Slow sand filtration for elimination of phytopathogens in water used in forest nurseries

Irrigation water from natural sources can be contaminated by fungi, Oomycota, or bacteria capable of causing serious diseases in seedlings in forest nurseries. Slow sand filtration (SSF) is a cost-effective technique for water decontamination prior to irrigation. The aim of the current study was to assess the effectiveness of SSF as a means of eliminating plant pathogens including Pythium sterilum, Fusarium solani, Xanthomonas campestris, Pseudomonas syringae pv. Syringae and Rhizobium radiobacter from the lake water source used for irrigation. The applied SSF was effective in removing 80–90% of fungal and Oomycota inoculum as well as 70% of the bacteria in the investigated water. Therefore, SSF represents a practical step to lowering the use of pesticides during production of planting stocks in forest nurseries and a valuable element in an integrated plant protection system.     

微生态制剂的作用机制及其对鸡生产的影响

本文综述了微生态制剂的分类、功能、作用机制及其对鸡生长性能、免疫机能、生产性能等的影响。     

微生物分类实验课改革探索

通过改革微生物分类实验课的教学方法,调整实验内容,将实验教学作为理论教学与实践相结合的桥梁,通过一系列的改革后,获得了良好的效果,为其他专业实验课程改革提供参考依据。     

废弃菌袋微生物处理后在育苗中的应用

利用废弃菌袋作营养基质,使用有机肥发酵剂,通过堆积有氧发酵,获得微生物菌肥,采用不同的用量应用到蓝莓和西伯利亚红松苗木的生产试验上,取得了初步的试验效果,能够促进苗木生长,生长量增加27%。为今后选择本地低温菌株和研发复合菌肥奠定了技术基础。     

Factors affecting the voluntary feed intakes of sheep grazing Pennisetum clandestinum (kikuyu) pastures: Observations in the animal

Abstract

Two experiments designed to establish possible reasons for the often‐observed low voluntary feed intake of animals grazing kikuyu pastures were conducted at two widely differing locations. Low digestibility and low rate of digestion limited feed intake only when sheep were grazing dry, wilted kikuyu. At other times, rumen contents were relatively low, and voluntary intakes appeared to have been controlled by other factors. The foaminess of the rumen under circumstances of a low rumen fill seems to suggest that a high saponin content could have limited intake. However, the fact that a high rumen fill coincided with a high in vitro foam production in one instance may imply that a high saponin content was not instrumental in limiting intake. Only the rumen ammonia concentration and the total nitrogen content of the leaves showed a consistent relationship with voluntary intake.     

Short‐Term Effect of Targeted Placements of Sheep Excrement on Grassland in Inner Mongolia on Soil and Plant Parameters

Abstract

Grazing animal excrement plays an important role in nutrient cycling and redistribution in grazing ecosystems, due to grazing in large areas and return in small areas. To elucidate the changes to the soil and pasture caused by sheep urine, fresh dung, and compost patches, a short‐term field experiment using artificially placed pats was set up in the autumn of 2003 in the Inner Mongolian steppe. Urine application significantly increased soil pH during the first 32 days in soil layers at depths of both 0–5 cm and 5–15 cm. Rapid hydrolysis of urea gave large amounts of urine‐nitrogen (N) as ammonium (NH₄ ⁺) in soil extracts and was followed by apparent nitrification from day 2. Higher inorganic N content in the urine‐treated soil was found throughout the experiment compared with the control. No significant effects of sheep excrement on soil microbial carbon (C) and soil microbial N was found, but microbial activities significantly increased compared with the control after application of sheep excrement. Forty‐six percent of dung‐N and 27% of compost‐N were transferred into vegetation after the experiment. The results from this study suggest that large amounts of nutrients have been lost from the returned excrement patches in the degraded grassland of Inner Mongolia, especially from sheep urine‐N.     

Effects of nitrogen enrichment on belowground communities in grassland: Relative role of soil nitrogen availability vs. soil acidification

Terrestrial ecosystems worldwide are receiving increasing amounts of biologically reactive nitrogen (N) as a consequence of anthropogenic activities. This intended or unintended fertilization can have a wide range of impacts on the above- and belowground communities. An increase in high N availability has been assumed to be a major mechanism enhancing the abundance of above- and belowground communities. In addition to increasing available N, however, N enrichment causes soil acidification, which may negatively affect above- and belowground communities. The relative importance of increased N availability vs. increased soil acidity for above- and belowground communities in natural ecosystems experiencing N enrichment is unclear. In a 12-year N enrichment experiment in a semi-arid grassland, N enrichment substantially increased both above- and belowground plant biomass mainly via the N availability-induced increase in biomass of perennial rhizome grasses. N enrichment also dramatically suppressed bacterial, fungal, and actinobacteria biomass mainly via the soil acidification pathway (acidification increased concentrations of H⁺ ions and Al³⁺ and decreased concentrations of mineral cations). In addition, N enrichment also suppressed bacterial-, fungal-feeding, and omnivorous + carnivorous nematodes mainly via the soil acidification pathway (acidification reduced nematode food resources and reduced concentrations of mineral cations). The positive effects resulting from the increase in belowground carbon allocation (via increase in quantity and quality of plant production) on belowground communities were outweighed by the negative effects resulting from soil acidification, indicating that N enrichment weakens the linkages between aboveground and belowground components of grassland ecosystems. Our results suggest that N enrichment-induced soil acidification should be included in models that predict biota communities and linkages to carbon and nitrogen cycling in terrestrial ecosystems under future scenarios of N deposition.