Global food insecuity is growing as the worldwide attempt to expand food production loses momentum. The grain surpluses that accumulated in the food exporting countries during the decades of the 1950s and the 1960s have disappeared. World food supplies are tightening and the slim excess of growth in food production over population is narrowing. Throughout the world pressures on the cropland are intensifying. Focus in this discussion of world population growth is on the loss of momentum the return of famine the North American breadbasket declining food security the conversion of cropland to nonfarm use thinning topsoil land productivity trends and the loss of irrigated land. As the decade of 1980 begins the growth in world food production is losing momentum and its excess over population growth is narrowing. In Africa if soils continue to deteriorate the 10 year decline in food output per person there could become chronic. If soil erosion and the other forces that have slowed food production in the world as a whole continue to intensify and the projected population increases occur then growth in food production could drop below that of population for the world as a whole. Responding effectively to the cropland threats associated with mounting food demands creates a dilemma for both farmers and governmental planners. Economic forces and political instincts encourage short-term measures yet pressures to wring too much from the land in the short run could destroy it over the long run. Wider public understanding of the longterm effect of cropland conversion and topsoil loss on food prices is the key to an effective worldwide response. The US Soil Conservation Service has outlined a national plan that would bring the annual loss of topsoil down to a tolerable level. Along with maintaining the conservation systems now in place some 158 million acres of the 413 million acre cropland base need additional attention. Of this total 17 million acres of cropland are eroding so rapidly that the Soil Conservation Service recommends that it be shifted from continuous row cropping and converted to either woodland grassland or longterm rotation. The remaining 141 million acres of cropland that are presently losing over 5 tons of soil per year are in need of the adoption of some form of conservation tillage. Officials in India are struggling with the same issues as officials and soil scientists in the US. Governments everywhere must consider the realignment of priorities that will allow soils to be stabilized.

https://science.sciencemag.org/content/sci/214/4524/995.full.pdf

World population growth, soil erosion, and food security

Measuring, modelling and managing gully erosion at large scales: A state of the art

Initiation and evolution of gullies along the shoreline of Lake Huron

The processes of sheet, rill and gully erosion on the slopes of the Russian Plain are controlled by the same factors as elsewhere: cover, erodibility, erosivity and landform. The combination of land-use history and variations in these bio-physical factors produced a history of erosion that is unique to this area. The most eroded soils occur in the Non-Black Earth area, especially where there are soddy-podzolic soils. Over the entire Russian Plain, 99 × 109 m3 of soil have been lost from the slopes since AD 1696. On the arable land, a layer 40 cm has been eroded. About 2 × 106 gullies more than 300 m in length have formed during the last 300 years, mobilizing about 4 × 109 m3 of sediment. About 97% of this vast amount of soil has been redeposited on the plain rather than transported to the oceans. The effect of the sediment on stream channels has been greatest in the headwaters, where large numbers of low-order channels have been completely infilled. Up to 5·6 m of sediment has accumulated in some of these small valleys. Copyright © 2003 John Wiley & Sons, Ltd.

Erosion and sedimentation on the Russian Plain, II: the history of erosion and sedimentation during the period of intensive agriculture

The Earth's surface erodes by processes that occur over different spatial and temporal scales. Both continuous, low-magnitude processes as well as infrequent, high-magnitude events drive erosion of hilly soil-mantled landscapes. To determine the potential variability of erosion rates we applied three independent, field-based methods to a well-studied catchment in the Marin Headlands of northern California. We present short-term, basin-wide erosion rates determined by measuring pond sediment volume (40 years) and measured activities of the fallout nuclides 137Cs and 210Pb (40–50 years) for comparison with long-term (>10 ka) rates previously determined from in situ-produced cosmogenic 10Be and 26Al analyses. In addition to determining basin-averaged rates, 137Cs and 210Pb enable us to calculate point-specific erosion rates and use these rates to infer dominant erosion processes across the landscape. When examined in the context of established geomorphic transport laws, the correlations between point rates of soil loss from 137Cs and 210Pb inventories and landscape morphometry (i.e. topographic curvature and upslope drainage area) demonstrate that slope-driven processes dominate on convex areas while overland flow processes dominate in concave hollows and channels. We show a good agreement in erosion rates determined by three independent methods: equivalent denudation rates of 143 ± 41 m Ma−1 from pond sediment volume, 136 ± 36 m Ma−1 from the combination of 137Cs and 210Pb, and 102 ± 25 m Ma−1 from 10Be and 26Al. Such agreement suggests that erosion of this landscape is not dominated by extreme events; rather, the rates and processes observed today are indicative of those operating for at least the past 10 000 years. Copyright © 2006 John Wiley & Sons, Ltd.

/pdf/quantifying-hillslope-erosion-rates-and-processes-for-a-7t514sryb3.pdf

Quantifying hillslope erosion rates and processes for a coastal California landscape over varying timescales

During the 1970s and 1980s the techniques of tillage and the area of cultivation on the Russian Plain remained virtually unchanged. Therefore, it is possible to assess both the rate and forms of erosion and sedimentation over almost all of the plain for this period of several decades. Using the SHI model and USLE, with coefficients derived for Russian conditions, observed gully density, area and volume, and a morphogenetic classification of streams, it has been possible to produce an assessment of the current state of erosion and sedimentation. The geographic patterns of both the rates and types of erosion and sedimentation are presented and partially explained. This assessment will be of considerable value as a ‘baseline’ against which to assess future changes as the area of cultivation and the methods of farming change, as well as to assess historical erosion and deposition. Copyright © 2003 John Wiley & Sons, Ltd.

Erosion and sedimentation on the Russian Plain, part 1: contemporary processes

The paper describes an attempt to determine the causes of the development of the present gully network in the steppe and forest-steppe of the European part of the USSR. The authors develop a technique that involves comparing the number of gullies derived from a map of gully density with the number of gullies derived from data on the expansion of the cropland area within the boundaries of the prerevolutionary guberniyas (major civil divisions). The authors conclude from the close correspondence of the two sets of figures that the great majority of gullies could have been formed as a result of the plowing up of the land over the 150 to 300 years of agricultural land use in the study region and can therefore be assumed to have arisen as a result of human activities.

The role of the human factor in the development of gullying in the steppe and wooded steppe of the european ussr

Members of the Soil Erosion Laboratory at Moscow University propose a technique for predicting the gullying hazard posed by human activities, with particular reference to the so-called Midland region of the USSR, comprising West Siberia, Kazakhstan and Central Asia. A map combining the present extent of gullying and the potential hazard is compiled. It suggests that the hazard is greatest in elevated or dissected portions of the permafrost zone because running water tends to have a thermal impact on the upper layers of frozen ground and reduces its resistance to erosion. The hazard is also serious in wooded steppe and northern steppe because of erodibility of the subsoil and intensive runoff. Potential gullying is less likely in the forest zone and deserts (except if irrigated), and poses the least hazard in the southern steppe and semidesert because of low precipitation and generally level landforms. It is estimated that 50 percent of the Midland region may become subject to medium or strong gullying as ...

The gullying hazard in the midland region of the ussr in conjunction with economic development

This paper describes a project undertaken by Moscow University geographers to evaluate and map the natural gully erosion hazard for plains areas of European Russia. Compilation of a series of maps on specific natural characteristics with a bearing on gully formation serves as the basis for the creation of a map depicting the natural susceptibility of areas to gully erosion used in forecasting the potential maximum density of the gully network. Translated by Anna Luchanskaya, Western Michigan University, Kalamazoo, MI 49008 from: Geomorfologiya, 1992, No. 3, pp. 25–31.

Ye. F. Zorina

Papers

Erosion and sedimentation on the Russian Plain, part 1: contemporary processes

The role of the human factor in the development of gullying in the steppe and wooded steppe of the european ussr

The gullying hazard in the midland region of the ussr in conjunction with economic development

New maps of gully erosion