麦秸还田不均匀对直播水稻生长的影响及对策

针对农业生产中秸秆还田出现的伤苗现象 ,进行了麦秸不均匀还田的微区模拟试验 ,结果表明 ,局部地段秸秆堆积会导致还原物质过多积累 ,严重影响稻种出苗、成苗 ,对水稻的苗期生长也有一定影响。前期干湿交替的水浆管理和适时移苗补缺 ,可以减轻过量秸秆还田所产生的负面影响     

我国有机肥资源及产业发展现状

科学减施化肥用量，合理配施有机肥对土壤肥力提升、农产品增质和减轻面源污染有着重要的意义。我国农业有机废弃物资源丰富，有机养分总量达到约 7 519.5万 t，其中 N、P 2O5、K2O养分总量分别为 3 096.3万、1 174.1万、3 249.1万 t，但是目前资源利用率不足 40%，不仅造成优良有机养分资源的浪费，同时带来环境污染风险的问题。如何高效利用有机肥资源是我国目前亟需解决的问题。本文总结有机肥相关文献和他人研究结果，综述了我国有机肥资源数量、利用现状，针对施用的问题，对产业发展提出了一些建议。     

Enzyme-linked immunosorbent assay for the pyrethroid deltamethrin

A competitive enzyme-linked immunosorbent assay (ELISA) for the detection of deltamethrin was developed. Two haptens, cyano[3-(4-aminophenoxy)phenyl]methyl 1R-cis-3-(2,2-dibromoethenyl)-2,2-dimethylcyclopropanecarboxylate and 3-[(+/-)-cyano[1R-cis-3-(2,2-dibromoethenyl)-2,2-dimethylcyclopropan ecarbonyloxy]methyl]phenoxyacetic acid, were synthesized and conjugated with thyroglobulin as immunogens. Four antisera were generated and screened against six different coating antigens. The assay that was the most sensitive for deltamethrin was optimized and characterized. The I(50) for deltamethrin was 17.5 +/- 3.6 microg/L, and the lower detection limit was 1.1 +/- 0.5 microg/L. This ELISA assay had relatively low cross-reactivities with other major pyrethroids, such as permethrin, phenothrin, bioresmethrin, cyfluthrin, and cypermethrin. Methanol was found to be the best organic cosolvent for this ELISA, with optimal sensitivity observed at a concentration of 40% (v/v). The assay parameters were unchanged at pH values between 5.0 and 8.0, whereas higher ionic strengths strongly suppressed the absorbances. To increase the sensitivity of the overall method, a C(18) sorbent-based solid-phase extraction was used for river water samples. River water samples fortified with deltamethrin were analyzed according to this method. Good recoveries and correlation with spike levels were observed.     

紫云英与化肥配施对稻田土壤养分和微生物学特性的影响

在安徽沿江双季稻区,通过4年田间定位试验研究了不同用量紫云英绿肥与化肥配施对水稻产量、土壤肥力和土壤微生物数量及活度的影响。结果表明,施用紫云英绿肥比不施肥增产40.75%~92.10%,比单施化肥处理增产26.30%~36.49%;与纯施化肥相比较,施用紫云英处理的微生物总量增加了48.26%~115.78%,微生物活度增加了5.88%~29.41%,且施用紫云英土壤全N、碱解N、有效P、速效K和有机质含量均较高。简单相关分析表明,土壤微生物特性与土壤全N、碱解N之间具有极显著的相关性。施肥土壤有机质含量与细菌总数之间无直接相关性,而与真菌、放线菌数量及微生物活度正相关。土壤微生物及土壤养分分析发现,化肥量70%与紫云英22 500 kg·hm-2配施比较适宜于安徽沿江双季稻区早稻生产。     

根外施钾对苹果树光合速率的影响研究

试验研究金矮生苹果树生育期根外施K对其光合速率的影响结果表明 ,根外施K可促进光合速率 ,一定程度缓和“午休”现象。苹果生育期 5～ 10月份 5次根外施K对促进与延长当年苹果树光合速率和营养积累有显著作用 ,其效应优于根外 1次施K和 3次施K处理 ,每次施K作用持续时间达 2 5d左右。     

Added nitrogen interaction as affected by soil nitrogen pool size and fertilization – significance of displacement of fixed ammonium

Displacement of NH₄⁺ fixed in clay minerals by fertilizer ¹⁵NH₄⁺ is seen as one mechanism of apparent added nitrogen interactions (ANI), which may cause errors in ¹⁵N tracer studies. Pot and incubation experiments were carried out for a study of displacement of fixed NH₄⁺ by ¹⁵N‐labeled fertilizer (ammonium sulfate and urea). A typical ANI was observed when ¹⁵N‐labeled urea was applied to wheat grown on soils with different N reserves that resulted from their long‐term fertilization history: Plants took up more soil N when receiving fertilizer. Furthermore, an increased uptake of ¹⁵N‐labeled fertilizer, induced by increasing unlabeled soil nitrogen supply, was found. This ANI‐like effect was in the same order of magnitude as the observed ANI. All causes of apparent or real ANI can be excluded as explanation for this effect. Plant N uptake‐related processes beyond current concepts of ANI may be responsible. NH₄⁺ fixation of fertilizer ¹⁵NH₄⁺ in sterilized or non‐sterile, moist soil was immediate and strongly dependent on the rate of fertilizer added. But for the tested range of 20 to 160 mg ¹⁵NH₄⁺‐N kg^–1, the NH₄⁺ fixation rate was low, accounting for only up to 1.3 % of fertilizer N added. For sterilized soil, no re‐mobilization of fixed ¹⁵NH₄⁺ was observed, while in non‐sterile, biologically active soil, 50 % of the initially fixed ¹⁵NH₄⁺ was released up to day 35. Re‐mobilization of ¹⁵NH₄⁺ from the pool of fixed NH₄⁺ started after complete nitrification of all extractable NH₄⁺. Our results indicate that in most cases, experimental error from apparent ANI caused by displacement of fixed NH₄⁺ in clay is unlikely. In addition to the low percentage of only 1.3 % of applied ¹⁵N, present in the pool of fixed NH₄⁺ after 35 days, there were no indications for a real exchange (displacement) of fixed NH₄⁺ by ¹⁵N.     

Effects of Oxalate and Humic Acid on Arsenate Sorption by and Desorption from a Chinese Red Soil

Studies on arsenate (As(V)) sorption and desorption have been mainly limited to soil minerals and sorption and desorption reactions in whole soils are poorly understood. In this study the sorption of As(V) by and phosphate-induced desorption from a Chinese red soil were studied in the presence of oxalate and humic acid (HA). Arsenate was strongly sorbed mainly through ligand exchange reactions on the soil. Arsenate sorption decreased in the presence of oxalate or HA. Oxalate and HA influenced As(V) sorption mainly by competing for sorption sites and reducing sorption sites, and oxalate could also decrease sorption through dissolving clay minerals. Oxalate and HA could also facilitate As(V) desorption from the soil. Both sorption and desorption kinetics were two stage processes. Sorption kinetics conducted from 0.2–840 h showed that As(V) sorption increased with increasing residence time. Sorption equilibrium was retarded and the maximum sorption decreased in the presence of oxalate or HA. Phosphate-induced desorption kinetics conducted on the soil with 24 h and 840 h of sorption equilibrium time showed a significant effect of equilibrium time on As(V) desorption. The presence of oxalate or HA during the sorption process resulted in more As(V) desorption. Due to the degradation of oxalate, soil treated with oxalate and with a sorption equilibrium time of 840 h showed no significant difference in desorption kinetics from untreated soil.     

以可再生能源技术为核心的生态家园模式效益分析——以密云县水泉村生态家园建设为例

以密云县水泉村为例介绍了一种以可再生能源技术为核心的生态家园模式，并用调查得到的数据从模式产生的经济效益、对能源消费的影响、对社会福利的贡献3个方面进行了具体的分析，指出此模式具有很好的盈利能力和投资回收能力，能拉动当地的经济发展并促进社会福利的增长，同时又避免了环境污染。     

Effects of Extrusion and Starch Removal Pretreatment on Zein Proteins Extracted from Corn Gluten Meal

In this study, the structure and selected properties of zeins extracted from corn gluten meal (CGM) pretreated by extrusion and removal of starch were investigated. The structure and properties of the zeins from pretreated CGM changed significantly. Pretreatments can decrease the extraction yields of zeins and change the granule shape and size of zein aggregates. The studies indicated that extrusion and removal of starch can significantly decrease the thermal enthalpy (ΔH₁ and ΔH₂) of zein from 1.94 ± 0.20 to 0.19 ± 0.10 and from 107.20 ± 0.80 to 78.62 ± 2.30 and J/g, respectively. The SDS‐PAGE results confirmed that the molecular weight of zeins from CGM was 24,000 and 27,000, and the molecular weight of zeins did not change with the pretreatment. On the other hand, the circular dichroism spectroscopy results showed that the processing of extrusion and removal of starch can change the secondary structure content of β‐sheets and β‐turns; these results indicated that extrusion and removal of starch can significantly break the secondary structure of zeins. Furthermore, extrusion and removal of starch can change the sulfhydryl content of zeins. The obtained results provided some fundamental information that is useful for further modification of CGM to improve its functional properties and industrial applications.