Urea Ammonium Nitrate Fertilizer Research Articles

Sweet Corn (Zea mays) Cultivar Sensitivity to Mesotrione*

Field studies were conducted in 1999 and 2000 at Simcoe, Ridgetown, and Exeter, Ontario, to evaluate the tolerance of nine sweet corn cultivars to mesotrione, applied preemergence (PRE) at 140 and 280 g ai/ha and postemergence (POST) at 100 and 200 g ai/ha. Urea ammonium nitrate fertilizer (28%) at 2.5% (v/v) and crop oil concentrate at 1% (v/v) were added to POST applications of mesotrione only. All cultivars were tolerant to mesotrione applied PRE. There was no injury, or reductions in plant height or yield with PRE applications of mesotrione at any location in either year. POST applications of mesotrione, particularly at 200 g/ha, caused significant phytotoxicity to ‘Calico Belle’ and ‘Del Monte 2038’. Other cultivars also showed phytotoxic symptoms; however, this injury was much reduced and did not occur at all locations each year. Sweet corn injury by mesotrione increased as rate increased. Del Monte 2038 also had significantly reduced plant height and yields. Other cultivars had no plant height or y...

Corrosion Characteristics of Mild Steel in Urea Ammonium Nitrate Fertilizer Solutions

Abstract Anodic polarization studies have been conducted on mild steel in urea ammonium nitrate (UAN) fertilizer solutions comprising 31 wt% urea ([NH2]2CO), 39 wt% ammonium nitrate (NH4NO3), and 30 wt% H2O, with a total N content of 28 wt% (UAN 28-0-0). It was determined that mild steel can spontaneously exhibit either active-passive or passive behavior when immersed in UAN solutions. At 23°C, specimens exhibiting active-passive behavior experienced corrosion rates of ∼2 mm/y for pH values in the range of 3 to 8.5. At pH values <3, the corrosion rate increased rapidly, reaching a value of 92 mm/y at a pH of 1.1. Specimens exhibiting passive behavior experienced corrosion rates of ∼0.002 mm/y for the pH range of 6 to 8.5. An increase in temperature from 23°C to 60°C increased the corrosion rate of specimens exhibiting active-passive behavior from ∼2 mm/y to ∼15 mm/y. To minimize corrosion, mild steel storage tanks for liquid UAN fertilizer should be kept free of sludges and other contaminants, which could...

EFFECTS OF LAYI NG HEN MANURE APPLICATION RATE ON WATER QUALITY

Excessive use of animal manure on agricultural lands can impact the quality of surface and groundwater resources. A three–year study (1998–2000) was conducted on nine 0.4–ha plots and on six 2.1–m 2 lysimeters to investigate the effect of two nitrogen (N) application rates from laying hen manure and one N application rate from urea ammonium nitrate (UAN) fertilizer on surface and groundwater quality. Experimental treatments included N application rates of 168 kg–N/ha from UAN fertilizer, and 168 kg–N/ha and 336 kg–N/ha from laying hen manure to corn plots. Subsurface drain and runoff water samples were collected and analyzed for nitrate–nitrogen (NO3–N) and orthophosphate (PO4–P). Results of this study indicate that application of hen manure at 336 kg–N/ha resulted in the highest average NO3–N and PO4–P concentrations in subsurface drain water in comparison with the application of 168 kg–N/hafrom either hen manure or UAN fertilizer. Application of manure at 168 kg–N/ha resulted in significantly lower NO3–N loss with subsurface drain water in comparison with NO3–N loss from the other two N treatments. Manure application at a rate of 336 kg–N/ha resulted in a higher concentration of PO4–P in surface runoff in comparison with manure application rate of 168 kg–N/ha. Application rate of manure had no significant effect on NO3–N concentration in surface runoff water. In addition, higher PO4–P losses were observed with surface runoff water in comparison with subsurface drain water. The use of manure at both low and high application rates in field plots resulted in significantly higher corn and soybean yields in comparison with the use of UAN fertilizer. Results of this study led to the conclusions that application of hen manure at a lower rate of 168 kg–N/ha can result in higher crop yields and minimal water pollution in comparison with same amount of UAN fertilizer or higher manure application rate.

Nozzle, Spray Volume, and Adjuvant Effects on Carfentrazone and Imazamox Efficacy1

Abstract: Field experiments were conducted to determine the influence of nozzle type, spray volume, and adjuvants on herbicide efficacy. Carfentrazone and imazamox, representing contact and translocated herbicides, respectively, were equally or more effective when applied with drift-reducing TurboDrop or Drift Guard nozzles than the conventional flat-fan nozzle in 95% of the comparisons. Imazamox was equally effective when applied in 47, 94, or 190 L/ha spray volume, regardless of nozzle type or adjuvant. Carfentrazone applied in 47 L/ha spray volume controlled flax and sunflower as well as in 94 or 190 L/ha, provided urea ammonium nitrate fertilizer and either nonionic surfactant or methylated vegetable oil were included in the spray mixture. Conversely, carfentrazone with only urea ammonium nitrate was less effective when applied in 47 than in 94 or 190 L/ha spray volume. Carfentrazone and imazamox applied in low spray volumes (47 L/ha) gave consistent control when an effective adjuvant was included in ...

Thiosulfate Inhibition of Urea Hydrolysis in Soils: Tetrathionate as a Urease Inhibitor

AbstractAmmonium thiosulfate [ATS, (NH4)2S2O3, 12‐0‐0‐26S] added to urea‐ammonium nitrate (UAN) inhibits urea hydrolysis after application to soil. Thiosulfate itself does not inhibit purified jackbean urease, so products of S2O2‐3 oxidation in soil (tetrathionate [S4O2‐6], Fe2+, and Mn2+) are the probable urease inhibitor(s). The objectives of this study were to (i) identify the primary urease inhibitor produced by ATS in soil and (ii) determine why the efficacy of the inhibitor is improved by increasing UAN droplet size. Jackbean urease (urea amidohydrolase, Type III from jackbean, EC 3.5 1.5) was inhibited by Fe2+ (100% inhibition at 0.3 mM), Mn2+ (100% at 6.3 mM), Fe3+ (97% at 6.3 mM), and S4O2‐6 (39% at 7.8 mM). Thiosulfate did not inhibit jackbean urease at concentrations up to 18.8 mM. When applied in a simulated UAN fertilizer band, S4O2‐6 was as effective as S2O2‐3; it inhibited soil urease (24%) to the same extent as S2O2‐3 (26%) but more than FeSO4 (0%) in two soils. Urease inhibition by all species was low in unbuffered 5‐h soil incubations (Fe2+ [14%], Mn2+ [3%], S4O2‐6 [10%], and S2O3 [7%]) with 25 mmol S kg−1. Urease inhibition by S4O2‐6 increased from 9% at pH 7 to 30% at pH 8.5 in buffered incubations. Since pH during urea hydrolysis increases with UAN droplet size, the increased efficacy of ATS with application of large UAN droplets is probably due to greater activity of S4O2‐6 as a urease inhibitor at pH &gt; 7. Tetrathionate is the primary urease inhibitor produced by ATS in soil. Reaction of urease sulfhydryl groups with S4O2‐6 is proposed as an inhibitory mode of action.

Leaf scorch onPennisetum clandestinumdryland pastures induced by liquid urea ammonium nitrate fertilizer

Transmission electron (TEM) and scanning electron microscopy (SEM) demonstrated that the application of liquid urea ammonium nitrate (UAN 32) fertilizer, in concentrated form, to dryland pastures resulted in leaf scorch and subsequent necrosis, irrespective of the level and concentration of the UAN solution applied. One week after UAN application, most treatments, except those which involved high application rates and high concentrations of UAN, snowed full cuticular and cellular recovery. Furthermore, chloroplasts and granal stacks recovered after such treatment. The addition of a urease inhibitor, ammonium thiosulphate (ATS 12), to the liquid fertilizer did not lower leaf cell damage, but may have aided the recovery process. The higher the application rate and the higher the concentration of the UAN, the greater the extent of damage to the outer waxy cuticle, guard cells and epidermal cells, and to the internal chloroplasts, grana and mesophyll cells. Guard and epidermal cells became flaccid and necrotic, while the cuticle readily peeled away from the leaf surface. Leaf browning was ascribed to the damage caused to the grana within the chloroplasts. Of the combinations tested, the least damaging to the leaf was the application of 69 kg N ha−1 at a concentration of 8% N, combined with a 5% volume/volume (v/v) ATS.