1425 Soil Sci. Soc. Am. J. 71:1425–1437 doi:10.2136/sssaj2007.0001 Received 22 June 2007. *Corresponding author (Lal.1@osu.edu). © Soil Science Society of America 677 S. Segoe Rd. Madison WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. The strong link between soil and civilization (Howard, 1940, 1947; Hyams, 1952, Diamond, 2005) is likely to become stronger in the future through an increase in anthropogenic demands on world soils. Agriculture began with the recession of glaciers about 10, 000 BP when the world population was merely 3 million (McEvedy and Jones, 1979; Smil, 2000, 2001). It was 30 million about 2000 BP, 300 million at the onset of the Christian era, and 600 million by about 1600 CE. The world population doubled to 1.25 billion in 1850, 2.5 billion at the end of World War II in 1945, and 5 billion in 1987. It is 6.5 billion in 2007, and projected to stabilize at about 10 billion by 2100 (United Nations, 1998; Fischer and Heilig, 1997; Evans, 1998; Cohen, 2003). Ensuring food security has been a concern of humanity since the dawn of evolution, but especially so since Malthus expressed his apprehensions about the ability of humans to feed themselves (Malthus 1798, 1803). Thus far, those holding Malthusian views (Paddock and Paddock, 1967a, 1967b; Ehrlich and Ehrlich, 1987, 1991, 1992; Ehrlich et al., 1993) have been proven wrong (Boserup, 1965; McRae, 1994) primarily by the soil fertility management technology based on the “mineral nutrition theory” advanced by Justus Von Liebig (Waksman, 1942; Brock, 1997; Hopkins, 1914), and its application to inputresponsive varieties of wheat, rice, corn, soybean etc. (Khush, 2001; Swaminathan, 2000). In this regard, the contributions of HaberBosch synthesis of ammonia to world’s food production cannot be overemphasized. It is because of the use of nitrogenous fertilizers on well-watered fertile soils that global average yield of cereals increased from 1 Mg ha−1 in 1900 to 3 Mg ha−1 in 2000. Wheat yields in United Kingdom and Holland increased from 2 Mg ha−1 in 1900 to >8 Mg ha−1 in 2000 (Smil, 2000). However, soil science is facing new and more daunting challenges during the 21st century: of doubling the production by 2050 while improving the environment and mitigating the global warming (Cassman and Harwood, PR ESID EN ’S M ESSA G E Soil Science and the Carbon Civilization

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Soil Science and the Carbon Civilization

The Anthropocene is a major new concept in the Earth sciences and this book examines the effects on geomorphology within this period. Drawing examples from many different global environments, this comprehensive volume demonstrates that human impact on landforms and land-forming processes is profound, due to various driving forces, including: use of fire; extinction of fauna; development of agriculture, urbanisation, and globalisation; and new methods of harnessing energy. The book explores the ways in which future climate change due to anthropogenic causes may further magnify effects on geomorphology, with respect to future hazards such as floods and landslides, the state of the cryosphere, and sea level. The book concludes with a consideration of the ways in which landforms are now being managed and protected. Covering all major aspects of geomorphology, this book is ideal for undergraduate and graduate students studying geomorphology, environmental science and physical geography, and for all researchers of geomorphology.

Geomorphology in the Anthropocene

1. Introduction 2. Rock weathering and desert surfaces 3. Aeolian geomorphology 4. Dunes 5. Rivers and slopes 6. Applied geomorphology in deserts: hazards, resources and the future 7. Regional variety.

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Arid and Semi-Arid Geomorphology

Over the past 50 years, oil mulching has been a common technique for sand dune stabilization in the southwest of Iran (Khuzestan province). However, concerns over the release of heavy metals from oil mulching have led to the search for alternative mulches that are capable of stabilizing sand dunes without environmental hazards. This study investigates the feasibility of using sugarcane residues for producing environment-friendly mulches. Dunder, Press Mud, and clay soil from the surrounding area near the sand dunes were used to make sugarcane mulches for comparison with the traditional oil mulch. A sand dune was selected as a sample bed for applying the mulch. To select the proper ingredients and treatments, Dunder, Press Mud, and clay soil were mixed with water by a trial-and-error method. The selected batch mix was then used to make the desired mulch and sprayed on a sand dune bed. Shear strength of surface soil (SSS), penetration resistance (PR), soil surface shear resistance (SSR), and erodibility of selected treatments were measured by the shear torvane, hand penetrometer, Zhang’s surface shear device, and the wind tunnel. The treatments were arranged in a factorial experiment within a completely random design with the factors including mulch type (seven sugarcane mulches and one traditional oil mulch), thickness (1 or 2 layers), and rainfall (rain and no rain). The results indicate that SSS and PR increased with mulch thickness; the average values of SSS and PR obtained with the two-layer treatments were 1.27‒1.33 and 1.13‒1.15 times as great as the single-layer treatments. Increasing fraction of sugarcane residues significantly increased the SSS and PR. Higher concentrations of organic matter, CaCO3, and electrolyte in the sugarcane mulches may have helped the bonding of soil particles and increased the SSS and PR. However, the oil mulch had the lowest SSS but the highest PR. This might be due to the lower viscosity of oil mulch that allows it to penetrate sand dunes more easily than sugarcane mulches do.

http://iar.shirazu.ac.ir/pdf_3446_153fe91a865c9105a02027fea61a2f43.html

The influence of sugarcane mulch on sand dune stabilization in Khuzestan, the southwest of Iran

Ecological patterns and processes in dune ecosystems have been a research focus in recent years, however the information on how dune stabilization influences the spatial scale dependence of plant diversity is still lacking. In this study, we measured the plant species richness, soil properties and altitude across four spatial scales (1, 10, 100 and 1,000 m2) at three different dune stabilization stages (mobile dune, semi-fixed dune and fixed dune) in Horqin Sandy Land, Northern China. We also examined the relationships between plant species richness, community composition and environmental factors along the gradient of dune stabilization. Our results showed that plant species richness increased with the increase of spatial scales in each dune stabilization stage, as well as with the increase of dune stabilization degrees. Canonical correspondence analysis (CCA) showed that plant distributions in the processes of dune stabilization were determined by the combined environmental gradient in relation to soil organic carbon (SOC), total nitrogen (TN), carbon/nitrogen (C/N), pH, electrical conductivity (EC), soil water content (SWC), fine sand (FS), very fine sand (VFS), silt and clay (SC), and altitude. Plant species richness was significantly and positively correlated to SOC and TN in mobile dune, and significantly and positively correlated to SOC, TN, C/N, VFS and SC in semi-fixed dune. However, no significant correlation between plant species richness and environmental factors was observed in fixed dune. In addition, plant species richness in different dune stabilization stages was also determined by the combined gradient of soil properties and altitude. These results suggest that plant species richness has obvious scale dependence along the gradient of dune stabilization. Soil resources depending on dune habitats and environmental gradients caused by dune stabilization are important factors to determine the scale dependence of species diversity in sand dune ecosystems.

Scale dependence of plant species richness and vegetation-environment relationship along a gradient of dune stabilization in Horqin Sandy Land, Northern China

The low-rainfall ecologies of the northern fringes of Nigeria are prone to desertification and sand dune activities that are phenomenal and extensive. Stabilization structures put in place by various governmental and non-governmental agencies to check desertification in northwestern Nigeria were evaluated with respect to efficiency, impact on soil development and yield of millet. The study focused on the active and stabilized sand dune formations in NW Nigeria. Various stabilization techniques were identified within Gidan Kaura (the study site) and results were compared with an unstabilized sand dune (control site). Results obtained indicated that the sand dunes within the study area are still active despite the numerous stabilization structures, some of which were established over 15 years ago. Shelterbelts were the most effective techniques in sand dune stabilization and soil development when properly sited across wind direction. Shelterbelts recorded significantly higher levels of pH, organic carbon, total nitrogen, exchangeable bases and micronutrients except for copper, when compared with all other treatments. The least effective of all the structures was mechanical fencing, probably due to the inadequate quantity of plant residues used in its construction. The impact of the various structures on the physical and chemical soil properties was evaluated for surface soils as were the structures on the yield of millet in stabilized dunes and non-dune areas. The results are discussed in depth in this paper.

A. B. Momodu

Papers

Impact of Sand Dune Stabilization Structures on Soil and Yield of Millet in the Semi-Arid Region of NW Nigeria