Environmental effects on the short-term response of tropical grasses to nitrogen fertilizer

1975 ◽  
Vol 15 (76) ◽  
pp. 679 ◽  
Author(s):  
GJ Murtagh
Keyword(s):  
Ammonium Nitrate ◽  
Nitrogen Fertilizer ◽  
Dry Matter ◽  
Limited Growth ◽  
Short Term ◽  
Tropical Grasses ◽  
Run Off ◽  
Moisture Supply ◽  
Moisture Potential ◽  
Term Response

The short term response of tropical grasses during spring to ammonium nitrate and urea fertilizers (1 12 kg N ha -1) was measured on kikuyu (Pennisetum clandestinum) at one site, and on setaria (Setaria anceps cv. Kazungula) at two sites. Fertilizers were applied at weekly intervals on 16 occasions at each site during the August-December period. Treatments were assessed in terms of the dry matter response (DMR) and apparent recovery of fertilizer nitrogen (NR), where DMR is the differences in dry matter yield of topdressed plots over the control and NR is the corresponding difference in nitrogen yield expressed as a percentage of the amount of nitrogen applied as fertilizer. These responses were measured at four, and sometimes at eight weeks, and were related to environmental variables by regression analysis. The DMR was more responsive than NR to changes in temperature. Both DMR and NR were very sensitive to changes in soil moisture potential, especially on wet soils, and to changes in effective rainfall (rainfall less run-off). If low temperature limited growth during the first four weeks after topdressing, both DMR and NR increased further when growth during 5-8 weeks extended into warmer periods. However, when moisture supply limited the response at four weeks, the NR remained depressed at eight weeks even with an improved moisture supply. Environmental factors influenced the response more than the type of nitrogen fertilizer and at four weeks, the respective overall DMR and NR from urea were 90 and 86 per cent of those from ammonium nitrate.

Urea as a nitrogen fertilizer for grass cut for silage

1992 ◽  
Vol 119 (3) ◽  
pp. 373-381 ◽  
Author(s):  
A. Lloyd
Keyword(s):  
Ammonium Nitrate ◽  
Nitrogen Fertilizer ◽  
Dry Matter ◽  
Ammonia Volatilization ◽  
Fertilizer Application ◽  
Early Spring ◽  
England And Wales ◽  
High Ph ◽  
Yield Decrease

SUMMARYForty-one experiments were carried out in England and Wales between 1983 and 1985 to compare ammonium nitrate and urea as N top dressings for multicut silage.The results showed that relative dry matter yields from the two fertilizers differed considerably between sites. However, compared with ammonium nitrate, there was a mean yield decrease with urea of 2% at the first cut and 5% at the second cut. Mean herbage N contents and apparent N recoveries were lower with urea than with ammonium nitrate at both the first and second cuts. It appeared, at least for first-cut dressings applied in early spring, that urea effectiveness increased with the amount of rain falling within 3 days of fertilizer application. The effect was much less obvious at the second cut.Urea effectiveness was not markedly reduced on soils of high pH or light texture, where higher ammonia volatilization losses might have been expected.

Field experiments comparing ammonium nitrate, ammonium sulphate and urea applied repetitively to grassland

1963 ◽  
Vol 60 (3) ◽  
pp. 297-304 ◽  
Author(s):  
J. R. Devine ◽  
M. R. J. Holmes
Keyword(s):  
Ammonium Nitrate ◽  
Ammonium Sulphate ◽  
Nitrogen Fertilizer ◽  
Dry Matter ◽  
Field Experiments ◽  
Total Yield ◽  
Calcareous Soils ◽  
Absorption Potential ◽  
Ammonia Absorption ◽  
Applied Nitrogen

1. Ten experiments were carried out on grassland in various parts of England and Scotland to compare ammonium nitrate, ammonium sulphate, urea with less than 1% biuret and urea with about 4% biuret. The grass was cut a number of times during the season and each nitrogen fertilizer was applied at rates supplying 30 and 60 lb. per acre of nitrogen in spring and after each cut except the last.2. Total yield and yields at most individual cuts of both dry matter and nitrogen in the herbage were increased by each increment of applied nitrogen.3. Ammonium nitrate and ammonium sulphate gave similar dry-matter yields at all cuts in six experiments, while in four on calcareous soils ammonium sulphate gave lower yields than ammonium nitrate at one or more cuts. Ammonium sulphate gave lower yields at the second or third cuts in more experiments than at the first cut.4. Urea with < 1% biuret gave lower dry-matter yields than ammonium nitrate at one or more cuts in eight of the ten experiments. Urea became less efficient relative to ammonium nitrate as the season advanced.5. The efficiency of urea with < 1% biuret relative to ammonium nitrate in each experiment was positively correlated with the ammonia absorption potential of the soil.6. Urea with < 1% biuret and urea with about 4% biuret gave similar yields.

YIELD AND COMPOSITION OF BROMEGRASS-ALFALFA AS AFFECTED BY AMMONIUM NITRATE AND AMMONIUM PHOSPHATE FERTILIZERS

1983 ◽  
Vol 63 (1) ◽  
pp. 169-172
Author(s):  
N. W. HOLT
Keyword(s):  
Ammonium Nitrate ◽  
Nitrogen Fertilizer ◽  
Dry Matter ◽  
Ammonium Phosphate ◽  
Dry Matter Yield ◽  
Monoammonium Phosphate ◽  
Phosphate Fertilizers ◽  
Total Uptake ◽  
Soil Zone ◽  
Fertilizer Rates

Nitrogen (N) fertilizer at rates to 44 kg/ha increased the dry matter yield of bromegrass-alfalfa at all levels of monoammonium phosphate application. Nitrogen fertilizer increased the yield of the grass and decreased the yield of alfalfa. As a result, N content of the forage was generally decreased while total uptake of nitrogen was increased with fertilizer. Rates of N to 22 kg∙ha−1∙yr−1 did not result in an accumulation of NO3–N in the 0- to 30-cm soil zone while higher rates only marginally increased soil NO3–N.Key words: Bromegrass, alfalfa, fertilizer

Unfolding the case of returnees: How the European Union and its member States are addressing the return of foreign fighters and their families

2021 ◽  
pp. 1-23
Author(s):  
Carlota Rigotti ◽  
Júlia Zomignani Barboza
Keyword(s):  
European Union ◽  
Perceived Threat ◽  
The European Union ◽  
Security Threat ◽  
Short Term ◽  
Member States ◽  
Foreign Fighters ◽  
Term Response

Abstract The return of foreign fighters and their families to the European Union has mostly been considered a security threat by member States, which consequently adopt repressive measures aimed at providing an immediate, short-term response to this perceived threat. In addition to this strong-arm approach, reintegration strategies have also been used to prevent returnees from falling back into terrorism and to break down barriers of hostility between citizens in the long term. Amidst these different strategies, this paper seeks to identify which methods are most desirable for handling returnees.

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