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.     

在水稻栽培中使用复合生物钾肥的方法

1.制作育苗土。取疏松、肥沃的菜园土或水稻田表层细土,每立方米外加“复合生物钾肥”1kg,优质腐熟(沤制好的)有机肥200kg,三元复合肥2kg,以及草木灰等土杂肥若干,充分混匀。2.苗床制作。整地、耙平,将配好的育苗土按需要的厚度平铺在上面,必要时覆盖塑料苗棚(膜)保温,即可播种     

科技商讯

水稻抗病虫害栽培技术取得突破 江苏张家港市植保植检站，研究出一项水稻无公害栽培技术，可以使水稻田少使用化学农药2次．每公顷少用化学农药2公斤。(电话：0512—58682110)     

8.8%环庚草醚·苄可湿性粉剂防除水稻田杂草试验

8．8％环庚草醚·苄可湿性粉剂由哈尔滨龙志农资化工有限公司生产，受黑龙江省农药管理检定站的委托，验证其对水稻田杂草的防除效果及对水稻的安全性，黑龙江省密山市农业技术推广中心2006年进行了8．8％环庚草醚·苄可湿性粉剂防除水稻田杂草试验。[第一段]     

水稻田一次性化学除草技术试验研究

稻田杂草危害是影响水稻产量的重要因素之一,应用化学除草剂防除稻田杂草是一项重要的技术措施。但是,除草剂品种单一、应用不当,会造成杂草优势种及群落结构变化,往往一次用药不能有效控制杂草危害,在水稻生长中后期,田间又出现草荒现象。因此,探索一套有针对性的水稻田一次性     

信阳市中、低产水稻田的改造利用技术

一、中、低产水稻田的形成原因 　　（一）水热条件的影响.这类稻田多分布于南部深山区中,有冷泉涌出或山涧水串灌,加上山底较窄,树木荫蔽、日照短,土体常年受地面水与地下水浸渍,水土温度低.通常当水土温度低于25℃时,水稻正常生长发育开始受到影响;低于12℃时就停止生长,尤其早春水温过低不利于水稻分蘖.常年积水的稻田,氧气得不到输送,容易产生有毒物质,例如低价铁、锰及硫化氢得不到排除,土壤微生物活动受抑,生物能源少,土壤养分供应缺乏,这是形成中、低产水稻田的重要原因.另外,在全市还有部分无灌溉条件的丘陵、岗地,常因水分不能满足而出现水稻低产.     

几种除草剂防除水稻田莎草药效试验

近几年，我场在防除莎草科杂草上，连续使用丁草胺、苄嘧磺隆，使莎草科杂草和扁秆草对其产生不同程度抗药性，以致莎草科杂草基数逐年上升，成为我场稻田的主要恶性杂草。为寻求新型除草剂，我场引进几个莎草除草剂，并对其进行药效试验。     

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.     

水稻田间化除要点

肥床旱育苗床肥床旱育苗床杂草多，危害大，在防治上要掌握适期，全面采用42％新野乳油喷雾，喷药半小时后盖膜。对漏治田块可掌握在秧苗三叶期后浇足板面水，然后用36％稻草净45克对水50公斤细喷雾。