Natural abundance of 15N in barley as influenced by prior cropping or fallow, nitrogen fertilizer and tillage

1991 ◽  
Vol 42 (5) ◽  
pp. 723 ◽  
Author(s):  
JA Doughton ◽  
PG Saffigna ◽  
I Vallis

The 15N abundance of nitrogen was measured in barley grown with 0, 50 and 100 kg/ha of applied nitrogen after pretreatments of either fallow or grain sorghum, where sorghum stubble was either incorporated, removed or retained on the soil surface (zero-till). Barley 15N abundance was assumed to reflect that of assimilated soil mineral nitrogen. Fallowing soil prior to establishment of barley accumulated 226 kg NO3-N/ha to a depth of 120 cm and resulted in an 88% increase in 15N enrichment of nitrogen in barley compared with that grown after sorghum. 15N enrichment was assumed to be mostly the result of isotope fractionation between 14N and 15N during denitrification of the large excess of NO3-N present prior to and during the experiment. Nitrogen fertilizer additions caused 15N depletion of nitrogen in barley. However, where fertilizer additions resulted in excess availability of NO3-N, subsequent denitrification and 15N enrichment of this NO3-N partially counterbalanced the 15N depleting effect of fertilizer additions. Where soil NO3-N levels were low (<25 kg NO3-N/ha) following sorghum there were no differences in 15N abundance of nitrogen in barley between tillage treatments. With additions of nitrogen fertilizer and the availability of excess NO3-N for denitrification, differences between tillage treatments occurred with some being significant. The ranking of stubble management treatments in terms of their effect on 15N enrichment of nitrogen in barley was incorporated > removed > surface retained.

1996 ◽  
Vol 126 (1) ◽  
pp. 63-74 ◽  
Author(s):  
M. A. Shepherd ◽  
R. Sylvester-Bradley

SUMMARYSoil mineral nitrogen (Nmin) was measured to 90 cm at a total of 12 sites in the UK in the autumn after an oilseed rape experiment, which measured responses to fertilizer N. On average, Nmin, increased by 15 kg/ha per 100 kg/ha fertilizer nitrogen (N) applied to the rape, up to the economic optimum amount of N (Nmin). There were larger increases in Nmin where fertilizer applications exceeded Nopt, thus super-optimal fertilizer applications disproportionately increased the amount of nitrate likely to leach over-winter. The small effects of sub-optimal N on Nmin were associated with large increases in N offtake by the oilseed rape, whereas the larger effects of super-optimal N on Nmin were associated with only small increases in N offtake. Over 70% of the variation in autumn Nmin was explained by the previous rape's N fertilizer rate and the topsoil organic matter content.Nitrogen applied to the rape increased grain yields of the succeeding wheat crops when no further fertilizer N was applied to the wheat. It was concluded that N applied to oilseed rape significantly affected Nmin after harvest, and these effects were not completely nullified by leaching over-winter, so soil N supply to the succeeding wheat crop was significantly increased. Responses in grain yield indicated that each 100 kg/ha N applied to the rape provided N equivalent to c. 30 kg/ha for the following cereal. Each 1% of soil organic matter further contributed N to the wheat, equivalent to 25 kg/ha.It is important to ensure that oilseed rape receives no more than the optimum amount of fertilizer N if subsequent leaching is to be minimized. Reductions below optimum amounts will have only a small effect on leaching. Substantial changes in the economic optimum N for rape production should be accompanied by adjustment in fertilizer N application to following wheat crops. Fertilizer recommendation systems for wheat should take account of the fertilizer N applied to the preceding oilseed rape and the topsoil organic matter content.


1995 ◽  
Vol 43 (3) ◽  
pp. 333-345
Author(s):  
C.L.M. De Visser ◽  
W. Van Den Berg ◽  
H. Niers

To study the relationship between the amount of soil mineral nitrogen before sowing of onions (Nmin) and the optimum amount of nitrogen fertilizer (Nopt), 36 multilevel fertilizer nitrogen trials were conducted in the Netherlands between 1978 and 1982. For 26 trials Nopt was within the studied range (0-200 kg N/ha) and could be estimated using a quadratic response function. A significant linear relationship between Nopt and Nmin before sowing was only found when Nmin in the layer 0-30 cm was considered. The same 26 trials were analysed together using a quadratic and a linear exponential response function. However, with both methods the yield predicted from Nmin did not prove to be superior to a fixed nitrogen application rate of about 125 kg of nitrogen/ha. A verification pointed out that the relationship overestimated the opt. amount of fertilizer nitrogen found in 8 independent multilevel fertilizer nitrogen trials. A fixed rate of 100-125 kg of nitrogen/ha yielded better results. The possible reasons for the absence of a strong relationship between the amount of soil mineral nitrogen before sowing and the opt. amount of nitrogen fertilizer are discussed.


1993 ◽  
Vol 41 (2) ◽  
pp. 95-109
Author(s):  
W.P. Wadman ◽  
J.J. Neeteson ◽  
G.J. Wijnen

In the period of 1983-1985, 18 field experiments with potatoes grown for industrial starch production were set up in the Netherlands to investigate the effects of poultry-slurry application on tuber yield and on soil mineral nitrogen. Slurry was applied in autumn with and without the nitrification inhibitor dicyandiamide (DCD) and in spring without DCD. Control treatments without slurry or DCD were included. Various nitrogen fertilizer rates were applied to all slurry treatments. In autumn, following slurry application without DCD, slurry-derived nitrate moved to the 0.3-0.6 and 0.6-1 m soil layers. Following DCD-application, most of the slurry-derived nitrate remained in the 0-0.3 m soil layer. Maximum yields as estimated from a nitrogen fertilizer response function were slightly increased by the slurry application. Nitrogen supplied from the slurry decreased the amount of fertilizer nitrogen needed for maximum yield. Increasing the amounts of soil mineral nitrogen in June from slurry or applied inorganic nitrogen fertilizer increased residual soil mineral nitrogen at harvest.


1984 ◽  
Vol 24 (125) ◽  
pp. 244 ◽  
Author(s):  
JA Doughton ◽  
J Mackenzie

A field trial was carried out on a black earth (Waco series) at Cambooya on the Eastern Darling Downs to compare the effect of black gram, green gram, grain sorghum and a summer fallow on soil mineral nitrogen (NO3-N + NH4-N) and the yield of grain sorghum grown in the following summer. The initial sorghum treatment severely depleted soil mineral nitrogen to 120 cm; even after a 173-d fallow, there was still 34 kg/ha less nitrogen present than initially in this treatment. Black and green gram also reduced levels of soil mineral nitrogen during crop growth, but these recovered to exceed pre-trial levels by 29 and 42 kg N/ha, respectively, after a winter fallow. The fallow treatment accumulated 100 kg N/ha of mineral nitrogen between January and October, but mineralization was markedly reduced from August to October. Sorghum grown on all plots in the second summer responded markedly to prior treatments, and grain yields and responses to nitrogen applied at 0, 34 and 68 kg N/ha reflected mineral nitrogen levels at planting. Yields of sorghum grain obtained without fertilizer after black gram, green gram and fallow were 8333, 7477 and 9663 kg/ha, respectively, compared with 4658 kg/ha after sorghum. Prior crops of both grams increased sorghum yield as much as a fertilizer application of 68 kg N/ha.


Geoderma ◽  
2018 ◽  
Vol 326 ◽  
pp. 9-21 ◽  
Author(s):  
Masuda Akter ◽  
Heleen Deroo ◽  
Eddy De Grave ◽  
Toon Van Alboom ◽  
Mohammed Abdul Kader ◽  
...  

1999 ◽  
Vol 50 (2) ◽  
pp. 115-125 ◽  
Author(s):  
Maria Stenberg ◽  
Helena Aronsson ◽  
Börje Lindén ◽  
Tomas Rydberg ◽  
Arne Gustafson

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