小麦秸秆浸泡于尿素溶液,通过吸附试验,利用半微量凯式定氮法,研究了小麦秸秆在不同尿素浓度下对氮素的吸附能力。结果表明:小麦秸秆对氮素具有吸附作用,理论最大吸附量为9mg/g纯氮(单位秸秆量的吸氮量),纯氮浓度为150mg/L(常规施肥水平)尿素溶液条件下,其吸附纯氮量达2.4mg/g;第1d内,小麦秸秆主要以吸水途径吸附尿素,1d后其可能以电子吸附和比表面能吸附为主;常规施肥水平下,以1hm2地秸秆还田量达4500kg计,可吸附拦截的纯氮总量约为10.8kg。这为小麦秸秆的还田利用在减少肥料流失方面的作用提供了理论依据。
The adsorption ability of wheat straw to nitrogen element in different concentrations of urea solution was studied by immersing wheat straw in urea solution and using the method of semimicro-kjeldahl determination.The results showed that wheat straw had adsorption ability to nitrogen element,and the theoretical maximum absorption quantity of 1 g wheat straw to pure nitrogen was 9 mg.Under the condition of 150 mg/L pure nitrogen in urea solution,the absorption quantity of wheat straw to pure nitrogen reached 2.4 mg/g.The wheat straw adsorbed nitrogen nutrient mainly by adsorbing water in the first day,and then mainly by electron adsorption and specific surface energy adsorption.At the level of conventional fertilization,when 4500 kg/hm2 wheat straw was returned to the field,around 10.8 kg pure nitrogen could be absorbed by wheat straw.The results could provide the theoretical evidence for returning wheat straw to the field and reducing the loss of fertilizer.