Monoammonium Phosphate Fertilizer Research Articles

Monoammonium phosphate (MAP) fertilizer drying kinetics in tray dryer

The drying behaviour of monoammonium phosphate fertilizer was examined in a static tray dryer, establishing kinetic parameters that may be used to improve the design of dryers. Drying temperatures ranged from 80 to 95?C, and surface air velocity was 0.50 m/s. The material was previously separated into two particle sizes, between 1.40 and 2.38 mm mean diameter. Drying curves were analysed qualitatively and seven empirical kinetic thin-layer models were fitted. The drying kinetic showed to be temperature-dependent: a moisture ratio reduction of 90% was achieved twice as fast at 95?C than at 80?C. On the other hand, particle size did not exert significant influence on the drying rate. The results showed a decreasing drying rate throughout the whole process. All studied models adjusted well to the experimental data: R2 values were all above 0.999. The two-term model generated the lowest RMSE and ?2 values, between 0.00621 and 0.010743 and between 0.000044 and 0.000115, respectively.

Cogranulation of Low Rates of Graphene and Graphene Oxide with Macronutrient Fertilizers Remarkably Improves Their Physical Properties

The beneficial effects of graphene (GN) and graphene oxide (GO) additives on the physical properties of monoammonium phosphate (MAP) fertilizer granules were investigated. Low doses (0.05 to 0.5% w/w) of GN and GO sheets were cogranulated with MAP and effects on the crushing strength, abrasion and impact resistance of prepared granules were evaluated. Cogranulation with 0.5% w/w GN sheets (MAP-GN) significantly enhanced the mechanical strength of MAP granules (∼18 times improvement) whereas inclusion of same amounts of GO sheets (MAP-GO) improved the strength to a lesser extent (∼8 times improvement). The cogranulation of GN also improved MAP granules resistance to abrasion (>70%) and impact resistance (>75%). Heating MAP-GO granules at 50 °C after granulation is shown to enhance their physical properties in comparison to MAP-GO granules dried under ambient temperatures. The advantages of GN and GO sheets compared with current additives in enhancing the physical properties of MAP granules are explained by...

Woodchip biochar with or without synthetic fertilizers affects soil properties and available phosphorus in two alkaline, chernozemic soils

Fertility enhancement with biochar application is well documented for tropical acidic soils; however, benefits of biochar coapplied with synthetic fertilizers (SFs) on soil fertility are not well documented, particularly for alkaline chernozems. We examined the short-term interactive effects of woodchip biochar amendment with fertilizers on selected soil properties, available phosphorus (P), and P fractions of two alkaline Chernozems from Manitoba. Treatments were (1) urea and monoammonium phosphate fertilizers, (2) biochar at 10 g kg−1, (3) biochar at 20 g kg−1, (4) biochar at 10 g kg−1with fertilizers, (5) biochar at 20 g kg−1with fertilizers, and (6) a control. Treated soils were analysed for pH, electrical conductivity (EC), and Olsen P concentration biweekly, and for P fractions, cation exchange capacity (CEC), organic carbon (OC), and wet aggregate stability after 70 d of incubation. Biochar amendment without fertilizers significantly increased soil pH and CEC but had no effect on EC, while coapplication with fertilizers significantly increased Olsen P and labile P concentrations. When coapplied with fertilizers, biochar did not significantly increase soil pH relative to the control. Results suggest that biochar improved soil properties and available P in alkaline Chernozems, and the beneficial effects were enhanced when coapplied with SFs.

Life cycle assessment of diammonium- and monoammonium-phosphate fertilizer production in China

A bottom-up approach coupled with national and regional statistical data was used to evaluate the environmental impacts of diammonium phosphate and monoammonium phosphate fertilizer production in China. The total environmental burden caused by both types of phosphate fertilizer production in China was mainly generated from climate change, terrestrial acidification, human toxicity, particulate matter formation, and marine ecotoxicity categories. Hubei and Guizhou Provinces were found to have the highest diammonium phosphate and monoammonium phosphate fertilizer yield and environmental effects, whereas Fujian, Jiangsu, Xinjiang, Henan, Sichuan, Shanxi and Hunan Provinces were small because of the distribution of phosphate rock mining and phosphate fertilizers production capacity. Optimizing the utilization efficiency of phosphoric acid, improving the reuse ratio of phosphogypsum, reducing the proportion of high-concentration phosphate fertilizer, and optimizing phosphate fertilization rate to crops in China are the key factors in reducing the overall environmental impacts.

Effect of Cogranulation on Oxidation of Elemental Sulfur: Theoretical Model and Experimental Validation

Core Ideas Fertilizers with ES are usually in granular form. Cogranulation of ES reduces its oxidation rate. This granulation effect was modeled based on the reduction in effective surface area. The model was verified against experimental data for ES‐fortified fertilizers. Most studies on elemental sulfur (ES) oxidation have focused on small ES particles mixed through soil, even though commercial ES fertilizers are usually in granular form. Although it has been recognized that cogranulation of ES decreases its oxidation rate, no attempt has been made to quantify this effect. We developed a conceptual model that predicts the “effective diameter” (the diameter of ES particles mixed through soil that would oxidize at the same rate as the granulated ES) by taking into account the effect of granulation on the effective surface area available to the ES in the granule cavity after the soluble macronutrient compound in the fertilizer has diffused away. To validate the model, the oxidation rate was determined for ES‐fortified monoammonium phosphate fertilizer with varying ES content (20–250 g kg−1), ES particle diameter (25 or 60 μm), and granule diameter (1.8 or 3.4 mm). The time to reach 50% oxidation varied from 17 d for small granules at the lowest ES content to 210 d for the large granules with the highest ES content. In agreement with the model predictions, reducing ES particle size did not affect the oxidation rate except at the lowest ES rate, whereas reducing granule size increased the oxidation rate. Predicted and observed oxidation rates were in good agreement, indicating that the model describes the effect of granulation with reasonable accuracy. This model may assist in improving formulation of ES‐containing fertilizers and guiding fertilizer recommendations.

Radiological assessment of Iraqi phosphate rock and phosphate fertilizers

Specific radioactivity of U-238, Ra-226, Th-232, and K-40 was measured for selected samples of Iraqi ore phosphate rocks, fertilizers, and phosphogypsum. Gamma spectroscopy system based on HPGe detector with efficiency of 30 % used for the analysis. The activity (in Bq/kg) of U-238 ranges between 53.1 and 682.7; Ra-226, between 15.1 and 409.7; and Th-232, between below detection level and 2.3 while K-40 activity was below detection level in all the samples. The result shows that about 13 % of initial U-238 transferred to the phosphogypsum while its activity in triple superphosphate samples increased to be about 166 % of initial U-238 in the ore phosphate rock while about 75 % of radium-226 in phosphate rock migrates to the phosphogypsum. The radiological hazards for workers and the public due to the using and manufacturing processes of the phosphate fertilizers were estimated. The radiation doses due to exposure to the direct gamma rays emitted from a stock of ore phosphate are found to be 0.16 μSv/h while doses caused by using three types of fertilizers are in the range of 0.03 to 2.2 mSv per fertilizer application. The use of monoammonium phosphate fertilizer causes a less effective dose because it contains low concentration of radium. The resulting radiation dose by using phosphogypsum as plaster material is 0.27 μSv per year, which could be considered negligible.

Dry Soil Reduces Fertilizer Phosphorus and Zinc Diffusion but Not Bioavailability

Dry sowing is a practice used in many semiarid agricultural systems where crops are planted early into dry soil to hasten crop emergence following the first rains of the season. This practice increases water use efficiency by promoting rapid canopy development early in the growing season when soils are warm. The question that arises from this practice is whether the efficacy of fertilizers, which are usually simultaneously placed below the seed at planting, is influenced by being in contact with the dry soil for a period of time before seed germination and crop emergence. Commercial granular and liquid monoammonium phosphate fertilizers enriched with Zn were incubated under dry and wet conditions to test the effects of dry sowing on fertilizer diffusion, lability, and subsequent availability to wheat (Triticum aestivum L. ‘Axe’) plants in the growth chamber using isotopic techniques. Fertilizer incubated in dry soil tended to have a much greater lability than in wet soil, but diffusion was limited. The restricted diffusion during the incubation did not negatively impact nutrient availability to plants subsequently grown in the growth chamber, however, and simulated dry sowing was not shown to have a detrimental effect on fertilizer efficiency.

EFFECTS OF CONVENTIONAL AND CONTROLLED RELEASE PHOSPHORUS FERTILIZER ON CROP EMERGENCE AND GROWTH RESPONSE UNDER CONTROLLED ENVIRONMENT CONDITIONS

A series of experiments on the effects of form and rate of seed row placed phosphorus (P) fertilizer were carried out under controlled environment conditions using flats of a P-deficient Brown Chernozemic soil from Saskatchewan, Canada. The experiments were conducted in the laboratory and growth chamber using rates of seed row placed granular P fertilizer up to 100 kg P2O5 ha−1. Two forms of monoammonium phosphate fertilizer were compared: 1) conventional MAP granules and 2) controlled release phosphorus (CRP) fertilizer granules (Agrium Inc, Denver, CO, USA.) made with a polymer coating to slow the release of phosphate to soil solution. Six crops were utilized in the study to provide a range of commonly grown cereal, oilseed, pulse and forage crops in Western Canada: wheat (Triticum aestivum), canola (Brassica napus), mustard (Brassica juncea), flax (Linum usitatissimum), yellow pea (Pisum sativum) and alfalfa (Medicago sativum). Parameters measured were percentage of planted seeds that had emerged after two weeks, plant biomass yield, and plant P uptake after four weeks. Most of the crops tested showed no negative impact on emergence with seed row placed conventional P fertilizer at rates up to ∼20 to 30 kg P2O5 ha−1. Pea, flax and mustard tended to be most sensitive to injury from high rates of seed placed MAP while wheat was least sensitive. The controlled release phosphorus fertilizer (CRP) product greatly increased the tolerance of crops to high rates of seed row placed P, with rates of 80 kg P2O5 ha−1 placed in the seed row producing no significant injury for most crops. This effect is attributed to the coating reducing the harmful salt effect that occurs when high rates of fertilizer are placed in the seed row in close proximity to the seed. Generally, a rate of 30 kg P2O5 ha−1 was sufficient to produce maximum early season biomass yield and P uptake for both conventional MAP and CRP fertilizers. Large differences in early P availability were not evident between the conventional P and controlled released P fertilizer products.

Effectiveness of seed-soaked Cu, autumn- versus spring-applied Cu, and Cu-treated P fertilizer on seed yield of wheat and residual nitrate-N for a Cu-deficient soil

Three field experiments were conducted from 2005 to 2007 to determine the effects of seed-soaking in Cu EDTA liquid, autumn versus spring application of granular Cu sulphate, and granular Cu-treated monoammonium phosphate (MAP) fertilizer on seed yield and Cu uptake of wheat, and residual nitrate-N in the soil profile on a Cu-deficient Dark Gray Luvisol (Boralf) sandy loam near Porcupine Plain, Saskatchewan, Canada. In exp. 1, seed soaked in Cu EDTA liquid at 0.04 to 0.16 kg Cu ha-1 increased seed yield substantially, in spite of a significant reduction in plant emergence in most cases. But, seed yield increases from the seed soaked in Cu EDTA liquid were lower compared with foliar-applied Cu EDTA liquid at 0.50 to 1.00 kg Cu ha-1, or compared with surface spray-broadcast and incorporation of Cu EDTA liquid into soil in spring prior to seeding at 4.0 kg Cu ha-1. Seed yield trend was two foliar applications of Cu EDTA liquid > soil surface spray-broadcast and incorporated Cu EDTA liquid > one foliar application of Cu EDTA liquid > seed-soaked Cu EDTA liquid. In exp. 2, for granular Cu sulphate in the first year, only previous autumn application increased seed yield significantly when applied at 4.0 kg ha-1. For spring application, seed yield was highest when solution Cu EDTA at 4.0 kg ha-1 was spray-broadcast on the soil surface and incorporated into soil prior to seeding. In exp. 3, application of granular Cu-treated MAP fertilizer had no significant effect on seed yield. The Cu uptake by seed usually followed`the same trends as seed yield. In all experiments, the partial factor productivity (seed yield per unit of nutrient applied) was much higher when N was applied in combination with Cu (15.3 to 29.8 kg seed kg-1 applied N ha-1) compared with N alone (5.7 to 7.7 kg seed kg-1 applied N ha-1). In exp. 1, the amounts of residual nitrate-N in the 0-90 cm soil profile after three annual N fertilizer applications were 3.3 to 4.0 times higher in the zero-Cu control than in the Cu fertilizer treatments. Overall, seed yields of wheat were highest with two foliar applications of Cu at low rates, or with soil spray/broadcast and incorporation of solution Cu in spring at a relatively high rate, which is also expected to have long-term residual effects on crop yield. For granular Cu sulphate, the results indicated that deficiency of Cu in wheat can be corrected by surface-broadcast application at a relatively high rate in the previous autumn, followed by its incorporation into soil in the spring at seeding. The results also indicate that by soaking wheat seed in Cu EDTA solution at a very low rate, Cu deficiency in wheat can be prevented and seed yield increased, but less than the other Cu treatments. Accumulation and downward movement of residual nitrate-N in the soil profile can be minimized by preventing Cu deficiency in wheat crop with combined application of Cu and N fertilizers. Key words: Application time, Cu source, foliar application, granular Cu, growth stage, placement method, rate of Cu, seed-soaked Cu, soil incorporation, solution Cu

Influence of biosolids on phosphorus sorption characteristics of a Vertisol in comparison with manures and fertilizer

Regulation of manure application in Manitoba has raised the question of whether or not biosolids application should be regulated in the same way. This study examined the effects of biosolids (BIO) applications on P sorption characteristics of a Vertisol in comparison with dairy cattle (DAIRY) and hog (HOG) manures, and monoammonium phosphate (MAP) fertilizer using the classical sorption isotherm and single point sorption index. Pertinent chemical properties and degree of P saturation (DPS) were also determined. The sorption maximum (Smax) in the control was reduced from 655 mg kg-1, to a range of 536–655 mg kg-1 with BIO, 559–650 mg kg-1 with MAP, 402–568 mg kg-1 with DAIRY, and 350–587 mg kg-1 with HOG depending upon the rate of P added. The lower DPS in the soil amended with BIO suggests a lower risk of P loss with biosolids compared with manures. The higher P sorption capacity of biosolids-amended soils compared with soils amended with manures suggest that Ca added with BIO increased the number of P sorption sites by a similar proportion to the amount of P added. Key words: Biosolids, P sorption isotherm, degree of P saturation, labile P, non-labile P

Cadmium and zinc in soil solution extracts following the application of phosphate fertilizers

This study investigated the solubility of cadmium and zinc in soils after the application of phosphate fertilizers containing those two metals. The solubility of cadmium and zinc was assessed by measuring their concentration in soil water extracts. Three monoammonium phosphate fertilizers containing various amounts of metals were applied on cultivated fields for 3 years at three different rates. In order to investigate the effects of long-term applications of fertilizers on the solubility of Cd and Zn, a similar design was used to apply contaminated fertilizers to soils in a laboratory experiment using a single fertilizer addition equivalent to 15 years of application. Phosphate fertilizers increased the concentration of Cd in soil extracts compared to control in 87% and 80% of the treatments in field and laboratory experiments respectively. Both increasing the rate of application and using fertilizer containing more Cd lead to higher Cd concentrations in extracts for the field and the laboratory experiments. The addition of the equivalent of 15 years of fertilizer application in the laboratory results in higher Cd concentration in extracts compared to the field experiment. For Zn, the fertilizer treatments enhanced the metal solution concentration in 83% of field treatments, but no significant correlations could be found between Zn inputs and its concentration in solution. In the laboratory, fertilizer additions increase the Zn concentrations in 53% of the treatments and decrease it in most of the other treatments. The decrease in Zn concentrations in the laboratory trial is attributed to the higher phosphate concentrations in the soil solution; which is presumed to have contributed to the precipitation of Zn-phosphates. For both trials, the metal concentrations in soil extracts cannot be related to the Zn concentration in the fertilizer or the rate of application. The high Zn to Cd ratio is presumably responsible for the Cd increase in the soil extracts due to competitive displacement by Zn. Finally, the observed acidification of soils with fertilizer application will also contribute to metal solubilisation.

Effect of Low‐Rate Commercial Humic Acid on Phosphorus Availability, Micronutrient Uptake, and Spring Wheat Yield

A greenhouse study was conducted to determine the effects of low‐rate commercial humic acid (HA) on phosphorus (P), iron (Fe), and zinc (Zn) availability and spring wheat yields, in both a calcareous soil and a noncalcareous soil. In Phase I, soluble P concentrations were monitored at 1.9, 3.8, and 5.7 cm from a monoammonium phosphate (MAP) fertilizer band that had either been coated with one of two HA products at the equivalent of 1.7 kg HA ha−1, a label rate, or left uncoated. Sampling occurred periodically up to 48 d after fertilizer application. In Phase II, uptake of P, Fe, and Zn and grain yield were measured in soils that had been fertilized with 7.5 or 25 kg P ha−1, either coated with HA or left uncoated. In Phase I, only three significant differences (P=0.05) out of 66 comparisons were found in soluble P concentrations between HA and control treatments at time points ranging from 4 to 48 d after fertilization. In addition, no significant differences were found in nutrient uptake, shoot biomass, or grain yield between HA and control treatments. These greenhouse results suggest that low commercial HA rates (∼1.7 kg HA ha−1) may be insufficient to enhance spring wheat growth.

The Effect of Preplant Monoammonium Phosphate Fertilizer and Compost on the Growth and Yield of 'Macoun' Apple Trees

'Macoun'/B.9 apple (Malus ×domestica Borkh.) trees were planted in May 1998 in ± compost or ± monoammonium phosphate (MAP) for a total of four preplant treatments: 1) 90 g phosphorus (P) per tree, 2) 128 kg compost per tree, 3) 90 g P and 128 kg compost per tree, and 4) and an untreated control. MAP did not increase tree growth or yield in any year of the study. Compost increased canopy width into the sixth year after planting, and increased tree height and trunk cross-sectional area (TCA) into the seventh year. Annual yield was increased by compost in the fifth and seventh years, but not fourth or sixth year after planting. Compost increased cumulative yield in the sixth and seventh years.

Response of ‘Jonagold’ Apple Trees in the First Three Years after Planting to Mono-Ammonium Phosphate Fertilization Under Replant Problem Conditions

The objective of the experiment was to examine response of immature apple trees to application of mono-ammonium phosphate (MAP) fertilizer on replant problem soil. The study was carried out during 2001–2003 under a greenhouse on ‘Jonagold’ apple trees/M.9 EMLA planted singly in 50 L polyethylene containers filled with a sandy loam soil with low status of both organic matter and phosphorus (P) in soil solution. This soil originated from an apple orchard unfertilized with P for 23 years. The biological test showed the presence of specific replant disease in the soil. Immediately before apple tree planting, the soil was mixed with MAP at rates of 1, 2, and 3 g L− 1. Trees grown in the soil untreated with MAP served as a control. Each year apple trees were drip-irrigated and supplied with nitrogen (N) at differentiated rates to achieve a level of 50 g N per plant. The results showed that MAP application increased soil solution P status. Simultaneously, MAP supply at rates of 2 and 3 g L− 1 caused a drop in soil pH value in the last two years of the experiment. MAP treatments increased both dry weight and length of fine roots (< 2 mm in diameter), vigor of trees, the number of flower clusters per tree, flower intensity, the number of fruits per tree, and P concentrations in leaf and fruit tissues. Fruits from MAP-supplied trees were firmer than those of the control trees. Mean fruit weight, titratable acidity, and soluble solids concentration of ‘Jonagold’ apples at harvest were not influenced by MAP treatment. Fruits from MAP-supplied apple trees had increased calcium concentration only in one year. It is concluded that pre-plant application of MAP at a rate of 1g L− 1can be recommended on coarse-textured soils with low P status in soil solution to increase precocity of apple trees. However, MAP-supplied apple trees have to be watered to avoid the risk of osmotic stress.

The effect of N and P fertilization on growth, seed yield and quality of industrial hemp in the Parkland region of Saskatchewan

Industrial hemp (Cannabis sativa L.) has sparked renewed interest in western Canada in recent years, and there is very little research information available on its fertilizer requirements. The objective of this study was to determine the effect of surface-broadcast ammonium nitrate and seedrow placed monoammonium phosphate fertilizers on the production and seed quality attributes of industrial hemp (cv. Fasamo and Finola). Field experiments were conducted on a Black Chernozem silty loam soil at Melfort, Saskatchewan, Canada, in 2000, 2001 and 2002. Increasing N rates significantly increased plant height, biomass, seed yield and seed protein content of hemp in all years. Seed-applied P fertilizer increased plant height in all years, and biomass in 2000, but reduced plant density, biomass and seed yield in 2001 and 2002. Finola consistently had lower plant height, earlier maturity, heavier seeds, and higher seed yield, seed protein content and seed oil content than Fasamo. The average amount of nitrate-N in the 0–60 cm soil was 40 kg N ha-1. Seed yield kg-1 of N was 9.4, 5.9, 4.5 and 3.7 kg ha-1 for Fasamo, and 10.6, 7.7, 6.0 and 4.5 kg ha-1 for Finola, respectively, at 40, 80, 120 and 160 kg ha-1 of soil plus fertilizer N. Key words: Fertilizer, hemp, nitrogen, phosphorus, rainfall, soil extractable P, soil nitrate-N, cultivars

Irrigated mountain meadow fertilizer application timing effects on overland flow water quality.

Nonpoint-source pollution from agricultural activities is currently the leading cause of degradation of waterways in the United States. Applying best management practices to flood-irrigated mountain meadows may improve agricultural runoff and return flow water quality. Prior research has focused on fertilizer use for increased hay yields, while few studies have investigated the environmental implications of this practice. We examined the effects of fertilizer application timing on overland flow water quality from an irrigated mountain meadow near Gunnison, Colorado. Application of 40 kg phosphorus (P) and 19 kg nitrogen (N) ha(-1) using monoammonium phosphate (11-52-0, N-P-K) fertilizer to plots in the fall significantly reduced concentrations of reactive P and ammonium N in irrigation overland flow compared with early or late spring fertilization. Reactive P loading was 9 to almost 16 times greater when fertilizer was applied in the early or late spring, respectively, compared with in the fall. Ammonium N followed a similar trend with early spring loading more than 18 times greater and late spring loading more than 34 times greater than loads from fall-fertilized plots. Losses of 45% of the applied P and more than 17% of the N were measured in runoff when fertilizer was applied in the late spring. These results, coupled with those from previous studies, suggest that mountain meadow hay producers should apply fertilizer in the fall, especially P-based fertilizers, to improve hay yields, avoid economic losses from loss of applied fertilizers, and reduce the potential for impacts to water quality.

KINETICS OF CADMIUM RELEASE FROM SELECTED TROPICAL SOILS FROM KENYA BY LOW-MOLECULAR-WEIGHT ORGANIC ACIDS

The low-molecular-weight organic acids (LMWOAs) commonly present in root exudates may influence the mobility and bioavailability of Cd in soils through the formation of soluble Cd-organic complexes in the soil rhizosphere. However, little is known about the dynamics of Cd released by LMWOAs from highly weathered tropical soils where large amounts of phosphate fertilizers are applied to correct phosphorus deficiency. Cadmium is a contaminant of phosphate fertilizers. The release of Cd from selected tropical soils treated with the Idaho monoammonium phosphate (MAP) fertilizer or the Cd perchlorate-added MAP chemical reagent by LMWOAs (10 -3 M and 10 -2 M) was investigated at 25 °C and at an ionic strength of 0.1 M NaN0 3 solution. The LMWOAs used in this study were acetic, citric, fumaric, malic, oxalic, and succinic acids. The surface soils used in this study were obtained from main agricultural areas in Kenya varying widely in physicochemical properties. The amounts of Cd released from the natural and the treated soils varied with the soils, the treatments, and the nature of the LMWOA. The amount of Cd released from the soils in the presence of LMWOAs also increased with the log stability constant values of the Cd-LMWOA complexes, indicating that Cd was brought into solution by LMWOAs as Cd-LMWOA complexes. A parabolic diffusion equation provided the best fit to the Cd released by LMWOAs during the short reaction period of 0.25 to 1 h. The overall diffusion coefficient values of the Cd released from the natural soils and the treated soils by LMWOAs varied with the soil type and the nature of the LMWOAs. The results showed that the LMWOAs enhanced the rate of Cd released from the soils, especially in the monoammonium phosphate-treated soils. The continuous release of Cd from the soils by renewal of LMWOAs indicates the sustaining power of the soils to replenish the Cd labile pool of the soils. The results also indicate that LMWOAs commonly present in the root exudates play a vital role in the mobilization of Cd in tropical soils and, hence, may influence its uptake by the plants.

Preplant Monoammonium Phosphate Fertilizer and Compost Affects the Growth of Newly Planted 'Macoun' Apple Trees

'Macoun'/Budagovsky 9 apple (Malus ×domestica Borkh.) trees were planted in May 1998 in one of four preplant treatments that were soil incorporation of: 1) control, no phosphorus (P); 2) 90 g P per tree; 3) 128 kg compost per tree; and 4) 90 g P and 128 kg compost per tree. Preplant addition of P had no effect on soil organic matter, P, magnesium (Mg), and calcium (Ca) in the first three seasons after planting, but lowered soil potassium (K) in the second season. Foliar nutrients, tree growth and flowering were also not affected by P. The addition of compost increased soil organic matter and P in the first season after planting, and pH, K, Mg, and Ca in the first three seasons. The addition of compost increased foliar nitrogen and K in all three seasons, and decreased foliar Mg in the first season. Compost incorporation increased shoot length in the first season, trunk cross-sectional area in the first two seasons, tree height and the number of growing points in third season, and flowering in the third and fourth seasons. Compost addition was more effective than P fertilization for increasing tree growth during the establishment years.

Buffered Phosphorus Fertilizer Improves Growth and Drought Tolerance of Woody Landscape Plants

Abstract The effects of alumina-buffered phosphorus (Al-P) were evaluated on growth and drought tolerance of woody plants and on seedling establishment of several tree species grown in containers with soilless media. Al-P reduced phosphorus leaching in all species. Vegetative growth of rhododendron (Rhododendron catawbiense Michx. cv. ‘English Roseum’), forsythia (Forsythia intermedia Zab. cv. ‘Spring Glory’), Ohio buckeye (Aesculus glabra Willd.), and bur oak (Quercus macrocarpa Michx.), measured as plant height, stem caliper, or biomass, was as fast or faster with Al-P as with Osmocote (17–6–10) or monoammonium phosphate fertilizer. Imposition of summer drought during the first growth season slightly reduced growth of rhododendron, with a stronger effect in the second year, while forsythia was more affected in the first season. Rhododendron plants fertilized with Al-P wilted more slowly than controls fertilized with Osmocote. Al-P fertilized forsythia plants grew faster than controls whether drought was imposed or not. Rhododendron plants produced more flower buds in the first year when fertilized with Al-P than with conventional phosphorus fertilizers. At the lower desorbing concentration, drought caused no reduction in percent of plants producing flower buds. A recharging treatment was tested at the beginning of the second season to replace P lost from the Al-P. Recharged Al-P reduced branching and flowering of rhododendron at the end of the second season, possibly as a result of damage from the recharging treatment.

Perturbation of Taranakite Formation by Ferrous and Ferric Iron under Acidic Conditions

Taranakite is an important reaction product of monoammonium phosphate fertilizer with soils. Its formation affects the transformation of nutrients in soils. The effect of different molar ratios of Fe(II)/Al and Fe(III)/Al on the formation of taranakite at pH 4.0 was investigated in this study. The results show that Fe(II) ion significantly perturbed the formation of taranakite at the Fe/Al molar ratio of 1.2 When the Fe/Al molar ratio was increased to 2.5, the formation of taranakite was completely inhibited by Fe(II), whereas, under the same condition, some crystalline taranakite was still observed in the Fe(III) system. Although Fe(III) had less effect on the crystallization of taranakite than Fe(II) at lower Fe/Al molar ratios, it also completely inhibited the formation of taranakite at the molar ratio of Fe(III)/Al ≥ 5. The solid products formed in the Fe(III) or Fe(II) system contained a substantial amount of Fe(III) and a much higher proportion of phosphate than that was required for the formation of NH4–taranakite. As indicated by the solution phase analysis at the end of the experiment, more Fe ions were present in the solution in the Fe(II) system, compared with the Fe(III) system, to perturb the nucleation and crystallization of taranakite. Since iron is a very common element in soil, taranakite formation may be perturbed in soils with high Fe content, especially under reduced and acidic conditions.