滴灌条件下揭膜时间对土壤酶活性及玉米吸氮量的影响

Effects of film-uncovering time on soil enzyme activity and maize nitrogen uptake under drip irrigation

为了了解玉米滴灌水肥试验研究揭膜时间和施肥处理对土壤脲酶活性、天门冬酰胺酶活性及玉米吸氮量的影响,试验设置了3个揭膜时间处理和1个未覆膜处理,每个处理考虑施肥和不施肥情况,共8个处理.研究结果表明:苗期揭膜、抽穗期揭膜和全生育期覆膜均会提高土壤NH4^+-N质量比和含水率,显著降低土壤脲酶活性,各揭膜处理差异不具有统计学意义;不同揭膜时间并不会显著影响土壤天门冬酰胺酶的活性;各揭膜处理可显著提高苗期玉米的吸氮量,但在施肥条件下全生育期覆膜处理却降低玉米吸氮;土壤水热和无机氮的质量比与土壤脲酶差异具有统计学意义,而覆膜下土壤脲酶活性的降低与土壤NH4^+-N和含水率升高有关;土壤天门冬酰胺酶活性与土壤水热和无机氮质量比差异不具有统计学意义;由试验可得东北地区玉米苗期或抽穗期揭膜可使土壤酶活性保持在适宜的活性水平,为玉米生长提供有利的土壤环境.

Effects of film-uncovering time and fertilization on soil urease activity,asparaginase activity and maize nitrogen uptake were studied under drip fertigation conditions to provide theoretical basis and reference for the optimal film-uncovering time of maize with mulched drip irrigation in Northeast China. Three film-uncovering treatments and a bare soil treatment were set in experiment. In each treatment,fertilization and no fertilization were included,thus there were a total of 8 treatments. The results show that the soil urease activity decreases significantly with increasing soil NH4^+-N and moisture in uncovering film treatments in seedling stage,uncovering in heading stage and filming in the whole growth period of maize,but the difference between film-uncovering treatments is not significantly statistical. The asparaginase activity in soil does not change significantly with covering duration. The maize nitrogen uptake can increase significantly in three film-uncovering treatments,but the nitrogen uptake declines in filming treatments in the whole growth period of maize under fertilizing condition. The correlations of soil urease activity with soil water,soil temperature and soil inorganic nitrogen content are significantly statistical,but the urease activity reduces because of the increase of both soil water and NH4^+-N. The soil asparaginase activity does not have a relationship with soil water,soil temperature and soil inorga-nic nitrogen content. Therefore,the film-uncovering treatments in seedling stage and uncovering treatments in heading stage can allow the soil enzyme activity to maintain a suitable activity level and provide a more favorable soil environment for the growth of maize.