城市污水处理厂污泥利用现状及潜在环境问题

根据国家环保总局要求,在2010年前全国主要城市的污水处理率要达到70%,这将使我国的水环境得到明显改善,另一方面也带来了污泥的处置和利用问题.污泥是一种优质的有机肥料,有选择地控制使用,既可满足作物生长对养分的需要,又可培育土壤.符合污泥固废“减量化”和“资源化”的处置要求.     

Effect of chemical fertilizers on the fractionation of Cu,Cr and Ni in contaminated soil

Effect of chemical fertilizers (urea, NH₄Cl, Ca(NO₃)₂, KCl and KH₂PO₄) on the fractionation of Cu, Cr and Ni was studied by a 4-month incubation experiment. Using sequential extraction procedure, it was found that the application of fertilizers could change the distribution of Cu, Cr and Ni in the fractions of soil. Applying urea (CO(NH₂)₂) significantly decreased the concentrations of Cu, Cr and Ni in water soluble plus exchangeable (WE) fraction, but increased those in Fe–Mn oxides bound (FM) fraction (p < 0.01). However, application of NH₄Cl caused an increase in the WE fraction by 27.7% for Cu, 111.5% for Cr and 20.4% for Ni. The CO(NH₂)₂ raised the soil pH from 4.51 to 4.96, whereas NH₄Cl lowered the pH of soil by 0.44 units. The WE fraction of the three heavy metals was significantly increased, while the FM fraction was significantly decreased by adding KCl (p < 0.01). Moreover, the supply of KH₂PO₄ reduced the WE and carbonate bound (CB) fractions of Cu, Cr and Ni in the soil, however, it raised Cu and Ni in the residual (RS) fraction and Cr in the FM fraction. In addition, the mobility index indicated that KCl and NH₄Cl increased the mobility of Cu, Cr and Ni in the soil, whereas urea and KH₂PO₄ decreased the mobility of the three metals in the soil. These results suggest that applying chemical fertilizers does not only provide plant nutrients, but may also change the speciation and mobility of heavy metals in the soil.     

桉树腐殖酸(HA)专用肥区域试验与配方的优选

采用随机区组设计,以等价投入的常规化肥为对照,开展专用肥多点施肥试验研究.通过专用肥对林木生长量、林相特征的影响分析,结果表明:与等价投入(肥料成本)的常规化肥相比,施用系列专用肥的林分生长量均显著或极显著地高于常规化肥处理,且叶片浓绿、树势强壮,施后19个月内,树高、胸径、材积分别提高了7.8%~51.8%、9.8%~53.0%和30%以上,叶片叶绿素含量提高26.3%~94.2%,叶面积指数提高41.0%~172.8%.经对HA桉树专用肥的增产性、适应性和稳定性的综合分析与评定,选出基肥专用的优化配方为:有机质≥30.0%、N P2O5 K2O≥6.0%(2.5-2.0-1.5)、腐殖酸总量≥8.0%,并加上适量的"绿滴"复合微生物菌剂(于施用时和基肥按每50 kg∶1 kg的量掺入);追肥专用的优化配方为:有机质≥20.0%、N P2O5 K2O≥20.0%(9-8-3)、腐殖酸总量≥6.0%.     

利用牡蛎壳粉制备缓释氮肥的初步研究

目前我国化肥当季利用率中，氮约为30％～35％．磷为10％～25％，钾为35％～50％远低于世界发达国家水平，造成肥料利用率低的主要原因是淋溶损失，尤以氮肥、钾肥为最。人们正在努力寻求提高肥料利用率的方法，其中之一是对肥料本身进行改性，开发适合于作物生长需求的新型肥料。研制缓／控释肥料是世界各国普遍采用的有效措施之一。缓释肥料的优点是利用率高，养分损失少，环境友好。但是，目前所用的作为缓释材料的高分子聚合物一般是难降解或不能降解，长期施用也会引起土壤污染。牡蛎壳为一种新型的天然材料，     

Does smallholder maize intensification reduce deforestation? Evidence from Zambia

Increasing food production to meet growing demand while reducing tropical deforestation is a critical sustainability challenge. This is especially true in sub-Saharan Africa, which faces serious food insecurity issues and where smallholder farming is the main driver of forest conversion. Competing theories imply opposite predictions as to whether deforestation increases or decreases with smallholder agricultural intensification, which can improve food security by increasing crop yields per area cultivated. This research provides new empirical evidence on the association between deforestation and smallholders’ use of modern inputs, in particular inorganic fertilizer on maize and improved maize seeds, using Zambia as a case study. We analyze this association nationwide in a spatially disaggregated manner at the lowest administrative level using machine learning-based small area estimation, which makes use of detailed nationally representative surveys on smallholder farm households for 2011 and 2014, and census data to statistically predict modern inputs use country-wide for 2011, when average maize yields were 1.28 tons/ha. Then, we evaluate the association between improved maize seed and fertilizer inputs and subsequent deforestation, while controlling for key geospatial covariates. The results support the land-sparing hypothesis, finding that smallholder farmers’ use of improved maize seed is negatively associated with deforestation on non-acidic (pH ≥ 5.5) soils, an effect that is enhanced by complementary inorganic fertilizer use. Fertilizer use on its own, however, is weakly associated with increased deforestation. Sustainable intensification via use of improved seeds on adequately fertile soils and improving soil health appears compatible with reducing both deforestation and food insecurity.     

Chloride source delineation in an urban-agricultural watershed: Deicing agents versus agricultural contributions

Analyses (n = 525) of chloride (Cl⁻), bromide (Br⁻), nitrate as nitrogen (NO₃-N), sodium (Na⁺), calcium (Ca²⁺) and potassium (K⁺) in stream water, tile-drain water and groundwater were conducted in an urban-agricultural watershed (10% urban/impervious, 87% agriculture) to explore potential differences in the signature of Cl⁻ originating from an urban source as compared with an agricultural source. Only during winter recharge events did measured Cl⁻ concentrations exceed the 230 mg/L chronic threshold. At base flow, nearly all surface water and tile water samples had Cl⁻ concentrations above the calculated background threshold of 18 mg/L. Mann–Whitney U tests revealed ratios of Cl⁻ to Br⁻ (p = .045), to NO₃-N (p < .0001), to Ca²⁺ (p < .0001), and to Na⁺ (p < .0001) to be significantly different between urban and agricultural waters. While Cl⁻ ratios indicate that road salt was the dominant source of Cl⁻ in the watershed, potassium chloride fertilizer contributed as an important secondary source. Deicing in watersheds where urban land use is minimal had a profound impact on Cl⁻ dynamics; however, agricultural practices contributed Cl⁻ year-round, elevating stream base flow Cl⁻ concentrations above the background level.     

土壤含水量和磷肥对马铃薯生长发育及抗旱生理的影响

研究了土壤含水量和磷肥对马铃薯生长发育及抗旱生理的影响,结果显示：（1）土壤含水量的下降导致马铃薯幼苗叶片含水量和叶绿素含量降低,可溶性糖、脯氨酸、丙二醛（MDA）含量、相对电导率（REC）及超氧阴离子（O₂^-·）产生速率升高,抗氧化酶活性增强,株高、茎粗、根长、匍匐茎数、地上部分干重降低,马铃薯块茎重量及块茎淀粉、蛋白质、Vc含量下降;（2）不同水分条件下增施适量磷肥,显著提高了马铃薯叶片含水量、叶绿素含量,相对增强了抗氧化酶活性,降低了相对电导率、MDA含量和活性氧水平,且马铃薯块茎重量及块茎淀粉、蛋白质和Vc含量显著增加。（3）比较包括对照在内的6种磷肥增施量,增施15.3 g·m^-2磷肥对马铃薯幼苗抗旱性及生长发育的促进效果最佳。综上所述,干旱胁迫显著抑制了马铃薯幼苗生长发育,而增施适量磷肥可通过提高渗透调节物质含量和抗氧化酶活性,有效缓解干旱胁迫下马铃薯幼苗叶片的脂质过氧化程度及细胞膜损伤,减轻干旱对生长发育的抑制,增强植株整体抗旱性。     

不同水肥处理的沙地玉米生长分析

在奈曼站农业观测场进行了5种水肥处理的玉米生长试验。结果表明,各处理的玉米株高快速生长期均从6月下旬始,至8月初达最高值。不施肥处理株高和茎粗生长在拔节后期落后于其他处理,早于其他处理停止生长。根量快速增长从6月底开始,至7月底结束,8月下旬根开始死亡,至9月20日,细根数量减少至峰值期的50%。高肥处理的根系增长率高于其他处理,其根密度值最大,不施追肥处理的最小。不浇水的处理在7月初雨季到来时根系开始快速增长。不施追肥的处理早于其他处理7d停止根系的增长。5种不同处理的根系生长动态趋势一致,均为单峰形。施肥量最大的处理(T₁)产量最高,不施肥的处理产量最低。玉米生长期多次灌溉并不能促进生长,相反使产量减少。     

不同施氮量对沙地春小麦株穗性状及产量的影响

在内蒙古奈曼旗对沙地春小麦进行了氮肥施量试验。结果表明,不同施氮量(尿素15.0~51.5g·m^-2)对沙地春小麦穗粒数、千粒重、有效小穗数及其百分率、籽粒产量、生物产量的影响具有显著差异,但对成穗数、株高的影响差异不明显。产量水平以施氮量为37.5g·m^-2时最高。     

化肥在农业生产中的地位与作用

化肥是提高作物产量的物质基础, 在过去的几十年中, 它在世界农业建设中起过巨大作用。近百年的肥料试验表明, 化学肥料具有和有机质一样的持续增产效果, 在提高作物产量、品质的同时, 还可培肥土壤。随着化肥工业的发展, 化肥的负作用会逐渐减小。