Winter wheat

The fact that is not radioactive means that it can be used safely in experiments in the field, but it also means that much patient work is needed to obtain results. The approach is demanding in terms of time, equipment, and skilled manpower, but it has made a great contribution to the understanding of the nitrate problem. The results that are outlined here are from experiments made by staff at Rothamsted, but key contributions have also come from Scotland and France. " The majority of the Rothamsted experiments involved winter wheat, but oilseed rape, potatoes, beans, and sugar beet were also grown. The soil is a factor in nitrate leaching, and three types were used, the flinty, silty clay loam at Rothamsted, a sandy loam at Woburn in Bedfordshire and a heavy sandy clay at Saxmimdham in Suffolk. 

Figure 1 Fate of N-labelled nitrogen fertilizer applied to a winter wheat erop. (Taken from Maedonald et...

How much does Nitrogen Fertilizer Contribute to Nitrate Leaching when Winter Wheat is Growiii We saw earlier that direct nitrate losses from nitrogen fertilizer given to winter wheat are often relatively small. We saw too that... 

Although winter wheat is grown on more land than any other crop in England and Wales, it is not usually grown continuously, because of problems from pests and diseases. Break crops are grown to interrupt the build-up of these problems, so we need to look at the behaviour of nitrogen under these and other crops, but much less information is available than for winter wheat. 

Up to Harvest. Oilseed rape and field beans are used as break crops for winter wheat on a variety of soils, and potatoes are used on the lighter soils. Sugar beet may also be grown, but this depends not only on the soil but also on the proximity of a sugar beet processing factor. Four Rothamsted-based experiments compared the effectiveness of winter wheat and winter oilseed rape in their use of labelled nitrogen fertilizer. Potatoes were included in two of these experiments and sugar beet and field beans in one experiment each. Two criteria based on the... 

Table 2 Efficiency of use of nitrogen fertilizer by winter wheat, winter oilseed rape, potatoes and sugar beet.

Data of a different kind, the nitrate losses through the held drains of the Brimstone experiment,also suggest that winter oilseed rape uses nitrogen fertilizer somewhat less efficiently than does winter wheat, but this experiment did not include the other crops discussed above. 

After Flarvest. How do the memory effects shown by the other crops compare with those of winter wheat Winter wheat did not show a memory effect after one year, but oilseed rape does seem to do so. Researchers of the Agricultural Development and Advisory Service found that nitrate production by microbes in the soil after a rape crop increased with the amount of fertilizer given to the crop (R. Sylvester-Bradley, personal communication). One reason may lie in this crop s habit of shedding its leaves as harvest approaches, which means that the microbes in the soil get early access to these residues. This habit might contribute to the apparently smaller efficiency of this crop in using nitrogen fertilizer. The crop may be just as efficient as winter wheat at taking up the fertilizer but drops... 

Winterweizen, m. winter wheat, winzlg, a. minute, tiny mean, petty. 

Keim, D.L. Kronstad, W.E. (1981). Drought response of winter wheat cultivars under field stress conditions. Crop Science, 21,11-15. 

McGowan, M., Blanch, P., Gregory, P.J. Haycock, D. (1984). Water relations of winter wheat. 5. The root system and osmotic adjustment in relation to crop evaporation. Journal of Agricultural Science, Cambridge, 102, 415-25. 

Hamilton, G.A., Hunter, K., and Ritchie, A.S. et al. (1976). Poisoning of wild geese by carbo-phenothion treated winter wheat. Pesticide Science 7, 175-183. 

J. Swinnen, J. A. Van Veen, and R. Merckx, Root decay and turnover of rhizodepos-its in field-grown winter wheat and spring barley estimated by C pulse labelling. Soil Biology and Biochemistry 27 211 (1995). 

J. K. Fredrickson and L. F. Elliott, Effects on winter wheat. seedling growth by toxin-producing rhizobacteria. Plant and Soil 83 399 (1985). 

R. F. Grant, The distribution of water and nitrogen in the. soil-crop system a simulation study with validation from a winter wheat field trial. Fertil. Res. 27 199 (1991). 

M. van Noordwijk, G. Brouwer, H. Koning, F. W. Meijboom, and W. Grzebisz, Production and decay of structural root material of winter wheat and sugar beet in conventional and integrated cropping systems, Agric. Ecosyst. Environ. 51 99... 

Stable in neutral to basic aqueous solution Unstable in acidic aqueous solution Flucarbazone-sodium is a post-emergent grass herbicide for use in winter wheat and spring wheat, including... 

A sound crop rotational system is of basic importance to the organic farmer. It reduces the risk of diseases and pests associated with monoculture, gives better control of weeds, spreads the labour requirements more evenly over the year, reduces the financial risk if one crop yields or sells badly and provides more interest for the farmer. For instance, take-all is a disease that cannot even be controlled chemically. Winter crops are more susceptible to take-all than spring sown crops and wheat is more susceptible than barley, so the safest position for winter wheat is immediately after a break crop. 

Some crops can be chosen in organic rotations that control weeds through shading, such as winter wheat, if attention is paid to row... 

Wheat is a deep-rooted plant which grows well on rich and heavy soils and in the sunnier eastern and southern parts of the country. Winter wheat can withstand most of the frosty conditions of this country, but is easily killed by water-logged soil conditions. It needs a pH higher than 5.5. It is the best cereal to grow when the soil is highly fertile, so it should follow grain legumes and root crops... 

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