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Geospatial simulations of airborne ice-penetrating radar surveying reveal elevation under-measurement bias for ice-sheet bed topography
- Oliver T. Bartlett, Steven J. Palmer, Dustin M. Schroeder, Emma J. MacKie, Timothy T. Barrows, Alastair G. C. Graham
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- Journal:
- Annals of Glaciology / Volume 61 / Issue 81 / April 2020
- Published online by Cambridge University Press:
- 28 May 2020, pp. 46-57
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Airborne radio-echo sounding (RES) surveys are widely used to measure ice-sheet bed topography. Measuring bed topography as accurately and widely as possible is of critical importance to modelling ice dynamics and hence to constraining better future ice response to climate change. Measurement accuracy of RES surveys is influenced both by the geometry of bed topography and the survey design. Here we develop a novel approach for simulating RES surveys over glaciated terrain, to quantify the sensitivity of derived bed elevation to topographic geometry. Furthermore, we investigate how measurement errors influence the quantification of glacial valley geometry. We find a negative bias across RES measurements, where off-nadir return measurement error is typically −1.8 ± 11.6 m. Topographic highlands are under-measured an order of magnitude more than lowlands. Consequently, valley depth and cross-sectional area are largely under-estimated. While overall estimates of ice thickness are likely too high, we find large glacier valley cross-sectional area to be under-estimated by −2.8 ± 18.1%. Therefore, estimates of ice flux through large outlet glaciers are likely too low when this effect is not taken into account. Additionally, bed mismeasurements potentially impact our appreciation of outlet-glacier stability.
Multi-method process maps: An interdisciplinary approach to investigate ad hoc modifications in protocol-driven interventions
- Thomas I. Mackie, Leah Ramella, Ana J. Schaefer, Monica Sridhar, Alice S. Carter, Abbey Eisenhower, Grace T. Ibitamuno, Marisa Petruccelli, Shawna V. Hudson, R. Christopher Sheldrick
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- Journal:
- Journal of Clinical and Translational Science / Volume 4 / Issue 3 / June 2020
- Published online by Cambridge University Press:
- 26 February 2020, pp. 260-269
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Introduction:
Implementation scientists increasingly recognize that the process of implementation is dynamic, leading to ad hoc modifications that may challenge fidelity in protocol-driven interventions. However, limited attention to ad hoc modifications impairs investigators’ ability to develop evidence-based hypotheses about how such modifications may impact intervention effectiveness and cost. We propose a multi-method process map methodology to facilitate the systematic data collection necessary to characterize ad hoc modifications that may impact primary intervention outcomes.
Methods:We employ process maps (drawn from systems science), as well as focus groups and semi-structured interviews (drawn from social sciences) to investigate ad hoc modifications. Focus groups are conducted with the protocol’s developers and/or planners (the implementation team) to characterize the protocol “as envisioned,” while interviews conducted with frontline administrators characterize the process “as realized in practice.” Process maps with both samples are used to identify when modifications occurred across a protocol-driven intervention. A case study investigating a multistage screening protocol for autism spectrum disorders (ASD) is presented to illustrate application and utility of the multi-method process maps.
Results:In this case study, frontline administrators reported ad hoc modifications that potentially influenced the primary study outcome (e.g., time to ASD diagnosis). Ad hoc modifications occurred to accommodate (1) whether providers and/or parents were concerned about ASD, (2) perceptions of parental readiness to discuss ASD, and (3) perceptions of family service delivery needs and priorities.
Conclusion:Investigation of ad hoc modifications on primary outcomes offers new opportunities to develop empirically based adaptive interventions. Routine reporting standards are critical to provide full transparency when studying ad hoc modifications.
A subglacial hydrologic drainage hypothesis for silt sorting and deposition during retreat in Pine Island Bay
- Dustin M. Schroeder, Emma J. MacKie, Timothy T. Creyts, John B. Anderson
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- Journal:
- Annals of Glaciology / Volume 60 / Issue 80 / December 2019
- Published online by Cambridge University Press:
- 23 December 2019, pp. 14-20
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Late Holocene sediment deposits in Pine Island Bay, West Antarctica, are hypothesized to be linked to intensive meltwater drainage during the retreat of the paleo-Pine Island Ice Stream after the Last Glacial Maximum. The uppermost sediment units show an abrupt transition from ice-proximal debris to a draped silt during the late Holocene, which is interpreted to coincide with rapid deglaciation. The small scale and fine sorting of the upper unit could be attributed to origins in subglacial meltwater; however the thickness and deposition rate for this unit imply punctuated- rather than continuous-deposition. This, combined with the deposit's location seaward of large, bedrock basins, has led to the interpretation of this unit as the result of subglacial lake outbursts in these basins. However, the fine-scale sorting of the silt unit is problematic for this energetic interpretation, which should mobilize and deposit a wider range of sediment sizes. To resolve this discrepancy, we present an alternative mechanism in which the silt was sorted by a distributed subglacial water system, stored in bedrock basins far inland of the grounding line, and subsequently eroded at higher flow speeds during retreat. We demonstrate that this mechanism is physically plausible given the subglacial conditions during the late Holocene. We hypothesize that similar silt units observed elsewhere in Antarctica downstream of bedrock basins could be the result of the same mechanism.
Contributors
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- By Mitchell Aboulafia, Frederick Adams, Marilyn McCord Adams, Robert M. Adams, Laird Addis, James W. Allard, David Allison, William P. Alston, Karl Ameriks, C. Anthony Anderson, David Leech Anderson, Lanier Anderson, Roger Ariew, David Armstrong, Denis G. Arnold, E. J. Ashworth, Margaret Atherton, Robin Attfield, Bruce Aune, Edward Wilson Averill, Jody Azzouni, Kent Bach, Andrew Bailey, Lynne Rudder Baker, Thomas R. Baldwin, Jon Barwise, George Bealer, William Bechtel, Lawrence C. Becker, Mark A. Bedau, Ernst Behler, José A. Benardete, Ermanno Bencivenga, Jan Berg, Michael Bergmann, Robert L. Bernasconi, Sven Bernecker, Bernard Berofsky, Rod Bertolet, Charles J. Beyer, Christian Beyer, Joseph Bien, Joseph Bien, Peg Birmingham, Ivan Boh, James Bohman, Daniel Bonevac, Laurence BonJour, William J. Bouwsma, Raymond D. Bradley, Myles Brand, Richard B. Brandt, Michael E. Bratman, Stephen E. Braude, Daniel Breazeale, Angela Breitenbach, Jason Bridges, David O. Brink, Gordon G. Brittan, Justin Broackes, Dan W. Brock, Aaron Bronfman, Jeffrey E. Brower, Bartosz Brozek, Anthony Brueckner, Jeffrey Bub, Lara Buchak, Otavio Bueno, Ann E. Bumpus, Robert W. Burch, John Burgess, Arthur W. Burks, Panayot Butchvarov, Robert E. Butts, Marina Bykova, Patrick Byrne, David Carr, Noël Carroll, Edward S. Casey, Victor Caston, Victor Caston, Albert Casullo, Robert L. Causey, Alan K. L. Chan, Ruth Chang, Deen K. Chatterjee, Andrew Chignell, Roderick M. Chisholm, Kelly J. Clark, E. J. Coffman, Robin Collins, Brian P. Copenhaver, John Corcoran, John Cottingham, Roger Crisp, Frederick J. Crosson, Antonio S. Cua, Phillip D. Cummins, Martin Curd, Adam Cureton, Andrew Cutrofello, Stephen Darwall, Paul Sheldon Davies, Wayne A. Davis, Timothy Joseph Day, Claudio de Almeida, Mario De Caro, Mario De Caro, John Deigh, C. F. Delaney, Daniel C. Dennett, Michael R. DePaul, Michael Detlefsen, Daniel Trent Devereux, Philip E. Devine, John M. Dillon, Martin C. Dillon, Robert DiSalle, Mary Domski, Alan Donagan, Paul Draper, Fred Dretske, Mircea Dumitru, Wilhelm Dupré, Gerald Dworkin, John Earman, Ellery Eells, Catherine Z. Elgin, Berent Enç, Ronald P. Endicott, Edward Erwin, John Etchemendy, C. Stephen Evans, Susan L. Feagin, Solomon Feferman, Richard Feldman, Arthur Fine, Maurice A. Finocchiaro, William FitzPatrick, Richard E. Flathman, Gvozden Flego, Richard Foley, Graeme Forbes, Rainer Forst, Malcolm R. Forster, Daniel Fouke, Patrick Francken, Samuel Freeman, Elizabeth Fricker, Miranda Fricker, Michael Friedman, Michael Fuerstein, Richard A. Fumerton, Alan Gabbey, Pieranna Garavaso, Daniel Garber, Jorge L. A. Garcia, Robert K. Garcia, Don Garrett, Philip Gasper, Gerald Gaus, Berys Gaut, Bernard Gert, Roger F. Gibson, Cody Gilmore, Carl Ginet, Alan H. Goldman, Alvin I. Goldman, Alfonso Gömez-Lobo, Lenn E. Goodman, Robert M. Gordon, Stefan Gosepath, Jorge J. E. Gracia, Daniel W. Graham, George A. Graham, Peter J. Graham, Richard E. Grandy, I. Grattan-Guinness, John Greco, Philip T. Grier, Nicholas Griffin, Nicholas Griffin, David A. Griffiths, Paul J. Griffiths, Stephen R. Grimm, Charles L. Griswold, Charles B. Guignon, Pete A. Y. Gunter, Dimitri Gutas, Gary Gutting, Paul Guyer, Kwame Gyekye, Oscar A. Haac, Raul Hakli, Raul Hakli, Michael Hallett, Edward C. Halper, Jean Hampton, R. James Hankinson, K. R. Hanley, Russell Hardin, Robert M. Harnish, William Harper, David Harrah, Kevin Hart, Ali Hasan, William Hasker, John Haugeland, Roger Hausheer, William Heald, Peter Heath, Richard Heck, John F. Heil, Vincent F. Hendricks, Stephen Hetherington, Francis Heylighen, Kathleen Marie Higgins, Risto Hilpinen, Harold T. Hodes, Joshua Hoffman, Alan Holland, Robert L. Holmes, Richard Holton, Brad W. Hooker, Terence E. Horgan, Tamara Horowitz, Paul Horwich, Vittorio Hösle, Paul Hoβfeld, Daniel Howard-Snyder, Frances Howard-Snyder, Anne Hudson, Deal W. Hudson, Carl A. Huffman, David L. Hull, Patricia Huntington, Thomas Hurka, Paul Hurley, Rosalind Hursthouse, Guillermo Hurtado, Ronald E. Hustwit, Sarah Hutton, Jonathan Jenkins Ichikawa, Harry A. Ide, David Ingram, Philip J. Ivanhoe, Alfred L. Ivry, Frank Jackson, Dale Jacquette, Joseph Jedwab, Richard Jeffrey, David Alan Johnson, Edward Johnson, Mark D. Jordan, Richard Joyce, Hwa Yol Jung, Robert Hillary Kane, Tomis Kapitan, Jacquelyn Ann K. Kegley, James A. Keller, Ralph Kennedy, Sergei Khoruzhii, Jaegwon Kim, Yersu Kim, Nathan L. King, Patricia Kitcher, Peter D. Klein, E. D. Klemke, Virginia Klenk, George L. Kline, Christian Klotz, Simo Knuuttila, Joseph J. Kockelmans, Konstantin Kolenda, Sebastian Tomasz Kołodziejczyk, Isaac Kramnick, Richard Kraut, Fred Kroon, Manfred Kuehn, Steven T. Kuhn, Henry E. Kyburg, John Lachs, Jennifer Lackey, Stephen E. Lahey, Andrea Lavazza, Thomas H. Leahey, Joo Heung Lee, Keith Lehrer, Dorothy Leland, Noah M. Lemos, Ernest LePore, Sarah-Jane Leslie, Isaac Levi, Andrew Levine, Alan E. Lewis, Daniel E. Little, Shu-hsien Liu, Shu-hsien Liu, Alan K. L. Chan, Brian Loar, Lawrence B. Lombard, John Longeway, Dominic McIver Lopes, Michael J. Loux, E. J. Lowe, Steven Luper, Eugene C. Luschei, William G. Lycan, David Lyons, David Macarthur, Danielle Macbeth, Scott MacDonald, Jacob L. Mackey, Louis H. Mackey, Penelope Mackie, Edward H. Madden, Penelope Maddy, G. B. Madison, Bernd Magnus, Pekka Mäkelä, Rudolf A. Makkreel, David Manley, William E. Mann (W.E.M.), Vladimir Marchenkov, Peter Markie, Jean-Pierre Marquis, Ausonio Marras, Mike W. Martin, A. P. Martinich, William L. McBride, David McCabe, Storrs McCall, Hugh J. McCann, Robert N. McCauley, John J. McDermott, Sarah McGrath, Ralph McInerny, Daniel J. McKaughan, Thomas McKay, Michael McKinsey, Brian P. McLaughlin, Ernan McMullin, Anthonie Meijers, Jack W. Meiland, William Jason Melanson, Alfred R. Mele, Joseph R. Mendola, Christopher Menzel, Michael J. Meyer, Christian B. Miller, David W. Miller, Peter Millican, Robert N. Minor, Phillip Mitsis, James A. Montmarquet, Michael S. Moore, Tim Moore, Benjamin Morison, Donald R. Morrison, Stephen J. Morse, Paul K. Moser, Alexander P. D. Mourelatos, Ian Mueller, James Bernard Murphy, Mark C. Murphy, Steven Nadler, Jan Narveson, Alan Nelson, Jerome Neu, Samuel Newlands, Kai Nielsen, Ilkka Niiniluoto, Carlos G. Noreña, Calvin G. Normore, David Fate Norton, Nikolaj Nottelmann, Donald Nute, David S. Oderberg, Steve Odin, Michael O’Rourke, Willard G. Oxtoby, Heinz Paetzold, George S. Pappas, Anthony J. Parel, Lydia Patton, R. P. Peerenboom, Francis Jeffry Pelletier, Adriaan T. Peperzak, Derk Pereboom, Jaroslav Peregrin, Glen Pettigrove, Philip Pettit, Edmund L. Pincoffs, Andrew Pinsent, Robert B. Pippin, Alvin Plantinga, Louis P. Pojman, Richard H. Popkin, John F. Post, Carl J. Posy, William J. Prior, Richard Purtill, Michael Quante, Philip L. Quinn, Philip L. Quinn, Elizabeth S. Radcliffe, Diana Raffman, Gerard Raulet, Stephen L. Read, Andrews Reath, Andrew Reisner, Nicholas Rescher, Henry S. Richardson, Robert C. Richardson, Thomas Ricketts, Wayne D. Riggs, Mark Roberts, Robert C. Roberts, Luke Robinson, Alexander Rosenberg, Gary Rosenkranz, Bernice Glatzer Rosenthal, Adina L. Roskies, William L. Rowe, T. M. Rudavsky, Michael Ruse, Bruce Russell, Lilly-Marlene Russow, Dan Ryder, R. M. Sainsbury, Joseph Salerno, Nathan Salmon, Wesley C. Salmon, Constantine Sandis, David H. Sanford, Marco Santambrogio, David Sapire, Ruth A. Saunders, Geoffrey Sayre-McCord, Charles Sayward, James P. Scanlan, Richard Schacht, Tamar Schapiro, Frederick F. Schmitt, Jerome B. Schneewind, Calvin O. Schrag, Alan D. Schrift, George F. Schumm, Jean-Loup Seban, David N. Sedley, Kenneth Seeskin, Krister Segerberg, Charlene Haddock Seigfried, Dennis M. Senchuk, James F. Sennett, William Lad Sessions, Stewart Shapiro, Tommie Shelby, Donald W. Sherburne, Christopher Shields, Roger A. Shiner, Sydney Shoemaker, Robert K. Shope, Kwong-loi Shun, Wilfried Sieg, A. John Simmons, Robert L. Simon, Marcus G. Singer, Georgette Sinkler, Walter Sinnott-Armstrong, Matti T. Sintonen, Lawrence Sklar, Brian Skyrms, Robert C. Sleigh, Michael Anthony Slote, Hans Sluga, Barry Smith, Michael Smith, Robin Smith, Robert Sokolowski, Robert C. Solomon, Marta Soniewicka, Philip Soper, Ernest Sosa, Nicholas Southwood, Paul Vincent Spade, T. L. S. Sprigge, Eric O. Springsted, George J. Stack, Rebecca Stangl, Jason Stanley, Florian Steinberger, Sören Stenlund, Christopher Stephens, James P. Sterba, Josef Stern, Matthias Steup, M. A. Stewart, Leopold Stubenberg, Edith Dudley Sulla, Frederick Suppe, Jere Paul Surber, David George Sussman, Sigrún Svavarsdóttir, Zeno G. Swijtink, Richard Swinburne, Charles C. Taliaferro, Robert B. Talisse, John Tasioulas, Paul Teller, Larry S. Temkin, Mark Textor, H. S. Thayer, Peter Thielke, Alan Thomas, Amie L. Thomasson, Katherine Thomson-Jones, Joshua C. Thurow, Vzalerie Tiberius, Terrence N. Tice, Paul Tidman, Mark C. Timmons, William Tolhurst, James E. Tomberlin, Rosemarie Tong, Lawrence Torcello, Kelly Trogdon, J. D. Trout, Robert E. Tully, Raimo Tuomela, John Turri, Martin M. Tweedale, Thomas Uebel, Jennifer Uleman, James Van Cleve, Harry van der Linden, Peter van Inwagen, Bryan W. Van Norden, René van Woudenberg, Donald Phillip Verene, Samantha Vice, Thomas Vinci, Donald Wayne Viney, Barbara Von Eckardt, Peter B. M. Vranas, Steven J. Wagner, William J. Wainwright, Paul E. Walker, Robert E. Wall, Craig Walton, Douglas Walton, Eric Watkins, Richard A. Watson, Michael V. Wedin, Rudolph H. Weingartner, Paul Weirich, Paul J. Weithman, Carl Wellman, Howard Wettstein, Samuel C. Wheeler, Stephen A. White, Jennifer Whiting, Edward R. Wierenga, Michael Williams, Fred Wilson, W. Kent Wilson, Kenneth P. Winkler, John F. Wippel, Jan Woleński, Allan B. Wolter, Nicholas P. Wolterstorff, Rega Wood, W. Jay Wood, Paul Woodruff, Alison Wylie, Gideon Yaffe, Takashi Yagisawa, Yutaka Yamamoto, Keith E. Yandell, Xiaomei Yang, Dean Zimmerman, Günter Zoller, Catherine Zuckert, Michael Zuckert, Jack A. Zupko (J.A.Z.)
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Contents
- O. T. Faulkner, J. R. Mackie
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Chapter 4 - The Native Farm
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Summary
In such a vast area as West Africa, with such varying climates as those described in Chapter 2, it is not surprising that agriculture should also vary greatly from place to place.
In the country near the coast, with its heavy rainfall and short dry season, the life of the native farmer is one long fight against the rank growth of vegetation. Clearing new land covered with thick bush or forest is a laborious operation; and, when the land is cleared, an enormous amount of labour is continually required to prevent the weeds and undergrowth from encroaching on the cleared area and destroying the crop. The farms therefore tend to be small and intensively cropped, and are indeed more in the nature of gardens than farms. Mixed cropping is the general practice, and the spacing of the plants is as close as possible. Two crops of cereals can be grown every year; and other crops can be interplanted with the yam crop, the most important crop of this area. By such heavy cropping, a whole family can live without difficulty on the produce of a comparatively small piece of land. The following quite typical example will give some idea of the intensity of the cropping on native food farms in the vicinity of Ibadan, in Southern Nigeria:
1st year. Bush cleared and burnt in July and late maize planted on the flat in September. Hills for yams made in November and yams planted in the same month.
2nd year. Early maize planted through the yams in March, cotton planted through the yams and maize in early August, maize harvested late in August. In addition, edible beans and gourds also grown in the cotton.
3rd year. Early maize with cassava planted through it.
4th year. Cassava.
5th year. Reverted to bush.
In the whole cycle of four years the land only received one thorough cultivation, namely when the hills were made for the yam crop. The labour of deep cultivation is reduced to a minimum, but weeding and shallow cultivation are done frequently.
West African Agriculture
- O. T. Faulkner, J. R. Mackie
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Originally published in 1933, this book was written to provide candidates for British government service in West Africa with information on agricultural practice in the region. The text is primarily based around discussion of the problems associated with farming in the area and the methods used to solve them, with particular stress placed on the economic side of agriculture. It also concentrates on one part of the region, that of Northern Nigeria, as a means of avoiding excessive detail which might confuse the reader. This book will be of value to anyone with an interest in the history of colonial administration and West African agricultural practice.
Chapter 2 - Climate and Soil
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Summary
The climatic feature which is common to all our West African colonies is the division of the year into two well-defined seasons, the wet and the dry. Since these colonies are all situated entirely within the tropics, they are of course subject to tropical temperatures ; but temperature is influenced by local conditions such as altitude and nearness to the coast, whereas the division into two seasons is constant throughout the whole of West Africa. As a broad generalization one may say that the length of the wet season and the total rainfall decrease as one goes inland from the coast, and that at the same time the average temperature increases; the highest temperatures and the lowest rainfall are found in the extreme north of Nigeria.
The rainy season occurs during the summer months, from April to September, and during the rains the prevailing wind comes from the south-west and is therefore sometimes spoken of as the “South-west monsoon of the Coast”. West Africa during the summer is situated within the South-east Trade Wind belt, but the Trade Winds are deflected from their course by the heating up of the Sahara and blow from the south-west instead of from the south-east, bringing with them the moistureladen clouds from the ocean which cause the rainfall. After the end of September the rains cease somewhat abruptly and the wind veers round to the north or north-west. This northerly wind, known as the “Harmattan”, is in marked contrast to the south-west wind. It blows straight across the Sahara, and instead of being moist it is intensely dry and is laden with dust particles, which at times are so thick that visibility is reduced to a few hundred yards. As soon as the Harmattan sets in everything becomes desiccated and all plant growth practically ceases. Its effect at first resembles that of an early frost in England. Owing to its extreme dryness, and the amount of evaporation it causes, it is at first a cool wind and the temperature falls rapidly, especially at night; but later on, in February, March, and early April, it becomes hot and scorching; and it is during this period that the highest temperatures are recorded.
Chapter 3 - Political Economy
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- O. T. Faulkner, J. R. Mackie
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Summary
There are practically no European planters in British West Africa, and relatively very few large estates under native ownership. Apart from the fact that the climate hardly permits of Europeans making a permanent home in the country, it has always been the policy of Government to keep the land for the people and to prohibit the alienation of any large blocks of land to any individual, African or foreign. The land is regarded as belonging to the local community, which, as a community, has absolute security of tenure and most of the rights of a freeholder.
The rights of the individual farmer within the community are determined by local “native law and custom”. This is generally unwritten and frequently exceedingly difficult to translate into terms that are readily intelligible to a European. Local native law and custom, moreover, naturally varies vastly from place to place; and it is also liable at times to very rapid changes in response to altered economic conditions. Since the law and custom is unwritten, the native courts which administer it may revise it, or may retard its changes. Experience shows, however, that the courts cannot permanently and entirely prevent the custom changing in response to changing conditions. Nor indeed can they attain complete consistency in their interpretation of the customs. Consequently it is extremely difficult to generalize about the rights of individuals. But it may be said that generally the individual farmer (or family) has a right, with some qualifications, to continue permanently to farm the land which he uses regularly. But apparently it is also a principle of native law and custom that every adult married male of a village, or whatever the communal unit may be, has an equal right to the use of a piece of land. If, therefore, the population of a village is already large enough to use all its land, and the population of married males increases by one, some readjustment is necessary, and has to be carried out by the village head or the village council of elders.
These two principles do not conflict, and present no difficulty, so long as land is plentiful. They seem to be preserved even when land is scarce, so long as the people are truly primitive; but they must inevitably fail, and have in fact failed, before the inroads of civilization.
PART II - CROPS AND STOCK
- O. T. Faulkner, J. R. Mackie
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Chapter 1 - Introductory
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- O. T. Faulkner, J. R. Mackie
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Summary
The application of scientific methods of investigation to the problems of agriculture in West Africa is a comparatively recent development. The only agencies that can undertake this are the Governments through their Agricultural Departments, and in their present form these departments are really a post-War development. It was the activities of traders that first led to the establishment of Colonial Government in West Africa, and this fact had a considerable influence for many years on the general policy of the Governments. Yet neither the early Governments nor even the Chartered Niger Company, took the view that their only duty or interest was to protect the traders and facilitate their operations. At a very early date many valuable plants were introduced from other parts of the tropics in the hope of their being adopted by the natives of the country, and eventually Botanic Gardens were established and officers appointed, whose special function was this introduction of new crops and economic plants. But the main object in view was still an immediate increase in export trade, and this tendency persisted even when Agricultural Departments were established. Indeed the motive for their establishment seems to have been chiefly the hope of inducing the people, by more consistent propaganda, to adopt new crops—which they had frequently proved reluctant to do, in spite of persuasion and promise of future profit. “Quick returns” in the shape of increased production of export crops were similarly expected of the new Agricultural Departments, and their efforts to achieve these quick returns left them little opportunity for such a study of local farming and local conditions as alone could show what improvements were really feasible and likely to commend themselves to the native farmer. In any case the departments at first lacked adequate funds and staff. None the less they did much useful spade work; and by the time the War started, they had been able to define in some degree the problems before them; and to indicate the possibilities of progress. The staffs and funds of the departments were just being increased when the War caused all their activities to be suspended until a fresh start was made in 1921 or 1922.
The principle which guides all the actions of the Governments of West Africa to-day is the principle of trusteeship.
Preface
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- By O. T. Faulkner, J. R. Mackie, Nigerian Agricultural Department
- O. T. Faulkner, J. R. Mackie
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Summary
It is hoped that the reader will not feel defrauded by the title of this book when he finds that it deals much more with agriculture in Nigeria than in the other colonies. The limitations of our first-hand knowledge of the latter is not the only reason for our concentrating so much on Nigeria. In the four countries there are roughly similar areas: for instance, the Northern Territories of the Gold Coast resemble the Northern Provinces of Nigeria. Even were we able to do so, we should be led into wearisome detail if we attempted to recount fully the differences in the agriculture of such corresponding belts. Yet it is hoped that a reliable account of a particular agricultural practice in Northern Nigeria may assist a resident of the Northern Territories of the Gold Coast to understand the corresponding practice there.
This book is written especially for the candidates for Government service in West Africa in the Administrative and Agricultural Departments; but we hope it may prove useful or interesting to those who intend to come out as missionaries. We have attempted to produce neither a standard text-book, nor a scientific treatise. Thus, matters such as climate and soil and the botany of the various crops have been very shortly discussed. Such information can be obtained from other sources. Our object has been to deal with some of the problems connected with farming in these countries and to emphasize the methods by which it is attempted to solve these problems. The economic side of the subject has been particularly stressed, as this is an aspect of tropical agriculture which has been but little dealt with in text books.
The details of the experiments on which statements are based have commonly been omitted. They are to be found in the annual bulletins of the Agricultural Department of Nigeria, and some of the more important have also been collected together in a special bulletin on “The Maintenance of Fertility by Green Manuring”.
The first part of the book is devoted to general subjects ; the second, to some of the more important details about individual crops.
Chapter 6 - Green Manuring
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- O. T. Faulkner, J. R. Mackie
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Summary
In a district of heavy rainfall, the moment bush is cleared and land is left bare fertility is lost at a surprisingly rapid rate. Washing and leaching are the principal factors which contribute to this loss, and in any system of permanent cultivation the necessity for keeping the ground covered with vegetation, and taking every possible step to prevent wash, is of paramount importance. Europeans have been slow to realize the importance of this point, and there is no doubt that the planters of Ceylon and Malaya are suffering for it to-day. The native farmer, by his method of mixed cropping and by leaving the stumps of the bush in the ground, effectively minimizes the loss by leaching, but his system of growing crops on hills instead of ridges, as is common in many parts of West Africa, allows much wash to occur, with the natural consequence of a loss of fine soil.
Growing plants have a remarkable influence in causing rain to enter the soil, instead of allowing it to run off from the surface, as any one can see for himself by merely comparing a lawn and a piece of bare ground during a heavy shower. But this is by no means all. Except when a soil is exceedingly dry, natural processes are always going on by which plant food is converted into the soluble state. Especially the nitrogen contained in the insoluble decayed organic matter is always rapidly changing into a soluble form. Unless there are plants growing on the land to take it up as fast as it becomes soluble, every rain leaches out much nitrogen. Experiments prove that the weight of crop which can be grown in West Africa, as commonly elsewhere, depends primarily on the supply of nitrogen. Bush fallows restore fertility by the accumulation of nitrogen in insoluble organic matter, which, when the land is again cultivated. will decompose and provide soluble nitrogen again There are also recuperative bacterial processes, by which enough nitrogen from the air is accumulated to provide for the growth of bush or grasses; but under cultivation the rate of loss by leaching, let alone the absorption by the crops, is much more rapid than the recuperative processes.
Index
- O. T. Faulkner, J. R. Mackie
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- West African Agriculture
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Chapter 5 - Shifting Cultivation
- from PART I - GENERAL
- O. T. Faulkner, J. R. Mackie
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- West African Agriculture
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- 17 October 2013, pp 43-49
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Summary
The practice known as “shifting cultivation” is almost universal throughout the whole of West Africa. Under this system the farmer clears a piece of land, crops it intensively for three or four years and then allows it to revert to bush again until it has regained its fertility, meanwhile clearing another area of bush land in order to make a new farm. The resting period may be anything from one year upwards, depending on the density of the population and consequent demand for land; but the commonest period is about four or five years. The continuance of such a system depends therefore upon abundance of land, and hitherto this condition has existed generally in West Africa. But there are large areas in Nigeria where it no longer exists and, with an increasing population and an expanding demand for the produce of tropical countries, it can only be a question of time before a shortage of land becomes more general.
The native does not deliberately destroy trees whose fruits are of economic value, but, when land is cleared for farming, such trees, especially young oil palms, receive a check to their growth, which is often quite deliberately given by heavy scorching and by the cutting off of many leaves. Even the stumps of valueless trees and large bushes are not destroyed; but their regrowth is checked temporarily by regular lopping so long as the land is in cultivation. The stumps of the bushy under growth have a great value in ensuring that, when land in due course reverts to fallow, it shall be a fallow of secondary bush rather than one of grass and annuals; for the former type seems to lead to a greater recovery of fertility, and also has the advantage that when the land is again cleared it is not infested with weeds.
Where there is high forest still available, it is preferred for cultivation to any secondary bush, so that shifting cultivation in such areas entails the continual destruction of forest, which is valuable both for its timber and for its effect on climate. In these circumstances shifting cultivation is obviously most wasteful.
Chapter 7 - Mixed Farming
- from PART I - GENERAL
- O. T. Faulkner, J. R. Mackie
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- West African Agriculture
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Although mixed farming is a Nigerian subject rather than a West African one at present, there will clearly eventually be an opportunity for this kind of farming in the Northern Territories of the Gold Coast and in the Gambia.
It has already been explained that permanent cultivation exists in Northern Nigeria around the big towns and villages wherever manure is available; that the ordinary farming is of the extensive type; that further extension is limited by the supply of labour; and that the country supports a vast number of cattle, which, however, are mainly owned by the pastoral Fulani herdsmen and not by the settled farmers. All the materials for building up a system of mixed farming are therefore already in existence.
In speaking of mixed farming, the picture which we have in mind is one in which every farmer owns cattle of his own, say two bullocks and one or two cows, together with his usual head of sheep, goats and fowls. He would keep his cattle in a pen and supply them with bedding, thus making farmyard manure of the highest quality all the year round. His bullocks would be used for ploughing, thus solving the labour problem; and his cows would breed calves and supply him with milk for his family or for sale. The calves would appreciate in value as the male animals come on for draught purposes and the females develop into milking cows. Such a system, if it became universal, could not fail vastly to increase the prosperity both of the individual and of the country. Indeed, it might well be asked why it has not become the custom of the country long ago.
Before the British rule, the settled farmer was commonly little more than a villein or slave; and, even if any farmer had the money to invest in cattle, he dared not do so, as they were apt to be forcibly taken away from him; or, at the best, such an obvious sign of increased wealth made him liable for excessive taxation. This state of affairs ended when the country was taken over by the British; and after a few years a number of settled farmers began to invest their savings in cattle. Recently the number of those who have done so has been steadily increasing.
Chapter 8 - Extension Work
- from PART I - GENERAL
- O. T. Faulkner, J. R. Mackie
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- West African Agriculture
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- 17 October 2013, pp 76-90
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Summary
The best principles to be followed in the extension of improved agricultural methods is a fruitful subject of discussion in most countries, and especially in those of which the people are illiterate or but slightly educated.
The extension of agricultural practices involves two measures: first the introduction of the new crop, variety, or practice to the farmers, and secondly the steps that are necessary to make its adoption possible or profitable. These latter measures are often very important and may involve the organization of a supply of the new seed in a pure condition; or the control of marketing, so that the pioneers may not fail to obtain the value of their new type of produce because the quantity is at first too small to attract the attention of the trade; or the provision, usually through the agency of co-operative societies, of the capital that the farmer needs for the new undertaking. These measures are often matters of some difficulty, and they are unquestionably an essential part of the functions of Government in such countries as West Africa. Such measures may perhaps seem to some to be outside the functions of Government, and they certainly are liable to lead to an undesirable diversion of the energies of the Agricultural Department into the business of seed supply or the organization of markets. But they are generally inevitable. It is, for instance, quite useless to ask a farmer to grow a new superior variety of export crop merely because it will command a higher price than the ordinary, if, in course of time, it should completely replace the ordinary. Such a distant conditional promise is of no use to anyone; it is necessary to assure the farmer that measures will be taken to obtain the proper price for him next harvest, however small may be the total quantity of the new superior type. The lack of such measures has in the past led to the failure of many “improvements”. But the measures needed in each instance, and in each country, are peculiar to the special circumstances, and can hardly be usefully discussed in general terms. It is proposed to deal here chiefly with the steps to be taken in introducing the new variety or method.
The oldest method might be described as that of universal official propaganda.
Chapter 13 - Root Crops and Minor Food Crops: Yams, Cassava, Sweet Potatoes, Coco Yams, Beans and Cowpeas, Bambara Groundnut, Onions and Vegetables
- from PART II - CROPS AND STOCK
- O. T. Faulkner, J. R. Mackie
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- West African Agriculture
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The yam is the main food crop of Southern Nigeria, and is an important food in the coastal belts of the other colonies. In Southern Nigeria one might almost say that all other crops are subsidiary to it. Deep cultivation, and the best land, are always reserved for this crop. The commencement of the yam harvest is an important event in the social life of the native, and the actual day is often formally fixed by the chief of the tribe. The varieties of yams are innumerable, most districts having a special variety which is locally much more popular than any other; but, in the main, the differences between the. varieties are not very great. Some are earlier than others, some have whiter flesh, some are more suitable for pounding than others, and so on. The most important of these characters is that of earliness or lateness. Where yams are interplanted with cotton, or where they are grown in a rotation which incorporates green manuring, there is obviously a great advantage in growing a variety which can be harvested as early as possible.
The yam crop often occupies the land for nearly a whole year. The best time for planting varies somewhat in different localities, but generally the crop can be planted either in November or early December, or in March or April. Yams are not often planted in the interval between these two periods, and experiments indicate that this is not merely a question of convenience, as, if they are planted then, they do not germinate well. Also, yams planted too early do not do so well as those planted in November. The choice between the two good periods mainly depends on the proportion of land which can be prepared at the end of the rains; for yams planted in the earlier period yield better than those planted in March.
The farmer starts working on his yam land just before the rains cease and continues until the hardness of the soil makes the work too laborious. Such areas are planted in November-December. If he then has insufficient land prepared, he waits until the rains break when the ground must be prepared and the yams planted as quickly as possible. Any further delay results in a very serious loss of yield.
Chapter 12 - Cereal Crops: Maize, Guinea Corn, Millets, Rice
- from PART II - CROPS AND STOCK
- O. T. Faulkner, J. R. Mackie
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- West African Agriculture
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Maize is grown to some extent everywhere in Nigeria and the Gold Coast except in the extreme north; in the districts within 90 or 100 miles of the coast it is the only cereal crop. There are several local varieties, which differ chiefly in the length of their growing period. It was presumably introduced several centuries ago, but many attempts that have since been made to introduce new exotic varieties have met with no success, as the native finds them less palatable than those to which he is accustomed.
The early maize crop in the south corresponds to the gero crop of the north, in that it is planted with the first rains and is the first food crop of the year to come on to the market. If planted in March or early April it is ripe in August; but much of the crop is harvested while still soft. By eating it in this stage the grower obtains a much more palatable food, and his wife avoids the rather laborious process of reducing the hard ripe grain to flour. In favoured positions, as on the banks of streams, maize can be, and is, planted in nearly every month of the year.
Early maize is usually planted on the sides of stale yam heaps without any digging or turning of the soil, and receives no cultivation other than weeding. The seed is sown at the rate of about 16 lb. per acre. Generally cotton, guinea corn or beans are planted through it at any time after it is well established.
If no other crop is interplanted in it, and the maize is sown correspondingly thick, an average good field of early maize will yield about 2000 lb. of dry grain per acre, but the yield obtained by the native farmer is not easily ascertainable. It is probably little more than 1000 lb. per acre, for his crop of maize is obviously much smaller than those on the experimental farms.
In Southern Nigeria, late maize is usually planted as soon as the rains recommence at the end of August, and it is harvested in December or January. It is often planted on the flat on newly cleared land where it is intended to plant yams in the following season.
PART I - GENERAL
- O. T. Faulkner, J. R. Mackie
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- West African Agriculture
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- 05 June 2016
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