Effect of fertigation frequency on soil nitrogen distribution and tomato yield under alternate partial root-zone drip irrigation

Alternate partial root-zone drip fertigation (ADF) is a combination of alternating irrigation and drip fertigation,with the potential to save water and increase nitrogen (N) fertilizer efficiency.A 2-year greenhouse experiment was conducted to evaluate the effect of different fertigation frequencies on the distribution of soil moisture and nutrients and tomato yield under ADF.The treatments included three ADF frequencies with intervals of 3 days (F3),6 days (F6) and 12 days (F12),and conventional drip fertigation as a control (CK),which was fertilized once every 6 days.For the ADF treatments,two drip tapes were placed 10 cm away on each side of the tomato row,and alternate drip irrigation was realized using a manual valve on the distribution tapes.For the CK treatment,a drip tape was located close to the roots of the tomato plants.The total N application rate of all treatments was 180 kg ha^(-1).The total irrigation amounts applied to the CK treatment were450.6 and 446.1 mm in 2019 and 2020,respectively;and the irrigation amounts applied to the ADF treatments were 60%of those of the CK treatment.The F3 treatment resulted in water and N being distributed mainly in the 0–40-cm soil layer with less water and N being distributed in the 40–60-cm soil layer.The F6 treatment led to 21.0 and 29.0%higher 2-year average concentration of mineral N in the 0–20 and 20–40-cm soil layer,respectively and a 23.0%lower N concentration in the 40–60-cm soil layer than in the CK treatment.The 2-year average tomato yields of the F3,F6,F12,and CK treatments were 107.5,102.6,87.2,and 98.7 t ha^(-1),respectively.The tomato yield of F3 was significantly higher (23.3%) than that in the F12 treatment,whereas there was no significant difference between the F3 and F6 treatment.The F6 treatment resulted in yield similar to the CK treatment,indicating that ADF could maintain tomato yield with a 40%saving in water use.Based on the distribution of water and N,and tomato yield,a fertigation frequency of 6 days under ADF should be considered as a water-saving strategy for greenhouse tomato production.

微润灌溉下施氮水平对大棚辣椒生长的影响

为探究微润灌溉下施氮水平对植物生长的影响,在大棚内用规格一致的土箱种植辣椒,该试验设置1.5、2 m两个压力水头,3个施氮水平(0、500、1000 mg/L尿素),即有1.5 m压力水头下施氮水平500 mg/L(A处理)、1.5 m压力水头下施氮水平1000 mg/L(B处理)、1.5 m压力水头下施氮水平0 mg/L(C处理)、2 m压力水头下施氮水平500 mg/L(D处理)、2 m压力水头下施氮水平1000 mg/L(E处理)、2 m压力水头下施氮水平0 mg/L(F处理)6个不同处理,每个处理重复试验3次,分析辣椒植株的生长状况以及产量。研究表明:2 m压力水头下大棚辣椒植株的生长状况均优于1.5 m压力水头,相同压力水头下500 mg/L施肥处理下的辣椒植株生长发育状况最好。

微润灌溉下施氮浓度对小白菜生长的影响

为探究微润灌水肥一体化条件下适合大棚小白菜生长的施氮浓度,试验设置在1.5 m压力水头下4个施氮水平0(CK)、200 mg/L(T1)、400 mg/L(T2)、600 mg/L(T3),每组处理重复3次。对不同处理下土壤含水率、小白菜株高、叶面积、鲜重及肥料增产贡献率进行测定分析,在相同压力水头下筛选适合小白菜生长的施氮浓度。结果表明:在微润管埋深15 cm,间距30 cm,压力水头为1.5 m情况下,施氮可以促进小白菜生长,施氮浓度为400 mg/L小白菜生长情况最好。低浓度施氮水平下,小白菜各生长指标随着施氮浓度升高而升高;而高浓度施氮水平对植株生长有抑制作用。作为一种新型灌溉模式,微润灌溉在大田的推广和应用仍需要不断探索和试验。

微润灌溉水肥一体化对空心菜生长的影响

为了探究微润灌溉条件下水肥一体化对空心菜生长的影响,试验设置了2个压力水头处理100 cm(H1)、150 cm(H2)和3个施氮(尿素)水平0 mg/L(N0)、500 mg/L(N1)、1000 mg/L(N2)6个处理。每个处理设置3次重复试验,对不同处理下土壤含水率、空心菜株高、茎粗、鲜重、干物质积累及氮农学效率进行了测定分析,探究不同压力水头和施氮浓度对空心菜生长的影响,筛选适合空心菜生长的较佳组合。结果表明:在微润管埋深20 cm,铺设间距25 cm条件下,150 cm压力水头较100 cm压力水头能促进植株生长发育,施氮浓度为1000 mg/L的处理比500 mg/L的处理空心菜株高、鲜重、干物质积累、氮农学效率明显要高。

“营配”新“玩”法,精准服务开启新纪元

目前,供电企业,特别是县一级的供电企业,配网管理相对比较粗放,各业务部门、各专业人员协同不足,数据录入与管理规范不清,导致了冗余、质量较差等问题。给电网的运行与维护带来许多问题,例如配电停电检修管控统筹度不强、容易产生重复停电等。文章引入电网物联网新技术和手段,探讨如何利用电力物联网,将营配数据通过强化制度标准、数据模型、业务流程等贯通,梳理“变电站-线路-变压器-用户”关系,与公司级主数据的应用与管控相匹配,识别电网薄弱环节,为电网运维的快速响应提供支撑。

SPS制备Zr_(3)Al_(3)C_(5)陶瓷的反应过程和力学性能研究

ZrC陶瓷在高温高压环境下具有较好应用前景,但其韧性低限制了其应用。Zr-Al-C三元层状化合物具有良好的力学性能,因此本文以Zr粉、Al粉、C粉为原料,采用放电等离子烧结技术制备出单相致密的Zr_(3)Al_(3)C_(5)陶瓷,研究了Zr_(3)Al_(3)C_(5)化合物的反应过程和力学性能。结果表明:合成温度为700℃,生成了大量的Zr-Al金属间化合物;当温度达到900℃时,ZrAl3化合物转变为Zr_(2)Al-(3)和ZrAl_(2),同时生成了Al4C3和ZrC化合物;当温度为1300℃时,出现了层状的Zr_(3)Al_(3)C_(5)化合物,但由于Al极易熔融使得局部不均匀,导致在1500℃时形成了Zr_(2)Al-(3)C4化合物,烧结温度达到1700℃时制备出单相致密的Zr_(3)Al_(3)C_(5)陶瓷,其硬度和杨氏模量分别达到了10.9 GPa和310 GPa,断裂韧性为3.8MPa·m^(1/2)±0.16MPa·m^(1/2),这是因为层状结构和细长的晶粒结构使得断裂过程中能量耗散,提高了其断裂韧性。