Phosphate in fibrophos

Trials have shown that fibrophos is a very effective source of Phosphate across a wide range of soil types throughout the UK. The Phosphate in fibrophos provides a long lasting as well as immediate supply to the growing crop.

Applications to both acid and alkaline soils have been shown to increase the available soil Phosphate within one month and this increase was maintained for at least 12 months.

Evaluation of fibrophos as a phosphatic fertiliser

Objective And Method
S.J.Richardson1993ADAS Huntingdon
Ryegrass was chosen as the test crop because sequential cuts allow an assessment of how quickly nutrients become available as well as revealing their overall availability. Two soils were used with very low P content. The pH's were 8.2 and 6.4 respectively. Cuts were taken whenever the most advanced plants reached 10-12 cm in height on each occasion.

Ashed Poultry Litter (fibrophos) was compared with TSP, Basic Slag and Rock Phosphate.
low phosphorus, high ph soil.
Foliage phosphorus content and uptake.
Table 1Phosphorus concentration in dried foliage (%)Phosphorus uptake by foliage (mg/pot)
TreatmentP2O5(kg/ha)Cut 4Cut 6Cut 4Cut 6
Basic Slag800.
Basic Slag1600.210.1 63.82.2
Rock Phosphate800.
Rock Phosphate1600.
Table 2Low phosphorus, normal Soil pH.
Herbage dry matter yield (g/pot).
TreatmentP2O5(kg/ha)Cut 1Cut 2Cut 3Cut 4Cut 5Cut 6Total
Basic Slag800.440.570.81.771.160.915.6
Basic Slag1600.450.630.781.81.31.376.3
Rock Phosphate800.40.560.781.470.990.985.1
Rock Phosphate1600.470.650.731.431.071.195.5
Standard Error or DeviationNSNSNS0.
Coefficient of variation19.810.411.18.18.416.55

Three months after sowing, yield was restricted in the nil treatment whereas all fertiliser treatments except Phosphate rock markedly increased yield. At that stage, both yield and phosphorus content of the foliage already indicated that the phosphorus in the fibrophos was at least as readily available, possibly more so, than that in basic slag and more readily available than that in Phosphate rock.

By cut 6 both yield and phosphorus uptake data for fibrophos showed it to be superior to basic slag and rock Phosphate. Of more significance however is the evidence that fibrophos is fully as effective as triple superPhosphate.

The design of the trial included TSP added in steps of 40Kg/ha P205 in order to allow the efficiency of fibrophos to be assessed: both yield and phosphorus uptake suggest it is 100% efficient within months of application.


As a long lasting source therefore, fibrophos is ideal for raising the soil Phosphate status and maintaining it. Used for this purpose when soil Phosphate is 0 or 1, fibrophos can be applied at 625Kg/ha (5 bags/acre) every two to three years depending on crop potential. This will provide an adequate level of Phosphate to ensure full effectiveness of Nitrogen or compound fertilisers.