The Hertz Corporation

About: The Hertz Corporation is a based out in . It is known for research contribution in the topics: Population & Soil water. The organization has 9562 authors who have published 11044 publications receiving 447929 citations. The organization is also known as: Hertz Rental Car & Hertz Rent-a-Car.

Soil microbial biomass is triggered into activity by trace amounts of substrate

Abstract: The microbial biomass in moist aerobic soils has an adenosine 5′-triphosphate (ATP) concentration of around 8–12 μmol ATP g−1 biomass C and an adenylate energy charge (AEC) of between about 0.8–0.95, both typical of micro-organisms undergoing exponential growth in vitro. In fact, only a very small fraction of the biomass can be in this condition at any time due to substrate limitations. Our hypothesis is that the microbial biomass expends energy to maintain a large ATP concentration and high AEC despite the expenditure of valuable energy reserves because this strategy offers an evolutionary advantage over one based on resting spores. Thus, by the time a spore becomes active in response to the presence of a suitable substrate, a more speculative organism may have captured it. We found that trace concentrations (i.e. μg g−1 quantities) of appropriate ‘trigger solutions’ of glucose, amino acids and root exudates can cause the biomass to evolve about 2- to 5-times more C as CO2 than was contained in the original ‘trigger solution’. The effect (essentially a “priming effect”) was mainly over with a single addition after 200 h, but the biomass could be reactivated with further additions. Addition of ‘trigger solutions’ to soils recently amended with cellulose produced an accelerated rate of mineralization of the cellulose until the experiment was terminated. We consider that our results describe a previously unreported response of the microbial biomass which equips it for survival in the generally substrate-poor soil environment.

A winter wheat crop simulation model without water or nutrient limitations

Abstract: A whole crop computer simulation model of winter wheat has been written in FORTRAN and used to simulate the growth of September- and October-sown crops of Hustler wheat at Rothamsted for the years 1978–9, 1979–80 and 1980–1. Results of the simulations, which are for crops with adequate water and nutrients, are compared with observations from experiments at Rothamsted. The model uses daily maximum and minimum temperatures and daylength to calculate the dates of emergence, double ridge, anthesis and maturity of the crops and the growth and senescence of tillers and leaves. In the simulations, the canopy intercepts daily radiation and produces dry matter that is partitioned between roots, shoots, leaves, ears and grain. Partial simulations, using observed LAI values, produced dry matter in close agreement with observations of late-sown crops, but consistently overestimated the total dry-matter production of the early-sown crops. Full simulation described satisfactorily the average difference in dry-matter production to be expected with changes in time of sowing, but did not give as close correspondence for individual crops. A grain growth submodel, that linked maximum grain weight to average temperatures during the grain growth period, correctly simulated the observed growth of individual grains in the 1981 crop. The benefits to be obtained by combining whole crop modelling with detailed crop observations are discussed.