5.1 The Principles of Soil Fertilization and Conservation

The ideal model of soil fertilization and conservation can be found in the natural forest.

A regular supply of organic matter

Adding and returning organic matter to the soil is essential. It is only organic matter which can provide the necessary elements (nutrients) for growing plants, and improving the chemical, physical and biological qualities of the soil. The amount of humus in the soil decreases through mineralization, thus resupplying lost humus every year is a must for maintain soil fertility and quality. Approximately 8 ton/acre of organic matter a year is necessary for this purpose. To improve soil quickly or to treat chemically spoiled soil, an initial addition of double this amount (16 ton/acre) is recommended. Organic matter can be added using various methods (mulch, green manure, compost, etc.). If enough organic matter is supplied to soil, no crop would face nutrient deficiency. It is ideal if sufficient organic matter of a farm is produced within it.

Cover the soil

The surface of the soil should always be covered by vegetation or organic matter. When the soil is left bare, it is easily attacked by rain, wind and sun heat – the main causes of degradation of the soil structure and soil erosion.

Mixing raw (not well decomposed) organic matter with the soil should be avoided as the early stages of the decomposition process will create many problems. These include:

Raw organic matter should not be mixed with the soil

Mixing raw (not well decomposed) organic matter with the soil should be avoided as the early stages of the decomposition process will create many problems. These include:

1. consumption of air in the soil causing oxygen deficiency – very important for plant roots
2. production of methane, a gas harmful to plant roots
3. increased (organic) acidity in the soil
4. disturbing the balance in micro-organisms by increasing harmful fungi and creating a low B/F ratio

All of these are harmful for plants and cause pest problems. Raw organic matter should only be put on the surface of the soil as mulch. Incases where raw organic matter needs to be mixed with soil (e.g. green manure), sufficient time should be given for complete decomposition before planting.

Plant trees and grasses in boundary areas

The boundary area of the farm should be covered by vegetation through the planting of perennial trees and grasses. The main purpose is to protect it from being easily broken by rain and to check top soil run off. In addition, this area then becomes a source of organic fertilizer, fodder, fuel, food (fruits) timber, etc. and it also acts as a wind breaker.

No use of agricultural chemicals

Agricultural chemicals may demonstrate quick action in supplying nutrients (N.P.K.) and killing insects but they should be avoided as they create an imbalance in the soil ecosystem. The acid of chemical fertilizer disturbs the activity of micro-organisms and the poison of chemical pesticide kills them. They both create an imbalance in micro-organisms and cause pest problems. In addition, the nutrient balance in plants will be disturbed through the supply of only a few nutrients causing disease and the insect attack. Farmers think that the use of both chemical and organic fertilizer is better for growing plants. This practice will never solve pest problems which result from an imbalance of micro-organisms in the soil and nutrients in the plants.