Dominant sources of dietary carbon and nitrogen for shrimp reared in extensive rice-shrimp ponds

Stable isotope analysis was used to determine the sources of dietary nitrogen (N) and carbon (C) for shrimp during the rearing phase in extensive rice‐shrimp ponds in My Xuyen and Gia Rai districts, Vietnam. Farm‐made feed was added as a food source in shrimp ponds in My Xuyen district, and based on stable isotope analyses, was generally a poor dietary source. The commercial formulated feed used in Gia Rai also appeared to contribute little directly to the nutritional needs of the shrimp. In contrast, the natural biota in all ponds appeared to contribute substantially. In particular, biota from beam trawls and benthic organic matter were the most likely sources of nutrition in My Xuyen ponds, while benthic organic matter was the main source in Gia Rai ponds. δ¹⁵N ratios in the natural biota in My Xuyen farms decreased over the growing season, suggesting increased N fixation in the case of the benthic organic matter reaching values as low as 1‰. This suggests N‐limitation in the ponds and that natural biota become increasingly dependent on N fixed by algae and/or other microorganisms. There is the potential to promote the growth of the plankton and hence, the other natural biota, by the judicious addition of fertilizer.     

序批式生物膜法处理水产养殖废水的研究

目前我国水产养殖废水直接排放的现象较多, 使受纳水体富营养化和生物多样性降低; 同时养殖水体中残饵、水生生物排泄物容易引起水体溶解氧下降、病原体增加并产生有害物质如氨氮、亚硝酸盐等, 引起养殖对象发病甚至死亡。提出采用以组合填料为载体的序批式生物膜反应器处理水产养殖废水。通过试验确定了最佳运行模式: 水力停留时间12 h, 其中瞬时进水y 厌氧( 3 h) y 曝气( 5 h) y 添加原水(添加比1B 3) y 缺氧( 3 h) y 曝气( 1 h) y 沉淀( 0. 5 h) y 排水( 0. 5 h), 并考察了试验对污染物的去除特性。试验结果表明了序批式生物膜法处理水产养殖废水的可行性, 对有机物、氨氮、TN、TP的平均去除率分别为91. 1%、85. 1%、751 8%、89. 5%, 处理后出水可回用于水产养殖。     

Soybean molasses as an organic carbon source in the farming of Litopenaeus vannamei (Boone, 1931) in a biofloc system

Soybean molasses was evaluated as a partial replacement for sugarcane molasses as a carbon source for biofloc development in the superintensive culture of Pacific white shrimp (Litopenaeus vannamei). A 50‐day study was conducted with juvenile (3.2 g) shrimp stocked in 16 800 L tanks at a stocking density of 250 shrimp m^?3. Control of total ammonia concentration was performed by the addition of combined mixtures of soybean and sugarcane molasses to the culture water. Three different molasses treatments were evaluated using different soybean‐to‐sugarcane molasses ratios: 15–85%, 38–62% and 60–40% respectively. The control group was treated only with sugarcane molasses. Water quality, chlorophyll a concentration, heterotrophic bacterial load, Vibrio spp. concentration and zootechnical indexes were all evaluated. Total ammonia concentration was controlled by heterotrophic and chemotrophic pathways. Biofloc formation, as quantified by measuring the total suspended solids, was not altered. The Vibrio spp. concentration showed a significant reduction in treatments with soybean‐to‐sugarcane molasses ratios of 38–62% and 60–40%. All combined mixtures of soybean and sugarcane molasses could maintain water quality and productivity in the superintensive culture of L. vannamei using the biofloc system. Thus, the potential use of a residue from agroindustry as a carbon source in a biofloc culture is demonstrated.     

氮肥施用量对遮阳小白菜产量和品质的影响

研究了遮阳条件下不同氮肥施用量对小白菜产量和品质的影响。结果表明:施氮量为150kg/hm2时,小白菜的产量达到最高,硝酸盐含量较低,且维生素C、可溶性蛋白质和可溶性糖含量等营养成分均显著高于其他处理;综合各种因素,小白菜的最佳施氮量为150kg/hm2。     

液体肥料施用装置设计与试验

针对液体肥料发展迅速和液体肥料施用装置发展不完善的现状,研制了一种可测量液体肥施用装置主要技术性能及参数的试验台,在此基础上对喷头流量影响因素作了三因素二次回归正交旋转试验,得出了液体肥料质量分数、电动机转速及喷头口直径大小对喷头流量的影响规律及主次关系。     

离心式撒肥机撒肥部件研究设计

通过分析推肥板在撒肥圆盘上的布置对肥料颗粒在撒肥圆盘上运动的影响,得出推肥板在撒肥圆盘上的布置形式,计算了肥料颗粒的抛撒半径。据此设计了一种离心式撒肥机用的撒肥部件,并简介了撒肥部件的结构及参数的确定。试验及大面积生产考核证明,该离心式撒肥部件效率高,肥料撒施均匀,能够满足新疆兵团农场对全耕层施肥的要求。     

桐梓县杂交玉米氮磷钾的合理配施效应

采用"3414"平衡施肥方案,在桐梓县肥力较高的小黄沙泥土上进行了杂交玉米的肥料效应田间试验.结果表明,增产效果最佳的肥料配方为处理6,即尿素32.6kg·667m-2、普钙62.5kg·667m-2、氯化钾26.7kg·667m-2;从经济效益分析来看,以低氮低磷中钾处理的肥料增产效益最好,其肥料的产/投比为2.42,其肥料配方为处理12(N1P1K2),即尿素13.6kg·667m-2、普钙31.25kg·667m-2、氯化钾13.3kg·667-2.     

袋控释肥对斑苦竹林氨挥发的影响

为优化施肥模式、节能减排、保护竹林生态环境,文章通过实验室优选挥发氨的收集检测方法,并设置不施肥(CK)、袋控释肥(BF)、撒施肥(SF)3种施肥模式进行斑苦竹的林间原位监测试验,探讨袋控释肥对集约经营的斑苦竹林氨挥发的影响。室内实验表明,磷酸通气法、硫酸通气法、硼酸密闭法的氨回收率分别为90%、70%、60%;靛酚蓝比色法和纳氏比色法检测的回收率分别为90%、77%。基于室内实验结果,采用磷酸通气法收集、靛酚蓝比色法测定,开展斑苦竹不同施肥模式下的氨挥发监测试验。结果显示,袋控释肥氨挥发总量为37 kg/hm²,损失总施氮量的15%;撒施肥氨挥发总量为137 kg/hm²,损失总施氮量的56%。相较传统撒施肥模式,袋控释肥能有效节能减排,降低氨挥发,减少施肥对空气的污染,保护竹林生态环境。     

新型肥料微量元素螯合肥的研究与应用进展

新型肥料因具有成本低、经济效益高,符合“高效环保、低碳节能”的现代农业发展需求等优点,近年来市场发展迅猛,其中螯合剂越来越多被应用于新型肥料生产。为此,从我国肥料应用现状出发,结合对不同类型微量元素的分类及对比,将螯合剂从来源方面分为合成法螯合剂、天然法螯合剂、生物化学法螯合剂和其他法螯合剂,并对其在肥料中的应用现状进行了综合分析;最终得出了螯合肥料的选择要通过高通量检测技术结合应用环境进行选择,走“有机无机相结合—速效持效相互补—螯合态部分替代”的综合路线,微量元素之间应该“速效型—持效型—螯合态型”相互配合才是微量元素肥料持续发展的最佳选择等结论。     

氮磷钾对绿玉菊生长的影响

采用水培方式,探讨不同浓度水平氮、磷、钾对绿玉菊生长的影响。分析了不同浓度氮、磷、钾处理下绿玉菊的株长、根长、叶绿素含量、丙二醛含量的关系。结果表明绿玉菊的株长和叶绿素含量随氮肥浓度的增加而增长;处理5(含氮7.5mmol.L-1,含磷0.2mmol.L-1,含钾3mmol.L-1)最符合绿玉菊水培生长要求。