南方水稻田除草剂迎来用药高峰

<正>目前南方大部分地区已完成水稻田播种,水稻直播田在南方各省呈逐年增加趋势,在每年的水稻直播田播种二十天内,有两次除草剂用药高峰期。期间的两次用药也推动了水稻田用药市场的逐步升温,各基层经销商也加紧了进货的步伐,向农民推荐各类土壤封闭除草剂以及除稗草、千     

养蟹水稻田怎样防虫

稻水象甲是水稻生产的大敌，一般发生减产20％～30％，严重时减产60％～70％，甚至造成绝收。由于稻水象甲具有繁殖极快、迁移性强．昼伏夜出的特点，近几年来的为害有逐年加重的趋势。目前防治稻水象甲的农药较多，但不外乎高中毒有机磷．呋喃丹和水稻田不提倡使用的菊酯类，对螃蟹危害严重，无法使用。     

水稻机收好处多

盘锦市水田面积160多万亩，1998年开始盘锦鼎翔集团在3万多亩水稻田进行机械收获的研究探索，试用了割灌机、割晒机等都未成功。2002年采用久保田、洋马等日、韩小机收面积98％以上，为农民增收提供了一条新途径。     

锐劲特防治稻田主要害虫的应用技术(2)

锐劲特是一种低毒、效果良好的化学农药,可代替高毒农药进行稻田虫害防治。详细介绍了稻纵卷叶螟、褐飞虱的危害特点,并提出了相应的防治措施,为大田害虫防治提供了生产经验。     

寒地水稻田节肢动物群落多样性调查分析

根据田间系统调查把稻田节肢动物群落按营养和取食关系划分为三个营养层(基位物种、中位物种、顶位物种)和不同的功能集团,在物种、功能集团和营养层三个组织层次水平上分析了稻田节肢动物群落的结构和多样性。结果表明:三类稻田中,施生物药剂稻田的生态稳定性最好,自然稻田的生态稳定性好于施化学药剂稻田的生态稳定性。     

冀东盐碱地区稻改棉高产栽培技术

河北省丰南市地处冀东滨海地区,受水资源缺乏之形势所迫,自1999年开始进行盐碱水稻田改种棉花早熟高产栽培技术试验研究与示范.历经两年,获得成功,500hm2示范田平均皮棉产量1350kg/hm2,霜前花率达到86%.为冀东地区退稻改旱、解决缺水问题找到了一条新途径.     

几种复配除草剂在杂草不同生育期应用对水稻田杂草的防效初报

介绍了应用丁草胺＋农得时,除稗特＋草克星,稻思达＋威农,禾大壮＋太阳星,神锄＋莎多茯等5种复配除草剂在稻田杂草三个不同时期的安全性及防治效果,试验结果表明：丁草胺1500mLhm^2 农得时225g/hm^2、除稗特900g/hm^2_草克星150n/hm^2,稻思达90g/hm^2 威农150g/hm^2对低龄杂草防效较好,总防效分别达到98．8％,99．1％和98．9％,禾大壮1500mL/hm^2 太原星150g/hm^2和神锄300g/hm^2＋莎多茯150g/hm^2对3龄时期杂草防效较好,总防效达到96．7％和96．3％,且对水稻生长无不良影响。     

三大作物田杂草防除现状与对策

一、三大作物田杂草与防除 1.水稻田水稻为我国种植的第一大作物,据2003年统计,水稻种植面积达28 201.3千公顷.稗草、鸭舌草、牛毛毡、节节菜等为水稻最主要杂草,其中稗草危害面积约1.3千公顷;其次为异性莎草、扁杆藨草、千金子、眼子菜、三棱草等,危害面积约300万公顷左右.     

重金属对水稻田土壤中藻类数量和种类的影响

研究表明水稻田土壤中藻类种群丰富,其中蓝藻11属、硅藻5属、绿藻7属、裸藻1属,数量上以蓝藻占优势,硅藻次之,绿藻、裸藻很少。经重金属铜、镍、铅、锌分别处理的土壤样品藻类数量变化很大,在低浓度时起促进作用,高浓度时起抑制作用,其临界值为铜10mg·kg~(-1),锌100mg·kg~(-1),镍>100mg·kg~(-1)。多种金属混合总体毒害增加,但铜、铅、毒害呈减弱趋势。除铜以外,这些重金属对藻类种群结构未有剧烈的影响,但铜在高浓度时对蓝藻的抑制作用比对硅藻的抑制作用强烈。     

Study of Dynamics of Floodwater Nitrogen and Regulation of Its Runoff Loss in Paddy Field-Based Two-Cropping Rice with Urea and Controlled Release Nitrogen Fertilizer Application

The article deals with the effects of urea and controlled release nitrogen fertilizer （CRNF） on dynamics of pH, electronic conductivity （EC）, total nitrogen （TN）, NH4^＋-N and NO3 -N in floodwater, and the regulation of runoff TN loss from paddy field-based two-cropping rice in Dongting Lake, China, and probes the best fertilization management for controlling N loss. Studies were conducted through modeling alluvial sandy loamy paddy soil （ASP） and purple calcareous clayey paddy soil （PCP） using lysimeter, following the sequence of the soil profiles identified by investigating soil profile. After application of urea in paddy field-based two-cropping rice, TN and NHa＋-N concentrations in floodwater reached peak on the 1st and the 3rd day, respectively, and then decreased rapidly over time; all the floodwater NO3--N concentrations were very low; the pH of floodwater gradually rose in case of early rice within 15 d （late rice within 3 d） after application of urea, and EC remained consistent with the dynamics of NH4^＋-N. The applied CRNF, especially 70% CRNF, led to significantly lower floodwater TN and NH4^＋ concentrations, pH, and EC values compared with urea within 15 d after application. The monitoring result for N loss due to natural rainfall runoff indicated that the amount of TN lost in runoff from paddy field- based two-cropping rice with urea application in Dongting Lake area was 7.47 kg ha^-1, which accounted for 2.49% of urea- N applied, and that with CRNF and 70% CRNF application decreased 24.5 and 27.2% compared with urea application, respectively. The two runoff events, which occurred within 20 d after application, contributed significantly to TN loss from paddy field. TN loss due to the two runoffs in urea, CRNF, and 70% CRNF treatments accounted for 72, 70, and 58% of the total TN loss due to runoff over the whole rice growth season, respectively. And the TN loss in these two CRNF treatments due to the first run-off event at the 10th day after application to early rice decreased 44.9 and 44.2% compared with urea, respectively. In conclusion, the 15-d period after application of urea was the critical time during which N loss occurred due to high floodwater N concentrations. But CRNF decreased N concentrations greatly in floodwater and runoff water during this period. As a result, it obviously reduced TN loss in runoff over the whole rice growth season.