Agronomy of Grassland Systems

by Craig J. Pearson , Ray L. Ison

• ISBN13: 9780521560108
• ISBN10: 0521560101
• Edition: 2nd
• Format: Hardcover
• Copyright: 1997-11-28
• Publisher: Cambridge University Press

Summary

The challenges facing grassland agronomists are becoming increasingly complex, with environmental and ethical issues assuming a greater significance alongside more conventional technical aspects. This new expanded edition, with an increased emphasis on systems thinking, has been revised to reflect current concerns, knowledge and practice. As such it addresses the need for a different approach to grassland agronomy, providing novel and provocative material to instruct, stimulate and enthuse the reader.

Table of Contents

Preface	xi
1. Overview: perspectives on grassland systems	1	(17)
1.1. The social construction of grassland systems	2	(2)
1.2. Grassland issues or problems	4	(4)
1.3. Systems thinking	8	(1)
1.4. Representing grassland systems	9	(6)
1.4.1. Modelling	10	(5)
1.5. Purposes of grassland systems	15	(2)
1.6. Further reading	17	(1)
2. The emergence of grassland systems	18	(19)
2.1. Biological and ecological models that give rise to grassland systems	20	(4)
2.1.1. Clementsian succession	20	(1)
2.1.2. `New' thinking	21	(2)
2.1.3. The origins of `range science'	23	(1)
2.1.4. Traditional or `mainstream' approaches to grassland system development	23	(1)
2.2. Technologies that reveal and conceal - a case study	24	(4)
2.2.1. Increasing productivity	25	(2)
2.2.2. Thirty to fifty years later	27	(1)
2.2.3. Stepping outside our traditions	27	(1)
2.2.4. Responsibility in technology design	28	(1)
2.3. Present grassland systems	28	(7)
2.3.1. Global distribution of grassland systems	28	(2)
2.3.2. Animal industries	30	(3)
2.3.3. Grassland plant domestication	33	(2)
2.4. The agronomic manipulation of grassland systems	35	(1)
2.5. Further reading	36	(1)
3. Generation	37	(23)
3.1. Sources of seed	37	(5)
3.2. Sown seed	42	(6)
3.2.1. Time, rate and depth of sowing	43	(1)
3.2.2. Method of cultivation and sowing	44	(1)
3.2.3. Nutrition and seed treatment	45	(1)
3.2.4. Grazing	46	(1)
3.2.5. Herbicides	47	(1)
3.2.6. Burning	47	(1)
3.3. Dynamics of the seed bank	48	(5)
3.3.1. Seasonality of seed banks	48	(1)
3.3.2. Dormant and active seed	49	(4)
3.4. Germination	53	(2)
3.5. Vegetative generation	55	(1)
3.6. Systems modelling	56	(3)
3.7. Further reading	59	(1)
4. Vegetative growth	60	(23)
4.1. Emergence	61	(2)
4.1.1. Seedling type	62	(1)
4.1.2. Seed size and genotype	62	(1)
4.1.3. Seed bed	63	(1)
4.2. Establishment	63	(2)
4.3. Forms of development	65	(4)
4.3.1. Apex position	65	(1)
4.3.2. Leaves	65	(2)
4.3.3. Branches or tillers	67	(1)
4.3.4. Roots	68	(1)
4.4. Growth	69	(4)
4.4.1. Interception of Tradition	70	(1)
4.4.2. Utilization of radiation	71	(1)
4.4.3. Carbon balance	71	(1)
4.4.4. Efficiency of net primary productivity	72	(1)
4.5. Regrowth	73	(1)
4.6. Environmental effects on growth	74	(2)
4.6.1. Water availability	74	(1)
4.6.2. Temperature	75	(1)
4.6.3. Nutrition	75	(1)
4.6.4. Fire	75	(1)
4.7. Competition	76	(2)
4.7.1. Thinning	76	(1)
4.7.2. Competitiveness and growth rate	76	(1)
4.7.3. Weeds	77	(1)
4.7.4. Trees	77	(1)
4.8. Grazing effects on growth and development	78	(2)
4.9. Long-term changes in species composition	80	(1)
4.10. Modelling plant growth	80	(2)
4.11. Further reading	82	(1)
5. Flowering and seed production	83	(16)
5.1. Juvenility	83	(1)
5.2. Morphological changes at flowering	84	(1)
5.3. Flowering	85	(4)
5.3.1. Environmental controls of flowering	85	(3)
5.3.2. Autonomous flowering	88	(1)
5.3.3. Development of the inflorescence	88	(1)
5.4. Fertilization and seed formation	89	(5)
5.4.1. Breeding systems	89	(2)
5.4.2. Anthesis and fertilization	91	(1)
5.4.3. Seed production	92	(2)
5.5. Implications for grassland growth and management	94	(3)
5.5.1. Flowering and growth rate	94	(1)
5.5.2. Flowering and quality	95	(1)
5.5.3. Selection of cultivars	95	(1)
5.5.4. Sowing time	96	(1)
5.5.5. Management by defoliation	96	(1)
5.5.6. Fertilizer application	97	(1)
5.5.7. Diseases and pests associated with flowering	97	(1)
5.6. Systems modelling	97	(1)
5.7. Further reading	98	(1)
6. Mineral nutrition	99	(20)
6.1. The nutrient network	99	(3)
6.2. Soil fauna and flora	102	(3)
6.2.1. Rhizosphere organisms	102	(3)
6.3. Uptake by plants	105	(2)
6.3.1. Uptake of inorganic nutrients	105	(1)
6.3.2. Cation anion balance	105	(1)
6.3.3. Soil acidification by legume pastures	106	(1)
6.4. Distribution of nutrients within the plant	107	(1)
6.5. Senescence and element release from dead material	107	(3)
6.5.1. Herbage death	108	(1)
6.5.2. Dung and urine	108	(1)
6.5.3. Decomposition	108	(2)
6.6. Animal intake	110	(1)
6.7. Losses from the system	110	(1)
6.8. Element deficiency and fertilizer needs	111	(1)
6.9. Implications for grassland growth and management	112	(5)
6.9.1. Pesticides and herbicides	112	(1)
6.9.2. Types of N, P, K, S fertilizer	113	(1)
6.9.3. Efficiency of utilization of fertilizer	114	(1)
6.9.4. Amount of fertilizer required	114	(2)
6.9.5. Timing of fertilizing	116	(1)
6.9.6. Type and method of application of fertilizer	116	(1)
6.9.7. Grassland maintenance and restoration	116	(1)
6.10. Models for nutrient management	117	(1)
6.11. Further reading	118	(1)
7. Herbage quality and animal intake	119	(21)
7.1. The basis of herbage quality	119	(7)
7.1.1. Chemical composition	120	(1)
7.1.2. Cell structure	121	(1)
7.1.3. Variation among species	122	(2)
7.1.4. Ageing	124	(1)
7.1.5. Environment	125	(1)
7.1.6. Palatibility and edibility	126	(1)
7.2. Injurious substances	126	(3)
7.3. Sward structure	129	(1)
7.4. Herbage availability: grazing pressure	130	(2)
7.5. Animal type and productivity	132	(2)
7.5.1. Animal type	132	(1)
7.5.2. Utilization of energy	133	(1)
7.5.3. Intake and productivity	133	(1)
7.6. Implications for management	134	(5)
7.6.1. Production systems	134	(4)
7.6.2. Research and development towards managing nutritive value	138	(1)
7.7. Systems approaches	139	(1)
7.8. Further reading	139	(1)
8. Grassland - animal interactions and management	140	(21)
8.1. Animal effects on grassland	140	(3)
8.1.1. Selective grazing	140	(1)
8.1.2. Pulling	141	(1)
8.1.3. Treading and poaching	142	(1)
8.1.4. Fouling	142	(1)
8.2. Grazing management systems	143	(6)
8.2.1. Production per animal and per area	143	(2)
8.2.2. Herd experience, composition and timing of operations	145	(1)
8.2.3. Grazing interval: set stocking and block grazing	146	(2)
8.2.4. Regional grazing systems	148	(1)
8.3. Conservation and supplementation	149	(6)
8.3.1. Carryover feed	149	(1)
8.3.2. Hay and silage	150	(2)
8.3.3. Crop residues and by-products	152	(1)
8.3.4. Fodder crops	153	(1)
8.3.5. Supplements	154	(1)
8.4. `Feed year' planning	155	(2)
8.5. Efficiency of livestock production	157	(2)
8.5.1. Energy budgeting	157	(2)
8.5.2. Legume versus nitrogen-fertilized grass systems	159	(1)
8.5.3. Efficiency of use of support energy	159	(1)
8.6. Systems perspectives	159	(1)
8.7. Further reading	160	(1)
9. Grassland systems design	161	(27)
9.1. Grasslands in farming systems	161	(10)
9.1.1. Farming systems perspective	161	(1)
9.1.2. Integration of grasslands and cropping	162	(4)
9.1.3. Economic analysis	166	(3)
9.1.4. Gender and culture	169	(1)
9.1.5. Farm technology	170	(1)
9.2. Grasslands and other forms of human activity	171	(3)
9.2.1. Agro-industrial systems for using grassland plants	172	(2)
9.2.2. Grasslands in aesthetics and conservation	174	(1)
9.3. Design of future grassland systems	174	(3)
9.3.1. Participation in designing	175	(2)
9.3.2. Future scenarios	177	(1)
9.4. Regional design	177	(3)
9.5. National issues	180	(3)
9.5.1. National purposes for grassland systems	180	(2)
9.5.2. Grassland research	182	(1)
9.6. Global design	183	(3)
9.6.1. Human health and food supply	183	(2)
9.6.2. Biodiversity	185	(1)
9.6.3. Sustaining organic matter and nutrients	185	(1)
9.6.4. Responding to climate change	186	(1)
9.7. Conclusion	186	(1)
9.8. Further reading	187	(1)
References	188	(30)
Index	218