MXPA99006724A - Zinc-ammonium phosphate fertilizers - Google Patents

Abstract

A process of obtaining a co-granulate of zinc and ammonium phosphate having a N/P ratio of 0.6 - 1.9 which includes initially feeding ammonium phosphate in finely divided form with a zinc source such as zinc oxide or zinc sulphate into a granulator wherein ammonia may also be fed into the granulator to increase the N/P ratio. The co-granulate is then obtained after drying.

Description

AMMONIUM PHOSPHATE AND ZINC FERTILIZERS FIELD OF THE INVENTION This invention relates to an improved ammonium phosphate and zinc fertilizer that is adapted to facilitate improved absorption of zinc in the soil or by plants when compared to phosphate fertilizers. of conventional ammonium and zinc.

BACKGROUND OF THE INVENTION Zinc is an element that is an essential trace element of soil and is often lost from soils by leaching during weathering and soil formation such that many soils contain less than 50 parts per million of zinc (ppm) (Gilkes CSBP and Farmers Ltd.- Productivity Focus, Jaunary 1994). In this reference, it is also stated that zinc fertilizers produce substantial increases in the yield and quality of grains, pastures, fruits, fibers and animals and thus it can be concluded that the absorption of zinc in soil and plants is an extremely important criterion. important of the efficiency of zinc fertilizers in use. Zinc fertilizers are discussed in Chapter 3 of the Proceedings of the International Symposium on "Zinc and Soil and Plants" that took place at The University of Western Australia on September 27-28. 1993 and that has now been published by Kluwer Academic Published and edited by A.D. Robson. In this reference, it is stated that the four most common classes of zinc fertilizers include: (i) inorganic sources such as ZnS04, ZnO, ZnC03, Zn (N03) 2 and ZnCl2; (ii) synthetic chelates including Zn (EDTA); (iii) natural organic complexes and (iv) inorganic complexes such as Zn (NH) and ZnS04. ZnS04 zinc sulfate is the most common source and is sold in crystalline and granulated form. This is also true for ZnO but the effectiveness of zinc oxide is low when it is sold in granular form due to its very low solubility in water. The most common method of application of zinc is by application in soils. Zinc fertilizers are applied mainly to soils in combination with NP (nitrogen-phosphorus) fertilizers that can include diammonium phosphate (DAP) or monoammonium phosphate (MAP) either by granulation incorporation or bulk combination in general with other granular fertilizers. Granular NP fertilizers are used as carriers for zinc because they allow a more uniform distribution with granulation devices conventional ones that are described for example in the international publication No. WO 95/21689. However, when zinc sources are incorporated into NP fertilizers during wet granulation, under the relevant conditions of high temperature and humidity, chemical reactions can reduce the plant's availability of some zinc sources. For example, insoluble zinc ammonium phosphate (ZnNH4P04) can be formed in the presence of ammonium ion and phosphate ion in the granulator. Thus, zinc and ammonium phosphate is formed that is not available for harvest, especially in neutral or alkaline sandy soils under dry conditions. In another example, when a synthetic chelate such as ZnEDTA is mixed with phosphoric acid prior to ammoniation, the acid decomposition of the chelate molecule results in decreased availability of some Zn fertilizers as described in Mortvedt, 1968, J. Agr. Food Chem. 16 241-245. In relation to the bulk combination of zinc fertilizers with granular NP fertilizers, an advantage obtained through this procedure is that fertilizer grades can be produced that will require the recommended proportions of zinc, nitrogen and phosphorus for a given objective yield . However, the main disadvantage of this procedure is that the Zinc segregation during the combination operation and with subsequent handling. Segregation results in a non-uniform application that is critical with zinc because the zinc application rate is low. Segregation occurs mainly due to the fact that the particle size of the zinc fertilizer is substantially smaller than that of the NP granules and thus the combined fertilizer will have localized cavities or cavities of excessively high Zn concentrations. The coating of Zn fertilizers on granular NP fertilizers can eliminate the possibility of segregation. The zinc fertilizer must be ground to a finely divided state such as less than 0.25 mm to adhere to the NP granules. Nevertheless, it has been found that the coating method in some cases is ineffective due to the separation between the NP fertilizer core and the Zn coating by which the coating falls and provides a substantial "powder" of finely divided particulate material that It returns to the resulting fertilizer less effective in use as well as it is of harmful value. Reference is made to US 4154593 which is concerned with a granulation process of ammonium phosphate wherein the ammonium phosphate is subjected to a cutting operation in a kneading mill or mill. knead and is also subjected to ammonia before being passed to a rotating drum granulator in the form of a suspension or melt. Additional ammonium sulfate can also be passed to the granulator in the form of a suspension or also melted as additional amounts of ammonia. A heat of reaction is generated in the granulator wherein at least a portion of the components that can react from the suspension or melt are reacted. This reference is also concerned with the addition of zinc as a solid filler which is also introduced to the granulator. However, it is considered that as the ammonia and ammonium phosphate in the form of a suspension or melt are added to the granulator, then this means that the zinc will react with the ammonium phosphate or ammonia to form a resulting complex to prevent Zinc is freely available for absorption into soil and plants. In other words, available zinc is "blocked" and absorption is prevented. AU 554749 relates to a process for producing fertilizer containing micronutrients wherein the fertilizer containing particulate phosphate such as ammonium phosphate is treated with a mineral acid and the fertilizer material is subjected to a rotor in the presence of micronutrient material in particles of a zinc compound in such a way that the zinc compound is adhered or glued to the external surfaces of the fertilizer material while the external surfaces are wetted with acid. Accordingly this reference is an example of granular NP fertilizer coating with micronutrients and these therefore have a separation advantage that is presented as described above. US 3560192 discloses a similar coating process wherein the granules of the fertilizer are coated with micronutrients in the presence of a binder consisting of a zinc chloride solution. However, the micronutrient is still applied to the external surfaces of the granules of the fertilizer and separation can still occur as described above in relation to AU 554749. RU 2034817 relates to the production of granular fertilizer comprising the addition of a mixture of calcium carbonate and magnesium carbonate to ammonium phosphates and wherein the resulting mixture is granulated at a temperature of 80-100 ° C. The problem of the absorption of zinc in soil and plants is not discussed in this reference. Similar comments apply to GB 1263719 which relates to stirring or stirring of ammonium phosphate, urea and a potassium salt at an elevated temperature in the presence of 0.0-5.0% by weight of water based on the mixture and drying of the resulting granules at a temperature below 90 ° C. The addition of zinc is not specifically mentioned in this reference and the problem of improving the absorption of zinc in plants or soil is not addressed. BE 861277 refers to ammonium sulfate fertilizers that also contain trace elements, copper and zinc, where 0.2-0.6 parts of copper and 0.7-2.0 parts of zinc are incorporated by 1000 parts of the total composition. These compositions are prepared by dissolving trace elements in phosphoric acid and treating the resulting solution with ammonia until the N / P ratio is about 2.0. In this reference, the problem of improving the absorption of zinc in plants and soil is not treated and in any case the zinc must presumably be "blocked" due to the reaction with ammonium phosphate during granulation or by reaction with phosphoric acid. SU 1481230 is concerned with the addition of theophylline, a zinc-containing additive for moistening the phosphoric acid in the process, neutralization with ammonia, drying the resolution thus obtained and granulating the suspension. This reference does not teach the reaction of ammonium phosphate with zinc and in any case, zinc would not be available for absorption due to its reaction with phosphoric acid.

AU 445640 relates to the preparation of granular fertilizers wherein ammonium phosphate initially in particles having an initial atomic ratio of N: P in the range of 0.8: 1 to 0.95: 1 are granulated in the presence of water at a temperature 30-100 ° C and the treatment of such particulate material with ammonia during granulation. The particulate material may also contain potassium chloride, ammonium nitrate and urea. The use of zinc is not specifically mentioned in this reference. Reference can also be made to the Indian Journal of Agronomy, 1989, 34 (4) 487-488, which refers to the study of the effects of zinc-coated fertilizers in which the fertilizer is ammonium phosphate in relation to rice. This reference suffers from the problems referred to above where the zinc coating can be separated from the fertilizer. Reference may also be made to Koshino, Soil Science and Plant Nutrition, 1974, 20 331 or to the Journal of the Science of Soil and Manure, Tokyo, 1973, 44 (6) 217-222 where reference is made to coated ammonium phosphate with zinc and the absorption of zinc in soils. Accordingly, similar comments can be made in relation to this reference as was done previously in relation to documents AU 55449 or US 3560192.

In Giordano et al., 1978, Agronomy Journal 70 531-534, reference is made to studies in pots where fertilizer tablets are made by compressing the powdered fertilizer and micronutrients into tablets in a press. Therefore, this reference does not refer to a commercial granulation technique. Reference may also be made to Daug et al., 1992, Indian Journal of Agricultural Research, 26 (2) 91-99, which refers to zinc fertilizers prepared by combining or mixing dry and wet, including the use of diammonium phosphate. (DAP) as the fertilizer. Again, this reference is not concerned with the use of commercial granulation techniques and it would be seen that in relation to the mixture of DAP and the zihc compound no improvement is noted in relation to the absorption of zinc in the soil or plants.

BRIEF DESCRIPTION OF THE INVENTION Accordingly, it is an object of the invention to provide a method of manufacturing a cogranulated ammonium zinc phosphate fertilizer that provides relatively efficient zinc absorption in soil or plants. The process of the invention includes the following steps: (i) mixing prefabricated ammonium phosphate having an N / P ratio of 0.6-1.9 and a source of zinc in the form of a slurry, slurry or particles together to form a resulting cogranulate in a granulating vessel and (ii) cogranulate drying. The aim of the present invention is the provision of a cogranulate of zinc and ammonium phosphate sources wherein the source or compound of zinc is intimately mixed with the ammonium phosphate. Although it is not desired to be limited by theory it is believed that if a chemical reaction between ammonium phosphate and zinc compound can be avoided or minimized during granulation, then it will inhibit the "blockage" of zinc and thus facilitate the promotion of the cogranulado by means of which the zinc will be more easily available for its absorption in the ground and the plants. It is also believed that mixing prefabricated ammonium phosphate with a zinc compound in the form of a slurry, suspension or particles will facilitate the achievement of the aforementioned objective. A conventional granulation plant can be used as shown, for example in the international publication No. W095 / 21689. The granulator container is usually in the form of a rotating drum rotating around of a horizontal axis. However, such a granulating container may also comprise a kneading machine or kneading mill. The ammonium phosphate can be fed to the granulation vessel in finely divided form (for example, the size of the particles may be 0.05-10 mm, more preferably 0.05-4 mm and more preferably about 1 mm) after having been obtained commercially or produced in a remote site of the granulator vessel. Alternatively, ammonium phosphate can be prepared in the granulation plant by pre-reaction in a pre-neutralizer or tube reactor. Alternatively, the ammonia and phosphoric acid can be discharged to a reaction tower from an upper end thereof before forming an ammonium phosphate reaction product at the bottom of the tower. Preferably, the ammonium phosphate and the zinc source are mixed together before being fed into the granulator vessel or alternatively, they can be fed to the granulator vessel separately by conveyors or elevators for subsequent mixing to form the resulting co-granulate. In this latter embodiment, the zinc source and the ammonium phosphate can be mixed in the granulator vessel as a rolling bed. Ammonium phosphate is preferably MAP but DAP can also be used if desired. The proportion of N / P is more preferably 0.8-1.5 and more preferably 1.0-1.5 to avoid the addition of phosphoric acid to the granulator vessel. More preferably, the ratio of N / P is between 1.15-1.25. The zinc source can be a zinc salt in commercial use such as zinc sulfate and zinc oxide. Zinc oxide is used preferably. It will also be appreciated that the zinc source can be applied to the rotary granulating container in the form of a slurry of slurry or also in the form of solid particulate material as the case may be. Preferably, the zinc source can be fed to the granulator at a feed rate of 1000 Kg / h to provide a granulated product containing at least 2.5% Zn. It has also been found that ammonia can improve production rates since there is a decreased evaporation load placed on the dryer in the granulation plant. The ammonia would also increase the ratio of N / P in the ammonia phosphate. Thus, more specifically, when cold prefabricated solid MAP is fed to the plant, the MAP solubility increases when increasing the proportion of N / P that can be presented by ammonia. Therefore the granulation can be presented to a content of lowest unit that results in one. Lower evaporation load in the dryer. Accordingly, the ammonia can be charged to the granulator in gaseous form or bubbled in the granulator in combination with steam. Preferably, the steam can be fed to the granulator at a rate of 1,134 Kg / hour (2500 pounds / hour) in combination with 0.25 liters / second of ammonia although it will be appreciated that the speed at which the steam is fed to the granulator is dependent of the size of the granulator. It is also desirable to use cold steam instead of hot steam since the resulting fertilizer will have an improved zinc absorption compared to the case when hot steam is used. It is also preferred that ammonia is only used to a moderate degree, that is to obtain an N / P ratio of 1.15: 1.25 compared to excessive ammonia where an increased N / P ratio is obtained. The moderate ammonia also improves the absorption of zinc in the resulting fertilizer. The granulation process involving the mixing of zinc oxide with ammonium phosphate can be carried out in the presence of 2-6% water. The granulation temperature can reach 55-100 ° C and more appropriately between 60-80 ° C. The process of the present invention can also be carried out in a granulation plant at a typical production rate of 10-100 tons per hour and the most appropriate way 15-70 tons per hour. The ammonium phosphate fines can be added to the granulator at a rate of between 10-100 tons per hour and more appropriately between 30-100 tons per hour.

Description of the preferred embodiment Figure 1 represents a process diagram for a typical NP granulation plant. A feed (7) of MAP fines and feed (4) of zinc oxide are combined and passed to the granulator through the conduit (9). The steam mixed with ammonia (3) or separately bubbled is used to bubble below the fact in the granulator and to aid in the granulation. A spray liquor (6) or cleaner may in some cases be used to add more moisture to the granulation. A fine recycle stream can also be fed back to the granulator (11).

Then the granulated wet material (8) is fed to a dryer where heat is usually fed concurrently and moisture is removed. Then the dry material (12) is fed to screens or sieves where the product size is separated and either sent directly to storage or cooled (14) and sent to storage. The undersized material is recycled and the larger material is ground and also recycled to the granulator. The air stream (10) of the granulator is cleaned, usually in a Venturi cleaner or scrubber as shown and passed through a cyclone separator and through a stack as shown. The air stream in the dryer (5A) is passed through a cyclone separator and then passed (16) to a Venturi scrubber before passing through an additional cyclonic separator. The scrubber liquor from each cyclone separator is passed to a central seal storage tank as shown and is cross-linked through the conduit (5). When the additional mixture in the sidestream granulator (6) is not required, the liquor from the scrubber is accumulated for later disposal. Water (1) can be fed to the sealing storage plant of the scrubber liquor as shown. The air stream (16) of the Adjacent cyclone separator is fed to the venturi scrubber as shown. The discharge (15) of one of the cyclone separators is discharged to the recycled stream of fines (11).

EXPERIMENTAL SECTION EXPERIMENT 1 Materials and methods An experiment was carried out under greenhouse conditions at the Queensland Wheat Research Institute, Toowoomba, Queensland, Australia. Three wheat plants (var Pelsart) were established in each 200 mm pot. The soils used were from a black land of Yallaroi desert in northwestern New South Wales, Australia and a gray clay soil from the Kuppun desert, south west of Dalby, Queensland, Australia. The relevant characteristics of the soil are described in table 1. The proportions of application in each treatment are given in table 2. The zinc products were suspended in 20 ml of deionized water before application to the soil. The basal application of other nutrients was applied as follows: Phosphorus is applied to all treatments to increase the level in each pot to 236 mg Kg. "1 Each treatment was replicated three times Deionized water was applied to keep the soil at approximately the field capacity StZ was a fertilizer produced by the process of the invention and thus consisted of a cogranulate of MAP and ZnO.

Determination The dry matter production of each pot was carried out at 10% emergence of the shoot (91 days after sowing). Sub-samples of plants were taken for each plant tissue and zinc concentration. The absorption of apparent zinc in the upper parts of whole plants was calculated for each treatment as the product of the dry matter (g. Pot "1) and concentration of zinc in the dry matter of the plant (mg.Kg" 1).

Results Soil black soil-Yallaori Dry matter Product A significant difference in trends (P <0.2) was found among the tested products. The StZ produced the largest dry matter response followed by zinc sulphide, zinc oxisulfate and zinc oxide yield similar results as reported in table 3.

Proportion The response to the zinc application rate was highly significant. For each increase in the proportion of zinc, dry matter production increases. The most significant dry matter response is between 0 and 2.5 mg / Kg of zinc. Application rates greater than 2.5 mg / kg produce only a small dry matter response as reported in table 4. To establish the effectiveness of each form of zinc product, regression curves are fitted for each product when using a model quadratic. From the yield over 90% (MY 90%), a measure of relative effectiveness (RE) is calculated by using the formula: Proportion (standard product) X 100 RE = Proportion (other product) Zinc sulfate was used as the standard product for this determination. Based on ER figures, StZ was 76% as effective as zinc sulfate (see table 5) to increase dry matter in this soil. Zinc oxysulfate and zinc oxide were less effective than StZ. This classification is consistent with results of a previous experiment in this soil when using sorghum. The differences in RE between StZ and zinc oxide should be noted (see table 5) since the zinc form in StZ is zinc oxide. It is proposed that the difference in effectiveness is as a result of a synergistic effect between the close proximity of phosphorus and zinc in each particle rather than any change in chemical composition during manufacture. It has been proposed that the mechanism for zinc uptake enhanced with StZ may result from the proliferation of roots around the phosphorus concentrations (Kalra, YP and Soper, RJ, 1968, Agron. J. 60 209-212) that help in the absorption of zinc.

Zinc concentration in dry matter Product The response to StZ and zinc sulfate was significantly higher than zinc oxide and zinc oxides. zinc. The difference between the products remained relatively constant at ratios of up to 5 mg / kg of zinc but increased by 5-10 mg / kg (see figure 2). The difference between the products corresponds to the plateau or leveling of the dry matter response for zinc sulfate and StZ.

Proportion Zinc is a nutrient that increases in the plant tissue in proportion to the feeding, the increase is moderate by dilution during the "large" phase of growth of the response curve. In this experiment, the response to the velocity of zinc produces increases in the concentration of zinc in the tissue of the plant. A concentration of zinc in the plant tissue in whole stems of 15 mg / Kg was used as the critical level for wheat at approximately 10% flowering (Reuter, DJ and Robinson, JB, 1986, Plant Analisys, An Interpretation Manual, Inkarta Press, pp 67-71). The relative effectiveness of the zinc products to maintain the concentration in the tissue of the plant was determined by determining the rate of zinc fed by each product that had raised the concentration in the dry matter plant tissue to 15 mg / kg. Models were adjusted of quadratic regression to each product and the critical proportion was determined (see table 6). It was found that the proportion of zinc application required to raise the concentration in the tissue of the plant to the critical value was lower for zinc phosphate and StZ and higher for zinc oxisulfate and zinc oxide. The relative effectiveness of StZ (compared to zinc sulfate) was the same as for the production of dry matter to obtain the critical zinc concentration (~ 75%) while zinc oxisulfate and zinc oxide were more effective to increase the concentration of the tissue that the production of dry matter increased.

Zinc concentration in dry matter The absorption of zinc is the amount of zinc absorbed in the dry matter of the stems of the plant as calculated from the configuration of zinc and by the production of dry matter at each speed for each product.

Absorption of zinc in stems of whole plants Product It was found that the configuration of zinc absorption was determined by the concentration of zinc. The Differences in zinc concentration were greater than for dry matter production (see figures 3 and 4). It was found that zinc sulfate and StZ were the most effective ways when combining dry matter production and concentration. These produced a significantly higher absorption than zinc oxisulfate which in turn was significantly more effective than zinc oxide as reported in table 7.

Proportion Zinc absorption increased with each zinc addition as shown in table 8. The increase at each speed was significant (P <0.05).

Conclusion This experiment showed the difference of performance of different zinc products and between proportions d-application. It was found that StZ and zinc sulfate were more effective than zinc oxide and zinc oxisulfate for the production of dry matter and to increase the concentration of zinc in the plant tissue. It was found that the most effective proportion for the application was 1.5 to 2.0 mg of zinc per Kg of soil corresponding to a field speed of 1.8 to 2.5 Kg ha "1 of zinc applied to the sowing. Since the culture conditions during this experiment were extremely favorable compared to the field conclusions, it would be expected that the speeds suggested above would apply to fully irrigated production at lower rates may be appropriate for rainfed fields.

Results Soil of gray clay soil-Kupunn Production of dry matter Comparative Product No significant change (P <0.05) in accumulation of dry matter was found among four zinc products for Kupunn soil. However, zinc oxide, zinc oxysulfate and StZ showed a strong tendency (P <0.2) for zinc sulfate to produce higher dry matter in this soil as reported in table 9.

Proportion of application As a result of the variability of the response between the products through the application rates, the effect of zinc velocity on dry matter accumulation was not significant.

The level of soil extractable zinc (DTPA) of 0.3 mg Kg "1 suggests a high probability that the soil would be responsible for an application of zinc (Incitec Fertilizers Analysis Systems Interpretation Manual.) A lack of dry matter response suggests that either the critical soil level is not corrected for this type of soil or in another factor the yield is restricted.

Concentration of zinc in stems of whole plant Comparative product The amount of zinc absorbed by the crop and reflected in the concentration of tissue was dependent on the zinc product applied. The highest concentration of zinc was for StZ and zinc sulfate and the zinc and zinc oxide oxysulfate absorption was significantly lower (for as reported in Table 10). The concentrations in the average plant tissue generated by zinc oxysulfate and zinc oxide suggest that these products were ineffective and the plants in these treatments remained in a poor state.

Proportion of application In the absence of a response of dry matter to the proportions of application of zinc the concentration of zinc in the whole stems they showed the availability of zinc at the applied speed as reported in table 11. According to the concentrations of tissue in critical plant (15 mg / Kg) for whole shoots in wheat, indicated in Plan Analysis by Reuter and Robinson, 1986, supra, plants that do not receive zinc were deficient and a response of dry matter to the addition of zinc would not be expected. In the "poor" state of the control chart confirms the conclusion of the soil analysis that the zinc response potential exists. The reasons for a lack of response in dry matter are not presented the measures taken. In general, the concentration of zinc in the plant increases as the proportion of zinc added increases. The critical level for zinc in the plant was obtained between 1.25 and 5 Kg ha "1, the proportion of zinc required to reach the critical level that is significantly affected by the zinc product.

Zinc Compound Interaction and Application Rate To determine the relative effectiveness (RE) of the four zinc products in the absence of a dry matter response, regressions of zinc concentration in the plant tissue were carried out against the proportion of Application of zinc for each product. The effective proportion was determined as the proportion of each product to produce a zinc configuration in the plant of 15 mg / Kg. Based on the data in Table 12, it was determined that StZ was the most effective product to increase zinc concentrations in the plant tissue, followed by zinc sulfate. These data suggest that under high inlet / outlet wheat cultivation conditions the StZ should be applied at a rate that will provide approximately 2 Kg ha "1 zinc Zinc oxysulfate and zinc oxide (applied separately to phosphate) they were not effective sources of zinc in this type of soil.

Absorption of wheat in stems of whole plant Comparative product In the absence of a dry matter response, differences in zinc concentration in the plant tissue resulting from the zinc compounds applied, have been a primary determinant of the meanings of the differences in zinc sulfate. Zinc oxide produces the smallest absorption, zinc sulfate and zinc oxysulfate produce significantly higher absorptions. The StZ produces the highest absorption as reported in the table 13: Application rate Zinc absorption in plants generally increases with the application rate, however, the absorption efficiency decreases as the proportions increase (as reported in table 14). The apparent absorption efficiency calculated from the response data indicates that the efficiency was 1.92% for the speed of 1.25 mg / Kg "1 and fell to 1.2% for the speed of 10 mg / Kg" 1.

Product by proportion of application The comparison of the proportions of application between product types is affected by the unexplained variability between the zero zinc control treatments. If the zero zinc control treatment for each product is replaced by zinc oxide, StZ and zinc oxisulfate, the only response response of the product is zinc sulfate, which is treated more evenly. Significant responses in zinc absorption were measured for each product except zinc oxide. StZ and zinc sulfate generated significant absorption responses at 1.25 mg / Kg "1 and greater responses of this velocity were measured (as reported in Table 15.) StZ generally produces the highest absorption at each zinc velocity. .

A significant response to zinc oxisulfate was obtained at the rate of 5 mg / kg when placed between StZ and zinc sulfate and above zinc oxide, when available.

Conclusion The results of the comparison product in this experiment demonstrated that zinc sulfate and zinc in StZ are superior in the availability of plants to zinc oxisulfate and zinc oxide. In this soil, although dry matter responses were not gained, significant increase in zinc configuration and zinc absorption underlined the potential for dry matter response. It is found that the most effective proportion of zinc sulfate and zinc in the StZ is approximately 2 mg / Kg (equivalent to 2-2.5 Kg / ha) for the environmental conditions in which it was carried out in the experiment. The performance of the StZ in the Kupunn gray clay is similar to the results obtained in the black clay soil in the winter harvest evaluated previously in this report and in the corn.

Experiment 2 The objective of this experiment was to provide data to evaluate the effectiveness of zinc in StZ ammonia by: (i) measuring the bioavailability of zinc in StZ with ammonia compared to StZ without ammonia and conventional zinc fertilizer consisting of sulfate of zinc monohydrate and (ii) determine if the proportion of ammonia has any effect on the bioavailability of zinc.

Materials and methods The experiment was carried out as a greenhouse pot experiment at the facilities of Incitec Fertilizers, Toowoomba. The soil used in the experiment was a gray clay (poplar box wooden floor of a crop field south of Dalby). The sample was taken at a depth of 10 cm. The level of zinc in the soil had been confirmed as low for crop production by soil analysis (as reported in Table 16) and foliar symptoms of zinc deficiency in the crop growing on 1 soil at harvest time . The soil (3.6 Kg) was packed in 150 mm diameter pots containing plastic liners to prevent sewer system. The pots were irrigated to the capacity of approximately the field (predetermined). Nutrient background levels of N, K, S, Ca were added to the water to ensure that growth was not restricted for those nutrients during the experiment. Samples of the test fertilizer products, ammoniated StZ (molar proportions of N: P of 1.17, 1.22, 1.27, 1.36), StZ (molar ratio of N: P of 1.0) and zinc sulfate monohydrate (zinc sulfate) are planted at -2 mm before the measurement to allow the measurement of the small quantities required for each pot. The phosphorus levels in each treatment were compensated to the proportion applied in the higher P treatment by applying the appropriate proportion of monoammonium phosphate to the test product in the seed hole. The experiment was carried out as a central experiment, to investigate the response of the ratio in three products (zinc sulfate, 1.0 StZ and 1.36 StZ) to the equivalent of 0, 1, 2, 4, 6, Kg / ha of zinc and a complementary experiment consisting of all six products applied to 1, 2, 4, Kg / ha of zinc. Each treatment was replicated three times. Each pot was planted with 10 seeds of sorghum grain (Sorghum bicolor L. Moench) cv Buster MR in pairs, The fertilizer treatment is placed in a hole under the seed. The pots were thinned to three plants per pot in the three-leaf stage. The pots were irrigated with deionized water as required to keep the soil at an approximate capacity to the field capacity. Whole stems were harvested at the stage of the eighth leaf (60 days after sowing), dry matter yield and zinc and phosphorus concentrations were measured.

Results Accumulation of dry matter Zinc product A significant difference (p = 0.01) in dry matter production was measured between the fertilizer products (as reported in table 17). When compared to standard treatment, zinc sulfate 1. or StZ and 1.36 StZ were the only products to give a significantly deficient dry matter production. However, there was a tendency of 1.22 StZ and 1.17 StZ to be superior to other products. These products were significantly (p = 0.05) more effective than 1.0 StZ and 1.36 StZ.

Proportion of zinc The response to the proportion of zinc applied was highly significant (p <0.01), with the production of dry matter that reaches a material between the proportions of 1 and 2 kg / ha of zinc. This response ratio is similar to that recorded in previous experiments with Gr. StZ under similar test conditions. At zinc proportions greater than 2 Kg / ha of Zn there was a tendency for dry matter production to decrease. This decrease was demonstrated most strongly in the central experiment where the proportion of zinc of 6 kg / ha produced a significantly lower dry matter yield (p = 0.05) than the proportion of 2 kg / ha (see figure 5).

Zinc concentration in dry matter Zinc product It was found that the concentration of zinc in the dry matter varied with the product applied. There was a significant interaction (P <0.1) between the product and the proportion of zinc applied (as reported in table 18). Currently there is no published data regarding the critical zinc concentrations in the whole stems in the stage of the eighth leaf. It was concluded from the dry matter accumulation response and the response of the Zinc concentration to the proportion of zinc that the critical concentration for maximum dry matter production in this experiment was 10-14 mg / Kg (see Figure 6). When using the critical zinc concentration as a measure of product effectiveness, based on the average response was not considered due to the interaction between the proportion and products and as a result of the dry matter response that causes some dilution of the growth in the concentration of zinc. Under these circumstances, the absorption of zinc must be a more reliable discriminating factor to separate the performance of the product.

Zinc proportion The concentration in the plant tissue shows a significant increase (p <0.01) with increases in the proportion of zinc fertilizer. The increases in zinc concentration were significant (P <0.05) for each zinc addition, the largest increases occur where the dry matter production had reached a pot or was falling.

Zinc Absorption Zinc Product Of the zinc products tested, zinc sulfate produced the largest zinc absorption in whole plant stems. However, statistically (p = 0.05) the 1.27 StZ and 1.22 StZ products were equally effective as zinc sulfate. These three products were superior to 1.0 StZ, 1.36 StZ and 1.17 StZ.

Proportion of zinc The increase in zinc absorption with the proportion of zinc applied reflected the response of the strongest proportion in the concentration of dry matter and zinc in the dry matter. The linear response in the absorption of zinc suggests that the dominant factor in the absorption was the concentration of zinc. When the production of dry matter decreases for zinc proportions of 2 kg / ha of zinc, zinc absorption continued its increase.

Phosphorus The concentration of phosphorus in the tissue was not significantly different between the products but was reduced with the increased proportion of zinc. It was not thought that the reduction in the concentration in the tissue would have affected the results since the concentration was greater than 0.21% P criticism (Reuter and Robinson, 1986, supra) for all treatments. The response of absorption of P to the proportion of zinc reflected the response of dry matter instead of the response of the concentration of P in the tissue. This indicates that a mechanism for the reduction in P concentration is related to the division of growth rather than a direct P-Zn antagonism in the soil or plant.

Conclusion It was found that the soil selected for the experiment was sufficiently low in zinc available in the plant to give good discrimination between the proportions of zinc applied and between the products of the fertilizer. The concentration of dry matter, zinc in the plant and zinc absorption in the whole stems were increased by 29, 100 and 245% respectively, to the proportions of zinc applied. It is appreciated that the chemical forms of Zn and / or P in the products of StZ as in ammonia have been altered by the process of ammonia. The products with the highest ammonia (1.36 and 1.27) were lower than the lowest proportions (1.22 and 1.17) in dry matter production (see figure 7) and were similar to the StZ product. The products of the lowest proportions of ammonia were similar in dry matter production in the range of application rates to zinc sulphate, the standard measure of zinc availability in soil from fertilizer sources. In contrast to the results of dry matter production, the best zinc absorption performance was of the products 1.22 StZ and 1.27 StZ (see figure 8). These products were not significantly different from zinc sulfate. From this analysis, it is concluded that the amoniation of StZ at molar proportions of up to 1.27 did not significantly change zinc availability and that the addition of ammonia to a product N / P ratio of 1.27 is considered as a production stage standard. Since the grain yield was not measured for this experiment, it is recommended that the proportions of ammonia that give the highest dry matter yield (1.17 and 1.22) are given the greatest weight in determining the final ammonia ratio due to the more direct relationship between dry matter production and grain yield than zinc absorption and grain yield. This recommendation is made based on the determination of a single soil and it should be noted that previous experiments have shown that the relative performance of StZ products can be soil dependent used in the experiments. No determination has been made for these products, hence the effectiveness of the product can vary in different types of soil. The reasons for the superior performance of StZ 1.17 and 1. 22 with ammonia were not evident from the data generated in this experiment.

Overall conclusions (i) StZ zinc is available for wheat as determined by the dry matter response, zinc concentration in dry matter and zinc uptake in whole plant stalks in the anthesis. (ii) The proportion of StZ application required to produce a response was similar to zinc sulfate when averaged across the two types of soil evaluated. Zinc sulphate and StZ were superior to zinc oxide and zinc oxisulfate in both types of soil. (iii) The reasons for the difference in performance of zinc sulfate and StZ in different soils were not identified in this experiment therefore, until such factors are identified, the zinc application rates of both products should remain the same for a given circumstance. (iv) The recommended application rates for zinc derived from StZ should be in the range of 1-3 Kg ha "1 zinc (from temporary to irrigated respectively). (v) The difference in the performance of zinc oxide in StZ and the zinc oxide applied separately is consistent with the results of the graNo experiment, differences of this type, apparently due to the manufacturing method, have not been reported in the scientific literature to date. this property is unique to the StZ or is also associated with products produced by using coating technology (eg Tecfeed ™, Nutricote ™) As a result of the above, it is considered that the ammonium-zinc phosphate fertilizers of the invention exceeds those of the prior art in relation to the application of zinc / phosphorus compound fertilizers because the previous research data questioned the availability of Zinc to crops when such zinc / phosphorus compound fertilizers were previously used. Such errors have prevented the use of zinc as a component in "starting" fertilizers in the crop for many years. With the advent of the present invention and a better understanding of the zinc / phosphorus interaction in the fertilizer of the invention, it is considered that if a chemical reaction between the phosphorus source and a Zinc source during manufacture can be avoided or minimized, the zinc absorption to the plants will be considerably improved when compared with the previous technique. This means that the zinc fertilizer of the invention will be equally effective if it is applied in the diffusion or seeding of the (traditional) preplant or is incorporated with the phosphate in the seeding. It has now been established that the zinc in StZ is at least about 70-80% as effective as the zinc sulphate that makes up the StZ as a viable alternative to phosphate fertilizers mixed with zinc such as Phozinc ™ in the market. It is also suspected that the physical differences between StZ cogranulated and Phozinc would favor the use of StZ in summer cereals. It is likely that the superior performance of the StZ results from the clear spacing of the zinc source than in the Phozinc in winter cereals where the concentration of the fertilizer of the invention (gm "1) is significantly lower.

BOARDS Table 2 Table 3 production of dry matter from four sources of zinc product Table 4 Dry matter production is the response to the zinc application rate Table 5 comparison of the proportion of zinc of 90% of the maximum yield and relative effectiveness for four different products Table 6. Proportion of zinc application of four zinc sources to produce a critical zinc concentration of 15 mg / kg in whole wheat stems.

Table 7 effect of four sources of zinc on the absorption of zinc in plant stems in the emergence or sprouting of the head in wheat Table 8 effect of the increase in the concentration of zinc in the soil on the absorption of zinc in wheat in the bud of the head Table 9 production of dry matter (whole stems) as a result of the addition of zinc in four different compounds in wheat Table 10 zinc concentration (in whole stems) as a result of the addition of four zinc compounds in wheat Table 11 zinc concentration in whole wheat talus at five proportions of zinc fertilizer Table 12 relative effectiveness (RE) and effective proportion of different zinc products Table 13 zinc absorption (in whole stems) as a result of the addition of four zinc compounds in wheat Table 14 Absorption of zinc in whole wheat stems at five proportions of zinc fertilizer Application rate Absorption of zinc (mgKg "1) (grams / pot) 0.00 0.151 1.25 0.180 Table 15 Absorption of zinc in whole wheat stems in the head bud as it is affected by the applied zinc compound and the application rate Table 16 Selected characteristics of the soil used in the experiment Table 17 Effect of the zinc product and proportion of zinc on sorghum dry matter production Table 18 effect of the zinc product and proportion of zinc on the consideration of zinc in the sorghum dry matter Legends Table 15 * average of three other proportions of product control. Figure 2 Comparative experiment of the zinc product - Yallaroi Soil-wheat-1994 Figure 3 Comparative experiment of the zinc product - Yallaroi - wheat - 1994 Figure 4 Comparative experiment of the zinc product - Yallaroi - wheat - 1994 Figure 5 An increase in the supply of zinc from the soil increases the production of dry matter in sorghum. Figure 6 Determination of the critical concentration of the production of dry matter from the accumulation of dry matter and concentration of zinc in the tissue. Figure 7 The proportion of amoniation of StZ affects the production of dry matter in sorghum. Figure 8 The proportion of ammonia of StZ affects the concentration of zinc in the tissue in sorghum.

Claims (14)

1. Claims 1. A process for making a zinc and ammonium sulfate cogranulate that provides a relatively efficient zinc uptake in soil and plants when used as a fertilizer, which process is characterized in that it includes the steps of: (i) mixing • solid prefabricated ammonium phosphate having an N / P ratio of 0.6-1.9 and a source of zinc in the form of a slurry, slurry or particles together to form a co-granulate resulting in a granulating vessel and (ii) drying the cogranulated 2. The process according to claim 1, characterized in that the ammonium phosphate and the zinc source are mixed together before being fed to the granulator vessel. 3. The process according to claim 1 or 2, characterized in that the ammonium phosphate and the zinc source are mixed together in the granulator vessel. . The process in accordance with the claim 1, characterized in that the ratio of N / P is between 0.8-1.5. 5. The process according to claim 3, characterized in that the ratio of N / P is between 1.15-1.25. 6. The process according to claim 1, characterized in that the source of zinc is zinc oxide or zinc sulfate. 7. The process according to claim 5, characterized in that the source of zinc is zinc oxide. 8. The process according to claim 1, characterized in that ammonia is charged to the granulator vessel. 9. The process according to claim 7, characterized in that ammonia is charged to the granulator in combination with steam. 10. The process according to claim 9, characterized in that the ammonium phosphate comprises particles of a size between 0.05-4 'mm. 11. The process in accordance with the claim 9, characterized in that the particles are approximately 1 mm. 12. A zinc and amorphous phosphate cogranulate characterized in that it is obtained by the process according to claim 1. 13. A zinc and ammonium phosphate cogranulate characterized in that it has a minimum Zn content of at least 2.5% and a N / P ratio of 0.6-1.9. 14. A cogranulado of zinc and ammonium phosphate characterized because it has a ratio of N / P of 1.15-1.25 and a minimum content of Zn of 2.5%.