Influence of different textures on soil functional properties that are important to farmers
| Soil texture | Nutrient holding capacity | Water holding capacity | Water infiltration capacity | Aeration and workability | Potential for POM accumulation |
| CLAY Any type ending in Clay | good | good | poor | poor | good |
| SAND Any type ending in Sand | poor | poor | good | good | poor |
| LOAM Any type ending in Loam | moderate | moderate | moderate | moderate | moderate |
Guidance for managing ‘poor’ ratings:
- Soil texture cannot be changed. However, you can improve “poor” ratings by making regular additions of organic materials. This is the most effective strategy to improve all ratings across all textures: poor can become moderate, moderate can become good, etc.
- Adding crop residues, plant litter, composts and manures improves all of the soil functional properties in the table above related to nutrients, water and tilth.
- Farmers with sandy soils will need to add residues back to the soil more frequently since they are more quickly depleted in sandy soils.
- Farmers with clay soils will also be able to increase aeration, drainage and workability with organic material additions.
Guidance for managing acid soils using locally available materials in soils with different texture
Low soil pH negatively influences crop root growth, and hence crop yields.
Biochar or agricultural lime can be used to raise soil pH.
Often the recommended quantities to apply to the whole farm are quite large and may be out of economic reach of small scale farmers. However, it’s possible to have impact with smaller amounts, by concentrating it directly into the planting furrow or planting holes.
The table below gives guidance on amounts of lime or biochar to apply in a 5 m section of planting furrow (20 maize or sorghum plants) based on soil texture and your measured pH. If you use planting holes divide the amount among the planting hills that accommodate the 20 plants.
| Sands | Loams | Clays | |
| pH 4.5 or below | 1 kg lime or 1 gorogoro biochar | 1.5 kg lime or 1.5 gorogoro biochar | 2 kg lime or 2.5 gorogoro biochar |
| pH 4.5 to 6.0 | 0.5 kg lime OR 1 gorogoro biochar | 1 kg lime or 1.5 gorogoro biochar | 1.5 kg lime or 2 gorogoro biochar |