Effects of soil covers on air and soil temperature and on growth and yield of sugar-beets.

From 1976 to 1979, sugarbeet cv. Monohil was grown in soil screened in various ways with transparent plastic sheet. Soil and air temp. were measured from sowing until some time after emergence. The temp. 7 cm deep in the rows was closely associated with the width of the strips covering the rows. Perforated plastic was less effective. Increasing soil temp. alone did not increase growth or yield of sugarbeet. When the higher soil temp. was combined with a higher ambient air temp. the development of the crop was advanced by 10-14 days. Improvement in the microclimate positively affected DM production during the growing period and final sugar yield. The higher final sugar yields were more often the result of the higher beet wt. than of a higher sugar content. No evidence was found of the effects of high temp. on leaf damage, the number of bolters or changes in DM distribution in any of the experiments. (Abstract retrieved from CAB Abstracts by CABI’s permission

Maximization of arable crop yields in the Netherlands.

The yields in kg/ha were calculated for potatoes, sugar beet and winter wheat for conditions under which water and mineral supply were not limiting growth rates. The date at which a closed crop canopy can be obtained in spring was an important criterion for the yield. Growth analyses of silage maize and sugar beet confirm that relatively high yields can be further improved by accelerating leaf development in spring. (Abstract retrieved from CAB Abstracts by CABI’s permission

The effect of cutting frequency and nitrogen fertilizer rates on dry matter production, nitrogen uptake and herbage nitrate content.

In 3 trials with perennial ryegrass given N in the range 0-1000 kg/ha and from 3 to 28 times/yr, DM production, N uptake and NO3 content in relation to N application rates and cutting frequencies of herbage were compared. Higher N application rates increased the herbage yield more at longer growing periods than at higher cutting frequencies. N uptake was positively affected by the application rate and not or only slightly by the cutting frequency. Consistent with this, appreciably high N conc. (max. 5.4%) were found on av. in the herbage at high fertilizer N rates and frequent cutting than at lower rates and less frequent cutting (1.6%). NO3 content increased during the growing season, especially as the N application rate was higher and the growing periods longer. (Abstract retrieved from CAB Abstracts by CABI’s permission

Ontwikkeling en groei van produktiegras onder Nederlandse omstandigheden

Bedoeld voor onderzoek en onderwijs zijn verschillende onderzoeksresultaten bijeengebracht om een indruk te geven van de stand van zaken en de kennis m.b.t. groei en ontwikkeling van gra

Physics of IED Blast Shock Tube Simulations for mTBI Research

Shock tube experiments and simulations are conducted with a spherical gelatin filled skull–brain surrogate, in order to study the mechanisms leading to blast induced mild traumatic brain injury. A shock tube including sensor system is optimized to simulate realistic improvised explosive device blast profiles obtained from full scale field tests. The response of the skull–brain surrogate is monitored using pressure and strain measurements. Fluid–structure interaction is modeled using a combination of computational fluid dynamics (CFD) simulations for the air blast, and a finite element model for the structural response. The results help to understand the physics of wave propagation, from air blast into the skull–brain. The presence of openings on the skull and its orientation does have a strong effect on the internal pressure. A parameter study reveals that when there is an opening in the skull, the skull gives little protection and the internal pressure is fairly independent on the skull stiffness; the gelatin shear stiffness has little effect on the internal pressure. Simulations show that the presence of pressure sensors in the gelatin hardly disturbs the pressure field