THE ECONOMICS OF FERTILIZING BROMEGRASS IN SASKATCHEWAN

1989 ◽  
Vol 69 (3) ◽  
pp. 841-859 ◽  
Author(s):  
R. P. ZENTNER ◽  
C. A. CAMPBELL ◽  
H. UKRAINETZ
Keyword(s):  
Ammonium Nitrate ◽  
Unit Cost ◽  
Economic Advantage ◽  
Stand Age ◽  
Single Application ◽  
Net Returns ◽  
N Source ◽  
Nitrate N ◽  
Application Rates ◽  
N Rates

A 5-yr study on a Dark Brown Loam at Scott and a 9-yr study on a Gray Luvisolic loam at Loon Lake, Saskatchewan, were used to determine the effect of rate of urea (46-0-0) and ammonium nitrate (34-0-0) fertilization on net returns from bromegrass (Bromus inermis Leyss.) production when the N was broadcast annually or as a single application at the start of the experiment. Each N source was applied at annual rates of 0, 50, 100, and 200 kg N ha−1 and at single application rates of 0, 100, 200, 400, and 800 kg ha−1. The ammonium nitrate was also applied at rates of 600 and 1000 kg ha−1. Comparisons of the discounted present value of net returns (NPV) over the study periods showed that N fertilization was highly profitable for all treatments under most forage price, N cost, and interest rate situations. The application of ammonium nitrate was consistently more profitable than urea despite its higher unit cost. At Scott, the 5-yr economic advantage of ammonium nitrate over urea averaged $53–$117 ha−1 for annual applications and $34–$72 ha−1 for single applications when forage price was varied from $0.05 to $0.09 kg−1; at Loon Lake, the corresponding 9-yr advantage of ammonium nitrate averaged $48–$121 ha−1 for annual and $25–$59 ha−1 for single applications. When price was adjusted to reflect forage N and P composition, the economic advantage of using ammonium nitrate over urea was enhanced. For treatments receiving similar rates of total applied N by both methods of application, NPV was generally higher when the N was applied in smaller doses annually compared to all at one time. At Scott, this effect was consistent at all N rates and for both N sources, but at Loon Lake, where moisture was more favorable, single applications at lower N rates often provided similar NPV as for annual N applications. The most profitable fertilizer treatments at Scott and Loon Lake were the 100- and 200-kg ha−1 rates of ammonium nitrate-N applied annually. When forage yields were related to N rate, moisture, and stand age for the annual N application treatments the economic optimum N rates depended greatly on the expectations for moisture, level of risk aversion, and on the ratio of fertilizer N cost to forage price. The optimum application rates of ammonium nitrate-N averaged 7–14 kg ha−1 higher at Scott and 8–27 kg N ha−1 higher at Loon Lake compared to those for urea. Further, the optimum N rates were higher than the general recommendation for bromegrass grown in these regions; thus producers should consider using higher N rates than has been the tradition for maximum economic return.Key words: Net returns, bromegrass hay, N source, N rates, application method

RESPONSE OF AN ORCHARDGRASS-PERENNIAL RYEGRASS SWARD TO RATE AND METHOD OF UREA AND AMMONIUM NITRATE APPLICATION

1983 ◽  
Vol 63 (4) ◽  
pp. 719-725 ◽  
Author(s):  
A. A. BOMKE ◽  
R. A. BERTRAND
Keyword(s):  
Ammonium Nitrate ◽  
Perennial Ryegrass ◽  
Dry Matter ◽  
N Uptake ◽  
Split Application ◽  
Single Application ◽  
Forage Production ◽  
N Application ◽  
N Source ◽  
N Rates

Urea and ammonium nitrate were applied at rates of 75, 150 and 300 kg N/ha as either a single application in April or split into three equal increments, one applied in April and the second and third following cuts one and two. The orchardgrass-perennial ryegrass sward responded significantly to applied N in each year; however, the yield produced by the two sources differed in only one of the three years. In that year split applied ammonium nitrate gave 8% higher yields than similarly applied urea. The sources were found to be equivalent when applied in the spring. Split application of the N rates increased total annual dry matter yields in one of the three years regardless of N source. In all three years split application of N shifted forage production from cut one to cuts two and three. Key words: N uptake, split N application, orchardgrass-perennial ryegrass sward

N AND P FERTILIZATION OF BROMEGRASS IN THE DARK BROWN SOIL ZONE OF SASKATCHEWAN

1988 ◽  
Vol 68 (2) ◽  
pp. 457-470 ◽  
Author(s):  
H. UKRAINETZ ◽  
C. A. CAMPBELL
Keyword(s):  
Ammonium Nitrate ◽  
Dry Matter ◽  
First Year ◽  
N Recovery ◽  
N Source ◽  
P Concentration ◽  
Matter Production ◽  
Use Efficiency ◽  
N Rates ◽  
N Use

A 5–yr study was conducted on a Dark Brown loam at Scott, Saskatchewan to determine the effect of rate of ammonium nitrate-N (34–0–0) and urea-N (46–0–0) on bromegrass (Bromus inermis Leyss.) production and quality, N recovery and N use efficiency when the N was applied either annually or as a single application at the start of the experiment. The effect of phosphorus (P) on the above listed parameters was also assessed. Each N source was applied at once-only rates of 0, 100, 200, 400, and 800 kg ha−1 and annual rates were 0, 50, 100 and 200 kg ha−1. Phosphorus was applied in 1976, 1979 and 1981 at 100 kg ha−1 P2O5. Forage dry matter was positively related to precipitation received in April–June (r = 0.91**) and in April of the crop year plus the previous September (r = 0.80**). Dry matter response to N rates generally increased at a decreasing rate in early years but linearly in later years. Over the first 4 yr, annual applications of N resulted in up to 37% more dry matter than the single applications. Dry matter production was generally greater when ammonium nitrate was applied than when urea was used; these differences were more consistent at medium N rates. Dry matter was increased by P only when N was applied. Nitrogen concentration in forage was directly related to N rate in years of good precipitation, was greater in dry than wet years, and when N was applied annually, but was unaffected by N source. Phosphorus fertilization increased P concentration of forage but heavy dry matter production reduced P concentration. Annual N applications increased P concentration in forage only in the first year and N source had no effect. Toxic concentrations of NO3–N in the forage occurred in the first year only at N rates [Formula: see text] and were directly related to the amount of N applied. Except for the 800 kg ha−1 N rate in the second year, there were no further indications of NO3–N toxicity. Accumulated N use efficiency decreased linearly with increasing N rate and was greater for ammonium nitrate than for urea except at very high N rates. Accumulated N recovery was inversely related to N rate for the single method of application but unaffected by N rate applied annually. Over the first 4 yr, accumulated N recovery was greater for the single application at low N rates, but was greater for annual applications of N at high N rates. P fertilization increased N recovery.Key words: N source, bromegrass, N recovery, yield, quality, application method

RESPONSE OF BROMEGRASS TO N, P AND S FERTILIZER ON A GRAY LUVISOLIC SOIL IN NORTHWESTERN SASKATCHEWAN

1988 ◽  
Vol 68 (3) ◽  
pp. 687-703 ◽  
Author(s):  
H. UKRAINETZ ◽  
C. A. CAMPBELL ◽  
R. P. ZENTNER ◽  
M. MONREAL
Keyword(s):  
Ammonium Nitrate ◽  
Dry Matter ◽  
N Recovery ◽  
Fertilizer N ◽  
Single Application ◽  
N Source ◽  
Matter Production ◽  
Use Efficiency ◽  
Second Year ◽  
N Use

A 9-yr study was conducted on a Gray Luvisolic loam at Loon Lake, Saskatchewan to determine the effect of ammonium nitrate-N (34–0–0) and urea-N (46–0–0) on bromegrass (Bromus inermis Leyss.) production and nutrient quality, N recovery, and N use efficiency when the N was applied either annually or as a single application at the start of the experiment. The effects of phosphorus (P) and sulphur (S) were also assessed. Each N source was applied at single rates of 0, 100, 200, 400 and 800 kg ha−1 N and annual rates of 0, 50, 100 and 200 kg ha−1 N. The ammonium nitrate was also applied as a single dose at rates of 600 and 1000 kg ha−1 N. Phosphorus and S were applied every second year at 224 kg ha−1 P2O5 and 45 kg ha−1 S. Forage dry matter yields were positively related to precipitation received in May and July, and April–May, but negatively related to June precipitation. Forage dry matter production was greater over the first 8-yr period for annual N applications than for a single application receiving an equivalent amount of N; but fertilizer N recovered in forage over the same period was similar (about 30%) for the two methods of application. Dry matter yields were 19% greater after 4 yr and 26% greater after 8 yr when ammonium nitrate was used compared to urea. Recovery of fertilizer N in forage also favored the ammonium nitrate source. The application of low to moderate N rates depressed forage N and P concentrations when yield response was high but concentrations were increased by the highest rates of N fertilizer and by repeated annual applications of N. Toxic concentrations of NO3-N occurred in bromegrass in the first year when N was applied at or above 400 kg ha−1 as one application and also in the second year when N was applied at 800 kg ha−1. When N was applied annually at 200 kg ha−1, NO3-toxicity became a potential problem in later years as soil mineral N accumulated. Phosphorus and S fertilizers increased dry matter yields of forage; P fertilizer increased and S decreased forage P concentration. Annual N applications resulted in more uniform year-to-year yields and N uptake response compared to a single application and provided greater dry matter production without loss of nutritive quality. It was concluded that, in contrast to reports in the literature, the response of forage grasses to N is not site specific.Key words: N source, N recovery, N application method, N use efficiency, phosphorus, sulfur

Within-season grass herbage crude-protein- and nitrate-N concentrations as affected by rates and seasonal distribution of fertilizer nitrogen in a high yearly rainfall climate

2000 ◽  
Vol 80 (2) ◽  
pp. 277-285 ◽  
Author(s):  
S. Bittman ◽  
C. G. Kowalenko
Keyword(s):  
Crude Protein ◽  
Residual Effect ◽  
Residual Effects ◽  
Single Application ◽  
N Application ◽  
Total N ◽  
Nitrate N ◽  
N Concentration ◽  
Application Rates ◽  
Poor Indicator

An orchardgrass study in which three rates of N (100, 200 and 400 kg ha−1) each distributed in 1/0/0/0, 0.75/0.25/0/0, 0.50/0.25/0.25/0 and 0.25/0.25/0.25/0.25 proportions prior to four cut intervals examined crude-protein-N and nitrate-N concentrations in grass herbage at each cut in three trials. Crude-protein-N concentration frequently increased to a greater degree and in a different pattern (based on cut) than yield as the rate of N application increased. This showed that crude-protein-N by itself cannot be used as a method for determining the N sufficiency status of grass. Both rate and distribution of fertilizer N strongly influenced plant nitrate-N concentration; the degree of change varied considerably among cuts and trials. Plant nitrate-N concentration in the control did not correspond to yield responsiveness to N application, making it a poor indicator of the plant's need for fertilizer applications. Residual effects of N applications on plant nitrate-N were noted into the last cut of the season from a single spring application. The effect of N rate and distribution, then, was a function of immediate and residual effects of the applications. There was some evidence that N present in the soil in nitrate-N form enhanced the potential for high nitrate-N in the plant. Plant nitrate-N concentrations accounted for up to 29% of the total N in the plant with concentrations greater than 4000 mg N kg−1 at the highest N application rates. Plant nitrate-N did not exceed 1000 mg N kg−1, a concentration considered safe for ruminants, when 75 kg N ha−1 or less ammonium nitrate was applied as a single application prior to a growth interval for all cuts. Since grass protein- and nitrate-N concentrations respond differently than yield to N applications, a specific combination of rate and distribution of fertilizer will not necessarily produce maximum herbage quantity and quality simultaneously. Key words: Crude-protein-N, plant nitrate-N, residual effect, split applications

INFLUENCE OF THE SYSTEM OF RICE INTENSIFICATION ON RICE YIELD AND NITROGEN AND WATER USE EFFICIENCY WITH DIFFERENT N APPLICATION RATES

2009 ◽  
Vol 45 (3) ◽  
pp. 275-286 ◽  
Author(s):  
LIMEI ZHAO ◽  
LIANGHUAN WU ◽  
YONGSHAN LI ◽  
XINGHUA LU ◽  
DEFENG ZHU ◽  
...  
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
N Use Efficiency ◽  
System Of Rice Intensification ◽  
N Application ◽  
Application Rates ◽  
Rice Intensification ◽  
Use Efficiency ◽  
N Rates ◽  
N Use

SUMMARYField experiments were conducted in 2005 and 2006 to investigate the impacts of alternative rice cultivation systems on grain yield, water productivity, N uptake and N use efficiency (ANUE, agronomic N use efficiency; PFP, partial factor productivity of applied N). The trials compared the practices used with the system of rice intensification (SRI) and traditional flooding (TF). The effects of different N application rates (0, 80, 160 and 240 kg ha−1) and of N rates interacting with the cultivation system were also evaluated. Resulting grain yields with SRI ranged from 5.6 to 7.3 t ha−1, and from 4.1 to 6.4 t ha−1 under TF management. On average, grain yields under SRI were 21% higher in 2005 and 22% higher in 2006 than with TF. Compared with TF, SRI plots had higher harvest index across four fertilizer N rates in both years. However, there was no significance difference in above-ground biomass between two cultivation systems in either year. ANUE was increased significantly under SRI at 80 kg N ha−1 compared with TF, while at higher N application rates, ANUE with SRI was significantly lower than TF. Compared with TF, PFP under SRI was higher across all four N rates in both years, although the difference at 240 kg N ha−1 was not significant. As N rate increased, the ANUE and PFP under both SRI and TF significantly decreased. Reduction in irrigation water use with SRI was 40% in 2005 and 47% in 2006, and water use efficiency, both total and from irrigation, were significantly increased compared to TF. With both SRI and TF, the highest N application was associated with decreases in grain yield, N use efficiency and water use efficiency. This is an important finding given current debates whether N application rates in China are above the optimum, especially considering consequences for soil and water resources. Cultivation system, N rates and their interactions all produced significant differences in this study. Results confirmed that optimizing fertilizer N application rates under SRI is important to increase yield, N use efficiency and water use efficiency.

Aqueous ammonia compared with other nitrogenous fertilizers as solids and solutions on grass

1968 ◽  
Vol 71 (2) ◽  
pp. 195-203 ◽  
Author(s):  
D. R. Hodgson ◽  
A. P. Draycott
Keyword(s):  
Ammonium Nitrate ◽  
Ammonium Sulphate ◽  
Dry Matter ◽  
Field Experiments ◽  
Aqueous Ammonia ◽  
Single Injection ◽  
Maximum Yield ◽  
Italian Ryegrass ◽  
Dry Matter Yield ◽  
Single Application

SUMMARYField experiments with Italian ryegrass cut four times a year compared aqueous ammonia with ammonium sulphate and with a mixture of ammonium nitrate and urea (equal parts by weight). In 1963 four rates of nitrogen, 224, 448, 672 and 896 lb/acre, were applied as single and split dressings of injected aqueous ammonia, as solid ammonium sulphate and as injected solution of ammonium sulphate. There was little difference in total dry-matter yield between a single injection of aqueous ammonia and the split dressing of solid. Injecting ammonium sulphate solution eliminated scorch caused by single applications of solid supplying 448 lb N/acre or more and gave significantly greater dry-matter yields. A single application of 448 lb N/acre provided enough nitrogen to sustain the response of the grass to the end of the season.In 1964 a single injection of aqueous ammonia was compared with ammonium nitrate/urea applied as solid or solution at 280, 560 and 840 lb N/acre. There was no difference in total dry-matter yield between aqueous ammonia and ammonium nitrate/urea at rates of 560 and 840 lb/acre. At 280 lb/acre a split dressing of solid produced most dry matter. More than 280 lb N/acre was required, therefore, as a single application in spring to last the whole season, but this rate of nitrogen applied as a split dressing was almost sufficient to give maximum yield.In both experiments the seasonal distribution of dry matter was similar for single and split applications except in 1963 when large single injections of ammonium sulphate produced greater yields at the third cut than the split applications. The percentage of nitrogen recovered in the harvested grass decreased as nitrogen rate was increased and was greater from single than split applications. Recovery of nitrogen from aqueous ammonia was less efficient from four injections than one, and was greater in 1964 than 1963 due to better penetration of the sward by injector tines. Least nitrogen was recovered from surface-applied solutions of ammonium nitrate/urea. Regressions of dry-matter yield on nitrogen yield showed that single injections of aqueous ammonia were as efficient as other fertilizers tested.

Cultivation practices improving seed productivity of tetraploid red clover

2019 ◽  
Author(s):  
М. Новосёлов ◽  
Л. Дробышева ◽  
О. Старшинова ◽  
Э. Рекашус ◽  
А. Одноворова
Keyword(s):  
Ammonium Nitrate ◽  
Red Clover ◽  
Nodule Bacteria ◽  
Seed Productivity ◽  
Mineral N ◽  
Yield Increase ◽  
Seed Inoculation ◽  
Application Rates ◽  
Yield Capacity ◽  
Clover Seed

В статье изложены результаты исследований влияния инокуляции клубеньковыми бактериями и внекорневых обработок бором и минеральным азотом на семенную продуктивность клевера лугового сорта Марс. Цель работы определить оптимальные варианты внекорневой обработки растений бором и минеральным азотом, в том числе в сочетании с инокуляцией клубеньковыми бактериями, обеспечивающие максимальную семенную продуктивность клевера лугового сорта Марс. Установлено, что внекорневые подкормки минеральным азотом и бором в фазу начала цветения, а также инокуляция эффективным штаммом клубеньковых бактерий повышали его семенную продуктивность. Обработка растений бором повысила урожайность семян на 8,2. Совместное применение бора и инокуляции увеличило эффективность приёма до 20,0 к инокулированному и до 34,4 к неинокулированному контролю. Внекорневое опрыскивание аммиачной селитрой в чистом виде было эффективно в дозах 2,5 и 3,0 кг/га: прибавка к контролю составила соответственно 11,8 и 16,7. Комплексное применение бора и минерального азота наибольшую прибавку урожая семян дало в варианте B N3,0, которая составила 36,6. Инокуляция комплементарным штаммом Rh. trifolii увеличила урожайность семян клевера на 12,0. Обработка растений бором и аммиачной селитрой в различных концентрациях на фоне инокуляции была эффективной во всех вариантах (12,331,4 к инокулированному и 25,847,1 к неинокулированному контролю). Рекомендуется для повышения семенной продуктивности тетраплоидных сортов типа Марс проводить внекорневое опрыскивание растений в фазу начала цветения бором в дозе 0,4 кг/га в комплексе с аммиачной селитрой из расчёта 3,0 кг/га действующего вещества или инокулировать семена перед посевом комплементарными штаммами с последующей внекорневой подкормкой бором (0,4 кг/га) совместно с минеральным азотом (3,0 кг/га). This paper reports on red clover seed productivity affected by the inoculation with nodule bacteria and topdressing with B and mineral N. The aim was to determine optimal treatment rates and combinations leading to the highest seed productivity of clover Mars. Topdressing with B and N at flowering time combined with bacterium inoculation increased its yield capacity. B application improved seed yield by 8.2. B treatment together with inoculation improved clover performance by up to 20.0 and 34.4 compared to the inoculated and non-inoculated controls, respectively. Application rates of 2.5 and 3.0 kg ha-1 showed the best effect when topdressing by pure ammonium nitrate: yield increase amounted to 11.8 and 16.7, respectively. Variant B N3.0 provided the highest yield increase of 36.6. Seed inoculation with Rh. trifolii increased seed productivity by 12.0. Topdressing with different concentrations of B and ammonium nitrate was effective in all the variants on the background of bacterium inoculation (12.331.4 and 25.847.1 compared to inoculated and non-inoculated controls, respectively). Spraying with B (0.4 kg ha-1) and ammonium nitrate (3.0 kg ha-1) with or without seed inoculation by nodule bacteria are recommended to improve tetraploid clover performance.

Combined de-inking paper sludge and poultry manure application on corn yield and soil nutrients

2004 ◽  
Vol 84 (4) ◽  
pp. 503-512 ◽  
Author(s):  
Bernard Gagnon, Michel C. Nolin ◽  
Athyna N. Cambouris
Keyword(s):  
Soil Nutrients ◽  
Poultry Manure ◽  
Application Rate ◽  
N Immobilization ◽  
Paper Sludge ◽  
Corn Yield ◽  
Soil Organic C ◽  
Single Application ◽  
Organic C ◽  
Application Rates

Application of combined de-inking paper sludge and poultry manure may be an appropriate way to dispose of these residues and restore fertility of highly degraded soils. An experiment was initiated to determine the effects of a single application of this material, using two different application techniques, on corn yield and soil properties of two 12-ha fields of contrasting textures located in the Nicolet watershed in the province of Québec, Canada. De-inking paper sludge was mixed with poultry manure (PP) at a ratio of 25:1 and strip-applied before corn seeding. The study included three treatments: untreated control, a constant application rate, and variable application rates according to initial soil organic C content. The variable application rates were 10, 20 and 30 Mg dry weight ha-1. The strips were randomized within blocks, and the strips ran lengthwise in the blocks. Soil N immobilization and P release occurred on both sites at least 2 mo after PP incorporation, as measured at the corn eight-leaf and silk apparition stages by the anion-exchange membranes. Despite early N immobilization, grain yield was not affected whereas plant P uptake was increased by PP. At both sites, a single application of PP increased soil pH and major nutrient levels at harvest but had no significant effect on soil organic C. The application of PP also increased P saturation indices but the measured values were well below critical thresholds above which environmental risks would be high. The variable application rate treatment did not differ from the equivalent constant rate treatment for improving soil status and crop growth. This study indicates that mixing de-inking paper sludge and poultry manure may provide a cost-effective and environmentally friendly approach to land disposal of these wastes. Key words: Corn, paper sludge, poultry manure, precision farming, soil nutrients

Forest floor dynamics in a chronosequence of hardwood stands in central Nova Scotia

1986 ◽  
Vol 16 (2) ◽  
pp. 293-302 ◽  
Author(s):  
E. S. Wallace ◽  
B. Freedman
Keyword(s):  
Weight Loss ◽  
Nova Scotia ◽  
Forest Floor ◽  
Stand Age ◽  
Total Production ◽  
Clear Cutting ◽  
Nitrate N ◽  
Ammonium N ◽  
Field Samples ◽  
Mature Stands

A postclear-cutting chronosequence of hardwood stands in Nova Scotia was examined for patterns of forest floor weight, concentration of selected nutrients, rate of potential insitu litter decomposition (litterbags), and potential lab ammonification and nitrification. Some evidence was found that the forest floor experiences weight loss following clear-cutting. However, the large weight losses and clear pattern of recovery described by others for New Hampshire hardwood chronosequences were not observed. The lack of close agreement may have been a result of intra- and inter-stand variation in forest floor weight in our study. This spatial variation was greater than any effect as a result of clear-cutting. There was no significant relationship between insitu weight loss of leaves or twigs with stand age. No clear-cutting effect was observed in the laboratory for potential ammonification, which occurred readily in all stands (three clear-cuttings, three mature stands). Limed materials produced significantly more mineralized N (nitrate N + ammonium N) than did unlimed materials. Concentrations of ammonium N in F and H horizon field material were significantly higher on clear-cuttings than in mature stands. However, since this measurement reflects net rather than total production, it is not evidence that higher rates of ammonification occurred on clear-cuttings. Potential nitrification was not an important process in F and H horizon materials at their natural pH. Nitrification occurred readily in limed materials, but there were no significant differences among different aged stands. Concentrations of nitrate N in field F and H horizon material were low for all stands, with a mean of 9 ± 7 ppm (n = 350). However, in 7% of field samples, nitrate N ≥ 15 ppm was found; in 2%, ≥30 ppm was found.

Response of LibertyLink and WideStrike Cotton to Varying Rates of Glufosinate

2015 ◽  
Vol 29 (4) ◽  
pp. 665-674 ◽  
Author(s):  
Darrin M. Dodds ◽  
Christopher L. Main ◽  
L. Thomas Barber ◽  
Charles Burmester ◽  
Guy D. Collins ◽  
...  
Keyword(s):  
North Carolina ◽  
Growth Parameters ◽  
Fiber Quality ◽  
Field Studies ◽  
Application Rate ◽  
Yield Reduction ◽  
Single Application ◽  
Application Rates ◽  
Growth Development

Field studies were conducted in Alabama, Arkansas, Georgia, Louisiana, Mississippi, North Carolina, and Tennessee during 2010 and 2011 to determine the effect of glufosinate application rate on LibertyLink and WideStrike cotton. Glufosinate was applied in a single application (three-leaf cotton) or sequential application (three-leaf followed by eight-leaf cotton) at 0.6, 1.2, 1.8, and 2.4 kg ai ha−1. Glufosinate application rate did not affect visual injury or growth parameters measured in LibertyLink cotton. No differences in LibertyLink cotton yield were observed because of glufosinate application rate; however, LibertyLink cotton treated with glufosinate yielded slightly more cotton than the nontreated check. Visual estimates of injury to WideStrike cotton increased with each increase in glufosinate application rate. However, the injury was transient, and by 28 d after the eight-leaf application, no differences in injury were observed. WideStrike cotton growth was adversely affected during the growing season following glufosinate application at rates of 1.2 kg ha−1 and greater; however, cotton height and total nodes were unaffected by glufosinate application rate at the end of the season. WideStrike cotton maturity was delayed, and yields were reduced following glufosinate application at rates of 1.2 kg ha−1 and above. Fiber quality of LibertyLink and WideStrike cotton was unaffected by glufosinate application rate. These data indicate that glufosinate may be applied to WideStrike cotton at rates of 0.6 kg ha−1 without inhibiting cotton growth, development, or yield. Given the lack of injury or yield reduction following glufosinate application to LibertyLink cotton, these cultivars possess robust resistance to glufosinate. Growers are urged to be cautious when increasing glufosinate application rates to increase control of glyphosate-resistant Palmer amaranth in WideStrike cotton. However, glufosinate application rates may be increased to maximum labeled rates when making applications to LibertyLink cotton without fear of reducing cotton growth, development, or yield.

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