Relation between soil mineral nitrogen before sowing and optimum nitrogen fertilization in onions

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.

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NITROGEN FERTILIZER REQUIREMENTS OF FRUIT TREES AS RELATED TO SOIL MINERAL NITROGEN CONTENT IN SPRING

Mineral Nutrition of Fruit Trees ◽

10.1016/b978-0-408-10662-7.50067-3 ◽

1980 ◽

pp. 353 ◽

Cited By ~ 1

Author(s):

J. WEHRMANN ◽

H.C. SCHARPF

Keyword(s):

Nitrogen Content ◽

Nitrogen Fertilizer ◽

Fruit Trees ◽

Mineral Nitrogen ◽

Soil Mineral ◽

Soil Mineral Nitrogen

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Effect of nitrogen fertilizer applied to winter oilseed rape (Brassica napus) on soil mineral nitrogen after harvest and on the response of a succeeding crop of winter wheat to nitrogen fertilizer

The Journal of Agricultural Science ◽

10.1017/s002185960008881x ◽

1996 ◽

Vol 126 (1) ◽

pp. 63-74 ◽

Cited By ~ 36

Author(s):

M. A. Shepherd ◽

R. Sylvester-Bradley

Keyword(s):

Organic Matter ◽

Oilseed Rape ◽

Nitrogen Fertilizer ◽

Organic Matter Content ◽

Matter Content ◽

Mineral Nitrogen ◽

Fertilizer N ◽

Soil Mineral ◽

Soil Mineral Nitrogen ◽

Optimum Amount

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.

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Measurement of soil mineral nitrogen to predict the response of winter wheat to fertilizer nitrogen after applications of organic manures or after ploughed-out grass

The Journal of Agricultural Science ◽

10.1017/s0021859600077091 ◽

1993 ◽

Vol 121 (2) ◽

pp. 223-231 ◽

Cited By ~ 25

Author(s):

M. A. Shepherd

Keyword(s):

Winter Wheat ◽

Inorganic Nitrogen ◽

Poultry Manure ◽

Mineral Nitrogen ◽

Simple Relationship ◽

Pig Slurry ◽

Soil Mineral ◽

Soil Mineral Nitrogen ◽

Available N ◽

The Relationship

SUMMARYIn the autumns of 1985, 1986 and 1987, a total of 84 fields in England and Wales, which had received a recent dressing of organic manure or had recently been ploughed out of grass, was sampled to 90 cm depth to measure soil mineral nitrogen (Nmin i.e. NH4-N and N03-N). Amounts of Nmin varied widely between sites, indicating the difficulty in estimating soil supply following ploughing grass or manure application although type of manure and Nmin were related. Soils contained much inorganic nitrogen where manures containing a large proportion of readily available N (pig slurry or poultry manure) had been applied. Where manures containing straw were applied, Nmin was greater in the second year after application than the first. The relationship between Nmin and response of winter wheat to fertilizer was measured on 62 of the 84 sites sampled; there was no simple relationship between N min and response to N. For fields just ploughed out of grass, the relationship was particularly poor. However, for fields with a history of arable cropping, there was no response to N fertilizer when Nmin was > 300 kg/ha N in either autumn or spring. Below this amount, response to fertilizer N varied considerably even for sites with similar amounts of Nmin. Nmin measurements are of value in identifying soils containing sufficiently large N residues to allow fertilizer applications to be reduced, or even omitted, with confidence. Where residues are smaller, models need to be developed which take into account other factors, such as mineralization of organic nitrogen reserves, which modify nitrogen supply.

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Field experiments with slurry and dicyandiamide: response of potatoes and effects on soil mineral nitrogen

Netherlands Journal of Agricultural Science ◽

10.18174/njas.v41i2.625 ◽

1993 ◽

Vol 41 (2) ◽

pp. 95-109

Author(s):

W.P. Wadman ◽

J.J. Neeteson ◽

G.J. Wijnen

Keyword(s):

Nitrogen Fertilizer ◽

Field Experiments ◽

Inorganic Nitrogen ◽

Maximum Yield ◽

Soil Layer ◽

Nitrification Inhibitor ◽

Mineral Nitrogen ◽

Residual Soil ◽

Soil Mineral ◽

Soil Mineral Nitrogen

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.

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