Gabriele Stoll
Natural Crop Protection in the Tropics
Letting Information Come to Life
Methods of Field Protection
Plant Health and Disease Control
Plant strengtheners

Biofertilizers are essentially plant strengtheners. These are included in this book because they are very effective, but highly undervalued preventive 'crop protection' agents. This method is presented here to stimulate the utilization of this simple, flexible and low-cost way to produce a healthy crop. Most of the ingredients are locally available. Particularly in Central America, most of the mineral salts suggested are readily available and relatively inexpensive.
Biofertilizers originate from the fermentation of organic materials such as animal manure, milk whey, milk, sugarcane molasses, fruit juices, straws, ashes and many others through microbial activity. Microorganisms transform these organic materials and produce substances such as vitamins, complex acids and minerals indispensable for plant metabolism and nutritional balance. The compounds produced by the fermentation process are very rich in free energy, which is absorbed by the leaves (using the compounds as foliar fertilizers). By regulating starch, sugar and amino acid mobilization inside the plant, its resistance to disease and insect attack is increased .
Based on the availability of various waste materials that can be found on the farmer's own land, a great variety of biofertilizers can be prepared. They can range from simplest formulas to more sophisticated ones, which are enriched with complementary minerals, ashes, and meals depending on the requirements of a specific site or specific crops.
Such fertilizers and the ways to prepare them are already being used enthusiastically by farmers in Brazil, Uruguay, Argentina and the Andean countries across Central America through to Northern Mexico. In every country, the farmers have developed their own formulas according to their needs, with very successful results.

Enriched Biofertilizers
Enriched biofertilizers follow in principle the same preparation procedures as basic biofertilizers. In addition, they receive mineral salts and ashes according to the crops' nutritional needs (zinc sulphate, magnesium sulphate, manganese sulphate, copper sulphate, iron sulphate, cobalt sulphate, sodium molybdate, borax, calcium chlorate, phosphoric rock, ashes). During the fermentation, chemical and biological transformation of the mineral salts take place, which enable the absorption of many compounds that otherwise could not be assimilated directly by the plant, neither through the roots nor leaves. This results in more balanced plant nutrition, and makes plants less prone to infestation by insects and pathogens.

• Always use fresh cow manure collected very early in the morning.
• Always use a plastic container to avoid undesirable reactions with mineral salts.
• Use only clean fresh water, free of chlorine or fluoride.
• During fermentation, always store the biofertilizer in a shady    place away from the sunshine, otherwise important compounds  could be destroyed. Also store away from the rain.
• Always add new ingredients (mineral salts, milk, whey, molasses, sugar cane juice, or water) very slowly to avoid any possible fermentation interruption. Ideally they should be added drop by drop.
• Apply enriched biofertilizers more often and in a lower dosage than the simple biofertilizers. For example use a 0.5–1% solution every 3 or 4 days.
• Find out for your own situation which concentration and which frequency of application is most suitable.

The printed version contains more information about the following themes:

Basic biofertilizers
Enriched biofertilizer for tomatoes, broccoli, peppers and celery
Fermented compost extract
Plant-based growth stimulants

Snails and Slugs
Plant Health and
Disease Control