Linking models for assessing agricultural land use change

The ex-ante assessment of the likely impacts of policy changes and technological innovations on agriculture can provide insight into policy effects on land use and other resources and inform discussion on the desirability of such changes. Integrated assessment and modeling (IAM) is an approach that can be used for ex-ante assessment. It may combine several quantitative models representing different processes and scales into a framework for integrated assessment to allow for multi scale analysis of environmental, economic and social issues. IAM is a challenging task as models from different disciplines have a different representation of data, space and time. The aim of this paper is to describe our strategy to conceptually, semantically and technically integrate a chain of models from different domains to assess land use changes. The models that were linked are based on different modeling techniques (e.g. optimization, simulation, estimation) and operate on different time and spatial scales. The conceptual integration to ensure consistent linkage of simulated processes and scales required modelers representing the different models to clarify the data exchanged and interlinking of modeling methodologies across scales. For semantic integration, ontologies provided a way to rigorously define conceptualizations that can be easily shared between various disciplines. Finally, for technical integration, OpenMI was used and supplemented with the information from ontologies. In our case, explicitly tackling the challenge of semantic, conceptual and technical integration of models forced researchers to clarify the assumptions of their model interfaces, which helped to document the model linkage and to efficiently run models together. The linked models can now easily be used for integrated assessments of policy changes, technological innovations and societal and biophysical changes.     

Feeding behavior of feedlot lambs fed diets containing levels of cassava wastewater

In this study, we evaluated the effects of including cassava wastewater in the diet on the feeding behavior of feedlot lambs in 35 male uncastrated Santa Inês × Dorper crossbred lambs at an approximate age of 3 months, with an average live weight of 20.0?±?3.4 kg. Diets were formulated with hay of cassava shoots (roughage) and a concentrate based on corn and soybean, with a roughage:concentrate ratio of 50:50, plus inclusion of cassava wastewater at the levels of 0, 12, 24, 36, or 48 g/kg of the total diet. Feeding behavior was evaluated between the 46th and 52nd days of the experiment. Increasing cassava wastewater levels in the diet reduced (P?<?0.05) the intakes (kg/day) of dry matter and neutral detergent fiber as well as the efficiency of rumination (g/cud and g/h) of dry matter and neutral detergent fiber. The other behavioral parameters were not affected by wastewater inclusion in the diet. Therefore, the inclusion of up to 48 g/kg of cassava wastewater on fresh matter of diets is not recommended for feedlot lambs.     

Long-Term Variable Rate Lime and Phosphorus Application for Piedmont No-Till Field Crops

Variable rate (VR) fertilizer application is a paradigm with potential to improve input efficiency and farm profitability. It is widely marketed by commercial applicators in the southeastern US. However, field studies comparing VR with traditional management have not demonstrated consistent, positive results. The objectives of this study were: (1) to determine the soil impact, crop response and economic potential of VR phosphorus (P) and lime application in a North Carolina Piedmont no-till field crop system using intensive soybean [Glycine max (L.) Merr.] production and (2) to economically evaluate alternatives to standard commercial grid soil sampling for directing VR P and lime. A 23-ha long-term no-till field in the SE Piedmont was divided into 0.4ha plots assigned to either VR or uniform P and lime application. Grid soil sampling and VR P and lime application were done prior to four crops over 3 years: full season soybean, wheat (Triticum aestivum L.)–double cropped soybean, and full season soybean. Soil test P, pH and crop yield response to VR P were inconsistent. Soil pH in areas with low pH initially did increase in response to VR lime, but it took two to three applications to bring all of these areas to the target pH. Once VR-liming raised initially low soil pH to levels close to target, yield of soybean, but not wheat, were up to 0.74Mgha^–1 higher than with uniform lime. Even with significantly higher soybean yields associated with VR lime, 3 years of grid sampling and VR application were not profitable compared to uniform application. The results indicated that VR lime could be profitable if the initial grid sampling data were used either for 2 consecutive years, or if it was used to restrict future grid sampling to specific areas requiring further VR lime.     

Diurnal migration and responses to simulated rainfall in desert soil microarthropods and nematodes

Diurnal patterns of microarthropod abundance in surface leaf litter were related to its moisture content. Leaf litter moisture was nearly 7% by weight at 0800h but fell to less than 1% by mid-day. Oribatid and tydeid mites moved into litter in the early morning and back into the soil before mid-day. There were no significant differences in numbers of nematodes in litter or soil and 78–98% of the nematodes were anhydrobiotic (coiled) in soil and litter at all times sampled.Following simulated rainfall there were fewer microarthropods in litter at mid-day in the absence of marked decreases in soil and litter moisture content. During drying, there were gradual reductions in numbers and species diversity of litter microarthropods. Nematode numbers did not change as litter dried. Anhydrobiotic nematodes in the soil increased from 14% on day 1 to 85% on day 4. Between 24 and 36 h after simulated rainfall, the proportion of anhydrobiotic litter nematodes increased from 35 to 80%,.Within 1 h after simulated rainfall, there were marked increases in numbers and diversity of microarthropods in surface litter. No collembolans were extracted from dry litter controls but the wet litter was dominated by isotomid, sminthurid and onychiurid collembolans. There were increases in numbers and diversity of oribatid, tydeid and gamasid mites in the wet surface litter within l h after wetting compared to controls.     

Serine-7 of the RNA polymerase II CTD is specifically required for snRNA gene expression

RNA polymerase II (Pol II) transcribes genes that encode proteins and noncoding small nuclear RNAs (snRNAs). The carboxyl-terminal repeat domain (CTD) of the largest subunit of mammalian RNA Pol II, comprising tandem repeats of the heptapeptide consensus Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7, is required for expression of both gene types. We show that mutation of serine-7 to alanine causes a specific defect in snRNA gene expression. We also present evidence that phosphorylation of serine-7 facilitates interaction with the snRNA gene-specific Integrator complex. These findings assign a biological function to this amino acid and highlight a gene type-specific requirement for a residue within the CTD heptapeptide, supporting the existence of a CTD code.     

A Simple DNA Preparation Method for PCR Amplifications in Marker-Assisted Selection of Wheat

An important, but often limiting step in marker-assisted breeding is the efficient isolation of plant DNA for polymerase chain reaction (PCR) amplification. A simple method using an alkali treatment to extract wheat DNA for marker-assisted selection (MAS) in wheat breeding programs was compared to a commercial kit and cetyltrimethylammonium bromide (CTAB) extraction. DNA concentration from the alkali extraction was higher than the other two methods but purity was lower than CTAB extraction. The alkali extraction method was used on breeding lines to determine its usefulness. The alkali-extracted DNA samples were suitable for several PCR-based procedures, including random amplified polymorphic DNA (RAPD), microsatellite (simple sequence repeat, i.e., SSR) and sequence characterized amplified region (SCAR)analyses.