控释尿素掺混比例对旱地玉米产量、无机氮含量及氮肥利用率的影响

Effects of blend ratio of controlled-release urea and normal urea on yield,inorganic nitrogen content and nitrogen use efficiency of spring maize in the dryland area of Eastern Gansu Province

【目的】控释尿素一次性轻简化施肥技术应用于陇东旱塬区春玉米生产增产效果显著。本研究从控释尿素与普通尿素掺混施用对玉米产量、土壤无机氮含量、酶活性及氮肥利用率的影响角度,研究其增产机理。【方法】2020—2021年连续两年在陇东旱塬的庆阳市镇原县梧桐村,以‘先玉335’为供试品种开展了玉米田间试验。在施N 225 kg/hm^(2)的前提下,设置5个控释尿素与普通尿素的掺混比例:100%普通尿素(N0:10)、100%控释尿素(N10:0)、30%控释尿素+70%普通尿素(N3:7)、50%控释尿素+50%普通尿素(N5:5)、70%控释尿素+30%普通尿素(N7:3),以不施氮处理(N0)为对照。调查了玉米产量,0—40 cm土层土壤无机氮含量、酶活性,计算了氮肥利用率和籽粒品质。【结果】控释尿素与普通尿素掺混显著增加了玉米穗粒数和百粒重,提高了玉米产量,以N7:3处理两年平均产量最高(16618 kg/hm^(2)),较N0:10、N10:0和N0处理分别增产20.1%、13.6%和55.6%;纯收益和产投比较N0:10处理分别增加了0.71万元/hm^(2)和16.3%,较N10:0处理分别增加了0.55万元/hm^(2)和15.2%。N3:7、N5:5、N7:3比N0:10和N10:0处理显著降低了0—40 cm土层NO_(3)^(-)-N含量,比N0处理显著提高了0—20 cm土层土壤NO_(3)^(-)-N和NH_(4)^(+)-N含量,明显阻隔了NO_(3)^(-)-N向深层淋失。N3:7、N5:5、N7:3比N0:10、N10:0和N0处理降低了秸秆氮积累量,并相应提高了籽粒氮积累量,以N7:3处理效果最显著。随控释尿素掺混比例增加,土壤硝酸还原酶和脲酶活性呈增加趋势,而过氧化氢酶、蔗糖酶、亚硝酸还原酶活性呈下降趋势。与N0:10相比,N10:0、N3:7、N5:5和N7:3均显著提高了氮肥偏生产力、氮肥农学效率、氮肥利用率和肥料贡献率,以N7:3处理的氮肥利用率最高,2年平均为39.3%,较N0:10和N10:0处理平均分别提高33.1%和21.9%。N7:3处理玉米籽粒中赖氨酸含量显著高于其他处理,蛋白质含量也较N0:10、N10:0和N0处理分别提高3.1%、4.0%和5.6%,改善玉米籽粒品质的效果显著。【结论】控释尿素与普通尿素按7∶3掺混基施,可保持玉米整个生育期0—20 cm土层较高的硝态氮含量,减少硝态氮向20—40 cm土层淋失,因此,可显著提高玉米产量、品质、氮肥利用效率和生产效益,是陇东旱塬区适宜的氮素运筹措施。

【Objectives】The basal application of all the fertilizers by using controlled release urea in spring maize in the dryland area of Eastern Gansu Province has demonstrated the satisfactory effect on yield increase.Here we studied the effects of mixed ratio of controlled release urea and normal urea from the points of yield,soil inorganic nitrogen(N)content,and enzyme activity,and the nitrogen use efficiency(NUE)of maize.【Methods】Field experiments were conducted in 2020 and 2021 in Wutong,Zhenyuan county of Eastern Gansu,with the maize cultivar‘Xianyu 335’as test crop.The treatments included no fertilizer(N0),merely common urea(N0:10)and controlled rerelease urea control(N10:0),and the mixed application of controlled release urea and common urea and ratio of 3∶7,5∶5,and 7∶3.Except N0,all the fertilizer treatments had the same N total input(225 kg/hm^(2)).At maturating stage,maize yield,yield components and grain quality were investigated,and the NUE was calculated.The soil samples were collected at the same time for the determination of inorganic N content in 0-40 cm soil layer,and the enzyme activity in 0-20 cm layer.【Results】Compared with N0,all the fertilizer treatments significantly increased maize yield by increasing grain number per ear and 100-grain weight.N5:5 treatment produced the highest average yield(16618 kg/hm^(2)),which was 20.1% and 13.6% higher than N0:10 and N10:0.Compared with N10:0 and N0:10,N7:3 treatment enhanced net income by 7100 yuan/hm^(2) and 5500 yuan/hm^(2),increased output to input ratio by 16.3% and 15.2%.After maize harvest,the NO_(3)^(-)-N contents in 0-40 cm soil layer in the N3:7,N5:5 and N7:3 treatments were lower than N0:10 and N10:0,while the NO_(3)^(-)-N and NH_(4)^(+)-N in 0-20 cm soil layer were higher than N0,showing the blocking effect of NO_(3)^(-)-N leaching.All the N3:7,N5:5 and N7:3 treatments significantly reduced shoot N but enhanced grain N content,compared to N0:10 and N10:0,with the best effect in N7:3 treatment.The nitrate reductase and urease activities tended to increase with the increase of controlled release urea,while the activities of catalase,sucrase and nitrite reductase tended to decrease.Application of controlled release urea significantly increased N partial factor productivity,nitrogen fertilizer agronomic efficiency,nitrogen use efficiency and fertilizer contribution rate to yield.The 2-year average nitrogen fertilizer recovery efficiency of N7:3 was 39.3%,which was 33.1% and 21.9% higher than that of N0:10 and N10:0,respectively.N7:3 was also recorded the highest grain lysine content,and 3.1% and 4.0% higher protein content than N0:10 and N10:0,respectively.【Conclusions】The mix application of controlled-release urea and common urea in ratio of 7∶3 completely as basal fertilizer is effective in maintaining high soil available N content in 0-20 cm layer and preventing the deep leaching of NO_(3)^(-)-N across the whole maize seasons,so improving maize grain yield,quality,and production benefit,increasing nitrogen fertilizer efficiency,7∶3 is a suitable mix ratio for controlled-release urea and common urea for the spring maize production in the Loess Plateau area of Eastern Gansu.