One of the most widely acclaimed advantages of agroforestry is its potential for conserving the soil and maintaining its fertility and productivity. Generally, Agroforestry the new name for old agriculture practices. In agroforestry system crops plants or pasture are integrated with woody perennial to make the agriculture system more productive, adaptable, and sustainable. The combining effect of AF system makes the agroforestry forestry system more ecologically sustain, economically balanced and socially just. The integration of legume to the land increase the level of nitrogen, root of perennial plants penetrate sub soil to recycle the nutrients on top soil, it decreases the amount of soil erosion. Observation of interaction in natural ecosystems have identified a number of points which supports that Tree and other vegetation improvement of the soil: 

a. a) From time immemorial, farmers have known that they will get a good crop by planting in forest clearings

b.   b) Soils that develop under natural woodland and forest are known to be well structured, with good moisture-holding capacity and high organic matter content

c.     c) A forest ecosystem is a relatively closed system in terms of nutrient transfer, storage, and cycling

d.   d)  a forest ecosystem is a relatively closed system in terms of nutrient transfer, storage, and cycling

The various effects of agroforestry system that causes the soil more productive and sustainable and hence to improve soil are as follows:-

follows:-

 Maintenance or increase organic matter:- Various parts of tree and crops increase the amount of organic matter in the soil through leaf falling, degeneration of roots, root extraction etc. in Agroforestry system than mono cropping.  This has been proven and widely demonstrated, and is quantitatively known through studies of organic matter cycling under natural forest 

Nitrogen fixation: - Various types of Legume crops and trees increase the amount of nitrogen in the soil by nitrogen fixation. This property can be studied either by direct study of the soil or the study of root nodule activity.

 Nutrient uptake: - trees are more efficient than herbaceous plants in taking up nutrients released by the weathering of deeper soil horizons. Potassium, phosphorus, bases such as calcium and magnesium, and micronutrients are released by rock-weathering, particularly in the B/C and C soil horizons which tree roots often penetrate. Thus, nutrients in deeper soil horizons, that are unavailable to shallow-rooted crops, are taken up by deep-rooted trees.

 Protection from erosion: - The most serious effect of erosion is loss of soil organic matter and nutrients, and the resulting reduction in crop yield. Forest cover reduces erosion to low levels, primarily through ground-surface litter cover and vegetation; the protection afforded by the tree canopy is relatively slight. Trees and shrubs can also be employed, through proper planting arrangement and management, as effective barriers to control soil erosion (e.g., hedgerows for soil-erosion control).The erosion may be water erosion or win erosion. Water erosion is reduced by the effect of root and wind erosion is reduces by the protecting action of crop leaves.

Maintenance or improvement of physical properties of soil:-The major physical properties of soil are soil structure, soil texture, porosity, Bulk density, Moisture retention etc. Agroforestry system enhances and improves the soil physical properties by various Ways; such as, by increasing OM and hence better soil aggregation. By increasing the porosity of soil through soil penetration by roots. Integration of woody trees in the crop field causes better water retention on the soil.

 Modification of extremes of soil temperature:-The shading effect  of trees ,Increase organic matter ,minimum tillage, soil aeration, mulching makes optimum level of temperature for crop cultivation. , ground surface litter-cover greatly reduces the high ground-surface temperatures of bare soils in the tropics, which sometimes exceed 50°C. It is likely that leaf litter cover and shade produced by trees would have a similar effect.

Reduction of acidity: - Trees tend to moderate the effects of leaching through the addition of bases to the soil surface.