| Traditional nitrogen fertilizer used in agricultural production is lost due to volatilization,leaching and other ways,thus greatly reducing the nutrient utilization rate of nitrogen fertilizer.Studies have confirmed that nitrogen fertilizer combined with biochemical inhibitors and extrusion granulation can effectively inhibit nitrogen conversion,reduce nitrogen loss,improve nitrogen use efficiency and increase crop yield.In addition,large number of studies have shown that humic acid can not only promote plant growth,but also effectively improve the utilization rate of fertilizer nutrients.However,there are few studies on the preparation of large-particle fertilizer by extrusion granulation process after mixing biochemical inhibitors and humic acid with conventional fertilizer,and its effect on the transformation of nitrogen form is not clear.Therefore,in order to solve the above problems,this paper added different amounts of dicyandiamide（DCD,0,0.5%,1.0%,1.5%of pure nitrogen）,N-butylthiophosphotriamine（NBPT,0,0.15%,0.30%,0.45%of pure nitrogen）and humic acid（HA,0,10%,15%,20%of pure nitrogen content）,after extrusion granulation process,the preparation of 22-11-11 nutrient ratio of large granular fertilizer.The morphological transformation characteristics of N were explored by indoor constant temperature and humidity culture experiment,and the combination of biochemical inhibitor and humic acid addition with better effect was preliminarily screened.Then,by soil culture experiment and soil column leaching test,to explore its status in different application,different temperature（15℃,25℃and 35℃）and different moisture content（60%field capacity,70%field capacity,80%of field capacity）conditions on the influence of nitrogen transformation,and through the transformation and leaching characteristics of N further filter out the optimal ratio of fertilizer;Finally,the practical application effect of fertilizer combination was verified by pot experiment of Cabbage.The main results are as follows:（1）The addition of 0.5%DCD,0.45%NBPT and 15%humic acid（LTT-8 treatment）could effectively inhibit soil urease activity.Compared with LTT-1,the hydrolysis rate of amide nitrogen was delayed for more than 5 days,and the nitrification of ammonium nitrogen was also inhibited.The content of ammonium nitrogen was higher.The nitrate nitrogen content is low,only 367.55 mg?kg-1.Ammonia volatilization rate is gentle.（2）Ordinary granular fertilizer（CF）,powder fertilizer（PT）mixed with inhibitor and humic acid,large-particle fertilizer（LTT-8）with the best ratio selected at the initial stage and large-particle fertilizer（LPT）coated with inhibitor were used for indoor culture test and soil column leaching test.The results showed that the transformation trend of nutrient forms was similar in all fertilizer treatments under different temperature and water content.The large granular fertilizer coated with inhibitor had higher ammonium nitrogen content and lower nitrate nitrogen content,which could effectively inhibit nitrification and urease activity.The maximum time of amide nitrogen concentration was delayed more than five days compared with CF treatment.The results of soil column leaching test showed that the concentration of NH4+-N and NO3--N in the eluent was the lowest,and the leaching loss of N could be effectively reduced.（3）The effects of different fertilizer treatments on the yield and nutrient content of Chinese cabbage were studied by using CF as control and powder fertilizer with inhibitor and humic acid,large particle fertilizer with inhibitor and humic acid granulation and large particle fertilizer with inhibitor coating as experimental group.The results showed that compared with CF,the fresh weight of abovelground and water content of Chinese cabbage treated with inhibitor and humic acid granulation were increased by 43.59%,579.68%,14.00%,48.28%and139.58%respectively,and the root length was slightly decreased.It also promotes the growth of cabbages. |
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