Table Of ContentEast Africa's grasses and fodders
Tasks for vegetation science 29
Series Editors
HELMUT LIETH HAROLD A.MOONEY
University ofOsnabrock, Germany StanfordUniversity, Stanford, Calif., US.A.
East Africa's grasses and fodders:
Their ecology and husbandry
Joseph G. BOONMAN
Independent Consultant
Formerly ofKitale (Kenya)
•
Springer-Science+Business Media, B.V.
Library of Congress Cataloging-in-PublicationData
Boonman. J. G.
East Africa's grasses and fodders : ecology and husbandry I J.G.
Boonman.
p. cm. -- (Tasks for vegetarIan scIence; 29)
Includes bIblIographical references (p. ) and Index.
ISBN978-90-481-4176-0 ISBN978-94-015-8224-7(eBook)
DOI 10.1007/978-94-015-8224-7
I. Forage plants--Afrlca. East. 2. Grasses--Afrlca. East.
3. Pastures--Afrlca. East. 4. Grassland ecology--Afrlca. East.
I. TItle. II. Series.
SBI93.3.A353B66 1992
633.2'02'0967--dc20 92-23961
Printed on acid-free paper
This book was partly financed by the Netherlands Minister for Development Cooperation. Responsibility for the
contents and fortheopinions expressedrestssolelywiththeauthor; publication doesnot constitute anendorsement by
the Netherlands Minister for Development Cooperation.
All Rights Reserved
©SpringerScience+BusinessMediaDordrecht 1993
OriginallypublishedbyKluwerAcademicPublishersin1993.
Softcoverreprintofthehardcover Istedition 1993
No part of the material protected by this copyright notice may be reproduced or utilized in any
form or by any means, electronic or mechanical, including photocopying recording
or by any information storage and retrieval system,without written permission
from the copyright owners.
To EUy, my wife and home-editor who
helped thisbookdevelop withmorepatience
andencouragement than I hadany right to
expect
TABLE OF CONTENTS
Series editor's preface xvii
PART I: GENERAL
1. INTRODUCTION 1
1.1 Grasses for livestock, soils and environment 1
1.2 Schools of thought 2
1.3 Towards more intensive strategies 3
1.4 This book's approach 4
2. HISTORY OF GRASSLAND DEVELOPMENT (1900-1970) 6
2.1 Uganda 6
2.1.1 Green-manure crops 6
2.1.2 Grass rests in the crop rotation 6
2.2 Kenya 8
2.2.1 Veterinary control 8
2.2.2 Farmers' introductions 8
2.3 East Africa as a "gene centre" 9
2.4 The start of grassland research in East Africa 10
2.4.1 Early locations of grassland research 10
2.4.2 Mineral deficiencies (1920s) 11
2.4.3 Ecological approach (1930s) 11
2.4.4 Soil conservation 11
2.5 New varieties and commercial seed multiplication 12
2.6 Summary 12
3. THE GRASSLAND ENVIRONMENT 14
3.1 Climate of eastern Africa (l5°N-15°S) 14
3.1.1 Rainfall 14
3.1.2 Temperature 14
3.1.2.1 Temperature zones 17
3.2 Soils 17
3.3 The natural grassland environment 19
3.3.1 Grassland mapping 19
3.3.1.1 Ecological classification 20
3.3.1.2 Vegetation types 24
3.3.1.3 Ecological and physiognomic classification 25
3.3.2 Semantics 27
3.3.3 Primary and secondary grasses 28
3.4 Proposed zonation for grassland improvement 29
3.4.1 Zone I (Afro-alpine) 30
vii
viii
3.4.2 Zone II (Humid to subhumid) 30
3.4.2.1 Zone I1 (Kikuyugrass zone, 1750-3000m) 30
K1
3.4.2.2 Zone lIsT (Stargrass zone, 1250-1750m) 33
3.4.2.3 Zone I1 (Elephantgrass zone, <1250-1500m) 34
EL
3.4.2.4 Zone II (Coastal areas) 34
3.4.3 Zone III-high (>1000m) 35
3.4.3.1 Zones II+III-low (Coastal areas) 35
3.4.4 Zone IV 36
3.4.5 Zones V and VI 38
3.5 Summary 38
4. HUSBANDARY OF NATURAL GRASSLAND 40
4.1 Legumes in natural grassland 41
4.2 Secondary grasses and their communities 41
4.2.1 Kikuyugrass 41
4.2.1.1 Ecology of Kikuyugrass 41
4.2.1.2 Kikuyu grassland improvement 44
4.2.2 Stargrass 46
4.2.2.1 Ecology of Stargrass and general aspects 46
4.2.2.2 Star grassland improvement 47
4.2.3 Elephantgrass 49
4.2.4 Other natural grassland communities of Zone II 50
4.3 Primary grasslands of Zones III and IV 50
4.3.1 Grazing and botanical composition 51
4.3.1.1 Rotational grazing 53
4.3.2 Weed- and bush control 54
4.3.2.1 Acacia control in Ankole, western Uganda 54
4.3.2.2 Reseeding in West Pokot, Kenya 54
4.3.3 Burning 56
4.3.4 Mowing for conservation 57
4.3.5 Oversowing 58
4.3.5.1 Seed establishment 58
4.3.6 Fertilizers 59
4.4 Grassland at the coast 60
4.5 Fallow (post-cultivation) grass communities 61
4.5.1 African Couchgrass (Digitaria abyssinica) 61
4.5.2 Ecology and zonation of cultivated and weed grasses 62
4.6 Summary 64
5. FROM SHIFTING CULTIVATION TO CROP-GRASS ROTATIONS 65
5.1 Steps in crop intensification 65
5.1.1 Conventional bush fallow (shiftingcultivation) 65
5.1.2 From bush- to weedfallow 66
5.1.3 Continuous cropping 67
5.2 The control of soil fertility 67
5.2.1 Green manures (leguminous) 68
5.2.2 Kraal manure 69
5.2.2.1 Composition and effects of manure 69
5.2.2.2 Manure logistics 71
5.2.2.3 Night paddocks 71
5.3 The role of grass in the crop rotation 72
ix
5.3.1 Organic matter under grasses 72
5.3.2 Soil-chemicaleffects of grasses 73
5.3.3 Soil-physicaleffects of grasses 75
5.3.3.1 Differences between organic manures and grasses 77
5.3.4 Grass roots and soil structure 77
5.3.5 Soil erosion 79
5.4 Ley farming in Europe 80
5.5 Crop-grass rotation experiments in East Africa 81
5.6 Mixed-farming today 84
5.6.1 How to project cultivated grasses? 84
5.7 Summary 85
6. SPECIES OF CULTIVATED GRASSES 86
6.1 Potential species 86
6.1.1 Geographical and environmental restrictions 86
6.1.1.1 Environmental interactions 87
6.1.1.2 Zonation of cultivated grasses 87
6.1.2 Practical restrictions to numbers of species 88
6.2 Inputs alternative to genotype 88
6.3 Grass speciesperformance criteria 89
6.3.1 Herbage yield 92
6.3.2 Drought tolerance 95
6.3.3 Persistence 96
6.3.4 Nutritive value 97
6.3.5 Ease of management 100
6.4 Ecological significance of gene centre 101
6.4.1 Gene centre of southern Africa 102
6.5 Major cultivated pasture and fodder species 103
6.6 Rhodesgrass (Chloris gayana) 103
6.6.1 Adaptation 106
6.6.2 Husbandry 107
6.6.3 Ecotypes 108
6.6.4 Commercial varieties in East Africa 110
6.7 Setaria (Setaria sphacelata) 111
6.7.1 Adaptation 112
6.7.2 Husbandry 113
6.7.3 Animal production and nutritive value 114
6.8 Common Guineagrass (Panicum maximum) 115
6.9 Buffelgrass (Cenchrus ciliaris) 117
6.10 Molassesgrass (Melinisminutifiora) 118
6.11 Signalgrass (Brachiaria spp.) 120
6.12 Coloured Guinea (Panicum coloratum) 122
6.13 Hyparrhenia rufa 122
6.14 Stargrass (Cynodon spp.); Kikuyugrass (Pennisetum clandestinum) 123
6.15 Temperate grasses 123
6.16 Miscellaneous cultivated grasses 124
6.17 Summary 127
7. THE ESTABLISHMENT AND HUSBANDRY OF SOWN GRASSES 128
7.1 The first year: grass establishment 128
7.1.1 Direct sowing of grass seed 129
x
7.1.2 Date of sowing 130
7.1.3 Harrowing, rolling and sowing 130
7.1.4 Depth of sowing 130
7.1.5 Broadcast sowing 131
7.1.6 Sowing in rows 131
7.1.7 Grass seed rate 131
7.1.8 P-fertilizer in the seedbed 133
7.1.9 N-fertilizer in the seedbed 134
7.1.10 Weed control 134
7.1.10.1 Weed species 135
7.1.10.2 Chemical control 135
7.1.11 Early pasture husbandry after direct sowing 136
7.1.12 Undersowing 138
7.1.12.1 Undersowing to maize 138
7.1.12.2 Undersowing to wheat 139
7.2 The following years: pasture husbandry 139
7.2.1 Mixed-farming and rotational grazing 140
7.2.2 Seasonality in pasture production 140
7.2.2.1 Dry season 140
7.2.2.2 Seasonality within the rainy season 140
7.2.3 Manipulation of grass availability 142
7.2.3.1 The variation in age of the sown pasture 142
7.2.4 Fertilizers on sown and grazed pastures 143
7.2.4.1 N-topdressing 143
7.2.4.2 Strategic N-application 146
7.2.4.3 P-topdressing 147
7.2.5 Mowing as a husbandry tool 147
7.2.5.1 Mowing for conservation 148
7.2.5.2 Mowing as "topping" 148
7.2.6 Last-year pasture as holding ground 149
7.2.7 Other practical management aspects 149
7.2.8 Recommendations 150
7.3 Summary 150
8. GRASS SEED PRODUCTION IN KENYA 152
8.1 The Kenya grass seed sector 152
8.2 Systems of contract seed production 154
8.3 Home-grown seed 154
8.4 Husbandry of grass seed production 155
8.4.1 The first year's seed crop 155
8.4.2 Seed harvesting 156
8.5 Post-establishment crops 158
8.5.1 Rate and time of N-application 159
8.5.2 The effectof season 160
8.6 Causes of low seed yields in tropical grasses 160
8.6.1 Low seed yield in vegetatively propagated grasses 161
8.7 Field studies on seed formation processes 161
8.7.1 Tillering and heading 162
8.7.2 Spikelet development 166
8.7.2.1 Spikelet weight (lOoo-seedweight) 167
8.7.2.2 The Purity and Germination Capacity (PGS) 168
xi
8.7.2.3 PGS and harvest date 170
8.7.2.4 Seed shedding 170
8.7.2.5 Spikelet diseases and pests 171
8.7.3 Seed recovery 172
8.8 Conclusion 172
8.9 Summary 172
9. GRASS BREEDING AT KITALE 173
9.1 Variety maintenance 174
9.2 Source material for breeding 174
9.3 Breeding methods 175
9.4 Heading date (maturity class) 176
9.4.1 Heading date and plant vigour 177
9.4.1.1 Vigour and plant type 177
9.5 Gross and net variation in dependent characters 178
9.5.1 Heading date and seeding characters 179
9.5.2 Heading date and herbage characters 181
9.5.3 Genetic correlations in Nandi Setaria 183
9.6 Variety trials 184
9.7 Breeding Elephantgrass 184
9.8 Apomixis 186
9.9 Conclusion 186
9.10 Summary 189
10. LEGUMES IN SOWN AND GRAZED PASTURES 190
10.1 The clover model 191
10.2 Nitrogen fixation 192
10.2.1 Amounts of nitrogen fixation and transfer 193
10.2.2 The nutritive value of legumes 194
10.3 Husbandry of Desmodium-based pastures 196
10.3.1 Disappearance under rational grazing 197
10.4 Approaches to the problem of legume persistence 199
10.5 Other causes of legume disappearance 201
10.6 Legumes in early research in East Africa 201
10.7 How to maintain Desmodium in grazed pastures 204
10.8 Legumes in experimental grazing practice 205
10.8.1 Desmodium uncinatum (Silverleaf); 205
10.8.2 Desmodium intortum (Greenleaf); 206
10.8.3 Glycine(Neonotonia wightii) 206
10.8.4 Siratro (Macroptilium atropurpureum) 206
10.8.5 Centro (Centrosema pubescens) 207
10.8.6 Townsville Stylo (Stylosanthes humilis) 207
10.8.7 Stylo (Stylosanthes guianensis) 208
10.8.8 Stylosanthesfruticosa 208
10.8.9 Other speciesof Stylosanthes 209
10.8.10 Lotononis bainesii 209
10.8.11 Calopo (Calopogonium mucunoides) 209
10.8.12 Other tropical legumes 209
10.9 High-altitude pasture legumes 210
10.9.1 Kenya white clover (Trifolium semipilosum) 210
10.9.2 White clover (Trifolium repens) 211
