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close this bookSoil and Water Conservation (SWC) Technologies and Agroforestry Systems (IIRR, 1992, 171 p.)
View the documentMessage
View the documentWorkshop to revise
View the documentList of participants
View the documentCurrent program thrusts in Upland development
View the documentDegradation of the uplands
View the documentNutrient cycles in upland farms
View the documentEstablishing an swcsystem
View the documentFarm management practices that reinforce SWC
View the documentTraditional soil and water conservation (SWC) technologies
Open this folder and view contentsOptions for contour farming:
View the documentLand management practices for improved water conservation
View the documentIn-row tillage
View the documentMaking an A-frame
View the documentControlling Cogon and Talahib
View the documentUse of derris as botanical pesticide
View the documentFire control in the uplands
View the documentCultural management of pest infestation
Open this folder and view contentsOrganic fertilizer sources:
View the documentBiofertilizers
View the documentSelection of cover crops
View the documentBatao in the upland. Cropping system
View the documentIncreasing the woody contents in leaf litter
Open this folder and view contentsExamples of indigenous agroforestry systems:

Nutrient cycles in upland farms

Agroforestry aims to develop upland farms into self sustaining yet productive ecosystems. The key to this goal is an efficient cycling of nutrients within the system.

The nutrients required for plant growth consist of: Carbon (C), Hydrogen (H), Oxygen (O), which are all derived from air and water; the major nutrients: Nitrogen (N), Phosphonus (P) and Potassium (K), the secondary nutrients: Calcium (Ca), Magnesium (Mg) and Sulfur (S); and, the trace elements or micronutrients (around seven), which are all soilderives.

The soil-nutrient cycle operating in an upland farm can be viewed as a system consisting of stores, flows, gain, and losses.

Nutrient store:

- roots and shoots of all crops and trees
- plant residues
- soil organisms
- soil organic matter
- clay minerals (through fixation)
- soil solution Nutrient flows:
- plant uptake (via roots)
- mineralization (from plants to residues, via organisms to soil humus)

Nutrient gains:

- symbiotic, non-symbiotic fixation (for N only)
- rock weathering
- rain and dust
- organic materials from outside
- fertilizers

Nutrient losses:

- burning (for N and S)
- denitrification and volatilization (for N)
- leaching
- erosion
- harvest

Understanding these nutrient cycles is important for a farmer to be able to effectively manage them. This should also be the basis for determining what soil and water conservation measures are needed. Likewise, this should guide the farmer in a more rational use of fertilizers.


Nutrient cycle