Nitrogen Fertilisation and its Interaction with other Cultural Measures: Experience in the Federal Republic of Germany.
Summary:
Increased usage of nitrogen (N) fertilizer has made an important contribution to the increase in yields which has been seen over the past 25 years. Results of experiments to measure the effect of N fertilizer on yield and yield components as related to other factors including soil N supply, plant population, organic manuring supply of other macro- and micro-nutrients, cultivations, the use of growth regulators and plant protection measures are discussed and conclusions drawn on the importance of adjusting the N fertilizer regime in accordance with local conditions and farming methods.
H Sturm and H Effland, Limburgerhof Agricultural Research Station, BASF Aktiengesellschaft, Ludwigshafen, Germany.
27 Pages, 13 Figures, 3 Tables, 9 References.
Nitrogen Fertilisation and Methods of Predicting the Nitrogen Requirements of Winter Wheat in the Federal Republic of Germany.
Summary:
Various systems which have been proposed for the growing of high yields of winter wheat are briefly described, all of which involve prediction of the nitrogen (N) fertilizer requirement, whether from soil and/or plant analysis or by other means. The results of field trials comparing such methods are discussed and the conclusion is reached that any of the methods improve the chances of arriving at the correct N fertilizer treatment for any site. As might he expected from the shape of response curve there are only small differences in yield between the various systems. Mineralization of soil nitrogen is limited during the tillering period so that the greatest importance attaches to prediction of the rate of N to be applied in the early spring dressing, and, for this, the N-min method is efficacious. Predictions are improved when preceding crop and soil fertility are taken into account.
F A Becker and W Aufhammer.
34 Pages, 5 Figures, 9 Tables, 22 References.
The Use of Nitrogen Fertilizers in Intensive Wheat-growing in France'
Summary:
For many years, rates of application of nitrogen (N) fertilizer were decided pragmatically by modifying standard recommendations for each region. However, for the past ten years I.N.R.A. and I.T.C.F. have proposed a system designed to calculate the crop's nitrogen requirement to suit individual field conditions more precisely. The system is based on estimation of nitrogen balance in the soil and adjustment of N fertilizer rate accordingly. Despite difficulties encountered in application of the method, its use is increasing rapidly. While the system can be applied to any cropping system it is particularly well suited to intensive cultivation.
J C Remy, INRA, France.
Ph Viaux, ITCF, France.
26 Pages, 12 Figures, 8 tables, 22 References.
Intensive Wheat Production as Related to Nitrogen Fertilisation, Crop Protection and Soil Nitrogen: Experience in the Benelux.
Summary:
Improvement in growing techniques over the past ten years has greatly increased the yield of winter wheat. The effects on grain yield of methods of applying nitrogen, the use of growth regulators and crop protection measures are discussed. Special attention has been paid to methods to assess the need for fertilizer nitrogen based on the determination of mineral soil nitrogen, inclusive of their possibilities and limitations.
In Belgium and the Netherlands at least 18,000-20,000 grains per m2 are required to obtain yields of 10 tonnes per ha. This can be achieved with 200-250 plants producing 500-600 ears per m2.
Though high input systems consistently give the highest grain yields, the financial returns appear to be hardly competitive with those of the so-called recommended systems. Flexible systems, adapted to the actual crop situation, are preferred to 'blueprints' or similar rigid systems. To enable the best use of cultural practices, simulation techniques as to the behaviour of soil nitrogen and the outbreak of fungal diseases and pests, like EPIPRE in the Netherlands will be indispensable. Meanwhile, to fill the gap between general and individual recommendations and to integrate the farmers' experience, the use of so-called reference plots, including rates of fertilizer nitrogen, conducted by local advisors or farmer groups, can be of great help.
K Dilz, Institute for Soil Fertility, Haren, The Netherlands.
A Darwinkel, Research Station for Arable Farming and Field Production of Vegetables, Lelystad, The Netherlands.
R Boon, Soils Service of Belgium, Heverlee-Leuven, Belgium.
L M J Verstraeten, Catholic University of Leuven, Faculty of Agricultural Sciences, Heverlee-Leuven, Belgium.
32 Pages, 10 Figures, 13 Tables, 34 References.
The Role of Nitrogen in Wheat Production: Response, Interaction and Prediction of Nitrogen Requirements in the UK.
Summary:
Winter wheat is now the most important arable crop in the UK, and increased use of fertilizer nitrogen (N) has played a large part in achieving the current high yield levels.
The development and form of Agricultural Development and Advisory Service, Ministry of Agriculture Fisheries and Food nitrogen recommendations is described. Interactions possibly influencing response to N, the use of soil and plant analysis as response predictors, and effects of timing of N are reviewed.
The replacement of the present empirical methods of predicting nitrogen requirements by more precise mathematical methods is dependent upon an adequate experimental basis for the development and testing of new systems of predictions.
P Needham, Agricultural Development and Advisory Service (ADAS), London, UK.
23 Pages, 20 References.
Maximising Wheat Yields, and Some Causes of Yield Variation.
Conclusions:
There can be no one single answer to the question of why yields vary. Our tentative conclusion is that the highest yields are built up by getting a whole series of decisions on rates and timing correct. The experimental sites have until the present deliberately been sited to avoid fields where root disease could be expected, but work on this is developing. It is already clear that very consistent responses to foliar pathogen sprays are obtained, and this seems an essential component of any drive for high yields. The part played by water stress is as yet uncertain, though recent evidence suggests it is of rather little importance in normal years on medium and heavy textured soils. The exact control of nitrogen is important, and the complex processes involved require the development of reliable monitoring methods. Whilst we do not yet have evidence that any normal soils will not give these very high yields, the range of acceptable treatments is much narrower on some soils than others. Where a number of decisions are all quite critical, the chance of getting them all right becomes very small.
P B Tinker and F V Widdowson, Rothamsted Experimental Station, Harpenden, Hertfordshire, UK.
36 Pages, 6 Figures, 12 Tables, 47 References
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