SECTION 1   ExecutiveSummary      InformaciónEspañol
StrategyPaper                           Fundación La Salle(SP)

SECTION 2
Choluteca Declaration by Greenpeace                     Choluteca Declaration         Declaración de Choluteca Deforestación (SP)                 Letter to Greenpeace     

SECTION 3
FlasaAgreement (SP)       Contact:

SECTION 4                        About Shrimp        Acuicultura(SP)              Closed System                Future Opportunities           Shrimp by Greenpeace         SobreChitin(SP)

SECTION 5                      Tax papers are all in Spanish:                 Exoneración (SP)                    Seniat  (SP)   
 

SECTION 6                           All PDF Files:          AboutShrimp          Acuicultura (SP)              Choluteca Declaration by Greenpeace                              CholutecaDeclaration             Closed System              Contact                   Declaración de Choluteca       Deforestación(SP)     Executive Summary            Fertilizer research FlasaAgreement(SP)       FutureOpportunities            Fundación La Salle(SP) Exoneración(Sp)              InformaciónEspañol          Seniat(SP)                           Shrimp by Greenpeace
SobreChitin(SP)                          ResumenFertilizante(SP)     Letter to Greenpeace

Fertilizer research

Research conducted at the Organization for Tropical Studies (OTS) has lead to the widespread use of native species in reforestation in the Atlantic Lowland region of Costa Rica. To enhance local reforestation efforts, improved nursery production and site establishment techniques must be developed and practiced. The current nursery practices using plastic bags with clay soils and little organic matter incorporation result in planting stock with poorly developed root systems. Planting stock quality could be improved by using other types of containers and organic substrates. The main site constraint is weed competition. Herbicide and fertilizer may speed tree establishment.

The most common seedling production method in non-industrial forest nurseries in Costa Rica involves filling 500 or 750 cm3 perforated plastic (poly) bags. These smooth plastic bags cause root coiling, the spiral growth of roots at the bottom of the bag. This root deformation leads to toppling or basal sweep several years after planting. Planting stock quality is essential to reforestation success. If reforestation with native species is to succeed, farmers must be given the highest quality seedlings. Attributes of planting stock quality include morphological and physiological traits which enable seedlings to become established rapidly and undergo substantial growth during the first year of planting.

Seedlings of five commercially important and widely planted native hardwood species - Cordia alliodora (R.P.) Cham. (Boraginaceae), Hyeronima alchorneoides Fr. Allemao (Euphorbiaceae), Callophyllum brasiliense Cambess (Clusiaceae), Vochysia guatemalensis Donn. Sm., and Vochysia ferruginea (Vochysiaceae) - were grown under 11 nursery treatments to test the effects of container type and substrate quality. Treatments consisted of three container types: root trainers, paper pots, and plastic bags, and five substrates: soil with and without 10 g of N-P-K fertilizer, two composts, and a 50% mixture of soil and compost.

Height and diameter were measured on all trees. Leaf area, root length, dry weight of leaves, stems, and roots, and nutrient concentrations of plant tissues determined for a subset of seedlings. Seedlings were then planted in a 12-month field trial to determine the effects of initial seedling characteristics on final plant size, growth, and survival. The influences of weeding regimes, manual weeding and herbicide treatment, and a one-time application of fertilizer to half of the seedlings, were also tested.

Cordia alliodora responded to increased nutrient availability; total dry weight, height, and diameter were greatest for the plants grown in plastic bags with fertilizer. Hyeronima alchorneoides also responded to increased nutrient availability, but grew better in compost which had better physical characteristics and higher P availability than in soil amended with fertilizer. For both C. alliodora and H. alchorneoides, plant total dry weight, leaf area, and root length were greater for plants grown in root trainers filled with compost than in bags of unamended soil. For C. brasiliense, there were no significant differences between plants grown with and without fertilizer. Total dry weight of plants grown in compost was less than that of plants grown in soil with and without fertilizer. Seedlings of both V. guatemalensis and V. ferruginea were chlorotic and stunted when grown in compost.

Vochysia guatemalensis grew better in soil with fertilizer whereas V. ferruginea grew better in unamended soil. Cordia alliodora and C. brasiliense grown in root trainers had fewer deformations than plants grown in plastic bags.

Fertilzers, the word organic generally means that the nutrients contained in the product are derived solely from the remains or a by-product of an organism. Cottonseed meal, blood meal, fish emulsion, manure and sewage sludge are examples of organic fertilizers. Urea is a synthetic organic fertilizer, an organic substance manufactured from inorganic materials.

When packaged as fertilizers, organic products have the fertilizer ratio stated on the package label. Some organic materials, particularly composted manures and sludges, are sold as soil conditioners and do not have a nutrient guarantee stated on the package, although small amounts of nutrients are present.

Some organic fertilizers are high in one of the three major nutrients
(nitrogen, phosphorus, or potash,) but low or zero in the other two. Some are low in all three macronutrients. A few organic products can be purchased "fortified" for a higher nutrient analysis. The ingredients used to fortify organic fertilizers are organic materials; for example, rock phosphate to increase phosphorus, or greensand to increase potash.

Organic fertilizers depend on soil organisms to break them down to release nutrients; therefore, most are effective only when soil is moist and warm enough for the microorganisms to be active. Nutrient release by microbial activity, in general, occurs over a fairly long time period. One potential drawback is that the organic fertilizer may not release enough of their principal nutrient when the plant needs it for growth.
On the other Hand enough nutrients are left for the next year, when needed.
Cottonseed meal is a by-product of cotton manufacturing. As a fertilizer, it produces a somewhat acidic reaction; consequently, it is frequently used for fertilizing acid-loving plants such as azaleas, camellias, and rhododendrons. Formulas vary slightly, but generally, cottonseed meal contains 7 percent nitrogen, 3 percent phosphorus, and 2 percent potash. Nutrients are most readily available to plants in warm soils,
but there is little danger of burn.

Blood meal is dried, powdered blood collected from cattle slaughterhouses.
It is a rich source of nitrogen, so rich, in fact, that it may burn plants if used in excess. Gardeners must be careful not to exceed the recommended amount suggested on the label. In addition to nitrogen, blood meal supplies some essential trace elements, including iron.
Fish emulsion, a balanced, organic fertilizer, is a partially decomposed blend of finely pulverized fish. A strong odor is associated with most brands of fish emulsion fertilizer, but the smell dissipates within a day or two. Recently, deodorized brands have been developed.

Fish emulsion is high in nitrogen and is a source of several trace elements. Contrary to popular belief, too strong a solution can burn plants, particularly those growing in containers. In the late spring, when garden plants have sprouted, an application of fish emulsion followed by a deep watering will boost the plants' early growth spurt.

Manure is a complete fertilizer, but low in the amount of nutrients it supplies. Manures vary in nutrient content according to the animal source and what the animal has been eating. A fertilizer ratio of 1-1-1 is typical. Commonly available manures include horse, cow, pig, chicken and sheep.

The highest nutritional concentration is found in manure when it is fresh. As it is aged, exposed to weather, or composted, nutrient content is reduced. However, most gardeners prefer to use composted forms of manure to ensure lesser amounts of salts, thereby reducing the chance of burning plant roots. Because of its low concentration of plant nutrients, manure is best used as a soil conditioner instead
of a fertilizer. Typical rates of manure applications vary from a moderate 70 pounds per 1000 square feet to as much as one ton per 1000 square feet.

Sewer sludge is a recycled product of municipal sewage treatment plants. Two forms are commonly available: activated and composted. Activated sludge has higher concentrations of nutrients (approximately 6-3-0) than composted sludge. It is usually sold in a dry, granular form for use as a general purpose, longlasting, nonburning fertilizer.
Composted sludge is used primarily as a soil amendment and has a lower nutrient content (approximately 1-2-0).

There is some question about the long term effects of using sewage sludge products in the garden, particularly around edible crops. Heavy metals such as cadmium, sometimes present in the sludge, may build up in the soil. Possible negative effects vary with the origin of the sludge and with the characteristics of the soil where it is used.

Compared to synthetic fertilizer formulations, organic fertilizers contain relatively low concentrations of actual nutrients, but they perform important functions which the synthetic formulations do not. They increase the organic content and consequently the water-holding capacity of the soil. They improve the physical structure of the
soil, which allows more air to get to plant roots. Where organic sources are used for fertilizer, bacterial and fungal activity increases in the soil. Mycorrhizal fungi which make other nutrients more available to plants thrive in soil where the organic matter content is high. Organically derived plant nutrients are slow to leach from the soil
making them less likely to contribute to water pollution than synthetic fertilizers.

Planting stock characteristics as well as weeding regimes and fertilization influenced final plant size and plant growth during the 12-month period. Each species exhibited unique responses. For C. alliodora, initial plant size did not correlate with final plant size, however it did affect the relative rate of growth. Small plants with a low ratio of above- to below-ground biomass grew fastest. Weed control using herbicide improved growth, but survival was lower than in manually weeded plots. A significant interaction between weeding and fertilizing demonstrated that there was little benefit to fertilizing trees on weedy plots. Plant size at the time of planting determined final plant size of H. alchorneoides.
Large trees retained their size advantage because there were few differences between relative growth rates of the different nursery treatments. Weed control with herbicide and fertilization improved growth, but there was an interaction between nursery treatments and weeding. Small, poorly developed plants grown in paper pots and in bags of soil had a larger positive response to the application of herbicide than did the small plants grown in root trainers or bags with compost. Seedling vigor may be a function of plant size and root morphology. Despite initial differences in planting stock characteristics, these differences did not seem to influence the growth and final plant size of C. brasiliense.
Field fertilization also did not affect growth. Callophyllum brasiliense may be be suited to poor sites. Further research may be necessary to identify appropriate substrate and target seedling characteristics for this species. These unique responses may reflect differences among species in root morphology and ecological adaptations.
Producing high-quality planting stock is essential for successful reforestation strategies and will help ensure tree plantations as a viable land-use option, particularly for small farmers.