控释尿素与尿素配施对杭白菊栽培土壤生物学特性的影响

【目的】尿素和控释尿素是杭白菊栽培中常用氮肥,其对杭白菊产量和品质的影响已多有研究,但未见尿素与控释尿素配施对杭白菊栽培田土壤特性的影响研究。【方法】采用大田试验,以施氮量为120 kg/hm2、P5O2106kg/hm2、K2O 189 kg/hm2为基础,设:对照1不施氮肥(CK1);适量施氮肥仅施尿素,50%基施,15%7月15日追施,25%8月15日追施,10%10月15日追施(T1);尿素与控释尿素配施,基施为控释尿素(150 d)与尿素等比例混合基施,施用量占总施氮量的50%,追施为控释尿素(90 d)与尿素等比例混合8月15日追施,施用量占总施氮量的50%(R1)。减量施肥施N量为90 kg/hm2、P5O280 kg/hm2、K2O 142 kg/hm2,也设3个处理:对照不施氮肥(CK2);减量仅施尿素(T2);减量尿素与控释尿素配施(R2)。减量施肥方式同适量施肥。【结果】1)适量施肥土壤有效氮含量高于减量施肥,控释尿素与尿素适量配施、减量配施的土壤有效氮含量分别高于仅施尿素的33.55%、120.35%;2)杭白菊生育期内,适量施肥土壤细菌、真菌数量高于减量施肥。各处理土壤细菌、放线菌数量均呈单峰曲线,细菌最大值出现在7月,放线菌出现在8月。不同适量施氮方式土壤真菌数量呈单峰曲线,减量施肥呈双峰曲线。适量控释尿素与尿素配施土壤细菌、真菌数量比仅施适量尿素分别增加10.39%、39.83%,比减量施肥分别增加46.44%、51.81%;仅施尿素时适量施肥土壤放线菌数量比减量施肥增加127.84%,尿素与控释尿素不同配施量土壤放线菌数量差异不显著;3)减量施肥控释尿素与尿素配施、仅施尿素土壤过氧化物酶活性比相同施肥方式适量施肥分别增加76.79%,164.14%;相同施肥量仅施尿素土壤多酚氧化酶活性高于控释尿素与尿素配施。仅施尿素时适量施肥土壤磷酸酶活性高于减量施肥,尿素与控释尿素配施则反之;施肥方式相同减量施肥土壤脲酶活性高于适量施肥。【结论】适量施肥有利于提高土壤有效氮含量,增加土壤细菌、放线菌数量,控释尿素与尿素配施效果优于仅施尿素;施适量尿素土壤放线菌数量高于减量施肥,控释尿素与尿素配施对土壤放线菌数量影响不显著;控释尿素与尿素适量配施可降低土壤多酚氧化酶和过氧化物酶活性,因此本实验条件下,适量控释尿素与尿素配施有利于维持土壤良好的生态环境。

Effects of combined use of controlled-release urea and conventional urea on biological properties of Chrysanthemum morifolium‘Hangbaiju’

【Objectives】 The conventional urea and controlled-release urea are the commonly used N fertilizers in the cultivation of Chrysanthemum morifolium‘Hangbaiju’. Previous researches about the two fertilizersfocused on their yield and quality effects, fewer on effects of their combined use on the soil biological characteristics. The effects of normal and minimized amount of controlled-release urea combined with conventional urea on the soil biological characteristics were studied in the paper. 【Methods】 Field experiments were carried out with two fertilization levels and six treatments. The suitable fertilization rates of N 120 kg/ha, P₅O₂ 106 kg/ha and K₂O 189 kg/ha, respectively.There were three treatment under suitable fertilization: No N fertilization with suitable application of P and K (CK₁); Suitable rate of single conventional urea(Urea), 50% of N as basal fertilizer, 15% topdressing on 15 July, 25% on 15 August and 10% on 15 October (T₁); Suitable nitrogen amount of controlled-release urea combined with conventional urea(RUrea), 50% of controlled-release urea (control release time 150 days) combined with conventional urea as basal fertilizer, 50% of controlled-release urea(control release time 90 days) combined with conventional urea used as top dressing on 15 August(R₁). Minimized rate of N, P₅O₂ and K₂O were 90, 80 and 142 kg/ha, respectively. The fertilization pattern was the same as suitable fertilization.There were also three treatments under minimized fertilization:No N fertilizer with P₅O₂ and K₂O of 80 and 142 kg/ha, respectively(CK₂); Minimized amount of single conventional urea (T₂); Minimized fertilizer amount with controlled-release urea and conventional urea combined use (R₂). 【Results】 1)The available soil N contents were higher in treatments of suitable fertilizer amount than in minimized fertilizer treatments. Compared with urea, the soil available N contents with RUrea were increased by 33.55% under suitable fertilization, and 120.35% under minimized fertilization, respectively. 2) In all treatments, the population changes of both soil bacteria and actinomyces were in shape of single-peak curve, the highest population of bacteria was in July and that of actinomyces in August. The population changes of fungi in the soil exhibited a mono-peak curve under suitable fertilization, a bimodal curveunder minimized fertilization. Compared with single urea, the population of both bacteria and fungi in the soil treated byRUrea increased by 10.39% and 39.83% under suitable fertilizer amount, respectively, the increase were 46.44% and 51.81% under minimized fertilizer amount. The amount of actinomyces in the soil treated with urea increased by 127.84% under suitable fertilizer amount compared to minimized fertilizer amount, no significant difference between the suitable and minimized fertilization ofRUrea; 3) Under minimized fertilization, the activities of peroxidase increased by 76.79% in the soil treated with theRUrea, and 164.14% in the soil treated with urea compared to suitable fertilization. The activities of soil polyphenol oxidase inurea were greater than RUrea under the same fertilization rate. The activities of soil phosphatase was higher in suitable urea thanin minimized treatment, but on the contrary in the treatments of RUrea. Under the same fertilization pattern, the urease activities in the soil treated by minimized fertilization was greater than by suitable fertilization. 【Conclusions】 Suitable fertilization was favorable to enhance the available nitrogen content, increase soil bacteria and actinomyces population, and the combined use of controlled-release urea with conventional urea has more remarkable effects than single conventional urea. When the fertilizer are the combination of controlled-release urea and conventional urea, there is no obvious difference in the actiomyces population between the suitable and minimized fertilizer amount, but with single conventional urea application, the actiomyces population is obvious higher in the soil treated with suitable fertilization than with minimized fertilization. With controlled-release urea combined with conventional urea, the suitable amount of fertilization decrease the activities of polyphenol oxidase and peroxidase, indicating that suitable fertilization with nitrogen being controlled-release urea combined with conventional urea was favorable to sustain good environment.