Irrigation effects of cooling tower effluent on soil chemistry and alfalfa in the Rio Grande river basin

Development of alternative sources through wastewater reuse is important to meet water demands in arid regions. However, effects of wastewater irrigation on soil properties and crop performance must be evaluated before advocating its widespread use. Objectives of this study were to evaluate: (i) effects of prior evaporative disposal of saline‐sodic blowdown water (BW) on soil (fine‐loamy, mixed, and thermic Typic Calciorthods) properties in the disposal area, and (ii) effects of flood irrigation with three water qualities (control, BW 1X, and BW 2X) on soil salinity and alfalfa performance using a greenhouse soil column study (soil collected from same study area as objective (i)). Results indicated that although prior land disposal of BW had increased salinity and sodicity of soil, they were within the tolerance limits of the intended crop, alfalfa. Mass balance calculations indicated measured (15·6 Mg ha⁻¹) and calculated (13·2 Mg ha⁻¹) salt accumulation at the test site used for evaporative disposal were similar. Alfalfa grown using BW under greenhouse conditions produced prime quality hay and biomass yield similar to the control treatment (8·3 g column⁻¹ vs. 10·5 g column⁻¹ in control). Although 3·6 years equivalent of flood irrigation with BW 1X did not result in saline soil (BW 1X irrigated soils EC ranged from 2·2 to 3·5 dS m⁻¹), BW 2X irrigation resulted in saline soils. Sodicities of irrigated soils were greater in fine textured deep soils than coarse textured surface soils (e.g., SAR of 6·1 at 0–5 cm vs. 19·5 mmol^1/2 L^−1/2 at 30–60 cm in BW 1X), indicating the need for high solubility Ca amendments for long‐term irrigation with BW on fine texture soils within the soil profile. Copyright © 2010 John Wiley & Sons, Ltd.     

国外生物质能开发利用政策

面对日益加剧的能源安全、农业结构调整、农村社会发展、环境保护等问题,世界各国纷纷把目光投向生物质能。目前,生物质能是美国、欧盟利用量最大的可再生能源,在整个能源系统中也占有重要的地位。本文描述了国外生物质能的市场现状和需求,分析了国外生物质能政策的出发点和目标,详细介绍了美国、欧盟、巴西等地主要的生物质能政策。最后,本文总结出国外经验对我国生物质能政策的四点借鉴意义,提出了生物质能政策的指导方向。     

Long-term effects of tillage, cover crops, and nitrogen fertilization on organic carbon and nitrogen concentrations in sandy loam soils in Georgia, USA

Maintaining and/or conserving organic carbon (C) and nitrogen (N) concentrations in the soil using management practices can improve its fertility and productivity and help to reduce global warming by sequestration of atmospheric CO₂ and N₂. We examined the influence of 6 years of tillage (no-till, NT; chisel plowing, CP; and moldboard plowing, MP), cover crop (hairy vetch (Vicia villosa Roth.) vs. winter weeds), and N fertilization (0, 90, and 180 kg N ha⁻¹) on soil organic C and N concentrations in a Norfolk sandy loam (fine-loamy, siliceous, thermic, Typic Kandiudults) under tomato (Lycopersicon esculentum Mill.) and silage corn (Zea mays L.). In a second experiment, we compared the effects of 7 years of non-legume (rye (Secale cereale L.)) and legume (hairy vetch and crimson clover (Trifolium incarnatum L.)) cover crops and N fertilization (HN (90 kg N ha⁻¹ for tomato and 80 kg N ha⁻¹ for eggplant)) and FN (180 kg N ha⁻¹ for tomato and 160 kg N ha⁻¹ for eggplant)) on soil organic C and N in a Greenville fine sandy loam (fine-loamy, kaolinitic, thermic, Rhodic Kandiudults) under tomato and eggplant (Solanum melogena L.). Both experiments were conducted from 1994 to 2000 in Fort Valley, GA. Carbon concentration in cover crops ranged from 704 kg ha⁻¹ in hairy vetch to 3704 kg ha⁻¹ in rye in 1999 and N concentration ranged from 77 kg ha⁻¹ in rye in 1996 to 299 kg ha⁻¹ in crimson clover in 1997. With or without N fertilization, concentrations of soil organic C and N were greater in NT with hairy vetch than in MP with or without hairy vetch (23.5–24.9 vs. 19.9–21.4 Mg ha⁻¹ and 1.92–2.05 vs. 1.58–1.76 Mg ha⁻¹, respectively). Concentrations of organic C and N were also greater with rye, hairy vetch, crimson clover, and FN than with the control without a cover crop or N fertilization (17.5–18.4 vs. 16.5 Mg ha⁻¹ and 1.33–1.43 vs. 1.31 Mg ha⁻¹, respectively). From 1994 to 1999, concentrations of soil organic C and N decreased by 8–16% in NT and 15–25% in CP and MP. From 1994 to 2000, concentrations of organic C and N decreased by 1% with hairy vetch and crimson clover, 2–6% with HN and FN, and 6–18% with the control. With rye, organic C and N increased by 3–4%. Soil organic C and N concentrations can be conserved and/or maintained by reducing their loss through mineralization and erosion, and by sequestering atmospheric CO₂ and N₂ in the soil using NT with cover crops and N fertilization. These changes in soil management improved soil quality and productivity. Non-legume (rye) was better than legumes (hairy vetch and crimson clover) and N fertilization in increasing concentrations of soil organic C and N.     

Avian assemblages along a gradient of urbanization in a highly fragmented landscape

Our goal was to evaluate how avian assemblages varied along a gradient of urbanization in the highly fragmented landscape of coastal southern California. We measured species richness and abundance of birds within continuous blocks of habitat, within urban habitat fragments that varied in landscape and local habitat variables, and within the urban matrix at different distances from the wildland interface. These comparisons allowed us to characterize patterns of avifaunal response to a gradient of urban fragmentation. At the fragment scale, we found that fragment area was a strong, positive predictor of the total number of breeding species detected per fragment; total bird abundance per point count also increased with fragment size. Tree cover was higher in small fragments, as was the abundance of birds that typically occupy wooded habitats. Comparisons between core, fragment, and urban transects revealed differing patterns of response of individual bird species to urbanization. In unfragmented habitat, we recorded a relatively high diversity of urbanization-sensitive birds. In urban transects, these species were rare, and a relatively few species of non-native and anthropophilic birds were common. These urbanization-enhanced birds were also recorded in previous urban gradient studies in northern California and Ohio. Bird communities along the urban gradient reached their highest richness and abundance in fragments. The marked difference in vegetation structure between urban and natural landscapes in this arid shrubland system likely contributed to this pattern; the presence of native shrubs and exotic trees in fragments enabled both shrub and arboreal nesters to co-occur. As is characteristic of biotic homogenization, urban fragmentation in coastal southern California may increase local diversity but decrease overall regional avifaunal diversity.     

Potassium Management for Brown Midrib Sorghum × Sudangrass as Replacement for Corn Silage in the North-eastern USA

In recent years, there has been a growing interest in brown midrib (BMR) sorghum (Sorghum bicolor (L.) Moench.) × sudangrass (Sorghum sudanense Piper) hybrids (SxS) as a replacement for silage corn (Zea mays L.) in the north‐eastern USA. Recent studies suggest it is suitable for both rotational grazing and as a hay crop and could compete with corn harvested for silage in years when wet spring conditions prevent the timely planting of corn. However, little is known about its suitability as forage for non‐lactating cows that require low potassium (K) forages to prevent health problems. Our objective was to evaluate the impact of K fertilizer management (0, 112 or 224 kg K₂O ha^?1 cut^?1) under optimum N management (112–168 kg N ha^?1 cut^?1) on yield, quality and K concentrations of BMR SxS over a 2‐year period. Field trials were established on a fine loamy, mixed, active, mesic Aeric Fragiaquepts with medium K‐supplying capacity and characteristic of a large region in New York. Potassium application did not affect dry matter yields in either of the 2 years. Averaged over 2 years, neutral detergent fibre (NDF) significantly increased with K addition with similar but non‐significant trends observed in each of the years individually. The digestibility of NDF was unaffected by K application. Crude protein (CP) concentrations showed a significant decrease with K application in 2002 and similar trends were observed in 2003, although differences were not significant at P ≤ 0.05. The changes in NDF and CP did not significantly impact forage quality expressed as milk production per megagram of silage. Potassium application increased forage K concentration up to 13 mg K kg^?1 dry matter (in the first cut in 2003). Forage Ca and Mg concentrations decreased with K addition except for the first cut in 2002 where differences between 112 and 224 kg K₂O ha^?1 treatments were not significant. Without K addition in the 2‐year period, K concentrations in the forage decreased from 23 g kg^?1 for the first cutting in 2002 to 15 g kg^?1 for the second cut in 2003. Low K forage was obtained for all second‐cut forage unless 224 kg K₂O ha^?1 cut^?1 had been added. First‐cut forage was suitable only when no additional K had been applied. These results suggest low K BMR SxS forage can be harvested from initially high K soils without loss in dry matter yield as long as no additional K is added.     

Nitrogen, Phosphorus, Potassium, Magnesium and Calcium Removal by Brown Midrib Sorghum Sudangrass in the Northeastern USA

For the long‐term sustainability of the dairy industry in the Northeastern USA, manure nutrient application rates should not exceed crop nutrient removal once above‐optimum soil fertility levels are reached. Dairy producers have shown a growing interest in brown midrib (BMR) forage sorghum (Sorghum bicolor (L.) Moench.) × sudangrass (Sorghum sudanense Piper) hybrids (S × S) as a more environmentally sound alternative to maize (Zea mays L.) but data on S × S nutrient removal rates are scant. Our objectives were to determine N, P, K, Ca and Mg removal with harvest as impacted by N application rate, using six N rate studies in New York. One of the six sites had a recent manure history. Although site‐to‐site differences existed, N application tended to decrease P and K and increase N, Ca and Mg concentrations in BMR S × S forage. Nutrient removal and yield were highly correlated for all sites except one location that showed a K deficiency. The crop removed large amounts of P and K in the manured site, suggesting that BMR S × S is an excellent scavenger of these nutrients. If manure is applied mid‐season, forage K levels are likely too high for feeding to non‐lactating cows.     

从形态和分子特性来探讨美国长木植物园黄杨种质之间的关系

黄杨是栽植很广的庭园观赏灌木,美国长木植物园从世界各地收集了许多优良品种.仅从形态上来区别这些黄杨品种是很困难的.为鉴定20个黄杨优良品种,我们分别从形态特征（叶、习性和长势）和分子标记（AFLP标记）两方面着手,综合分析它们的亲缘关系.三个AFLP引物结合在75和500bp DNA片段间一共产生212个条带.每一个黄杨品种平均有74个条带,最低者有50条,最高者有108条;通常可用于签定的特有条带在0到15条之间.品种间的遗传距离介于0.028和0.439之间.用PAUP软件,我们得到一个UPGMA树状图,并将每一步有显著差异的标在图上.从分子特性来讲,这20个黄杨优良品种可能起源于4到5个种,并可很清楚地分为12个栽培变种.形态特征也支持分子特性的结论.由此可见,结合形态特征和分子标记是确定遗传关系、鉴定栽培变种和分子辅助定性育种的一个很好的方法.     

夏威夷群岛风光及园林植物纪事

夏威夷位于太平洋中部,包括132个海岛。其中8个主要岛屿位于亚热带气候区内,檀香山位列其中,它以奇特的自然环境和神奇的历史文化吸引众多游客,成为著名的休闲度假胜地。檀香山在保护生态环境、促进观光业持续发展上的经验值得中国借鉴。     

Analysis of Canadian and American legislation for controlling exotic species in the Great Lakes

• 1. The legislation of the Great Lakes jurisdictions dealing with control of exotic species introduced through ballast water, canals, and recreational boating was analysed to determine whether the USA and Canada have the capacity to manage nuisance exotic species effectively. Despite the deleterious ecological effects attributed to exotic aquatic species, there is a lack of complementary legislation between Canada and the USA to remedy this problem. Current legislation is fragmented at the bilateral, national, and the state/provincial level.
• 2. American legislative initiatives are far ahead of Canada's, especially for regulating ballast water in oceanic shipping. Canada lacks strong federal and provincial legislation to regulate ballast water in shipping and to prevent the secondary spread of exotic aquatic species through watersheds.
• 3. Legislation to regulate ballast water is developing quickly among the US federal government and the Great Lakes states. However, legislation affecting the spread of exotic nuisance species via canals and recreational boaters is needed to complement ballast water laws and to give agencies a broader mandate for management.
• 4. Amendment of the Boundary Waters Treaty Act, the Fisheries Act, and the Canada Water Act could give the Canadian federal government authority to regulate ballast water in vessels entering the St Lawrence and to begin the rehabilitation of aquatic habitats impaired by nuisance exotic species.
• 5. Preventing further species introduction and spread through the Great Lakes basin requires restricting certain shipping and boating practices. This can be achieved only by the enactment of complementary laws among all the American and Canadian jurisdictions.

Copyright © 2002 John Wiley & Sons, Ltd.     

美国树木城市评选对我国城市林业建设的启示

美国树木城市创建活动始于1976年,迄今已有近4 000个不同规模的城市或社区获此殊荣,近1亿美国人工作和生活在树木城市中。美国树木城市的标准体系相对简单,且以定性指标为主,强调城市林业的法制建设和组织宣传,城市林业长期发展规划,政府部门与民间团体、非政府组织和广大居民的参与及协调;并辅以树木城市发展奖励指标体系促进可持续发展。分析美国树木城市申报的标准、认定过程和城市林业建设的理念,对于我国建立与完善国家森林城市评选指标体系和城市林业建设法规,促进我国城市林业建设生态、高效和可持续发展有一定的借鉴意义。