Gafsa Phosphate Research Articles

Relative efficiency of phosphatic fertilisers in pasture topdressing

Abstract Pastures grown on Rosedale silt loam, a central yellow-brown earth yielded 22-54% more dry matter (DM) after addition of "Ibex" mono-calcium phosphate (IMCP) and 12% more DM after gypsum addition over a 2.5 year period with regular mowing cuts. In a comparison of phosphatic fertiliser forms, fertilisers were placed in the following order of decreasing effectiveness in terms of DM yield, P concentration, and P uptake data: Thermophos > superphosphate > 1:3 mixture of calcined “C” grade Christmas Island phosphate rock (CCIP) and superphosphate > CCIP = Gafsa phosphate rock > Nauru phosphate rock. CCIP and Gafsa improved relatively to Thermophos and superphosphate in the third year of the trial. Annual application of Thermophos, CCIP-superphosphate, and CCIP increased levels of Al-P and Fe-P in the soil. Superphosphate increased Al-P but not Fe-P. These manufactured fertilisers led to little change or a decrease in occluded-P and Ca-P levels. In contrast there was a large accumulation of Ca-P in the Gafsa and Nauru treatments which showed no change or a decline in Al-P and Fe-P levels. A single heavy application of the manufactured fertilisers increased Al-P and Fe-P in the first year after application but values declined in the second and third years. Heavy applications of Gafsa and Nauru phosphate rocks could not maintain the initial levels of AI-P and FeP. These treatments resulted in large accumulations of Ca-P in the first year followed by decreases in the second and third years. Bray No.1 and Olsen values for available P gave patterns of change similar to Al-P.

Sulphur, phosphate, and molybdenum coating of legume seed

Abstract The development of additional S, P, and Mo coating on rhizobia-coated legume seed for sowing in tussock grassland is described. The main response was to additional S, as elemental S, which approximately doubled establishment in coatings of 50–100% increase relative to bare seed weight. The effect was greater when seed was sown into existing vegetation than into cultivated soil, and on brown-grey soils. Response to phosphates was smaller and less consistent with coatings of 50–100%, and Calciphos and reverted superphosphate were better than Gafsa phosphate. Responses to types or levels of Mo were generally not significant. Manufacturing problems are discussed.

COMPARISON OF DIFFERENT FORMS OF PHOSPHATIC FERTILIZERS PART I: RAPE AND SWEDES

SummaryEighteen experiments were carried out in Wales and the West Midland Region, between 1966 and 1971 to compare granular basic slag with powdered basic slag and superphosphate (or triple superphosphate) as phosphatic fertilizers for rape and swede crops. At the swede sites additional comparisons involving ground mineral phosphates were also made.The fertilizer treatments were applied at sowing time and at rates supplying 28 and 56 kg P/ha for rape and 28 and 56, or 44 and 88 kg P/ha for swedes. Large increases in yield of rape and swedes to the lower rate of phosphate application were recorded at most sites but, in general, only very small additional responses were obtained to the higher dressing.For both rape and swede crops, the relative effectiveness of the different phosphatic fertilizers varied somewhat between sites. Comparisons of the superphosphate and basic slag treatments show that the former gave slightly higher yields at most sites. Granular basic slag was marginally inferior to powdered slag for swedes but in general the differences between the effects of superphosphate (or triple superphosphate) and the two forms of slag were small.The effects of the Gafsa phosphate treatments for swedes were variable, being as effective as superphosphate or basic slag at some sites and much less so at others. This inconsistency detracts from their over‐all usefulness. There was no definite advantage in the finely‐ground (80 per cent through 300 mesh (50 μm)) material over the relatively coarser (60 per cent through 100 mesh (150 μm)) product.Moroccan mineral phosphate was inferior to the Gafsa phosphates for swedes, particularly at the most responsive sites.

Influence of Arbuscular Mycorrhiza and Source of Phosphorus on Root Development and Nodulation of <i>Acacia mangium</i> Seedlings on Degraded Soils

A pot study on the effect of arbuscular mycorrhiza (AM) and phosphate rock (PR) on root development and nodulation of Acacia mangium seedlings on degraded (tin tailing) soils was conducted in the glasshouse of Universiti Putra Malaysia (UPM), Malaysia. Two arbuscular mycorrhiza (AM) inoculation treatments, viz., (i) with AM and (ii) without AM in combination with three P sources like Gafsa phosphate rock (GPR), China phosphate rock (CPR) and triple superphosphate (TSP) including a control (without P) were studied in split plot design. Six sets of this treatment combination were established for destructive sampling at 60, 75, 90, 105, 120 and 135 days after planting (DAP). Root biomass yields and root volume of inoculated seedlings given TSP and GPR were identical and superior to that with other treatments throughout the study. The P sources were in the order of TSP>GPR>CPR for enhancing root development irrespective of AM inoculation. The uninoculated seedlings required 15 to 20 more days to produce an equivalent root biomass to that of inoculated seedlings. Number and weight of nodules of AM inoculated seedlings given TSP and GPR were also higher than those with other treatments. As a cheaper source GPR in combination with AM might be used for growing A. mangium seedlings on degraded tin tailings. Keywords: Acacia mangium, Arbuscular mycorrhiza, Phosphate rock, Root development, Nodulation, Degraded soil DOI: http://dx.doi.org/10.3329/bjm.v23i2.871 Bangladesh J Microbiol, Volume 23, Number 2, December 2006, pp 102-106

Comparative Trials of Seed Pelleting, Inoculation and the Use of High Lime Dressings in Upland Reclamation

SUMMARYAt 3 centres in North, South and Central Wales, respectively, trials were made to compare the establishment and growth of white clover using seed pelleted with lime or with lime + Gafsa phosphate on unlimed soil, and non‐pelleted seed on limed or unlimed (control) soils. All treatments were divided into inoculated and uninoculated sections using an effective strain of Rhizobium trifolii. There were significant differences in clover establishment between the unlimed control plots and those that received 3 tons of ground limestone/acre but no overall significant effect of inoculation. The no. of nodules/plant was increased significantly both by high lime applications and by lime pelleting with inoculation. Both high lime and lime pelleting gave higher clover contents of the sward, and the total increase in clover due to inoculation was also highly significant. While the percentage clover in the sward derived from pelleted seed is low compared with that in the high lime plots it is considered that the use of inoculated pelleted seed is a cheaper and easier method of upland reclamation than applying heavy dressings of lime.

The Use of Inoculation and Pelleting in the Establishment of White Clover under Mountain Conditions

Summary. Aberystwyth S.184 and New Zealand Certified Mother white clover (Trifolium repens) seed was inoculated with an effective strain of Rhizobium trifolii and pelleted with lime and lime and Gafsa phosphate. When sown in conjunction with S.59 red fescue (Festuca rubra) on rotary cultivated Nardus‐Festuca mountain pasture treated seed gave a significantly better establishment of clover than the uninoculated, non‐pelleted seed of the same varieties.

Field experiments on phosphate fertilizers: A joint investigation

The results of over 400 field experiments testing different kinds of phosphate fertilizers are summarized and are discussed with special reference to the reactions of the soils used. The classifications were:‘very acid’ soils—pH below 5·5, ‘acid soils’— pH 5·6 to 6·5, neutral soils—pH over 6·5. All comparisons are made in terms of fertilizers supplying the same amounts of total phosphorus.In war-time experiments Gafsa and Morocco rock phosphates were about two-thirds as efficient as superphosphate for swedes and turnips grown on very acid soils. In 1951–3 experiments on very acid and acid soils Gafsa phosphate was practically equivalent to superphosphate for swedes, but for potatoes it was as effective as only one-third as much phosphorus supplied as superphosphate; on neutral soils Gafsa phosphate was useless. For establishing grassland on acid soils Gafsa and Morocco phosphate were equivalent to about onethird as much phosphorus supplied as high-soluble basic slag. Rock phosphates were somewhat more effective for promoting growth of established grassland but they remained inferior to high-soluble basic slags and to superphosphate. Curacao rock phosphate was roughly equivalent to Gafsa phosphate for swedes and grass. Florida pebble phosphate was much less effective and was judged unsuitable for direct application. Mixtures of rock phosphate with superphosphate were not more efficient than equivalent amounts of the separate components used correctly.Silicophosphate was practically as effective as superphosphate for swedes grown on very acid and acid soils; it was less efficient on neutral soils. For potatoes silicophosphate was nearly as effective as superphosphate on very acid soils; it was much less efficient on acid and neutral soils. Silicophosphate was roughly equivalent to high-soluble basic slag for grassland.Mixtures of superphosphate with lime, serpentine, and low-grade basic slag were prepared, most of the water-soluble phosphorus being converted to insoluble forms. In experiments on swedes and potatoes these basic superphosphates were not superior to untreated superphosphate. For establishing grassland on very acid soils, the mixtures were slightly superior to ordinary superphosphate.Dicalcium phosphate was practically equivalent to superphosphate for swedes on all groups of soils. For potatoes dicalcium phosphate was more efficient than superphosphate on very acid soils, on less acid and neutral soils it was inferior to superphosphate.