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Organic food systems meeting the needs of Southern Africa.

Book cover for Organic food systems meeting the needs of Southern Africa.

Description

This book reports on long-term comparative organic farming systems' research trials carried out over the last 5 years in the Southern Cape of South Africa, as well as research into the successes and failures of the organic sector and the technical tools required for sustainable development in South Africa, Zambia, Uganda and Tanzania. It includes 24 chapters organized into 4 parts. Part 1 (Chapter...

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Chapter 22 (Page no: 303)

Soil fertility changes and crop yields from the first 4 years of the Mandela trials.

Long-term farming systems trials (the Mandela Trials) showed that organic farming systems initially had lower yields than conventional systems in the first 2 years (20% and 31% lower, respectively). In the third (drier) year, the yield gap was closed once soils had improved biologically and available soil phosphate had been supplemented with rock phosphate, and the organic system outyielded conventional by 11%. In the fourth (wetter) year, nitrogen-poor compost caused low yields in the organic system, and conventional yields were 27% higher than organic. Soil became less acid under organic management, and soil organic matter (SOM) levels improved, as did available potassium. The organic farming systems were supplied with less than a quarter of the nutrients supplied to the conventional system, but yields were comparable throughout. From the second season, crop rotation for both organic and conventional systems outyielded cabbage monocropping systems, but this was only statistically significant in the fourth year; the benefit of crop rotation was greater for organic systems, probably because in the fourth year the low nitrogen nutrition in the organic system affected monocropped cabbage severely, while rotated cabbage benefited from the previous cowpea (legume) crop. The rotation was: cabbage (heavy feeder) followed by sweet potato (light feeder) followed by cowpea (legume). Water use efficiency was better for the organic system with mulch helping to reduce evaporation and SOM improving the water and nutrient holding capacity of the soil. Soil microbiology was more diverse for the organic system and biological pest and disease control, although slower and not very effective against cutworm, was able to keep pests and diseases at acceptable levels.

Other chapters from this book

Chapter: 1 (Page no: 3) The developing organic sector in Southern and Eastern Africa: what have we learned about sustainable development? Author(s): Auerbach, R.
Chapter: 2 (Page no: 21) An overview of global organic and regenerative agriculture movements. Author(s): Leu, A.
Chapter: 3 (Page no: 32) Organic research contributes to sector development and good organic policy: the Danish, Swiss, American and African case studies. Author(s): Auerbach, R.
Chapter: 4 (Page no: 42) The Organic Academy of IFOAM-Organics International: training multipliers in the developing world. Author(s): Hauptfleisch, K.
Chapter: 5 (Page no: 51) Understanding a food systems approach. Author(s): Strassner, C. Kahl, J.
Chapter: 6 (Page no: 60) BERAS - a global network of food systems with examples from Sweden, Haiti, Tanzania and India. Author(s): Hertwig, J.
Chapter: 7 (Page no: 81) The likely impact of the 2015-2018 drought in South Africa: lessons from the 2008 food price crisis and future implications. Author(s): Auerbach, R. Piek, H. Battersby, J. Devereux, S. Olivier, N.
Chapter: 8 (Page no: 100) The use of participatory rural appraisal (PRA) to support organic food systems in Africa. Author(s): Auerbach, R.
Chapter: 9 (Page no: 113) Strengthening participation in the organic value chain for small-scale farmers in Southern KwaZulu-Natal, South Africa. Author(s): Troosters, W. Auerbach, R. Haysom, G.
Chapter: 10 (Page no: 130) Participatory Guarantee Systems as an organic market entry point for small-scale farmers in South Africa. Author(s): Mashele, N. J. Auerbach, R.
Chapter: 11 (Page no: 139) Development of an inclusive value chain for peri-urban micro-farmers. Author(s): Purkis, M.
Chapter: 12 (Page no: 151) Supporting vulnerable communities in the Eastern Cape: assessing the rainfall evidence. Author(s): Auerbach, R.
Chapter: 13 (Page no: 176) Water efficiency, energy efficiency and suburban vegetable production. Author(s): Auerbach, R. Caude, A.
Chapter: 14 (Page no: 185) Experiential training of farmers and university diploma students in KwaZulu-Natal and the Southern Cape. Author(s): Auerbach, R.
Chapter: 15 (Page no: 199) The National Organic Agriculture Movement of Uganda. Author(s): Nalunga, J. Auerbach, R. Ssekyewa, C.
Chapter: 16 (Page no: 209) Factors contributing to adoption or disadoption of organic agriculture in Zambia. Author(s): Munthali, R. Auerbach, R. Mataa, M.
Chapter: 17 (Page no: 217) The rapid incineration field test as an accurate, cost-effective and practical tool for estimating soil carbon in Africa. Author(s): Ackhurst, A. Auerbach, R. Louw, J.
Chapter: 18 (Page no: 233) The Nelson Mandela long-term comparative organic farming systems research trials: baseline study and trial design. Author(s): Auerbach, R. Mashele, N. J. Eckert, C.
Chapter: 19 (Page no: 250) Comparative water use efficiency and water retention in the Mandela trials. Author(s): Eckert, C. Auerbach, R. Lorentz, S.
Chapter: 20 (Page no: 264) Biological and chemical soil fumigation and pest and disease management comparisons in the Western Cape. Author(s): Niekerk, A. van Auerbach, R. Lamprecht, S.
Chapter: 21 (Page no: 284) Initial assessment of selected biological soil health indicators in organic versus conventional cropping systems in field trials in South Africa. Author(s): Sibiya, M. Habig, J. Storey, S. Labuschagne, N.
Chapter: 23 (Page no: 327) Urban agriculture: challenges and opportunities in urban water management and planning. Author(s): Wesselow, M. Kifunda, C. Auerbach, R. Siebenhüner, B.
Chapter: 24 (Page no: 337) A future strategy for organic development in Southern Africa. Author(s): Auerbach, R. Purkis, M.