HALF A CENTURY OF CROPLAND CHANGE*

ABSTRACT. The census concept of total cropland is a better measure of effective agricultural land than is total farmland, which includes extensive areas of woodland owned by farmers. The cropland area of the United States dropped from 478 million acres in 1949 to 431 million acres in 1997, for a net loss of less than 1 million acres, or roughly one‐fifth of 1 percent, per year. In the midwestern agricultural heartland most counties changed less than 5 percent in the half‐century, and more counties gained than lost. The West was a crazy quilt of change, and in the East most counties lost more than 10 percent. Major metropolitan counties lost a few percentage points more than did adjacent areas, but at a lower rate per capita than the nation as a whole. Most of the loss of cropland was in marginal agricultural counties with soils of low inherent fertility and topography unsuited to modern farm machinery. The loss of cropland to suburban encroachment may be cause for intense local concern, but attempts to thwart development cannot be justified on grounds of a net national loss of good cropland.     

Nitrous Oxide Flux Estimates for South-Eastern Australia

Nitrous oxide (N₂O) fluxes for south-easternAustralia have been estimated using a combination ofthe in situ N₂O and radon (Rn) measurementsmade at the Cape Grim Baseline Air Pollution Station,in north-west Tasmania. The average N₂O fluxesfrom the south-eastern mainland of Australia and fromTasmania over the nine years of record analysed (1985–1993) have beenfound to be 130 ± 30 kgN km^-2yr^-1 and 160 ± 45 kgN km^-2yr^-1respectively. These fluxes are larger than expectedand a significant dependence of the flux on rainfallis observed, with greater fluxes in the spring (October–December) andduring periods of positive SouthernOscillation Index. A large flux (1,300 ± 500kgN km^-2 yr^-1) from a nearby island (KingIsland) was also estimated from the data record,indicating a strong source, although the small size ofthe island means that it is not a significant sourcefor Australia.     

Shaken, Not Stirred

In a remarkable and yet largely unheralded piece off legislation, the New Zealand government has reshaped national provisions for earthquake insurance. Three major sets off issues emerge from the 1993 Earthquake Commission Act and warrant detailed investigation. The A ct will encourage significant changes in patterns of regional development in New Zealand, it heralds a simultaneous globalisation and localisation of earthquake risk through the mechanism of insurance and it gives new regulatory powers to insurers in New Zealand society.     

Atmospheric Effects of the Emerging Mainland Chinese Transportation System at and Beyond the Regional Scale

Local surface travel needs in the Peoples Republic of China (mainlandChina) have traditionally been met largely by nonpolluting bicycles. A majorautomobile manufacturing/importing effort has begun in the country over thelast decade, and planning documents indicate that the Chinese may strive toacquire more than 100 million vehicles early in the next century. By analogywith large automotive fleets already existing in the western world, bothregional and global scale pollution effects are to be expected from theincrease. The present work adopts the latest projections of Chinese automobilemanufacture and performs some quantitative assessments of the extent ofpollution generation.Focus for the investigation is placed upon the oxidant ozone. Emissions of theprecursor species nitrogen oxides and volatile organics are constructed basedon data for the current automotive sector in the eastern portion of the UnitedStates. Ozone production is first estimated from measured values forcontinental/oceanic scale yields relative to precursor oxidation. Theestimates are then corroborated through idealized two dimensional modeling ofthe photochemistry taking place in springtime air flow off the Asian land massand toward the Pacific Ocean. The projected fleet sizes could increase coastaland remote oceanic ozone concentrations by tens of parts per billion (ppb)in the lower troposphere. Influences on the tropospheric aerosol system andon the major greenhouse gas carbon dioxide are treated peripherally. Nitrogenoxides created during the vehicular internal combustion process willcontribute to nitrate pollution levels measured in the open Pacific. Thepotential for soot and fugitive dust increases should be considered as theautomotive infrastructure develops. Since the emerging Chinese automotivetransportation system will represent a substantial addition to the globalfleet and all the carbon in gasoline is eventually oxidized completely, asignificant rise in global carbon dioxide inputs will ensue as well.Some policy issues are treated preliminary. The assumption is made thatalterations to regional oxidant/aerosol systems and to terrestrial climate areconceivable. The likelihood that the Chinese can achieve the latest vehiclefleet goals is discussed, from the points of view of new production, positivepollution feedbacks from a growing automobile industry, and known petroleumreserves. Vehicular fuel and maintenance options lying before the Chinese areoutlines and compared. To provide some perspective on the magnitude of theenvironmental changes associated with an Asian automotive buildup, recentestimates of the effects of future air traffic over the Pacific Rim aredescribed.     

INSTRUMENTATION FOR GEOLOGICAL FIELD WORK ON THE MOON

A human return to the Moon will require that astronauts are well equipped with instrumentation to aid their investigations during geological field work. Two instruments are described in detail. The first is a portable X-ray Spectrometer, which can provide rapid geochemical analyses of rocks and soils, identify lunar resources and aid selection of samples for return to Earth. The second instrument is the Geological and Radiation environment package (GEORAD). This is an instrument package, mounted on a rover, to perform in-situ measurements on the lunar surface. It can be used for bulk geochemical measurements of rocks and soils (particularly identifying KREEP-enriched rocks), prospect for ice in shadowed areas of craters at the poles and characterise the lunar radiation environment.     

From Code to Conduct. Professional Ethics in New Zealand Geography

There has been a major resurgence of interest in ethical matters among geographers during the past 3–4 years, both in New Zealand and internationally. This paper outlines some of the important arguments for behaving ethically in geographical research. It then argues that, rather than adopting a Code of Ethics in isolation, serious consideration needs to be given to the business of teaching ethics. The paper proposes a two-part teaching-and-learning strategy - the first part provides students with written and lecture material on ethics, and the second section presents real life case studies of ethical dilemmas confronted by geographers, which are used for detailed discussion in tutorial meetings.