The effect of repeated liquid swine manure applications on soil nutrient supply rates and growth of different hybrid poplar clones

Non-Peer ReviewedIntensive hog operations generate large amounts of manure that must be dealt with in an environmentally responsible and economically practical manner. Repeated applications of liquid swine manure within nearby hybrid poplar plantations recently has been proposed as an effective alternative manure management practice, given that these fast-growing tree species have high soil moisture and nutrient demands and, therefore, represent a tremendous sink for the applied effluent. The objectives of this two-year study were to: i) evaluate the effect of repeated broadcast applications of liquid swine manure on soil nutrient supply rates and growth of five hybrid poplar clones (CanAm, Hill, Katepwa, Walker, and WT-66V) and, ii) assess the relationship between growing season soil nutrient supply rates, measured using in situ burials of ion-exchange membrane (Plant Root Simulator™-probes), and growth of different hybrid poplar clones. There was a limited effect of applied hog effluent on soil nutrient supply rates after the first year and hybrid poplar growth after two years, which is surprising considering the application rate was three times larger than the agronomic rate typically applied. The limited measureable difference following manure addition may be attributable to a number of factors, including: substantial volatilization, microbial immobilization, increased leaching and denitrification losses, timing of manure application being out of sync with temporal nature of nutrient uptake by the trees, and a delayed growth response as absorbed nutrients are retranslocated within the trees. Determining the effects of repeated applications of hog effluent on soil nutrient supply rates and subsequent tree growth should help to support effective management strategies, in terms of developing practical effluent management practices required to mitigate any adverse environmental effects, but also increasing plantation productivity and the concomitant non-wood product benefit of increasing biodiversity within the agricultural landscape

The effect of weed control method on soil nutrient availability and growth of different hybrid poplar clones

Non-Peer ReviewedDuring the early establishment phase outplanted hybrid poplar seedlings are the most vulnerable to lethargic growth or mortality because of interspecific competition with non-crop plant species for available soil moisture and nutrients. Consequently, there is a need to develop practical weed control practices that are not only successful at controlling non-crop plant species, but also cost-effective for producers looking to minimize their input costs. The objectives of this two-year study were to: i) evaluate the effects of different combinations of in-row (plastic mulch, herbicide, and control) and between-row (tillage, herbicide, and control) weed control practices on soil nutrients bioavailability and the early growth of four hybrid poplar clones (Walker, Assiniboine, WP-69, and Hill) and, ii) assess the relationship between growing season soil nutrient supply rates, measured using in situ burials of ion-exchange membrane (Plant Root Simulator™-probes), and growth of different hybrid poplar clones. Determining the effects of different weed control practices on growth-limiting edaphic properties and subsequent seedling growth should help to support effective management strategies, in terms of selecting an efficacious and cost-effective weed control strategy that promotes the establishment and growth of hybrid poplar seedlings, while minimizing the input costs incurred by the producer

Determining soil nutrient requirements for growing hybrid poplar

Non-Peer ReviewedUnder conditions of adequate soil moisture, reductions in the early growth of tree seedlings mainly are attributable to soil nutrient limitations. Monitoring soil nutrient availability, therefore, is important for ensuring optimal tree nutrition and promoting successful seedling establishment and growth. Notwithstanding the importance of routine soil testing practices in supporting annual crop production, less than 10 % of the fields in western Canada currently are managed based on annual soil testing practices. Consequently, producers see limited utility in the fertilizer recommendations provided to them based on conventional soil tests. The objective of this three-year study was to measure nutrient supply rates at several hybrid poplar plantations in northern Saskatchewan, using in situ burials of ion-exchange membrane (Plant Root Simulator™-probes), and relate these data to plantation productivity during the early establishment phase. Determining the relationship between soil nutrient supply rates and seedling growth should help to support effective management strategies, in terms of proper site selection and elucidating possible fertilizer requirements

Selective Exposure to Berita Harian Online and Utusan Malaysia Online: The Roles of Surveillance Motivation, Website Usability and Website Attractiveness

News media allows audiences to be selective in determining both their news sources and type of news stories they read. This study examined factors influencing selective exposure to the online editions of two mainstream Malaysian newspapers, Berita Harian and Utusan Malaysia. Using selective exposure theory as the theoretical lens, this study compared both newspapers in terms of their audiences’ level of surveillance motivation, and how audiences rate the newspapers’ websites with respect to usability and attractiveness. This study used a within-subject experimental research design that exposed 51 subjects to both Berita Harian and Utusan Malaysia online newspapers. The results of the experiment indicate that Berita Harian and Utusan Malaysia online were significantly different in terms of website usability; however, no significant differences were found in terms of surveillance motivation or website attractiveness between the two newspapers. Further analysis indicate that the only significant predictor of selective exposure was website usability. This study highlights the importance of website usability for online newspapers wanting to harness audience selectivity