Evaluation of N2fixation and N absorption activity by relative ureide method in field-grown soybean plants with deep placement of coated urea

SummaryEfficiency of N contained in some modified urea fertilizers was studied for wetland rice grown in an alkaline, low organic matter Fatehpur loamy sand (Typic Ustipsamment) soil having an average percolation rate of 109 mm/day. In the four field experiments, sulphurcoated urea (SCU) produced significantly more rice grain than urea supergranules (USG) or divided applications of urea or ammonium sulphate. Application of SCU at 58 kg N/ha yielded as much rice grain as was produced by divided application of urea at 116 kg N/ha. The N uptake data suggested that SCU-N was more efficiently translated into grain yield than urea N. Granular (7-day release rate 19%) and forestry (7-day release rate 29%) grades of SCU were equally effective. However, application of half the N basally through SCU and the remaining half top dressed as urea failed to outyield all urea divided in three applications. The indigenous coated materials, rock-phosphate-coated urea and urea gypsum, also did not perform better than divided urea applications as these did not possess a 7-day release rate less than 95%. Urea supergranules placed in the reduced zone of the soil could not come to the level of divided application of urea or ammonium sulphate. The N uptake data indicated that USG-N was correspondingly inefficiently utilized by rice. When the deep placement aspect of USG was combined with slow-release properties of SCU in the form of sulphur-coated urea supergranules (SCUSG), the performance of this product was inferior even to the divided application of urea. Undissolved or partially dissolved granules of SCUSG could be recovered even after the harvest of the crop.

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Fertilizer–use efficiency of amended urea materials in flooded rice

The Journal of Agricultural Science ◽

10.1017/s0021859600085178 ◽

1989 ◽

Vol 112 (2) ◽

pp. 277-281 ◽

Cited By ~ 2

Author(s):

H. S. Chauhan ◽

B. Mishra

Keyword(s):

N Uptake ◽

Deep Placement ◽

Fertilizer Use ◽

Urea Supergranules ◽

Neem Cake ◽

Prilled Urea ◽

Matter Production ◽

Neem Cake Coated Urea ◽

Coated Urea ◽

Use Efficiency

summaryIn a field experiment on a typic hapludoll in 1983 and 1984, deep placement of urea supergranules at 40 and 80 kg N/ha proved to be the best N source, of five tested, for grain production, but at 120 kg N/ha it was similar to neem-cake-coated urea. The results showed that deep placement of urea supergranules can save fertilizer use by 60% compared with prilled urea to obtain the same yield. Shellac-coated urea and dicyandiamide-coated urea was more effective than prilled urea in 1984. Differences in dry-matter production and grain yield were directly related to N uptake by the plants. On average, apparent recovery of applied N increased from 35% for prilled urea to 55, 52·5,46·5 and 37·5% for urea supergranules, neem-cake-coated urea, shellac-coated urea and dicyandiamide-coated urea, respectively.

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