Urea as a fertilizer Laboratory and pot-culture studies

Low, A. J.; Piper, F. J.

doi:10.1017/s0021859600047730

Cited by 32 publications

(7 citation statements)

References 6 publications

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“…This was explained by Olcuda and Takahashl (1959), Low andPiper (1961), andCooke (1962), who showed that the rapid ammonium accumulation and rise in pH resulting from the hydrolysis of urea in soils cause damage to vegetative material. This problem can be reduced by drilling fertilizer urea to the side of seeds or young plants (Widdowson and Penny, 1963), but, as Cooke (1964) has pointed out, this method of reducing damage to vegetative material by fertilizer urea is not applicable when urea is used for the purposes for which its high nitrogen content and ease of handling make it so suitable, namely side-dressing of row crops and top-dressing of cereals and pastures.…”

Section: Chapter II Literature Review Urea As a Nitrogen Fertilizermentioning

confidence: 98%

Inhibition of urease activity in soils

Bremner

Douglas

1971

Soil Biology and Biochemistry

230

137

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Section: Chapter II Literature Review Urea As a Nitrogen Fertilizermentioning

confidence: 98%

Inhibition of urease activity in soils

Bremner

Douglas

1971

Soil Biology and Biochemistry

230

137

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“…Where urea is broadcast over plants in pots there is a loss of nitrogen (Low & Piper, 1961) and one would expect, if the urea was acting as an N source for the clover, that the dry matter production might be greater where the urea was applied 12-5-15 cm below the soil surface. The yield was higher in seven of nine cuts though the difference in total was not quite significant (P = 0-05).…”

Section: Discussionmentioning

confidence: 99%

The effect of nitrogenous fertilizers on white clover

Low¹,

Armitage²

1970

J. Agric. Sci.

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The comparative effects of very heavy dressings of ammonium sulphate and urea on the growth of established plants of white clover (S100) have been studied in pot culture. Five applications each of 26.3 kg N/ha were applied over 9 months in 3 different ways (i) direct contact of the fertilizers with the leaves, (ii) only with the stolons or surface roots or (iii) applied 12-5 cm below the soil surface.The ammonium sulphate broadcast over the leaves reduced the growth of the clover whilst urea under the same conditions caused temporary damage with very little reduction in dry weight compared with the control. When the ammonium sulphate was applied to the soil surface or 12-5 cm below, there was appreciable reduction in dry weight but less than when the fertilizer was in contact with the leaves. Under the same conditions, urea did not reduce growth.The pH of the soil fell to about 4-6 with ammonium sulphate (control 6-1) but only slightly with urea.Root development was not affected by urea but greatly reduced with ammonium sulphate. With both fertilizers the root nodules were very pale in colour and few in number compared with the control. xTyrrpT}/-)•nTTpT'TO'Nr a n n u m as a m m o n i u m nitrate (15-5% N ' N i t r ochalk') to plots of pure white clover and found little When nitrogen fertilizers are applied to grass-effect on yield although there were indications of a clover swards, the proportion of clover tends to depression at the highest rate. The fertilizers were fall. Clovers may bo able to obtain all the nitrogen applied twice in the year with 2 cuts between they require for maximum growth from the air so applications. that applying a nitrogen fertilizer may have noIn small grass-clover field plots at Jealott's Hill effect. The grasses on the other hand depend on where the effect of ammonium sulphate, amrnon-'available nitrogen' in the soil: the greater the mm nitrate and urea applied in solution to the amount the more vigorous their growth (although plants was studied, there was least reduction in the there is an upper limit) and the greater the competi-proportion of white clover where urea was used, tion with the clovers growing with them for light, Though each treatment 'scorched' the leaves, urea space, water etc. particularly as grasses in general did so least. As there were equal weights of nitrogen are considerably taller than for example white in equal volumes of solution, the osmotic pressure clover. Some consider this competition sufficient to of the urea solution was about 33 % that of the account for the virtual disappearance of white ammonium sulphate and about 50% that of the clover with high rates of N fertilizer. There are, ammonium nitrate: consequently as plasmolysis however, some indications in the literature (Heddle, would be least with the urea one might expect the 1966) that in part at least the suppression of the smallest damage. clover may be a direct effect of the applied nitrogen.Damage to clover plants by nitrogenous fertiAs fertilizer N depresses nodulation of clover, lizers may...

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“…A consideration of all the available data from the field experiments permits several tendencies, some of which are considered in the related paper by Low & Piper (1961) to be listed:…”

Section: Discussionmentioning

confidence: 99%

Urea as a fertilizer

Templeman¹

1961

J. Agric. Sci.

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The results of the grassland experiments show that as a straight nitrogen fertilizer urea was, on average, slightly less effective than the conventional materials. In the majority of individual experiments there was no significant difference between the yields from urea and those from ‘Nitro-Chalk’; on the other hand, in a very few experiments the urea yields were much lower. The arithmetic means of the averages in each series of grassland experiments indicate that urea gave total yields about 93% of those from ‘Nitro-Chalk’ and the average response (i.e. difference from control) from urea was about 85% of that from ‘Nitro-Chalk’.The available data for cereals are considerably less than for grassland but here again there is an indication of the infrequent slightly lower efficiency of urea.On kale the results are confusing. At times urea was safe but in one experiment heavy dressings incorporated in the seed-bed caused serious damage.

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Urea as a fertilizer Laboratory and pot-culture studies

Cited by 32 publications

References 6 publications

Inhibition of urease activity in soils

Inhibition of urease activity in soils

The effect of nitrogenous fertilizers on white clover

Urea as a fertilizer

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