Nitrogen Release from Polymer‐Coated Urea: Effect of Seasons and Growing Degree‐Days

The increase of the efficiency of the nitrogen fertilization promotes reduction of the applied dose and decreases the losses of nitrogen (N) to the environment. The objective of this work was to evaluate the yield and the relative chlorophyll index (IRC) in cabbage crop under cover fertilization, using enhanced-efficiency nitrogen fertilizers, compared to urea, in variable doses. The experimental design was randomized blocks in a 3x4+1 factorial scheme (three sources, four rates and control), with four replications. The N sources used were: common urea (U), urea treated with urease inhibitor NBPT® (UN) and Kimcoat® polymer coated urea (UK). The N rates used were 0, 40, 80, 160 and 320 kg ha-1, divided in two fertilizations at 20 and 40 days after transplantation. Up to 160 kg ha-1 of N, there was no difference between N sources and N rates for both yield and RCI. The enhanced-efficiency N sources (UN and UK) promoted higher averages compared to common urea, possibly due to the higher N losses from common urea. Thus, the use of urease inhibitors or polymers associated with urea is a promising strategy to improve cabbage yield, as well as reducing N losses to the environment.

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Evaluation of Finger Millet Varieties under Rainfed Condition of Eastern India

Journal of AgriSearch ◽

10.21921/jas.v4i03.9018 ◽

2017 ◽

Vol 4 (03) ◽

Author(s):

M. K. Singh ◽

VINOD KUMAR ◽

SHAMBHU PRASAD

Keyword(s):

Field Experiment ◽

Finger Millet ◽

Yield Potential ◽

Growing Degree Days ◽

Eastern India ◽

Degree Days ◽

Rainfed Condition ◽

Net Returns ◽

Humid Environment ◽

Use Efficiency

A field experiment was carried out during the kharif of 2014 and 2015 to evaluate the yield potential, economics and thermal utilization in eleven finger millet varieties under the rainfed condition of the sub-humid environment of South Bihar of Eastern India. Results revealed that the significantly higher grain yield (20.41 q ha-1), net returns (Rs 25301) and B: C ratio (1.51) was with the finger millet variety ‘GPU 67’ but was being at par to ‘GPU28’and ‘RAU-8’, and significantly superior over remaining varieties. The highest heat units (1535.1oC day), helio-thermal units (7519.7oC day hours), phenothermal index (19.4 oC days day-1) were recorded with variety ‘GPU 67’ followed by ‘RAU 8’ and ‘GPU 28’ and lowest in ‘VL 149’ at 50 % anthesis stage. Similarly, the highest growing degree days (2100 oC day), helio-thermal units (11035.8 oC day hours) were noted with ‘GPU 67’ followed by ‘RAU 8’ and ‘GPU 28’ at maturity. The highest heat use efficiency (0.97 kg ha-1 oC day) and helio-thermal use efficiency (0.19 kg ha-1 oC day hour) were in ‘GPU 67’ followed by ‘VL 315’.

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Nitrogen Recovery from Enhanced Efficiency Fertilizers and Urea in Intensively Managed Black Walnut (Juglans nigra) Plantations

Forests ◽

10.3390/f12030352 ◽

2021 ◽

Vol 12 (3) ◽

pp. 352

Author(s):

Joshua L. Sloan ◽

Francis K. Salifu ◽

Douglass F. Jacobs

Keyword(s):

Black Walnut ◽

Juglans Nigra ◽

Water Soluble ◽

Growth And Yield ◽

N Recovery ◽

Competing Vegetation ◽

Fertilizer N Recovery ◽

Coated Urea ◽

Intensively Managed ◽

Polymer Coated Urea

Intensively managed forest plantations often require fertilization to maintain site fertility and to improve growth and yield over successive rotations. We applied urea-based “enhanced-efficiency fertilizers” (EEF) containing 0.5 atom% 15N at a rate of 224 kg N ha−1 to soils under mid-rotation black walnut (Juglans nigra L.) plantations to track the fate of applied 15N within aboveground ecosystem components during the 12-month period after application. Treatments included Agrotain Ultra (urea coated with a urease inhibitor), Arborite EC (urea coated with water-soluble boron and phosphate), Agrium ESN (polymer-coated urea), uncoated urea, and an unfertilized control. Agrotain Ultra and Arborite EC increased N concentrations of competing vegetation within one month after fertilization, while neither Agrium ESN nor uncoated urea had any effect on competing vegetation N concentrations during the experiment. Agrotain Ultra and Arborite EC increased δ15N values in leaves of crop trees above those of controls at one and two months after fertilization, respectively. By contrast, Agrium ESN and uncoated urea had no effect on δ15N values in leaves of crop trees until three months after fertilization. Fertilizer N recovery (FNR) varied among ecosystem components, with competing vegetation acting as a sink for applied nutrients. There were no significant differences in FNR for all the urea-based EEF products compared to uncoated urea. Agrium ESN was the only EEF that exhibited controlled-release activity in this study, with other fertilizers behaving similarly to uncoated urea.

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Comparative Efficiency of Polymer-coated Urea for Lowland Rice in Semi-Arid Tropics

Communications in Soil Science and Plant Analysis ◽

10.1080/00103624.2021.1925689 ◽

2021 ◽

pp. 1-11

Author(s):

Rajan Bhatt ◽

Manmohanjit Singh

Keyword(s):

Lowland Rice ◽

Comparative Efficiency ◽

Coated Urea ◽

Polymer Coated Urea ◽

Semi Arid

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Determining the critical period for weed control in high-yielding cotton using common sunflower as a mimic weed

Weed Technology ◽

10.1017/wet.2019.68 ◽

2019 ◽

Vol 33 (6) ◽

pp. 800-807 ◽

Cited By ~ 3

Author(s):

Graham W. Charles ◽

Brian M. Sindel ◽

Annette L. Cowie ◽

Oliver G. G. Knox

Keyword(s):

Weed Control ◽

Critical Period ◽

Yield Loss ◽

Field Studies ◽

Growing Degree Days ◽

Degree Days ◽

Weed Density ◽

High Level ◽

The Cost ◽

Planting Season

AbstractField studies were conducted over six seasons to determine the critical period for weed control (CPWC) in high-yielding cotton, using common sunflower as a mimic weed. Common sunflower was planted with or after cotton emergence at densities of 1, 2, 5, 10, 20, and 50 plants m−2. Common sunflower was added and removed at approximately 0, 150, 300, 450, 600, 750, and 900 growing degree days (GDD) after planting. Season-long interference resulted in no harvestable cotton at densities of five or more common sunflower plants m−2. High levels of intraspecific and interspecific competition occurred at the highest weed densities, with increases in weed biomass and reductions in crop yield not proportional to the changes in weed density. Using a 5% yield-loss threshold, the CPWC extended from 43 to 615 GDD, and 20 to 1,512 GDD for one and 50 common sunflower plants m−2, respectively. These results highlight the high level of weed control required in high-yielding cotton to ensure crop losses do not exceed the cost of control.

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