The fertiliser nitrogen requirement of cereals grown on sandy soils

Autor: J. Webb, Frances M. Seeney, Roger Sylvester-Bradley
Rok vydání: 2000
Předmět:
Zdroj: Journal of the Science of Food and Agriculture. 80:263-274
ISSN: 1097-0010
0022-5142
DOI: 10.1002/(sici)1097-0010(20000115)80:2<263::aid-jsfa530>3.0.co;2-c
Popis: The responses to fertiliser-N of winter wheat and winter barley grown on sandy soils were measured in 72 experiments in England from 1990 to 1994. Yield without fertiliser-N (Y(0)) was c 1.1 t ha-1 greater following root crops than following cereals. Following potato crops given organic manures, Y(0) was c 1.2 t ha-1 greater than following unmanured potato crops, but Y(0) was no greater following sugarbeet to which organic manures had been applied. Only after the two driest winters was there sufficient variation in soil N supply in spring (SNS(s)) for this to show a relationship with Y(0). However, Y(0) increased with increasing N mineralisation during the growing season (AM) in the three years it was measured. There was no consistent effect of sowing date on Y(0). Following potatoes, yield at optimum fertiliser-N (Y(opt)) decreased as sowing date was delayed, but this was not so after cereals, sugarbeet or overall. There was no increase in Y(opt) with SNS(s) or AM, but Y(opt) decreased with increasing moisture stress (S) in June. The mean yield response to N(opt) (delta Y) was c 0.4 and 0.8 t ha-1 smaller following potatoes and sugarbeet respectively than following cereals, but not consistently so as there were large interactions between site, year and previous crop. Following root crops, delta Y was c 0.6 and 1.4 tha-1 less after sugarbeet and potatoes respectively that had been given organic manures. Without the addition of organic manures, delta Y following potatoes was similar to that following cereals. Regression on SNS(s) and AM accounted for 28 and 15% respectively of the variance in delta Y. The optimum economic fertiliser-N application (N(opt)) was similar, at c 140 kg ha-1, following cereals and potatoes. Following sugarbeet, cereal N(opt) was only c 110 kg ha-1. The differences according to previous crop reported here are consistent with mineralisation of crop residues on sandy soils being more rapid than on other soils; the potato residues were rapidly mineralised in autumn and lost by leaching over winter. Residues from later-harvested sugarbeet were mineralised during the growing season of the subsequent cereal crop. Fertiliser-N requirements were, at c 110-140 kg ha-1, smaller than has been found on other soil types, and less than current recommendations for wheat. Requirements were significantly reduced in years of drought stress. No differences were found in N(opt) between wheat and barley. These data do not justify the current advice to invariably reduce fertiliser-N to cereals following potatoes by 20-25 kg ha-1 on these sandy soils. On average a reduction of c 20 kg ha-1 could be made following sugarbeet, with a further reduction of c 40 kg ha-1 N if manures had been applied to the previous sugarbeet crop. A reduction of 40 kg ha-1 N could also be made where cereals followed a potato crop to which manures had been applied. Further refinements on the basis of measurements of soil mineral N could not be justified. Seasonal variation in N response due to drought stress makes recommendations difficult on these soils. Adopting the fertiliser-N recommendations proposed here would produce N surpluses to the soil of c 37, 10 and 27 kg ha-1 respectively following cereals, sugarbeet and potatoes when cereal grain is removed but straw incorporated. On farms where straw is removed, N surplus would be largely eliminated. Our recommendation that no reduction in fertiliser-N application to cereal crops grown on sandy soils should be made following potatoes will not increase fertiliser-N use and is not expected to increase nitrate leaching. Some reduction in nitrate leaching may be achieved if recommendations following cereal crops and sugarbeet are made in accordance with the results reported here.
Databáze: OpenAIRE
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