Integrated nutrient supply

Table of contents:

• Towards 'integrated nutrient supply' - Editorial
  1 - 3
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  written by ILEIA editorial team
  In many regions of the Third World the decline of soil fertility is alarming. In our opinion a drastic change in the approach to nutrient supply is urgently needed to increase the production of food for a growing population and to stop the rapid increase in soil degradation and destruction of natural ecosystems. Nutrient supply should be seen as an integrated part of the farming system.
• Improved fallow: Increasing the productivity of smallholder farming systems
  4 - 7
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  written by Dieter Prinz
  Improved fallow, defined as \"the targeted use of planted species in order to achieve one or more of the aims of natural fallow within a shorter time or on a smaller area”, can be seen as a very promising method to increase the productivity of smallholder farming systems in the tropics. A stable production system can be built up and an increase in area productivity achieved by using one or several forms of improved fallow combined. But if yields per hectare are to be doubled, all the elements of \"Integrated Nutrient Supply\" available will have to be used.
• Nitrogen transfer from legumes
  8 - 8
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  written by Marjolein Hanegraaf
  In traditional farming systems in the tropics the efficiency of using external inputs is very important since the financial means of the farmer are low. The Rhizobia/legume symbiosis is an appropriate source of nitrogen in this type of farming. In this contribution the optimum management of legumes as part of a multiple cropping system is discussed in three phases: establishment of the symbiosis, nitrogen content of the legume, and transfer of the fixed nitrogen to other crops.
• Cover crops on acid soils: Experiences in the humid tropics
  9 - 10
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  written by Kurniatun Hairiah , Meine van Noordwijk
  In the humid tropics, the leaching of nitrogen and other nutrients to the subsoil may occur throughout the growing season. Mixed cropping systems of shallow and deep rooted crops can therefore be advantageous. On acid soils maize may develop only shallow root systems; combination with deep-rooted cassava gives a better nutrient utilization than a monoculture.
• Sunnhemp: Experiences in Tanzania
  11 - 12
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  written by Gerold Rupper
  Although Gaby Stoll has mentioned Crotalaria juncea (Sunnhemp) in her book \'Natural Crop Protection on Local Farm resources in the Tropics and Subtropics\', it does not seem that the full efficiency of Sunnhemp has been recognised. This is even the fact in Tanzania where this plant has been cultivated on a large scale in the Ruvuma Region and less in practical other regions. Professors and lecturers of the Sokoine University of Agriculture, Morogoro, only became aware of the potentialities of Sunnhemp when a four day workshop was held at Peramiho, the centre of Sunnhemp cultivation and the seat of a Sunnhemp Seed Bank, in October 1986.
• How-to-use rock phosphate
  13 - 13
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  written by Coen Reijntjes
  During recent years an impressive number of phosphate rock discoveries in Africa as well in Latin America and Asia have been registered. As transformation of the phosphate rock into super phosphate is of ten not possible the question can be raised whether fine grounded phosphate rock can be used for agricultural production. Recently interesting research in this field has been executed by researchers of The Netherlands, Niger and India. Let us see what is published by them.
• Micro-nutrient drain
  14 - 14
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  written by Ravi Sharma
  Is the green revolution killing the goose that lays the golden egg? Is it draining the very soil where the high-yielding varieties are planted? It would seem so. Scientists are discovering to their dismay that intensive cropping is removing the crucial micronutrient elements -zinc, iron, copper, manganese, magnesium, molybdenum, boron- which form only one per cent of the weight of a plant but control various aspects of a plant\'s processes. Zinc helps the plant use nitrogen and phosphorus, iron is responsible for the synthesis and maintenance of chlorophyll and so on. For instance, Ludhiana district of Punjab records the highest yields of many crop but it also records the most alarming deficiency of micronutrients.
• Soil conservation and shifting cultivators (1)
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  written by Andrew Millington
  When, because of overpopulation, the balance between degradation and recovery breaks down and soil erosion and other types of degradation become a problem. What then can be done in short-fallow shifting cultivation systems to ameliorate the effects of erosion? Evidence from Sierra Leone suggests there are possible solutions. Solutions that fit both the technical requirements of tropical soils and the socio-economic aspects of the local production systems.
• Cycles of poverty
  17 - 21
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  written by Phil O'Keefe
  Rural poverty is the essential cause of environmental degradation in sub-Saharan Africa. For the people living in the rural areas, low income is a major problem. In general, the price paid to these rural producers for their crops is artificially low. This low price structure serves as a subsidy for urban dwellers encouraging urban migration and discouraging rural production. Estimates of the size of this urban subsidy indicate that, in Africa south of the Sahara farm prices would have to double to provide realistic incentives to farmers.
• The moon and agriculture
  22 - 24
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  written by Hans Carlier
  The moon has always exercised a magical attraction on us. The moon, which sets enormous masses of water in motion and so causes ebb and flood in the sea. It is also common knowledge that the menstrual cycle in woman keeps pace with the lunar cycle. Above all other planets, the moon is the most apprehensible and most farmers throughout the world take the moon into account in their work, consciously or unconsciously.