Principles of Potash Use |
print
version (pdf 234kb) |
Organic manures
Inadequate allowance is still frequently made for the nutrient contribution from manures. Use standard figures unless specific analysis is available for consistent materials, and deduct the total amount of potash in manure applied if the soil Index is 2 or more. For soils at Index is 0 or 1, K added in manures can be thought of as helping to increase soil reserves and normal applications of fertiliser K should be given.
| Typical nutrient content of animal manures | ||||||||
| DM % |
Total Nutrients | Available Nutrients(1) | ||||||
Phosphate |
Potash |
Phosphate | Potash | |||||
| Fresh FYM (2) | ||||||||
| Cattle Pig |
25 |
3.5 |
8.0 |
kg/t | 2.1 |
7.2 |
||
| Poultry Manures | ||||||||
| Layer manure Broiler/turkey litter |
30 |
13 |
9.0 |
kg/t | 7.8 |
8.1 |
||
| Slurries | ||||||||
| Dairy (3) Beef (3) Pig (3) |
6 |
1.2 |
3.5 |
kg/m3 | 0.6 |
3.2 |
||
| Separated cattle slurries (liquid) | ||||||||
| Strainer box Weeping wall Mechanical separator |
1.5 |
0.3 |
2.2 |
kg/m3 | 0.15 |
2.0 |
||
(1) Nutrients that are available to the next crop (2) Potash values will be lower if FYM is store in the open or for long periods (3) Adjust nutrient content if % DM is higher or lower
|
||||||||
Cost pressures
A difficult financial situation should not persuade farmers to reduce levels of potash below the guidelines in this leaflet. Whilst the soil K targets are not precise cut-off points, it must be recognised that the risk of yield and quality penalties generally increases with lower soil K levels. In view of the fact that potash is not lost from most soils and that it is the least expensive of all major nutrients, such risks do not seem worthwhile.
The estimation of potash offtake and the replacement of this quantity remains the most important aspect of fertiliser policy for K.
Timing
Individual recommendations for specific crops are detailed in other PDA leaflets.