Effects of nitrogen applied through new carriers on yield and quality of sugarcane

SUMMARYIn a field experiment at Lucknow in 1985/87 and 1986/88, the ‘new’ N carriers urea super granules (USG), neem-cake-coated urea (NCU) and dicyandiamide-treated urea (DCD) and the traditional source of N, prilled urea (PU), were used to supply 150 kgN/ha to the plant crop (first crop after planting) of the cultivar Col 148. The ratoon crop was fertilized at 0 and 150 kgN/ha with PU over all the plant crop treatments. In both plant and ratoon crops, N application increased cane yields but decreased quality: differences in yield resulting from use of the new carriers were not significant, though the fertilizers tended to increase the final plant population density. Uptake and recovery of N were significantly greater using USG, NCU and DCD than using PU. The direct effect of N was 184 kg cane/kg of N applied to the ratoon crop but residual and cumulative effects of N applied to the plant crop on yield and quality of the ratoon crop were small. Adequate direct application of N is therefore suggested for increasing the yields of ratoon cane.

Effect of Coated and Uncoated Urea on the Carry-over of Nitrogen from Jute to Paddy Rice in the Humid Sub-tropics

SUMMARYPaddy rice was grown without fertilizer after jute which had been supplied with nitrogen as neem cake coated urea (NCU), wax coated urea (WCU), ammonium sulphate or standard urea at rates of 0, 40, 80 or 120 kg N ha−1. NCU or WCU applied to jute increased the dry matter and grain yield of the rice, suggesting that enough nitrogen is left behind to grow a subsequent rice crop without further fertilizer application.

Fertilizer–use efficiency of amended urea materials in flooded rice

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.

Minimizing volatilization and leaching losses of nitrogen by different nitrogen carriers in Japanese mint (Mentha arvensisL.)

Japanese mint, an important essential-oil-bearing crop, is cultivated for menthol used in cosmetic and pharmaceutical industries. It requires a high level of nitrogen fertilizer, between 150 and 250 kg N/ha depending on the agro-climatic conditions (Ghosh & Chatterjee, 1976; Yadav, Mohan & Ram, 1983). During the crop cycle (January–August), frequent irrigations and high intensive rains result in poor N recovery especially on light-textured soils. With a view to reduce losses of N and improve N recoveries, the relative efficiency of neem-cake-coated urea, laccoated urea and urea supergranules has been investigated in comparison with prilled urea in Japanese mint.

Studies on the nitrification inhibitor, dicyandiamide (DCD), for increasing the efficiency of nitrogen applied to rice

SummaryA field experiment, made during the rainy seasons oof 1982 and 1983 at the Indian Agricultural Research Institute, New Delhi, studied the effects of blending urea with dicyandiamide (DCD) on the yield and yield components of rice. DCD-blended urea was as effective as neem-cake-coated urea in respect of yield components as well as grain and straw yield of rice and when all the nitrogen was applied 10 days after transplanting both the materials produced significantly more grain and straw than prilled urea. Urea super granules (USG) were superior to DCD-blended, as well as neem-coated, urea.

Coated and Uncoated Urea in Ramie Leaf Production

SUMMARYRamie (Boehmeria nivea Gaud.), which can provide fodder in addition to bast fibre, was supplied with nitrogen in three different forms: as neem cake coated urea (NCU), lac coated urea (LCU) and standard urea, at rates of 60, 120, 180, 240 and 300 kg N ha−1 annually in four equal applications. The ramie was cut four times a year for two years. NCU increased fresh weight, leaf dry matter yield and leaf protein at almost every cutting compared with the other forms of nitrogen, and there was an indication of increased residual nitrogen in the soil. Leaf dry matter and protein content increased with increasing levels of nitrogen up to 180 kg ha−1. It is suggested that coating urea with neem cake makes it a better source of nitrogen for ramie leaf production.