%,respectively.Compared with SF100,the accumulated ammonia volatilization of SF85and SF70 decreased by 8.0%and 22.6%,respectively.Compared with OF100,the accumulated ammonia volatilization of OF85 decreased by 4.9%and 24.5%,respectively.（3）The substitution of organic fertilizers had reduced the cumulative amount of ammonia volatilization in protected vegetable fields.The average cumulative ammonia volatilization of CK,SF,OF,and CF were 1.2963、1.6558、1.8989 and2.0335 kg NH3/hm2,respectively;Compared with the CF group,the average ammonia volatilization in the SF and OF groups decreased by 18.57%and 6.62%,respectively;At the same irrigation amount,a 20%reduction of organic fertilizer can significantly reduce the accumulation of ammonia volatilization.Compared with CF70 and OF70,the cumulative ammonia volatilization of SF70 decreased by 24.5%and 7.5%,respectively;Compared with CF85 and OF85,The ammonia volatilization of SF85decreased by 20.1%and 20.2%,respectively;Compared with CF100 and OF100,the ammonia volatilization of SF100 decreased by 11.8%and 9.8%,respectively.（4）In the process of tomato cultivation in protected house,the field management method（OF70）that used organic fertilizer instead of chemical fertilizer while irrigating 30%less than conventional irrigation volume was optimal,which can not only reduce the volatile amount of ammonia in the facility vegetable field but also maintain the normal yield of tomato. |
