The effect of tyres and a rubber track at high axle loads on soil compaction-Part 2: Multi-axle machine studies

This paper reports on a study of the effect of the passage of multi-axle harvesting machines on the soil physical properties. In particular, it investigates the effect of the rear tyre of a combine harvester on the amount of soil compaction subsequent to the passage of the front tyre/track. The work was conducted in controlled laboratory conditions to determine the effect of a simulated self-propelled combine harvester with a total machine weight of 30–33 t. This was assessed by embedding talcum powder tracer lines in the soil to measure soil displacement and soil density changes. Dry bulk density and penetrometer resistance were also measured. The results showed that the benefit of the rubber track found by Ansorge and Godwin [2007a. The effect of tyres and a rubber track at high axle loads on soil compaction: Part 1: Single Axle Studies. Biosystems Engineering 98 (1), 115–126] was maintained after the additional passage of the rear tyre. After the passage of a track the effect of rear tyre size was insignificant, but the rear tyre size had a significant influence on soil density when following a leading tyre. This was due to a higher strength layer at the soil surface created by the track which was able to withstand the load of the subsequent passes and protect the soil below from further compaction. Results similar to those found for a tracked machine were also achieved by three passes of a 900 mm section width tyre at 5 t load and 0.5 bar inflation pressure. The track results for the 33 t machine were very similar to those of a smaller combine harvester with a total load of 11 t and similar rut width. The study confirmed the benefit of tracks with regard to soil compaction and emphasised the fact that total axle loads and machine weights are less important than how the loads are distributed to the soil

Soil and crop responses following application of biosolids-derived organomineral fertilisers to ryegrass (Lolium perenne L.) grown in pots

Biosolids-derived organomineral fertilisers (OMF) were produced using a novel technique reported in earlier studies. This technique enables addition of N and potash to biosolids granules to form a balanced NPK fertiliser. Two fertiliser products; OMF10 (10:4:4) and OMF15 (15:4:4), were formulated and tested in a glasshouse facility on pot-grown ryegrass in comparison with urea and biosolids granules at N application rates ranging from 0 to 300 kg ha-1. The aim of this research was to contribute to the understanding of nutrients management and dynamics in grass crops fertilised with OMF. The study focused upon dry matter yield (DMY) and crop responses to applied fertiliser, nitrogen use efficiency (NUE) and fertilisers’ effect on soil fertility. Results indicated that ryegrass responds linearly to application of OMF increasing DMY by about 2% to 27% compared with biosolids but to a lesser extent than urea (range: 17% to 55%). NUE was related to the concentration of readily available N in the fertiliser; urea and OMF showed significantly greater (P<0.05) N recoveries than biosolids (26% to 75%, and 19% to 29%, respectively). Total nitrogen in soil and SOM increased (P<0.05) depending on the concentration of organic-N in the fertiliser applied. DMY was lower but more sustained overtime in biosolids-treated pots. OMF application did not result in significant changes in soil extractable-P levels whereas for urea, it decreased significantly while it showed a significant increase in biosolids-treated pots, where soil-P Index changed from 5 to 6. In OMF-treated soil, soil P Index remained close to constant overtime thereby supporting the purpose of the formulations tested

DISCUSSION: STRUCTURE OF AGRICULTURE: THE POLICY ISSUE

Agricultural and Food Policy,

Dietary elimination of children with food protein induced gastrointestinal allergy – micronutrient adequacy with and without a hypoallergenic formula?

Background: The cornerstone for management of Food protein-induced gastrointestinal allergy (FPGIA) is dietary exclusion; however the micronutrient intake of this population has been poorly studied. We set out to determine the dietary intake of children on an elimination diet for this food allergy and hypothesised that the type of elimination diet and the presence of a hypoallergenic formula (HF) significantly impacts on micronutrient intake. Method: A prospective observational study was conducted on children diagnosed with FPIGA on an exclusion diet who completed a 3 day semi-quantitative food diary 4 weeks after commencing the diet. Nutritional intake where HF was used was compared to those without HF, with or without a vitamin and mineral supplement (VMS). Results: One-hundred-and-five food diaries were included in the data analysis: 70 boys (66.7%) with median age of 21.8 months [IQR: 10 - 67.7]. Fifty-three children (50.5%) consumed a HF and the volume of consumption was correlated to micronutrient intake. Significantly (p <0.05) more children reached their micronutrient requirements if a HF was consumed. In those without a HF, some continued not to achieve requirements in particular for vitamin D and zinc, in spite of VMS. Conclusion: This study points towards the important micronutrient contribution of a HF in children with FPIGA. Children, who are not on a HF and without a VMS, are at increased risk of low intakes in particular vitamin D and zinc. Further studies need to be performed, to assess whether dietary intake translates into actual biological deficiencies

Analytic results for two-loop Yang-Mills

Recent Developments in computing very specific helicity amplitudes in two loop QCD are presented. The techniques focus upon the singular structure of the amplitude rather than on a diagramatic and integration approachComment: Talk presented at 13th International Symposium on Radiative Corrections, 24-29 September, 2017,St. Gilgen, Austria, 9 page

An investigation into the fertilizer particle dynamics off-the-disc

The particle size range specifications for two biosolids-derived organomineral fertilizers (OMF) known as OMF10 (10:4:4) and OMF15 (15:4:4) were established. Such specifications will enable field application of OMF with spinning disc systems using conventional tramlines spacing. A theoretical model was developed, which predicts the trajectory of individual fertilizer particles off-the-disc. The drag coefficient (Cd) was estimated for small time steps (10-6 s) in the trajectory of the particle as a function of the Reynolds number. For the range of initial velocities (20 to 40 m s-1), release angles (0° to 10°) and particle densities (1000 to 2000 kg m-3) investigated, the analysis showed that OMF10 and OMF15 need to have particle diameters between 1.10 and 5.80 mm, and between 1.05 and 5.50 mm, respectively, to provide similar spreading performance to urea with particle size range of 1.00 to 5.25 mm in diameter. OMF10 and OMF15 should have 80% (by weight) of particles between 2.65 and 4.30 mm, and between 2.55 and 4.10 mm, respectively. Due to the physical properties of the material, disc designs and settings that enable working at a specified bout width by providing a small upward particle trajectory angle (e.g., 10°) are preferred to high rotational velocities. However, field application of OMF with spinning discs applicators may be restricted to tramlines spaced at a maximum of 24 m; particularly, when some degree of overlapping is required between two adjacent bouts. The performance of granular fertilizers can be predicted based on properties of the material, such as particle density and size range, using the contour plots developed in this study