生态沟渠对小流域农田排水中氮磷的拦截效果研究

农田养分大量流失已成为农业面源污染的主要来源之一,研究自然降雨排水条件下生态沟渠对稻作区小流域农田排水中氮(N)、磷(P)的拦截效应具有重要意义。以流入湘北津市市毛里湖区的生态沟渠为研究对象,连续2年系统研究多级植物组合截留后N、P的沿程变化规律及拦截效率。结果表明:生态沟渠对稻作区小流域农田排水中TN、NH4^+-N、NO3^--N和TP均有一定的拦截净化作用。2016年和2017年生态沟渠对农田排水中TN平均拦截率分别为58.49%、47.61%,对NH4^+-N平均拦截率分别为77.29%、69.72%,对NO3^--N平均拦截率分别为58.77%、47.79%,对TP平均拦截率分别为67.07%、54.47%。总体认为,生态沟渠能有效拦截农田排水中N、P,减轻周围环境受纳水体的污染负荷。

生态沟渠吸收氮磷效果研究

采用模拟沟渠试验,研究了9种水生植物吸收氮磷能力的差异,并选择氮磷吸收能力较好品种构建生态沟渠和氧化塘,研究其氮磷吸收效果。结果表明,种植水生植物后模拟沟渠水中氮磷残留量显著减少,美人蕉、狐尾藻、珍珠梅、海寿花和茭白的生物量高,氮磷的吸收量大,其中种植美人蕉和狐尾藻效果最佳。农田排水中氮磷通过生态沟渠水生植物吸收后浓度显著降低;主沟总氮、可溶性氮和总磷浓度平均降低39.6%、40.1%和36.9%;支沟总氮、可溶性氮和总磷浓度可再平均降低6.6%、10.3%和13.6%;氧化塘总氮和总磷浓度可再降低17.7%和13.3%。生态沟渠可有效拦截水体氮磷,具有净化水质的良好生态效益。

控释尿素减少双季稻田氨挥发的主要机理和适宜用量

【目的】研究施用控释尿素减少稻田氨挥发的主要机理,及有效减少氨挥发的施用量,为充分发挥控释尿素的环保效应提供参考。【方法】盆栽试验于2017年在湖南农业大学试验基地大棚内进行,供试土壤为潮砂泥田水稻土,供试早稻、晚稻品种为中早39和泰优390,供试控释氮肥为树脂包膜控释尿素。设置不施氮肥(CK)、普通尿素(U)以及控释尿素等氮量(CRU1)、减氮10%(CRU2)、减氮20%(CRU3)和减氮30%(CRU4)6个处理。采用密闭室间歇通气法监测双季稻田氨挥发特征,监测同期田面水铵态氮(NH4+-N)和硝态氮(NO3--N)浓度、pH值及土壤温度动态变化。【结果】施用控释尿素(CRU)显著降低了稻田氨挥发损失,各施氮处理稻季氨挥发累积损失量表现为U>CRU1>CRU2>CRU4≈CRU3。与U处理相比,CRU处理明显降低了氨挥发速率峰值,且不同程度减少了稻田氨挥发累积损失量,减排程度可达50.3%~70.1%。CRU处理氨挥发损失率为5.6%~8.13%,且早、晚稻均以CRU3和CRU4处理较低。与U处理相比,早、晚稻CRU处理施基肥后田面水中的铵态氮浓度峰值分别降低74.5%~80.4%、53.4%~76.0%,施分蘖肥后分别降低69.5%~89.1%、67.3%~80.3%。U、CRU1、CRU2、CRU3和CRU4处理早稻田面水平均pH值分别为7.26、7.22、7.25、7.32和7.14,各处理差异不显著;晚稻田面水平均pH值分别为7.85、7.71、7.72、7.72和7.66,CRU处理均显著低于U处理。U处理氨挥发速率和田面水铵态氮浓度呈极显著正相关(r=0.8813),与硝态氮浓度呈显著负相关(r=-0.5319);CRU处理与U处理变化规律类似,CRU3和CRU4处理氨挥发速率与田面水铵态氮浓度达到显著正相关(r=0.5388和0.4245),各处理氨挥发速率与田面水pH值和10 cm土层温度相关不明显。【结论】施用控释尿素可显著降低稻田水面中的铵态氮含量,减少由于施肥导致的pH值增加,因而显著降低了稻田的氨挥发损失量,减少了氨挥发损失率。早稻和晚稻均以控释尿素施用量减少20%~30%的氨挥发减排效果最为明显。

葡萄生产化肥控失增效研究进展

葡萄水果产业近年来发展迅速,合理的施肥和科学的管理对葡萄的生产和质量至关重要。化肥控失可减少N、P等元素的流失,提高化肥利用率。本文对葡萄的营养特点、施肥期、施肥中存在的问题及化肥控失技术进行了系统的综述,以期为葡萄生产上化肥的合理施用提供参考。

Increase in yield and nitrogen use efficiency of double rice with long-term application of controlled-release urea

Controlled-release urea(CRU)has better characteristics than conventional urea for synchronizing nitrogen(N)release with plant uptake.Understanding the effects of CRU on crop yield and N use efficiency(NUE)has long been the key to evaluate the performance of CRU.A long-term experiment over five consecutive years was conducted in Changsha,Hunan Province,China,to investigate the effects of polyethylene-coated urea with a 90-d release period on the yield and NUE of double rice(early and late crops are grown in the same year),the amount of residual soil mineral N and the soil–plant N balance,as well as on the economic benefits.Four N fertilizer treatments including CK(no N fertilizer),U(conventional urea),CRU1(polyethylene-coated urea with equal N application rate to U)and CRU2(20%reduction in N application rate of CRU1)were established.The results indicated that CRU1 application increased the yield and NUE of double rice by 11.0 and 13.5%,respectively,compared with U.Higher yield and NUE of late rice were found than in early rice in CRU treatments.Compared with conventional U,the yield and NUE of early rice in the CRU1 treatment were increased by 6.0 and 10.2%,respectively,and those of late rice were increased by 15.4 and 13.8%,respectively.There was no significant difference between CRU1 and CRU2 in double rice yield.Furthermore,CRU treatments(including CRU1 and CRU2)had higher apparent residual Nmin rate(ARNR)and apparent N recovery rate(ANRR),but lower apparent N loss(NS)than the conventional U treatment.Concentrations of NH_(4)^(+)-N and NO_(3)^(-)-N were greater in the surface soil(0–20 cm)and lower in the deeper soil layer(40–60 cm)with CRU treatments than in the U treatment after harvest.Moreover,CRU application produced a greater economic benefit than conventional U application.In general,CRU outperformed U fertilizer in terms of rice yield,NUE,soil–plant N balance,economic benefit,and CRU2 provided greater comprehensive benefits than CRU1.It is suggested that CRU application is beneficial for solving N management challenges in the production of rice.

Study on the Effects of Nitrogen and Phosphorus Absorptionby Ecological Ditches

By using the simulated ditch experiment,the differences of nitrogen and phosphorus absorption capacities of 9 aquatic plants were studied,and the better varieties of nitrogen and phosphorus absorption capacity were selected to construct the ecological ditch and oxidation pond to study the nitrogen and phosphorus absorption effect.The results showed that the nitrogen and phosphorus residues in the simulated ditch water were signi ficantly reduced after planting aquatic plants.The biomass of Canna glauca,Myriophyllum elatinoides,Sorbaria sorbifolia,Pontederia cordata and Zizania was high,and the uptakes of nitrogen and phosphorus were high.Among them,the effect of planting Canna glauca and Myriophyllum elatinoides was the best.The concentration of nitrogen and phosphorus in farmland drainage decreased signi ficantly after being absorbed by aquatic plants in ecological ditches;the concentration of total nitrogen,soluble nitrogen and total phosphorus in main ditches decreased by 39.6%,40.1% and 36.9% respectively on average;the concentration of total nitrogen,soluble nitrogen and total phosphorus in branch ditches decreased by 6.6%,10.3% and 13.6% on average.The concentration of total nitrogen and total phosphorus in the oxidation pond could be further reduced by 17.7%and 13.3%.Ecological ditches can effectively intercept nitrogen and phosphorus in water,and have good ecological benefits of purifying water to obtain improved water quality.

氮磷减量对棉花—油菜轮作系统作物产量及氮磷流失的影响

长期不合理施用化肥导致土壤酸化、大气污染等一系列环境问题,化肥合理减施将有利于提高肥料利用率、促进耕地健康发展。本试验采用田间试验,以常规施肥(棉花季N∶390 kg/hm^(2),P_(2)O_(5)∶105 kg/hm^(2);油菜季N∶180 kg/hm^(2),P_(2)O_(5)∶54 kg/hm^(2))为对照,研究洞庭湖区域旱地棉花—油菜轮作下氮磷肥减量(10%、20%、30%)对作物产量及氮磷养分流失的影响。结果表明:与常规施肥相比,氮磷肥减量10%、20%对作物产量影响不显著,但明显提高肥料利用率,显著减少旱地氮磷径流损失;养分流失以棉花季为主,且棉花花铃期为关键时期。氮磷肥减量20%处理氮、磷肥利用率较常规施肥处理分别提高了5.41%、12.23%(棉花季)和10.91%、11.91%(油菜季);氮磷肥减量处理总氮、总磷流失量分别为0.69~5.48 kg/hm^(2)、0.08~0.24 kg/hm^(2)(棉花季)和0.17~0.34 kg/hm^(2)、0.05~0.11 kg/hm^(2)(油菜季),较常规施肥处理分别降低了5.94%~31.20%、12.80%~44.02%(棉花季)和18.88%~37.61%、10.18%~24.85%(油菜季)。综上,在本研究所设肥料减量范围内,氮磷肥减量20%处理能稳定作物产量、提高肥料利用率,降低氮磷流失。

控释尿素减施对双季稻田氮素渗漏淋失的影响

大量施用氮肥引起的土壤氮素淋失是稻田氮素损失的一个重要途径.为探究自然降雨过程中典型双季稻田氮渗漏淋失特点,采用田间渗漏池法,通过大田小区试验,研究控释尿素减施对稻田土壤60 cm深处渗漏水中氮淋失和水稻产量的影响.结果表明:施肥初期出现氮渗漏淋失峰值,这是防控的关键时期;双季稻生长季控释尿素减氮20%(0.8CRU)和减氮30%(0.7CRU)处理全氮淋失量分别为42.3和37.7 kg·hm^(-2),均显著低于常规尿素(CU)处理(53.9 kg·hm^(-2)),且0.7CRU处理显著低于等氮量控释尿素(1.0CRU)处理(51.3 kg·hm^(-2));各施氮处理全氮渗漏淋失率为11.9%~13.5%,处理间差异不显著.0.8CRU和0.7CRU处理较CU处理明显提高了水稻产量和氮肥吸收利用率,显著增加了氮收获指数.总之,控释尿素减氮20%~30%能保证水稻产量和防控稻田氮渗漏淋失.